f-lBRARY 2 The Bronch AND D 1 ULMONAKY 3 1.001) bSSliLh i vaMMmMoaHMMaMMi -^■c*3s^^='"aaa»"--' THE GIFT OF JyJ jJULLox^i/i^ %<\yyrc v\X ::::::::;:::: : i .Aa.v,)...i..jc.1-3L... ::......: 'Ir.O.J.S/A'/.... 7673-1 Cornell University Library QL 835.E94 3 1924 024 786 364 <.nn,c«.i ^•^ Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924024786364 THE BRONCHI AND PULMONARY BLOOD-VESSELS EALLANTVNE, HANSON AND CO. LONDON AND EDINBURGH THE BRONCHI AND PULMONARY BLOOD-VESSELS: THEIR ANATOMY AND NOMENCLATURE; WITH A CRITICISM OF PROFESSOR ^EBVS VIEWS ON THE I BRONCHIAL TREE OF MAMMALIA AND OF MAN. BY WILLIAM ^WART, M.D. Cantab., F.R.C.P. Lond.. PHYSICIAN TO ST. GEORGE'S HOSPITAL; PHYSICIAN TO THE BELGRAVE HOSPITAL FOR CHILDREN LATE ASSISTANT-PHYSICIAN AND PATHOLOGIST TO THE BROMPTON HOSPITAL FOR CONSUMPTION AND DISEASES OF THE CHEST. LONDON : BAILLIERE, TINDALL, & COX, 20-21 KING WILLIAM STREET. STRAND. \All rights reserved.] 3 PREFACE These pages have a general purpose which extends beyond the limits announced in their title. They represent an attempt to remove the too prevalent impression that the field of pulmonary investigation, having yielded all its fruit, is henceforth likely to remain barren. Although advised, not long ago, by an eminent physician, to turn my attention to some other organ less " worked out " than the lung, I have found no reason to complain of my subject, and I may even succeed in showing that, so far from this being an exhausted territory, there remain within it some districts almost unexplored. The investigations set forth in this volume were long retarded in their progress by accidental circumstances and by inherent difficulties. The fact that they were opportune and in some respects indispensable, first impressed itself upon me in the course of a pathological research preparatory to the " Gulstonian Lectures on Pulmonary Cavities," delivered before the Eoyal College of Physicians, in 1 8 8 3 . At an early stage of that preparation I had become conscious that an anatomical inquiry should have preceded rather than followed the study of Pulmonary Cavities. I had also realized that the task should be approached in a spirit of completeness. This conviction is answerable for much delay, and may be thought a reasonable excuse for the perhaps excessive attention awarded to many details apparently devoid of practical interest. Moreover, a suspicion had arisen in my mind that the present deficiencies in our anatomical knowledge (some part of which it will be my endeavour to fill) might perhaps be held responsible for the halting and spasmodic feature vi PKEFACE. in the development of Pulmonary Surgery, contrasting with the steady progress made in the surgery of other organs. The detriment suffered by Medicine from the imperfection of the anatomical data, with which phy- sicians and surgeons alike have been content to work, may have been less obvious, thanks to a certain vagueness inseparable from all branches oi purely medical knowledge ; but it will probably be shown to have been neither less serious nor less extensive. The valuable and suggestive book of Professor Aeby, a solitary worker in this field, came into my hands at a comparatively late stage of the inves- tigation. Any fertilizing influence which it may have exerted upon my own thoughts I gratefully acknowledge ; but, above all, I am indebted to Pro- fessor Aeby for having rendered inevitable a completeness even greater than was at first intended. Against an authority so eminent, and teachings which had already met with such wide acceptance, any incomplete array of facts would have been marshalled in vain. Although on questions relating to comparative anatomy I am ill prepared to speak, those of Professor Aeby's views which fall within the range of human anatomy may be criticized from a position which, I believe, is now adequately guarded. Theoretical matter has largely encroached upon the following pages in connection with that criticism ; and in itself the work, although exclusively devoted to anatomical facts, cannot claim to be practical in the strict sense of the word. It may nevertheless indicate the path which will lead to practical results. Clinical utility was its original motive, and if it should at least succeed in stimulating a search for the practical appli- cation of an improved knowledge of the bronchi and of the pulmonary blood-vessels, neither the motive nor the performance will need further justification. I am grateful to Dr. Sheridan Delepine for having given me the benefit of some of his own experience and results in similar studies. Dr. Delepine's researches on dichotomy, on the alternation in the mode of origin of air- tubes, and on recurrent bronchi not only possess the merit of absolute priority : they have directed and greatly helped my observations on these PREFACE. Vll points ; and, in the main, his results have been fully confirmed by my investigations. To my brother, Dr. Charles Ewart, I am indebted for much assistance in the revision of the proofs, and for other valuable help. I also welcome this long-desired opportunity for gratefully acknow- ledging the cheerful and inspiring friendship of my former colleagues at the Brompton Hospital, and for expressing my special obligation to Dr. Pollock (then Senior Physician, now Consulting Physician), and to Dr. Eeginald Thompson, my predecessor in the ofBce of Pathologist; for much encouragement in pathological study, and for personal kindnesses, without which this contribution to the Anatomy of the Chest might not have become possible. 33 OtTEZON Stebet, Mayfaie, Nmemher i, 1888. POSTSCEIPT. On reaching Switzerland, after sending this book to press, I learned, with deep regret, from Dr. Euedi that Professor Aeby died on July 7, 1885, mourned by numerous friends and colleagues in scientific research. The hope that the following pages would have called forth correcting remarks from that great authority whose views they have ventured to criticize, is now at an end. Had I received the sad intelligence before leaving England, I should have made some verbal alterations in the text, which are now impossible, and it only remains for me to sorrowfully inscribe to the memory of Professor Aeby a work which has been written with the highest regard for his talent and scientific achievements. H&TBL BUOL, DAVOS-PLATZ, January 28, 1889. CONTENTS. PAGE Intkoduction : The Scope and Division op the Wobk . . . . i SECTION I. PRESENT KNOWLEDGE OF THE ANATOMY OF THE LUNG AND OF THE BRONCHI.— PROFESSOR AEBY'S RESEARCHES ON THE BRONCHIAL TREE.— CRITICISM OF PROFESSOR AEBY'S THEORIES ... 6 Summary op Pbbsbnt Knowledge concbeninu the Anatomy op the Lung . . 9 Bough Sketcli of the External Shape and Relations of the Lungs .... 9 General Internal Structure 'ii The Pulmonary Lobule .12 The Alveoli 14 The Pulmonary Blood-vessels : the Pulmonary Artery ; the Pulmonary Veins . . 16 The Lymphatics of the Lung .... 18 The Nerve-supply to the Lungs .... 19 SuMMAEY op Present Knowledge concerning the Bronchi and their Vascular AND Nerve-supply 21 ■ Arrangement and Structure of Bronchi . . .21 The Bronchial Blood-vessels .... 23 Nerve-supply to the Bronchi ... ... .24 Analysis op Professor Aeby's Work " On the Bronchial Tree " ... 25 Professor Aeby's Facts . . 26 Professor Aeby's Theories . . . 28 Criticism op Peopbssob Aeby's Views ... 29 Professor Aeby's First Theory : the Bronchial Stem viewed as an Axial Structure . 29 Professor Aeby's Second Theory : Monopodio Branching in the Bronchial Tree, in- stead of Dichotomy 32 Professor Aeby's Third Theory : the Eparterial and Hyparterial System ... 36 SECTION II. THE DETAILED ANATOMY OF THE BRONCHIAL SYSTEM STUDIED FROM THE BRONCHIAL CASTS AND FROM DISSECTIONS .... 40 The Methods employed 40 Dissection 40 Intra-brouchial Injections 41 Modus Operandi 44 Xll CONTENTS. PAGE The Metallic Beonchial Cast .... .... 46 General Kemarks on Metallic Bronchial Casts . • . . 46 General Configuration of the Metallic Cast of the Bronchial Tree ... 47 Remaeks on the Nomenclature op Bronchi and Blood-vessels ... 49 Peopbssoe Abby's Nomenclature and the Author's Elementary Nomenclature s ' Preliminary Observations .... 51 Professor Aeby's Nomenclature studied from the Diagram . . . S^ Synopsis of Professor Aeby's Nomenclature and of the Author's Nomenclature . 54 and S5 The Author's Nomenclature, studied from the Diagram S^ Closer Inspection op the Bronchial Cast. — Modes op Division op Bronchi . 59 Concluding Bemabks on some Important Features common to all Bronchi . 65 The Main Bronchi 67 What is strictly to be understood under the Term ' ' Main Bronchus " 1 . Description of the Main Bronchi The Bronchus Intermedius, or Continuation of the Eight Main Bronchus, below the Origin of the Upper Lobar Branch Elementary Sketch op the More Important Divisions op the Bronchial Tree, studied prom the Metallic Cast ... .... The Right Bronchial Tree . . . ... The Left Bronchial Tree ... . . . Deferred Criticism . ... The Detailed Anatomy and Nomenclature op the Bronchial Tree Preliminary Remarks The Subdivision of the Anatomical Description Terminology and Notation . . . Code of the Lettered Notation ... The Pulmonary Apex. — The Right Apex and its Bronchial Supply General Survey of the Bronchial Distribution to the Right Apex The Right Upper-lobar Bronchus . . . . . . The Ascending-apical Distribution . . . . Distribution of the Sight Anterior Ascending-cipicui Trunk Distribution of the Sight Posterior Ascending-apical Trunk The Left Apex and its Beonchial Supply The Left Upper-lobar Bronchus (Bronchus Impar) and the Pectori-apical Stem General Survey of the Bronchial Distribution to the Left Apex . Distribution of the Left Ascending-apical Bronchus . Distribution of the Left Anterior Ascending-apical Trunh Distribution of the Left Posterior Ascending -apical Trunh Left Axillary Distribution Distribution of the Posterior Axillary Trunk . ... Distribution of tlie Left Axillary Trunk . The Left Infra-apical Interspace .... The Right Axillary Distribution Distribution of the Sight Axillary Division Distribution i>f the Sight Setro-axillary Division The Pectoral Region.— Right Pectoral Distribution General Survey of this District The Bronchi of the District .... 67 69 74 77 77 80 83 8S 85 8S 87 88 89 89 90 92 93 95 98 98 100 102 102 103 104 104 107 108 108 109 no III III III CONTENTS. Xlll The Peotobal Region.— Right Pbctokal Disteibution— (contmuerf). Distribution of the Bight Sterno-pectoral Trunk Distribution of the Bight Mid-pectoral Trunk The Left Pectokal Distribution .... Distribution of the Left Outer-peetordl Trunk . Distribution of the Left Sterno-pectoral Trunk The Caediao Region.— Beonchial Supply to the Right Cakdiac Right Middle Lobe General Remarks concerning the Middle Lobe The Right Cardiac Distribution .... Distribution of the Bight Mammary-cardiac Trunk Distribution of the Bight Sterno-cardiac Trunk Distribuiion of the Bight Posterior Mammary-cardiac Trunk Beonchial Supply to the Left Caediac Disteict General Survey of the Left Cardiac District Distribution of the Left Anterior-cardiac Trunk Distribution of the Left Posterior-cardiac Trunk The Eostbeioe-hoeizontal Region Preliminary Remarks ... . . The Right Postebiob-hoeizontal Disteibution . Bight Mid-axillary Horizontal Distribution Bight Superficial Mid-dorsal Distribution The Left Postebiob-hoeizontal Disteibution . General Survey of the District The Bronchial Supply to the District . Left Oblique Mid-dorsal Distribution .... Left Mid-axillary Horizontal Distribution The Rbteo-caediac Disteict Preliminary Remarks .... ... The Right Reteo-caediac Disteict The Left Reteo-caediac Disteict . .... The Basic Region Remarks concerning the Right and the Left Pulmonary Base General Survey of the Bronchial System of the Right Base . General Survey of the Bronchial System of the Left Base . Some Differences between the Right and the Left Base The Antbeioe-basic Disteict.— Right Antbeioe-basic Disteibution The District supplied . ... The Bronchial Supply .... The Left Antbeioe-basic Disteibution The District supplied .... The Bronchial Supply . Left Mammary Distribution . Left Oardio-basic Distribution, The Axillaey-basic Disteict.— The Right The District supplied . The Bronchial Supply .... Disteict, ob Axillaey- basic Disteibution PAGE 112 "3 ii6 117 117 119 119 120 120 121 124 125 1 25 126 127 128 128 129 130 131 134 «34- 134 135 136 138 138 138 139 142 142 143 144 145 146 146 .146 ISO «So 150 151 152 1 54 IS4 IS4 XIV CONTENTS. PAGE The Left Axillary-basic Disteibution iSS The Left Axillary-basic District compared with the Eight 'SS The Bronchial Supply to the District 'S^ The Lesser Postbeioe-hoeizontal Disteict.— The Bight Lessee Postbeioe-hoei- zontal disteibution '6° Preliminary Remarks .... . . i6o The Bronchial Supply . . i6o The Posteeioe-basic District.— The Right Posteeioe-basic, or Doesi-basic Dis- teibution ... .162 The District supplied . . . . • • '^2 The Bronchial Supply ... ... 162 Bight Lateral Dorsi-baaie Distribution . . . ■ • ' °S Bight Dor si-basic Distribution . . . ■ • '°° Left Postekioe-basic Disteibution . . ... ■ • 166 The District supplied ... • '^^ The Left Lesser Posterior-horizontal Distribution ... .... lo7 The Left Posterior-basic Bronchial Supply . . 167 Left Descending Oblique-dorsal Distribution . ....•• i°° Left Dorsi-hasic Distribution '"9 SECTION III. THE ANATOMY OF THE PULMONARY BLOOD-VESSELS, STUDIED PROM THE METALLIC OAST AND FROM DISSECTIONS 172 Genbeal Remaeks on the Pulmonaey Blood-vessels and theie Relations to Each Other AND TO the Beonchi 172 General Relations of the Blood-vessels to the Bronchial Tree . ... 172 General Relations of the Pulmonary Arteries to the Bronchi I73 General Relations of the Pulmonary Veins to the Bronchi I7S General Relations of the Pulmonary Veins to the Pulmonary Arteries .... 176 Differences between the Pulmonary and the Systemic Arteries 177 Differences between the Pulmonary and the Systemic Veins . ... 1 78 Disteibution op the Right Pulmonary Aetbey 18' Broad Sketch of the Right Pulmonary Artery and of its Great Divisions within the Lung 181 Detailed Account op the Distribution op the Right Pulmonaey Aetbey. — Aeteeial Supply to the Upper Lobe 182 The Right Pectori-apical Artery and its Branches . . .... 183 Distribution of the Bight Tectoral Artery , . . . . . . . .183 Distribution of the Bight Ascending-apical or Axillary-apical Artery . .184 Distribution of the Bight Pulmonary-axillary Artery ... . . 185 Aeteeial Supply to the Right Middle Lobe 186 Aeteeial Supply to the Right Lowee Lobe 186 The Right Descending Pulmonary Artery and its Branches 186 Distribution of the Bight Posterior-horizontal Artery 187 Distribution of the Bight Lesser Posterior-horizontal, Betro-cardiac and Basic Arteries 1 88 CONTENTS. XV PAOB Distribution of the Left Pulmonaey Aetbey 189 General Remarks on the Mode of Distribution of the Left Pulmonary Artery . .189 Aetbeial Supply to the Left Upper Lobe 189 Arterial Supply to the Inner and Central District of the Left Apex. — The Left Pectori- apical Trunk and its Apical Branches ... ... 190 Distribution of the Left Ascending-apical Trunh . igo Arterial Supply to the Posterior and Outer District of the Left Apex. — The Left Axil- lary Pulmonary Artery . . 190 Aetbeial Supply to the Left Peotoeal District . ... igi Akteeial Supply to the Left Caediao Region .... . . 192 Aetbeial Supply to the Left Lower Lobe. — The Left Descending Pulmonaey Aetery 193 Distribution of the Left Posterior-liorizontal Artery ... ... 193 Arterial Supply to the Left Base . • • I9S Distribution of the Left Anterior-hasic Artery ... . . 195 Distribution of the Left Axillary-basic Arterij ... • • '95 Distribution of the Left Posterior -basic Artery . . . ■ 1 96 The Right and the Left Pulmonary Arteries contrasted .... 196 THE PULMONARY VEINS 198 Mode of Origin and of Distribution, and General Relations of the Pulmonary Veins . 198 Distribution of the Right Pulmonary Veins. — Venous Distribution to the Right Upper Lobe .... 200 Right Superior, or Ascending, or Anterior Pulmonary Vein ... . . 200 Venous Supply to the Sight Inner-apical District . . . 202 Venoiis Supply to the Bight Pectoral Begion . . . 203 Venous Supply to the Bight Central and Outer-apical District . 205 Venous Distribution to the Right Middle Lobe .... 207 Venous Distribution to the Right Lower Lobe . . 208 The Right Inferior, or Posterior Pulmonary Vein ... . 208 Distribution of tlie Bight Posterior-horizontal Vein . . 210 Distrihaion of the Bight Lesser Posterior-liorizontal Vein . . 211 Distribution of the Bight Descending Posterior-basic Vein . 211 Distribution of the Bight Deep Transverse-, or Anterior-basic Vein . .212 Distrihulicm of the Bight Betro-cairdiac Vein 212 Concluding Remarks concerning the Left Auricle and the Right Inferior Pulmonary Vein and its Branches .... . . ... 212 ' DiSTEIEUTION OF THE LEFT PULMONARY VEINS .... ... 214 Preliminary Remarks on Some of the Differences between the Right and the Left Pul- monary Veins 214 Venous Distribution to the Left Upper Lobe . . . . . .217 The Left Superior, or Ascending, or Anterior Pulmonary Vein . .217 The Venous Distribution to the Left Apex .218 Distribution of the Left Transverse-apical Vein 219 Distribution of the Left Anterior Ascending-apical Trunk 219 The Left Pectoral Venms Distribution .... . . . 220 Venous Supply to the Left Cardiac Begion .... . . 221 Remarks on the Left Apical Venous Supply .221 INTEODUCTION. THE SCOPE AND THE DIVISION OP THE WOEK. In the department of pulmonary anatomy, whether normal or morbid, a very Modem large share of study has been devoted, in modern times, to microscopical chiefly his- appearances. The extreme periphery of the lung, comprising the bronchioles '"log^^"'- and the air-cells, has been exhaustively investigated. To such an extent has research been concentrated upon them, that attention appears to have been diverted, in the interval, from the imperfection of our knowledge of the anatomy of coarser and less superficial structures. In comparison with the Compiira- searching description of purely histological details, text-books of anatomy oTcoaree^*^ contain but scanty information concerning the general arrangement of parts ^""'o^y- within the lung. And yet, from a practical standpoint, our most obvious and fundamental importance requirement would seem to be an accurate knowledge of the course followed latter. by the air-tubes and by the pulmonary blood-vessels, and of their mutual and general relations. Without this knowledge neither our aetiology of the pathological processes, nor our clinical diagnosis and treatment of pulmonary diseases can enter upon a phase of systematic development. In the pathology of the nervous system the greatest advances have been Analogy made since the investigation of morbid changes within the nerve-cells has anatomy of been supplemented by the study of the contintiity of the nerve-fibres which syg[g°^^ establish distant communications between them. Although this analogy can only be argued in a very broad sense, it serves to illustrate by contrast the present stage of our knowledge of the pulmonary structure. Our information concerning the terminal structures — viz., the trachea and the air-cells, the heart and the pulmonary capillaries — is fairly complete, and, in some respects, minute ; but their connecting links have received only a collective notice. The special object of the present work is to supply some part of this The object defect by furthering our knowledge of the individual components of the lung, thewOTk.° and especially of the divisions of the bronchi and of the pulmonary blood- vessels. As an introduction to the results obtained in this investigation, a pre- Advan- limiuary survey of the facts which have hithei-to been taught in relation preliminary XVI CONTENTS. Venous Distribution to the Left Lower Lobe . ■ ■ 222 Left Inferior or Posterior Pulmonary Vein ... . ■ ■ • 222 Venous Supply to the Left Posterior-horizontal District . ■ 222 Venous Supply to tlie Left Pulmonary Base .... ■ 224 The Left Anterior-hasic Vein .... ... • . 224 Tlie Left Axillary-hasic Vein . .... 225 The Left Posterior-liasic Vein ...... . . • 226 LIST OP SYNOPTICAL TABLES OP THE BRONCHI, PAGES Synopsis of Professor Aeby's Nomenclature and of the Author's Nomenclature of the Primajy Branches of the Main Bronchus, or its Continuation . . 54, S3 Table I. Bronchial Supply to the Eight and to the Left Apex . . 96, 97 II. Right and Left Pectoral Distribution . . . . . 114,115 III. Eight and Left Cardiac Distribution . . . 122, 123 IV. Right and Left Posterior-horizontal Distribution . . . 132, 133 V. Right and Left Retro-cardiac Distribution . .... 140, 141 VI. Eight and Left Anterior-basic Distribution .... . 148, 149 VII. Right and Left Axillary-basic and Lesser Posterior-horizontal Distribu- tions 156,157 VIII. Eight and Left Posterior-basic Distribution ...... 164, 165 LIST OP ILLUSTEATIONS. FIS. iT PAGE 1. Front View of the BroncMal Tree dissected and preserved in the wet state. (From a Photograph.) 42 2. Dry Specimen of the Bronchial System. Front View. (From a Photograph.) . . 43 3. Front View of the Metallic Cast of the Bronchial Tree, isolated by dissection, and of the Pericardial Membrane. (From a Photograph.) 46 4. Back View of the Metallic Cast of the Bronchial Tree, isolated by dissection, and of the Pericardial Membrane. (From a Photograph.) . . . . 47 5. Professor Aeby's Diagram of the Bronchial Tree ... 52 6. Author's Rough Diagram ... . . • • • S3 7. Four Fragments of the Bronchial Cast of a child, in which several deep-seated lobules have taken the metallic injection ; cleaned by maceration. (From an enlarged Photograph.) . . . . 60 8. Preparation of the Chief Bronchi, dissected in the moist state and allowed to dry after being packed full of dried sponge, and stiffened with wire. (From a Photograph.) 75 9. Eough Diagram of the Bronchial Tree. Front View .80 10. Drawing from a Metallic Cast of the Bronchi. Front View, from the left . .116 11. Drawing from a Metallic Cast of the Bronchi. Posterior View 130 12. Dissection of the Bronchi, of the Pulmonary Artery and of the Pulmonary Vein, dried. Eight Lung — Front View. (From a Photograph, — considerably reduced.) 174 13. Dissection of the Bronchi, of the Pulmonary Artery and of the Pulmonary Vein, dried. Left Lung — Front View. (From a Photograph, — considerably reduced.) . 175 14. Eough Coloured Diagram of the Bronchial and of the Vascular Distributions . . 180 15. Drawing from a Metallic Cast of the Bronchi, Pulmonary Arteries and Pulmonary Veins, obtained in a somewhat obese female subject ; isolated by dissection. Front View, from the right ... 188 16. Drawing from the same specimen as Fig. 15. Back View, from the left . . .192 17. Eough Diagram of the Bronchial, Arterial and Venous ramiiications . . . .198 18. Rough Diagram of the chief Pulmonary Veins and of the upper part of the Left Auricle. Front View . . • • 202 19. Drawing from a MetaUio Cast of the Bronchi, Pulmonary Arteries and Pulmonary Veins; isolated by dissection. Front View, from the right .... 208 20. Drawing from the same specimen as Fig. 19. Left Lateral and Posterior View . . 222 INTEODUCTION. THE SCOPE AND THE DIVISION OF THE WOEK. In the department of pulmonary anatomy, whether normal or morbid, a very Modem large share of study has been devoted, in modern times, to microscopical chiefly his- appearanoes. The extreme periphery of the lung, comprising the bronchioles *°i°S"=*i- and the air-cells, has been exhaustively investigated. To such an extent has research been concentrated upon them, that attention appears to have been diverted, in the interval, from the imperfection of our knowledge of the anatomy of coarser and less superficial structures. In comparison with the Oompara- searching description of purely histological details, text-books of anatomy of coarse contain but scanty information concerning the general arrangement of parts '^'"^*°™y- within the lung. And yet, from a practical standpoint, our most obvious and fundamental importance requirement would seem to be an accurate knowledge of the course followed latter. by the air-tubes and by the pulmonary blood-vessels, and of their mutual and general relations. Without this knowledge neither our aetiology of the pathological processes, nor our clinical diagnosis and treatment of pulmonary diseases can enter upon a phase of systematic development. In the pathology of the nervous system the greatest advances have been Analogy made since the investigation of morbid changes within the nerve-cells has anatomy of been supplemented by the study of the continuity of the nerve-fibres which "yg^g"^^ establish distant communications between them. Although this analogy can only be argued in a very broad sense, it serves to illustrate by contrast the present stage of our knowledge of the pulmonary structure. Onr information concerning the terminal structures — viz., the trachea and the air-cells, the heart and the pulmonary capillaries — is fairly complete, and, in some respects, minute ; but their connecting links have received only a collective notice. The special object of the present work is to supply some pai"t of this The object defect by furthering our knowledge of the individual components of the lung, the worfr." and especially of the divisions of the bronchi and of the pulmonary blood- vessels. As an introduction to the results obtained in this investigation, a pre- Advan- liminary svucvey of the facts which have hitherto been taught in relation preliminary A THE BRONCHI AKD PULMONARY BLOOD-VESSELS. survuy of existing knowledge concerning the lungs and the bronchi. Quotatioug necessary. Theoretical and con- troversial matter. Professor Aeby's work. to the lung and to the bronchi, would, I think, present definite advantages, inasmuch as it might enable the reader to connect any accruing information with that previously available. With this view, I have included in the introductory section a brief summary of the most important facts at present known in connection with pulmonary and bronchial anatomy. The informa- tion contained in the summary has been derived from the anatomical text- books, and especially from Quain's " Elements of Anatomy," fi-om which verhdim quotations have sometimes been taken with a definite object. For the purposes of the investigation a summary of this kind was specially needed as a means of calling attention to occasional difierences existing between the prevalent anatomical descriptions of parts, and the description herein given ; and some literal quotations were, from this point of view, indispensable. In contrast with the dry facts of the anatomical summary, theoretical considerations had also to be introduced in connection with previous literature. Putting aside the text-books on general anatomy, the literature of the subject maybe said to consist of a single book, "The Bronchial Tree of Mammalia and of Man," by Prof. Aeby.* For obvious reasons it was necessary to award to that work a full consideration, and to discuss, sometimes adversely, the important statements of fact and of opinion which it contains. This controversial matter, especially when relating to theory, was made to precede, as far as possible, the anatomical section. But some questions, referring to anatomical descriptions, had to be postponed till the latter section. Materials used. Dissections and intra- pulmonary injections. The research was conducted with the help of numerous dissections and of several injections, which were all performed by myself. The descrip- tions based upon them are illustrated by diagrams or by fac-similes of the preparations. Some of the dissections were partial ; others comprised, besides the bronchial system, both sets of pulmonary blood-vessels. The intra-pulmonary injections were likewise of two kinds, single and compound. Although the results obtained by injections have been very satisfactory, especially considering the difficulties which attended their performance, yet greater success will probably be achieved by other experimenters, possessed of the advantage of technical training and of adequate mechanical assistance. Need for a nomencla- ture of bronchi and of pulmonary blood- vessels. The want of a nomenclature of the air-tubes had been seriously felt by me ever since my attention had been specially directed to pulmonary anatomy. When studying the pathological relations of pulmonary cavities I had been led by the necessities of the subject to suggest a name for one * " Der Bronchialbanm der Saugethiere und des Menschen, nebst Bemerkungen fiber den Bronchialbaum der Vogel und Eeptilien," Von Prof. Dr. Ch. Aeby, in Bern. Leipzig, Verlag von Wilhelm Engelmann. l8So. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 3 of the more important bronchi. But in the attempt to deal with the much larger subject of the anatomy of the bronchial system the same need was experienced, with yet greater urgency. A successful study of the bronchial tree was found to be impossible without the assistance of names identifying the many structures under consideration. Indeed, it may be said that the need for a nomenclature was never more acutely felt than during the pro- gress of its elaboration. As regards the Pulmonary Blood-vessels, the practical importance of distinguishing by separate names their several trunks was recognised as being hardly second to the importance of the nomenclature of the bronchi themselves. A separate nomenclature of the Bronchial Blood-vessels is not Thebron- required, although their anatomy may, in the future, require a little more vessels. detail than is generally allotted to them in the text-books. Several dissections of these vessels were made by me, but I refrained from attempting their injection, and I have nothing to add to the description usually given of them. In spite of the great theoretical interest which attaches to the study of this special circulation, inasmvich as it offers little promise of any practical usefulness, its comparative neglect in these pages may perhaps not be considered a serious gap. The whole nomenclature is contained, in a condensed form, in the Synoptical synoptical tables which occur in the anatomical section of the book. In the construction of the tables an endeavour has been made to convey some idea of the relations existing between the air-tubes. Throughout these pages, in view of the amount of detail involved in the Marginal descriptions, marginal notes have been introduced. These will facilitate reference^ whilst serving as a running summary. A similar purpose explains the extensive use of black type in the impression. The advantage likely to accrue to the reader from the clearness and the boldness of this type in so intricate a study as the present one, greatly outweighs the disfigurement of the book which has been entailed thereby. The illustrations included in this volume are of three kinds : — The illus- trations. ( 1 ) Photographic reproductions of dissections and of bronchial casts ; (2) Artists' drawings from the bronchial casts, and from the combined casts of the bronchi and pulmonary blood-vessels ; (3) Diagrams constructed from the dissections and from the metallic casts. I should have gladly relied upon the exclusive use of the photographic ObjeoUons method for the sake of its automatic accuracy. But in the case of the p^^J, bronchial casts, which possess considerable depth, this advantage is counter- g^gjjj^ balanced by the inability of the process to do even justice to the repre- grams. 4 THE BRONCHI AND PULMONARY BLOOD-VESSELS. sentations of different planes. The results obtained were so discouraging, especially in the case of the casts obtained by injecting the two sets of pulmonary blood-vessels in addition to the bronchi, that the attempt had to be abandoned. The large drawings were made with great care under my own supervision. Scale of The cross lines, which appear in several of the drawings and photo- Sent"'^'^" gravures, represent even distances, and serve the purposes of a scale of combined measurement. They were obtained by placing in front of the objects, when productiou drawn or photographed, a frame, upon which fine wires had been stretched jec s. ^^ intervals of twenty millimetres. I have not attempted to repeat the determinations of the aperture of angles of bifurcation or of the diameter of the bronchial tubes which have been carried out by Professor Aeby in the case of the trachea, of the main bronchi and of their primary divisions. An approximate idea of these values may, however, be obtained by studying the drawings, which, as it has been explained, carry their own scale. Thedia- Diagrams were resorted to as the only means of adequately repre- senting some of the anatomical relations described in the text. They proved to be too intricate to be safely entrusted to other hands, and, although roughly expressing the facts which they were intended to convey, they unfortunately bear evidence of lack of skill in drawing. One of the diagrams was chromo-lithographed in three colours, with a view to a clearer rendering of the mutiial relations of the bronchi and of the two sets of pulmonary blood-vessels. THE PLAN OF THE WORK. The book is divided into three sections : — Section I. Introductory matter, containing : A summary of current knowledge concerning (i) the structure of the lung, (2) the structure and arrangement of bronchi; An account of Professor Aeby's researches on the bronchial tree of mammalia and of man ; An account of the theories proposed by that observer, with comments thereon. Section II. detailed anatomy of the bronchial system, studied from the bronchial cast and from dissections. In this section will be found : A description of the methods employed ; THE BRONCHI AND PULMONARY BLOOD-VESSELS. 5 Eemarks on the nomenclature of the bronchial tree ; Professor Aeby's nomenclature and the author's nomenclature compared ; Observations on the modes of division of bronchi ; A description of the main bronchi ; An elementary sketch of the more important divisions of the bronchial tree, studied from the metallic cast ; Introductory remarks on terminology and notation ; A systematic description and nomenclature of the entire bronchial tree ; with a comparison between homologous bronchial districts in the right and in the left lung. Section III. ANATOMY OF THE PULMONARY BLOOD-VESSELS. This section includes : General remarks on the pulmonary blood-vessels : their relations to each other and to the bronchi ; The detailed anatomy of the pulmonary artery; The detailed anatomy of the pulmonary vein. ( 6 ) SECTION I. OUR PRESENT KNOWLEDGE OF THE ANATOMY OF THE LUNG AND OF THE BRONCHI. PROFESSOR AEBY'S RESEARCHES ON THE BRONCHIAL TREE. CRITICISM OF PROFESSOR AEBY'S THEORIES. 'Jho bronchi viewed anatomi- cally as internal Bupporta for the pulmonary substance, and tor its vascular system. Eigidity a feature of the larger tubes only. As an introduction to tlie present section, I offer some reasons for not isolating the study of the bronchial system from the study of the lungs. The bronchial system may be considered as fulfilling an anatomical as well as a physiological purpose. The soft, though elastic, mass of pulmonary substance requires for its support some internal structure endowed with greater firmness. Not only does the lung need this support as a whole; it also depends upon it for the preservation of the mutual relations of its various parts. In addition, throughout the pulmonary substance, adequately fixed joints, or fulcra, are indispensable for the control of the individual movements of each of its segments. Moreover, a large number of blood- vessels, deficient in rigidity, yet more frail lymphatics, glands and nerves, must find definite lodgment and protection. All these objects are admirably served by the air-tubes, which therefore possess, in relation to the other pulmonary constituents, the value of an endo-skeleton. The firmness and the rigidity of the bronchial tubes are not, however, proportionate to their size. The smallest among them are totally deficient in cartilages, and receive, instead of giving support ; and those of rather larger size possess only as much cartilage as will ensure their patency, and are not, in the ordinary sense, rigid tubes. It is, therefore, most probable that better support would be afforded by the powerful walls of a moderate number of large tubes than could be given by a multitude of smaller divisions such as might have resulted from a very eai-ly splitting of the air-channels into their lobular or sub-lobular branches. Physioio- An analogous inference is also arrived at from physiological considera- vanlage' tions. The main object of the bronchi being the distribution of air to the gained respiratory tissue, if this distribution can take place along large common the large tubes as far as the immediate neighbourhood of the individual respiratory THE BRONCHI AND PULMONARY BLOOD-VESSELS. 7 surfaces, a great saving of space, of material and of friction would be the size of tie result. Such a distribution would bear a strong resemblance to the water- tubp.e. distribution within a town, where single tubes do not proceed from a central reservoir to each house or block, but where a "main" provides all the houses in each street with short hydrants, intended to convey water to special tubes proceeding to as many rooms. The bronchial system has, however, other functions unparalleled in our engineering. It is meant to discharge, as well as to admit gases : — and not gases alone, but occasionally also fluids and solids in the shape of mucus. The delivery of breathed air must, further, be capable not only of a gentle and even motion, but of swift and powerful blasts. Purposes of this kind would clearly be better served by a system of central tubes of large diameter, receiving short tributaries, than by a considerable number of long narrow tubes incapable of accumulating much pressure, and occasioning very great friction. Similar d priori considerations would likewise lead us to foretell in any The bron. long and narrow lung the existence of one or more large, centrally rangement placed tubes, extending almost to its extremity, and distributing to the i'^l^^^^^ respiratory zones which they traversed a series of short supplying tubes. siiape of In a short but broad lung, we should expect the large central tube Theghort to be of insignificant development, and the supplying or " lateral " tubes to and broad, be of considerable length and obliquity. In both cases we should regard the long and peculiarity of bronchial distribution as the direct outcome of definite anatomical shapeT and physiological necessities. What has been said in reference to the lung as a whole, is also applicable to each of the pulmonary lobes. And, in general terms, in any independent part of the lung, some indication of the arrangement of its bronchi may be gathered from the configuration of the part. The two bronchial types indicated above are relatively displayed by the majority of quadrupeds on the one hand, and by man on the other hand. Beautiful illustrations of both forms are contained in Professor Aeby's work,* to which the reader is referred. The preceding remarks are intended to show that an advantage may be The study gained by studying the bronchial system in connection with the lung itself, bronchi Perhaps the chief difierences between Professor Aeby's views and my own 5?' '".''f , '^ , , , , , '' , '' dissociated have theu' origin m the more isolated position allotted by him to the con- from the sideration of the bronchial system, as though the latter almost possessed an the luug. abstract type, and a certain independence from surrounding influences. Additional divergence has doubtless arisen from Professor Aeby's endeavour Difference to frame, on the lines of one of the two morphological varieties to which auUio?b ♦ " Der Bronchialbaum der Saugethiere und des Mensohen." Leipzig, 1880, 8 THE BRONCHI AND PULMONAEY BLOOD-VESSELS. point of reference has been made, a general type for the whole mammalian series ; thaToT whereas the present investigation concerns essentially the opposite variety. Professor ^(; ^i^q game time, although the scope of this research is limited to man, a cnrsory allusion to the conditions existing in Mammalia cannot be omitted entirely from a criticism of the German work, since in the latter the study of the mammalian lung is inseparably bound up with that of the same organ in man. ( 9 ) SUMMARY OF OUR PRESENT KNOWLEDGE CONCERNING THE ANATOMY OF THE LUNG. A. — Bough Sketch of the External Shape and Relations of the Lungs. General Shape. — The lungs share the intra-thoracic cavity with the irregularly heart, which is received in the space left by the concavity of their opposed sJape."" mesial surfaces. Their shape cannot with accuracy be compared to that of any simple geometrical figure. Viewed laterally, they present, however, a roughly coniform appearance ; and, indeed, they have been described as analogous to the two lateral halves of a cone. But their apex is blunt and irregular, and their base is not perfectly horizontal, being bevelled at the expense of the posterior surface, and being moreover concave instead of plane. Surfaces and Borders. — In addition to a hasie surface, and to a Three basic margin, each lung presents two other surfaces and two other borders. s°erifa"' The borders are anterior or sternal, and posterior or vertebral^ the latter being vertebral, very blunt and smooth, the former (as well as the basic edge) extremely sharp. The mesial surface, which joins the sternal to the vertebral border, Three is relatively short, and would be yet shorter but for the concavity necessitated p^eta{ ' by the presence of the heart. The entrance into the lung of the great ^Hf^ vessels, and of the bronchus, breaks up the smoothness of this surface. The parietal surfacej on the contrary, is absolutely smooth and, following the broad lateral curve of the thoracic wall, it far surpasses in ext.ent the other sm-faces. Fissures and Lobes. — The lungs are divided into loles by interlobar fissures or septa. In both lungs a long ohlique fissure, beginning in the upper Long portion of the posterior surface, and ending at the anterior part of the base, figg^rTin completely separates the upper lobe from the lower lobe. But the right lung ^°^^ '""gs- presents in addition a short horizontal fissure situated at the junction of the Short upper with the middle third of the lung, and confined to its anterior aspect, fissure in It extends anteriorly as far as the sternum, and posteriorly it opens into the *''® "S^** great oblique fissure. In this manner it isolates, at the lower and anterior Three lobes part of lung, a third lobe, the middle lohe, which otherwise might have Sngf "^ formed part of the upper lobe. The normal division of the left lung into two 10 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Two lobes lobes, and of the right lung into three, is subject however to frequent in the left. • i -i- irregularities. Pulmonary The Pleura, — Destined, like the heart, for a life of constantly recur- ring movement, the lungs are sunk into the serous cavities of the pleura, which they completely fill, and they derive from the visceral layer of the membrane a complete and closely adherent investment, which also extends for a short distance over the surface of the main bronchus on either, side. Pulmonary Pulmonary and Bronchial Vessels. — The lungs bear important re- chiai ' lations to the heart, from which they receive large arterial and venous trunks ; vessels. ^^^ ^q some of the large systemic arteries and veins, notably to the aorta from which they derive, through the bronchial arteries, their nutrient blood. Within them are also contained lymphatic channels, glands, and nerves, respectively continuous with the general lymphatic system, and with the cerebro-spinal and sympathetic nervous systems. The root of Pulmonary Root. — The main bronchus, and the pulmonary blood- audhiius. vcssels, nervcs and lymphatics, are gathered together in the shape of a broad pedicle, as they enter the lung along the middle-third of its mesial surface. In this manner they constitute an excellent attachment for the organ, without greatly interfering with the freedom of its movements. The pleura, which covers them as they approach the lung, is from them reflected to the pulmonary surface. This it closely invests, and penetrating between the lobes, it adapts itself to the opposed surfaces of the interlobar fissures. The pedicle, thus formed, is commonly called the " Eoot of the Lung." It is received into the " hilus," or longitudinal incisure of the mesial pulmonary surface. Intra- Within the hilus, owing to the large size of the early bronchial divisions, portion o7 ^'^^ o^ ^^^^ pulmonary vessels, and to the presence of lymphatic glands and root. of a tenacious fibrous tissue which firmly cements together the several structures, the intra-pulmonary portion of the " root " forms a compact mass which excludes all respiratory tissue. Beyond this the blood-vessels and the bronchial tubes rapidly diverge, and bifurcate in the lung ; and the angles of bifurcation of the latter afford lodgment for the deep pulmonary lobules. Lobar The Main Bronchi. — The left bronchus divides into two branches for oUhemain the supply of the upper and of the lower lobe respectively, and the blood- bronchi, yessels undergo an analogous division. But the right bronchus, after giving a large branch for the upper lobe, divides again into a middle-lobar and an inferior-lobar bronchus. The more recent account of the mode of division of the main bronchi, as given by Professor Aeby, will be found on p. 70. The relative position of each bronchus in the root of the coiTesponding lung is described by Quain, in the following words : — Relations of "The root of the right lung lies behind the superior vena cava and part whhin"root. <^f t^^ right auricle, and below the azygos vein which arches over it to enter the superior cava. That of the left lung passes below the arch of the aorta and in front of the descending aorta. The phrenic nerve descends in front THE BRONCHI AND PULMONARY BLOOD-VESSELS. Il of the root of each lung, and the pneumogastric nerve behind, whilst the ligamentum latum pulmonis is continued from the lower border. The bronchus, together with the bronchial arteries and veins, the lymphatics and lymphatic glands are placed on a plane posterior to the great blood-vessels, whilst the pulmonary veins are in front of the arteries. The pulmonary plexuses of nerves lie on the anterior and posterior aspect of the root beneath the pleura, the posterior being the larger of the two. " On the right side the undivided portion of the bronchus is altogether above the pulmonary artery ; on the left side the undivided portion of the bronchus, which is considerably longer than on the right side, extends to below the level of the left pulmonary artery which crosses it. On both sides the pulmonary veins are below the corresponding arteries." Volume and Weight of the Lungs. — The volume of the lungs is piffeivnce stated by Aeby {loc. cit., p. 85) to be almost one-quarter less in women than d°e to^sex in men. He gives the following measurements : — In men : Eight lung = 873"0 c.c. Left lung = 744" 8 c.c. In women: Right lung = 70 5 "2 c.c. Left lung = 585-3 c.c. In both sexes the right lung would exceed the left in volume by 1 5 per cent, (almost as 11 to 10, the proportion previously taught). According to Aeby (foe. cit., p. 91) it may be proved by calculation that and due to. the lungs of infants contain the same elements as those of adults, their size '^°''' only being different. He assumes that the diameter of air-cells in the new- born is one-third less than in the adult. On this basis the subsequent growth of the lung is held by him to be entirely explained by the increase in the size of the alveoli, without any addition to their number. Reid (quoted by Quain) found the average weight in twenty-nine males Average to be 24 oz. for the right lung and 2 1 oz. for the left. In twenty-one ^^ufts.' '° females the weights were respectively 17 oz. for the right and i 5 oz. for the left lung. B. — General Internal Structure. Tubular Structure. — The lung is constructed entirely upon the General tubular plan. From apex to base it exclusively consists of subdividing air- structure, tubes — the multiplied and amplified continuations of the calibre of the trachea ; and these are accompanied by numerous blood-vessels* lymphatics, and nerves, and bound together by areolar tissue. Parenchyma. — Nevertheless, throughout the greater part of the orgau, disguised the tubular character is disguised by the ubiquitous presence of an alveolated ja^edparen- structure, inflated, during life, with more than its own bulk of air. This is j^J"^* *' the pulmonary parenchyma. It may be termed (in contrast with the more chiai centrally situated pulmonary root) the pulmonary or brotichial periphery. ^^^^ ^''^' This term is applicable to the parenchyma even in the depths of the lung. 12 THE BRONCHI AND PtJLMONARY BLOOD-VESSELS. For, however deeply it may be situated, the parenchyma represents the ter- minal subdivisions of the tubular system, and is morphologically equivalent to those portions of the same tissue which are quite superficial, and imme- diately covered by the pleura, and becom- Root-zone. — In the central zone, on the contrary, the tubular character i°^the'root- ^^ unmistakable. The air-tubes are larger, subdivide sparingly ; and, to the zone. exclusion of all pulmonary substance, they admit in their interstices nothing beyond large blood-vessels, lymphatic glands, nerves, and fibrous tissue. It is unnecessaiy to enter here upon a description of this relatively uncompli- cated district. More essential, for the present^ is a brief sketch of the general anatomy of the peripheral parts, which constitute the bulk of the lung. Bronchial Periphery. — The Lobule. — In all situations, excepting the extreme sub-pleural layer, the pulmonary periphery is made up of two sets of tubes: (i) Minute terminal air-tubes and blood-vessels 5 (2) slightly larger air-tubes and blood-vessels, which are destined for more distant districts, and pass onwards between the former. Pulmonary The terminal air-tubes, and their attendant blood-vessels, lymphatics, and lobules. nerves, are arranged in definite groups, of the average size of a pea or small hazel-nut. These groups are surrounded by a membrane analogous to the Fori- pleura and constitute the lobules. By the peri-lobular membrane the con- lobuiar taiued pulmonary parenchyma is entirely separated from all air-distributing tubes and blood-vessels which do not belong to the lobule. The lung, Inasmuch as any free, or extra-lobular pulmonary parenchyma does not exist, gate^o?^*" ^^^ ^^^S ™^y ^^ regarded as an aggregate of lobules, between which ramify lobules the distributing blood-vessels and air-tubes. If all the lobules could be chiaiand removed, the distributing tubes would be laid bare, and would form an l^me-^ empty framework, a soft endo-skeleton, difiering from the central zone, or work. root-zone, only by the lesser size and firmness of its tubes, and by the large vacant inteiTals left between them. Preparations of this kind may be obtained either by dissection alone, or by the combined methods of bronchial and vascular injections, and of subsequent dissection or maceration. This bronchial and vascular skeleton will be the subject of careful study in later parts of the work. C. — The Pulmonary Lobule. General Characters. — ^Although liable to many variations in size and in shape, all lobules agree in the possession of certain general characters. To each lobule belong : — (l) A peri-lobular membrane. Lobular (2) A single bronchiole, which furnishes the entire air^supply. This is fobufai- " known as the lobular bronchiole ; and the air-tube which gives rise ^^?°,"^g to lobular bronchioles may be termed the sub-lobular bronchiole. THE BRONCHI AND PULMONARY BLOOD-VESSELS. I 3 (3) A lobular branct of the pulmonary artery, which accompanies the Lobular bronchiole. "ZT^r^ (4) Two or more lobular branches of the pulmonary vein. (5) Lymphatic vessels. (6) Nerve filaments attached to the bronchiole. The average size of lobules, according to Sappey (" Anat. Descrlpt," Average vol. iv. p. 450, 1874), is one cubic centimetre; but some may exceed that ^"'^' volume, whilst others may attain only half these dimensions. They steadily increase in size with the growth of the lung and decrease increase in when the latter shrinks with age. In this respect they difEer from the youth; alveoli, the individual capacity of which grows uninterruptedly throughout ^uagT "" life. Assuming the correctness of Sappey's estimate of the average size of lobules, and of Aeby's estimate of the volume of the lung (both measured in the state of collapse), a rough estimate of the number of lobules might be readily obtained by a simple calculation. Each lobule probably possesses not only a definite place but definite Thecharac- relations and a fairly constant shape. A study and a description of individual vlduai '" '' lobules would not however be rewarded by any practical result. It will '"^U'^y , Bufi&ce to remember that lobules exist everywhere as far as the boundary of constant. the root-zone, crowding together at the surface, and filling all available space in the depth of the lung. Their mutual contact is almost direct, with inter- the single intervention of a thin layer of connective tissue continuous tissue.' with the sub-pleural tissue. According to Sappey (loo. cit., p. 449) the inter-lobular interval is more appreciable, and the inter-lobular tissue more abundant, at the surface of the lungs of infants than of those of adults. Varieties in Shape and Position of Lobules. — The shape of Pyramidal, individual lobules, being influenced by their suiToundings, is in a certain ^l^d sense accidental, and therefore varies endlessly. Sappey (loc. cit., p. 450) fobufeT***"* groups these varying shapes under three types: (i) The superficial lobules are pyramidal, their apex pointing centrally; (2) the marginal lobules are wedge-shaped, their thin edge coinciding with that of the lung; (3) the deep lobules are facetted more or less evenly. All lobules agree in being pedunculated. Between the deep lobules and superficial those more superficially placed, no essential difference exists, except in iXil^T'-''' the direction of their attachment. The bronchial and vascular supply approaches the peripheral lobules from their proximal extremity (the extremity nearest the pulmonary root). This relation is reversed in the case of the deep lobules. These are the oSshoots from bronchial divisions which are distal to the angles of bifurcation in which they nestle. They are in other words recurrent lobules. In an intermediary position are recurrent found the lateral lobules which form the bulk of the internal substance of Jobuiee ; the lung. The angle which their axis forms with that of their parent lobules. 14 THE BBONCHI AND PULMONARY BLOOD-VESSELS. bronchus varies with their distance from the surface, and according to the situations which they are destined to fill. The lobule as struc- tural " pul- monary unit." The air- cell as functioual " respira- tory uuit." lutrtu- lubular and terminal bron- chioles. Final bifurcation. Increase in calibre. Change in epithelium. The lobule is not, in a functional sense, the ultimate respiratory- element ; it consists of many respiratory units. But, anatomically speaking, it is the icUimate pulmonary unit. The respiratory units are the air-cells. Possessing delicate elastic walls, densely pervaded with capillaries, and lined with the thinnest epithelium, the air-cell is especially fitted for the respiratory interchange of gases. The two functions, upon which the latter may be said to depend, are represented by the elasticity of the air-cell, which permits it to expand passively, but sub- sequently ensures its recoil, and by its thinness, which allows the transit of gases to and from the blood coursing within its capillaries. Thus the remotest periphery is exclusively entrusted with the performance of the respiratory function. We may, therefore, consider the infundibtohcni, or, better, the aheohis, as the functional respiratory unit within the king. What has been said of the air-cell illustrates by contrast the full meaning of the term pulmonary unit applicable to the lobule. Within the latter are contained, invested by a membrane resembling the pleura, all the tissues which belong to a whole lung. It closely imitates the lung in outward appearance and in functional behaviour, and it is accurately described by the metaphorical expression, "miniature lung." We may therefore speak of the lobule as the structural or pulmonary unit in contrast with the functional or respiratory unit into which passes the terminal bronchiole. D.— The Alveoli. Minute Anatomy. — For a full description of the arrangement within the lobule works on Histology must be consulted. The short account which is here introduced for the sake of completeness is based upon the description contained in Quain's "Anatomy" (edit. 1882). After entering the lobule the bronchiole divides into intra-lohular branches, and finally into terminal bronchioles. Similar bifurcations are suflFered by the blood-vessels, which ultimately break up into a capillary network. The final dividing of bronchioles is by bifurcation. This fact was demonstrated to me very kindly by Dr. Sheridan Del6pine, and in so clear a manner that no doubt remains in my mincl. The bifurcation in question difiers from all those which have preceded it, in the circumstance that its products are not smaller, but individually larger than the bifurcating tube ; and from this they also differ in kind. The structure of their walls is modified. They possess a non-ciliated squamous epithelium instead of the non-cUiated cuboidal epithelium found in the smallest bronchioles. THE BEONCHI AND PULMONARY BLOOD-VESSELS. I 5 The products of this ultimate bifurcation, the infundibula, are generally infnn- described as multilocular air- sacs, growing iu thickness towards the '*''^'^*' periphery, and furnished with lateral and with terminal alveoli and with an inter-alveolar passage. According to Quain, for some distance before this inter- final stage the terminal bronchiole is beset with lateral air-cells, here and pall^o. there at first, then more thickly, so as to lose its cylindrical shape. Where the lateral air-cells make their appearance the columnar ciliated epithelium ceases, the muscular layer almost disappears, and the longitudinal elastic bundles break up into the fashioned peripheral network. The Epithelium. — " The change in the character of the epithelium Pavement- first occurs in the so-called respiratory bronchioles, where patches of small firsf j^™"' pavement-epithelium cells begin to appear amongst the ciliated cells, P"''"!"*^- especially in the neighbourhood of the air-cells upon the wall of thesft tubes. At the end of the respiratory bronchiole, near the . passage to the infun- dibula all the cells which line the wall of the tube are of the non-ciliated pavement variety. But the air-cells themselves, both those which are scattered over the respiratory bronchioles and those which cover the infundibula, as well as intermediate portions of the infundibula which occur here and there between the air-cells, possess an epithelium. The cells of Alveolar the epithelium are of two kinds — viz. : (i) large, thin, very delicate, irregular largefnon- in size and shape, lying over the blood-vessels, but also in many cases """l^ated; extending over the interstices between them ; they appear not to possess a nucleus; and (2) small, flat, polygonal, nucleated cells, which lie singly or small, in small groups of two or three cells between the others, and always in the cells interstices of the capillary network. (In the foetus the alveoli are entirely ^piuariesi- lined with small granular pavement-cells, but with the distension which the latter follows upon the first respiratory efforts, the cells become transformed into foetus. the large thin epithelium cells above described.)" Numeration and Measurement of Air-cells. — Although much divergence exists in the various accounts given of the structure of bronchioles, of infundibula, and of air-cells (and especially of their mutual relations), with the air-cell or alveolus a definite quantity is reached, as regards both size and structure. Their number is also capable of being roughly calculated. The aggregate number of air-cells in both lungs was estimated by Estimated Huschke at 1700 — 1800 millions. In quoting these figures Professor air^eiis? Aeby states that they are much too high. His own calculations are based upon an estimate of 250 air-cells in each cubic millimetre (each cell having a diameter of 0'2 mm., and a surface of 0'I2 5 sq. mm.). Assuming that the • total volume of the male lung is equivalent to 1 6 1 7 cubic cm., and that of the female lung to 1290 cubic cm., he arrives at the figures 400 and 300 millions as representing the probable number of air-cells. The entire extent of the respiratory surface is given as varying between Extrat of 40 and 50 'square metres. But Aeby points out that in the stage of deep area. i6 THE BKONCHI AND PULMONARY BLOOD-VESSELS, Diameter of air-cells, larger in males ; greatest at apex and margins ; increases with ago. inspiration the male lung would expand to a surface of 1 29-84 metres, and the female lung to a surface of I03'52 metres. The diameter of air-cells in the human lung is, according to Quain Qoc. cit.), most commonly, about x^th of an inch (0-25 mm.), but it varies from yi^th to -yVtb of an inch. " The air-cells are larger on the surface than in the interior, and largest towards the thin edges of the organ ; they are also very large at the apex of the lung. Their dimensions go on increasing from birth to old age, and they are larger in men than in women. In the infant the diameter is usually under a^th of an inch." The alveoli, according to Eossignol (Sappey, loc. cit., p. 464), continually enlarge from birth, when their capacity measures 0*05 mm., to middle age (40), when it measures 0*23 mm., and to advanced age (70-80), when it attains 0-34 mm. E. — The Pulmonary Blood-vessels. The following description is extracted from Quain's " Elements of Anatomy." Several of the statements which it contains will be again referred to in the third section. Situation of pul- monary arteries. No anasto- mosis. Single layer of capillaries. Close net- work: occasion- ally pro- jecting into air-cell. Branches to terminal bron- chioles. I. — The Pulmonaky Aeteky. Distribution and Belations. — " The branches of the pulmonary artery accompany the bronchial tubes, but in their remote ramifications they subdivide more frequently. The main arterial trunk runs down immediately behind * the main bi'onchial trunk, giving off corresponding branches as it proceeds. They ramify without anastomoses, and at last terminate in small arteries about xxnnr i^ch in diameter, which lie between the alveoli partially encircling their mouths. From these vessels the capillary network arises, and covers each alveolus, passing in the inter-alveolar septa between the adjacent air-cells. As was pointed out by Eainey, the capillary network, in these partitions, is single in the lungs of man and mammalia, although it forms a double layer in the lungs of amphibia and of reptiles." " The capillaries are very fine, and the network they form is so close that the meshes are scarcely wider than the vessels themselves. They are very superficial, being covered only by the thin layer of tessellated epithelium above mentioned ; and in the partitions between contiguous alveoli the vessels of the network project on either side in an arched or loop-like manner into the cavities of the alveoli. The mucous membrane of the bronchial tubes, especially near the air-cells, is partly supplied with blocd from branches of the pulmonary artery." * The italics are mine. For my account see pp. 181 to 197. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 7 II. — The Pulmonary Veins. Distribution and Relations.* — " The radicles of the pulmonary veins Origin from arise from the capillary network of the alveoli, and from that of the smaller from bion- bronchial tubes. The branches of these veins which arise from the in- "hioies. fundibula near the surface of the lung, frequently do not accompany the bronchia and arterial branches, but are found to run alone for a short distance through the substance of the organ. They finally either join some deeper Deep and vein which passes hy the side of a bronchial tube, or they remain superficial, ^^^^s. ""^ forming a wide-meshed plexus near the surface of the lung, finally tending towards the hilus to join the larger veins near the root of the lung, also Frequent forming, according to Eossignol, frequent lateral communications." mosis. "The veins from the more deeply situated infundibula form frequent communications, and finally coalesce into large branches which accompany the bronchial tubes and the arteries, and thus proceed to the root of the lung." " In their course through the lung, the artery is icsually found above and Relations. behind a bronchial tube, and the veins below and in front." The Muscular Layer. — Striped muscular fibres are found on the four striped pulmonary veins where they join the left auricle (Landois, Text-book longit'u- of Human Physiology, translated by Stirling, vol. i. p. 68, 1885). eSar,*^ "These fibres (which are arranged as an inner circular, and an outerwear . -I ■, 1 ■-, ,.11 ■ 1 auricle; longitudinal layer) can be traced to the hilus of the lung m man and some mammals ; in the ape and rat they extend on the pulmonary veins right into the lung. In the mouse and bat, again, the striped muscular fibres pass ^^° ""^^^j so far into the lungs that the walls of the smaller veins are largely composed even in of striped muscle (Stieda)." In connection with the last statement it is in- yejns. teresting to note that " independent rhythmical contractions are often noticed Ehythmic in the pulmonary veins as well as in the venae cavse after the heart has ceased to beat. (Haller, Nysten.) [This beating can also be observed in those veins in a rabbit after the heart is cut out of the body.] " Diflferences between Pulmonary and Systemic Vessels. — " The pulmonary vessels difier from the systemic in regard to their contents, in- asmuch as the arteries convey dark blood, whilst the veins carry red blood. The Pulmonai-y Tijii -piiT • veins less pulmonary veins, unlike the other veins 01 the body, are not more capacious capacious than their coiTesponding arteries ; indeed, according to Winslow, Santorini, nonary ' Haller, and others, they are somewhat less so. These veins have no valves, arteries. Lastly, it may be remarked that, whilst the arteries of different lobules are ^°'^^^'^^^- usually independent, their veins freely anastomose " (Quain). In connection with the pulmonary blood circuit, the description of the bronchial blood-vessels should also be consulted in anatomical text-books. * All italics are mine. Compare the description given at p. 198. i8 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Eacliclos from (i) alyeoli. (2) bron- chioles. Lyraijhoid tissue. Inter- epithelial radicles. Snb-pleuval plexus. Deep plexus. Termina- tion of effer ent ducts. Bronchial glands. F. — The Lymphatics of the Lung. Mode of Origin and of Termination. — According to Quain, tlie pulmonary lymphatics have two modes of origin : — (i) From the inter-alveolar lympliatic capillaries lymphatic vessels arise, which lie, in twos or threes, in contact with the pulmonary arteries and veins, frequently anastomosing. They may sometimes completely invest the blood-vessels. (2) The lymphatics originating in the bronchial mucous membrane, traversing the muscular coat, give rise to a plexus in the fibrous layer, which is specially developed on the side adjacent to the pulmonary artery. " Lymphoid tissue, according to Arnold, is found in various parts — viz., under the pulmonary pleura; in the peri-bronchial and peri-vascular tissue ; in the bronchial wall and around the alveolar passages.'' " The branched connective-tissue corpuscles, and cell-spaces, with which the inter-alveolar lymphatics are in connection at their origin, send pro- cesses upwards to the inner surface of the alveoli, between the epithelial cells." The sub-pleural lymphatic plexus is in connection with the inter-alveolar lymphatics of the pulmonary surface. "At the root of the lung the superficial and deep lymphatics unite into a few anastomosing trunks before entering the bronchial lymphatic glands From the latter two or three trunks issue, which ascend along the trachea to the root of the neck, and terminate, on the left side in the thoracic duct, and on the right in one of the right lymphatic trunks." " The bronchial glands are ten or twelve in number. The largest of these occupy the interval between the right and left bronchi at their diver- gence, whilst others of smaller size rest upon the first divisions of these tubes for a short distance within the lungs." stomatain Stomata and Fseudo-stomata. — Klein (The Anatomy of the Lym- pkm™"^ phatic System, 1875, and Proceedings of the Royal Society, Jan. 1874) has described at the surface of the pulmonary pleura stomata, placing in com- mimication the cavity of the pleura with the pleural and with the inter-alveolar sub-pleural lymphatics. After pointing out the effect upon the intra-pulmo- Influence of nary lymph-stream of the alternating expansion and contraction of the lung, " Likewise it is clear that during inspiration those lymphatic branches also will become distended that originate in the septa of the super- ficial alveoli of the lung, and discharge themselves, as has been mentioned, into the network of the sub-pleural lymphatics. During respiration, again, they will become compressed." The branches connecting the intra-pulmonary and the pleural lymphatics " represent, so to speak, the safety-valves for the sub-pleural lymphatics during expiration." respiratory -, t q movements ^^ aciu on lymph- stream. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 9 Dybkowski (Arbeiten aus der Physiolog., Anstalt in Leipzig, 1866) stomata had previously described the existence of stomata in the parietal pleura : pleura?'* these stomata are stated to be absent from the pleura which covers the ribs, although present in their interspaces. [The following observations, quoted by Landois (Text-book of Physio- logy, Stirling's translation, vol. i. p. 224, 1883) refer to the fine anatomy of the intra-pulmonary system : — According to Pierret and Renaut every air-cell of the lung of the ox is surrounded by a large lymph space, such as occurs in the salivary glands. Nothnagel found that, if blood was sucked into the lung of a rabbit, the Kapid blood corpuscles were discovered within the interstitial connective-tissue of exS-ava- of the lung after 3^-5 minutes, and he concludes that the communica- sated biocd. tions between the cavity of the air-cells and the lymphatics must be very numerous. According to Klein, pseudo-stomata, opening into the canaliculi, exist in Psendo^ the cement-substance uniting the epithelial cells of the alveolus : they are between most easily seen in the distended air-cell. They would afford passage for ai^j^^oiar lymph corpuscles and particles of pigment ; but according to v. Wittich denied the latter are independent of any pre-existing apertures and make their way through the soft semi-fluid cement-substance.] Intra-alveolar Channels. — Wiwodzoff (Wiener Med. Jahrb., Bd. xi. 1866), quoted by Klein {loc. cit., p. 29), describes, in the connective-tissue of the alveoli of dogs and horses, small lymph canals, the larger of which run parallel to the elastic fibres, and then follow the course of the capillary blood-vessels, but in many cases cross the latter, and in their meshes become Canaiienii confluent, so as to form lacuncp. laounai. Sikorsky (Centralblatt fiir Med. Wiss., No. 52, 1870), quoted by Klein (loc. cit.), likewise described canaliculi and lacunge, the latter being situated at the nodes where the canaliculi anastomose, and exclusively in the meshes between capillary blood-vessels. G. — The Nerve-supply to the Lungs. An anterior and a posterior pulmonary plexus are stated to be formed by Anterior branches of the vagus in association with sympathetic fibres ; and their branches tsrior"^ enter the root of the lung and accompany the bronchial divisions. Remak, pulmonary ° . . . . plexus, and subsequently Stirling, have described in connection with these nerves, solitary and grouped ganglia of minute size. The pulmonary branches of the vagus are divided by Quain into two sets, Pulmonary distributed to the anterior and to the posterior aspect of the root of the lung, from vagus : '■ The anterior pulmonary nerves, two or three in number, are of small size, anterior, They join with filaments of the sympathetic ramifying on the pulmonary s'™''^'"- artery, and with these nerves constitute the anterior pulmonary plexus. 20 THE BRONCHI AND PULMONARY BLOOD-VESSELS. posterior, lai-ger. Sympa- thetic supply- Behind the root of the lung the pneumogastric nerve becomes flattened, aiid gives several branches of much larger size than the anterior branches, which, with filaments derived from the second, third, and fourth ganglia of the sympathetic, form the posterior pulmonary plexus. Offsets from this plexus extend along the ramifications of the air-tube, through the substance of the lung." See also infra, the nerve supply to the bronchi, ( 21 ) SUMMARY OF PRESENT KNOWLEDGE CONCERNING THE BRONCHI AND THEIR VASCULAR AND NERVE SUPPLY, A. — Arrangement and Structure of Bronchi. The following account is based upon the description contained in Quain's "Elements of Anatomy" (eighth edition, 1882), from which quotations are given. General Structure. — Before entering the lungs, the bronchi present Bronchi the same structure and appearance as the trachea. Their posterior wall is trachea iu membranous, and their roughly cylindrical anterior and lateral surfaces are s*™"''^'*. supported and stiffened by semicircular cartilaginous bands. The right bronchus, short and wide (about i" or 2*5 cm. in length), as Vena it descends into the lung, is crossed from above and from behind by the iu|m pul- wma azygos ; and it lies at first above, and subsequently behind the right ™tg^J pulmonary artery. The left bronchus, nearly twice as long as its fellow, terminates about Aortic an inch lower than the latter. " The left bronchus crosses over the front of left p'ui- the gullet and descending aorta ; the arch of the aorta turns backwards and ™°g^ to the left over it, and the left pulmonary artery lies first above it, and then on its anterior surface." " Before entering the substance of the lung the right bronchus gives off Lobar the branch to the upper lobe, and is then continued on into the lower lobe, the branch for the middle lobe being given off from the continuation. The corresponding branch of the left bronchus is considerably larger and enters the upper part of its lung."* " The principal divisions of the bronchi, as they pass into the lungs, Subdivi- divide into tubes of less caUbre, and these again subdivide in succession into divergence smaller and smaller tubes, often distinguished as bronchia, bronchioles, or °f*"''"bes. bronchial tubes, which, diverging in all directions, never anastomose, but i^°geg^^*°' terminate separately. The larger branches diverge at rather acute angles, but the more remote and smaller ramifications spring less and less acutely. After Angles of divergence, * Since the difference in size between the right and the left upper lobar bronchi is not considerable, we must infer that the expression " corresponding branch " applies, in the text, to a branch corresponding to the bronchus which is supplied to the right middle lobe. But, in itself, the sentence in question is evenly ambiguous. ■y o THE BRONCHI AND PULMONARY BLOOD-VESSELS. Lobular bron- chioles. Fibrous coat. Cartilages. a certain stage of subdivision each bronchial tube, reduced to a small size (about I mm.), is termed a lobular^ or ' respiratory hvnchial tube ' (Kolliker), and Its walls become beset with small hemispherical saccules termed air-cells or alveoli." The Bronchial Wall. — The sUnidure of the bronchial wall is essentially fibrous, but It contains abundant elastic and muscular fibres (the former being chiefly longitudinal, the latter chiefly transverse in their direction), in addition to the cartilages which keep the tubes patent, and to the mucous membrane which lines them internally. The cartilaginous hoops (from 6 to 8 In the right bronchus, from g to 12 in the left) resemble on a smaller scale the tracheal cartilages. A three-limbed cartilage, common to both bronchi and to the trachea, adds strength to the junction between the three tubes. It Is not perfectly symmetrical, and the right bronchus, when viewed from within the trachea, therefore appears to occupy more than half the sectional area of the latter. The muscular layer, consisting of unstrlped fibres which are transversely placed, and are inserted not only Into the extremity and along the neigh- bouring internal surface of the hoops, but also into the Inter-cartilaginous structure, Is contained within the fibrous membrane. A few longitudinal muscular bundles lie outside the continuous transverse layer. The white longitudinal strias (or "flutings"), visible Inside the tubes along their posterior wall, are due to powerful elastic bundles placed beneath the mucous membrane, and connected with the elastic fibres which pervade the bronchial walls. The submucous tissue contains numerous glands and some adipose tissue. The miwous membrane, rich In lymphoid tissue, is lined by a layer of columnar. Epithelium, ciliated epithelium, and subjacent smaller cells (Debove's membrane), with scattered lymphoid cells, all supported by a basement membrane. The columnar cells are rendered Irregular at their lower extremity by lateral pressure. Goblet-cells are of frequent occurrence among them. Elongated cells are also seen, possessing a free prolongation upwards, and a simple or forked attachment to the basement membrane. The mucous glands (compound, racemose, with columnar or cubical epi- thelium) lie within the fibrous layer of the Inter-cartilaglnous membrane. But the larger glands are situated more posteriorly, outside the fibrous mem- brane, or partly within Its thickness. The orifices of the ducts, which traverse the muscular and mucous layer, may be seen at the internal surface. Structure of Smaller Bronchi. — The mucous membrane, the columnar epithelium, the elastic and the muscular fibres are all continued for a considerable distance into the lung, almost as far as the smallest tubes. The cartilages soon lose their horse-shoe shape, and their parallel arrangement, and take the form of irregular scales, loosely scattered over the whole circumference of the small tubes, which are cylindrical. Where the latter divide, they possess incomplete cartilaginous rings, and these rings present Transverse muscular fibres ; a few longi- tudinal. Longi- tudinal elastic bundles, Mucous membmne, and Debove's membrane. Lymphoid tissue. Mucous glands, lying ex- ternal to fibrous coat. Cartila- ginous scales instead of hoops. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 23 " a sharp concave ridge projecting inwards into the tube." Progressively Bron- smaller and further apart, the cartilaginous scales are no longer found in i mm. in bronchioles less than i mm. in diameter. Inside the cartilaginous layer, the foserarti- miiscular fibres, completely encircling the tubes, fonn at first a continuous i*g«- coat ; but they are less abundant beyond bronchioles i mm. in diameter ; they occur as separate rings even in the smallest tubes (and also, according to Scattered Moleschott, in company with elastic fibres, at the orifice of alveoli). fibres.'^ The Jibrous coat is represented in the smallest tubes by areolar tissue, and ;ireoiar in the walls of alveoli by an exceedingly delicate connective tissue, kept in elastic *° shape by curved elastic fibrils. ^''"'^■ B.— The Bronchial Blood-vessels. Their Origin. — The bronchial arteries are said to vary in number Bronciiial (from one to three on each side). Their origin is also variable : they may varyfu arise from the aorta or from an intercostal artery. The bronchial veins, number and . ongin. which will be seen to collect only part of the blood supplied by the bronchial arteries, open, on the right side into the vena azygos, and on the left into the left upper azygos vein. Their Distribution. — Although the larger branches of the bronchial vessels lie upon the air-tubes, their area of distribution is not solely bronchial. They supply, in addition : — (a) The lymphatic glands and areolar tissue at the root of the lung. Blood (b) The pleura pulmonalis and the sub-pleural and inter-lobular tissue.* fhrpieurl" (c) They are also believed to distribute nutrient blood to the pulmonary puimonaiis, 1 n ,1 10 pulmonary parenchyma, and vasa vasorum to the pulmonary vessels, &c. substance, glands, &c. The special supply to the bronchial wall ends in two capillary plexuses, capmary The outer plexus, destined for the muscular layer, has transverse meshes ; i^-yers for . .. « ,. mucous the rich, inner plexus, distributed to the mucous surface, presents a longitu- and for J. 1 . muscular dmal arrangement. layer. ^Relation to Pulmonary Blood-circulation. — An important anas- Anasto- tomosis occurs, at the extremity of the smaller bronchioles, between the bronchial capillary plexuses of the bronchial and of the pulmonary circulation. More- ^"'^ ?"'■ , ^ , , monary over it is stated by Zuckerkandl (quoted by Quain) that even some of the capillaries. veins which originate in the walls of the larger bronchial tubes, or in the Some bronchial glands, or at the posterior surface of the pericardium, terminate bronchial veins. in the large pulmonary veins, setting up in this manner a contamination, J^^^l^^^' which must be considered normal, of the arterialized blood within the latter, pulmonary Zuckerkandl (quoted by Landois, loc. cit., p. 223) states that the * The pulmonary pleura and the surface of the lung also receive (according to Turner, quoted by Quain) small branches from the intercostal arteries, which are conducted to the lung along the Ugamentum laium pulmonis. 24 THE BRONCHI AND PULMONARY BLOOD-VESSELS. veins of the smaller bronchi (fourth order onwards) open into the pulmonary veins, and that the anterior bronchial (? veins) also communicate with the pulmonary veins. C— Nerve-supply to the Bronchi. The source of the pulmonary nerve-supply has already been described (see p. 19). Landois' "Text-book of Physiology," translated by Stirling (1885, vol, 1. p. 225), contains the following description: — delation of "Several sections of nerve-trunks are usually found in a section of a fibres to l^i'gQ bronchial tube. These nerves lie inside the cartilages and are in close arteries of relation with the branches of the bronchial arteries. Medullated and non- Numerous medullated nerve-fibres occur in the nerves, which also contain numerous ^ngiia. ^™^^^ ganglia (Eemak, Klein, Stirling). In the lung of the calf these ganglia are so large as to be macroscopic." Mode of " The exact mode of termination of the nerve -fibres within the lung has tenninatiou yg^; ^q ^q ascertained in mammals, but some fibres pass to the bronchial not ascer- "^ ' ^ tained in muscles, others to the large blood-vessels of the lung, and it is highly probable that the mucous glands are also supplied with nerve filaments. In the com- paratively simple lungs of the frog, nerves with numerous nerve-cells in their course are found (Arnold, Stirling), and in the very simple lung of the newt there are also numerous nerve-cells disposed along the course of the intra- In frog pulmonary nerves. Some of these fibres terminate in the uniform layer of inpnu" non-striped muscle which forms part of the pulmonary wall in the frog and monary newt, and others end in the muscular coat of the pulmonary blood-vessels muscle, and ... r •/ muscular (Stirling). The functions of these ganglia are unknown, but they may be vessels. Compared to the nerve-plexuses existing in the walls of the digestive tract." ( 25 ) ANALYSIS OF PEOFESSOR AEBY'S WORK "ON THE BRONCHIAL TREE.". At the time when Professor Aeby's work* was published, no modern No modem treatise of importance was in existence on the subject of the anatomy of the onThis™ bronchial system, and since its publication, as far as T am aware, no other subject. work dealing with the same matter has appeared. Professor Aeby's views have Aeby's been transcribed into various anatomical text-books, and anatomists have oepted either actually expressed their acceptance of them or, by withholding any °ppo°g'ej adverse criticism, have given them their tacit assent. These views therefore rank among the recognized additions to anatomical knowledge, and, as such, they possess a claim to our most careful consideration. The Bronchial Tree of Aeby. — The term " bronchial tree " is The obviously metaphorical, and should be understood as such whenever used in g'te^"?." '* these pages. A literal meaning is however capable of being attached to this expression. According to Aeby the bronchial distribution resembles a tree, not only in possessing branches, but because the branches are all derived from a trunk or stem which preserves its individuality, and its axial character, from its origin to its termination. For each lung this " bronchial stem " is represented by the main bronchus. The alleged breaking up of the bronchus into two equivalent lobar Older view bronchi on the left side and into three on the right, as hitherto described in diyiaion anatomical text-books, has for him no existence in reality. Far from dis- ?* ™*™ • 1 I • 1 1 1 • bronchus appeanng at so early a stage, the mam bronchus m both lungs gives a rejected. succession of branches, and itself proceeds as an independent structure as far as the lower extremity of the lung. Moreover, each of the branches which Monopodio it delivers in this course arises singly, according to a plan of " monopodic outs''™ evolution." branches. Hitherto symmetry was held to be the guiding principle in the pulmonary symmetry structure, and dichotomy was supposed to be the means to that end. But \°l^f°^^ Professor Aeby finds that symmetry holds very limited sway in the lung, and Dichotomy dichotomy he absolutely rejects as contrary to his own anatomical observations. ™*enabie. * " Der Bronchialbaum der Saugethiere und des Menschen, nebst Bemerkungen fiber den Bronchialbamn der Vogel und Eeptilien." Leipzig, i88o. 26 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Theoretical aspects of Professor Aeby's ivork. Facts mingled with theories. From what has been said, a suflficiently clear idea may be gained of the originality of views, and of the boldness in their expression, which charac- terize the work. To use his own words, in " breaking with tradition," Professor Aeby has done signal service to anatomy. He has cast upon us the duty of testing, in the light of his new facts, the truth of older teachings. So long as theories only are proposed as substitutes for the latter, we shall do well to hesitate before we agree to the exchange. And it cannot be denied that Professor Aeby's book, so remarkable in respect of anatomical study, is no less remarkable for the amount of theory which it contains. But his theories are so closely dovetailed with facts, that to single them out is a work of nicety. This will be best accomplished by means of a careful analysis of the book, and by a separate consideration of its various contents under separate headings. With this object, all controversy must, for the present, be postponed. I. — Professor Aeby's Pacts. The facts brought forward by Professor Aeby may be arranged in two classes : A. Facts in refutation of previous anatomical errors. Several of these corrections relate to the behaviour of the main bronchi and of the pulmonaiy artery, and possess great importance. They will be f nlly given elsewhere. New ana- B. Facts of another class are entirely novel. Thus some of the state- facts^' ments refer to individual branches arising from the bronchial stem, in other words, to primary bronchi, which had not hitherto been the subject of anatomical description. This study was unfortunately not pushed far by Aeby ; and the purely anatomical descriptions are few and short. They will be noticed in connection with the systematic description of the bronchial tree. Old errors corrected. Extensive investiga- tion of dimensions of air-tubes, angles of diver- gence, &c. Mensiu'a- tion of the bronchi and of the " Epar- terial," and "Hypar- terial " branches, and of their internodia. On the other hand, within this relatively limited range of anatomy, Professor Aeby has crowded an astounding number of exact observations re- lating to measurement, which render the work a monument of patient research. It would be impossible to do justice to so great a mass of facts even in mere summary. But the following headings will give some idea of the direction which his labours have taken : r. Measurements of the angle of inclination of the main bronchus, and of its branches ; 2. Direction of the bronchial branches ; 3. Measurement of the " eparterial" and of the " hyparterial " sections of the bronchial stem, expressed in percentages of the length of that stem ; 4. Length of internodia separating the first four ventral hyparterial branches, expressed in percentages of the length of the bronchial stem ; THE BRONCHI AND PULMONARY BLOOD-VESSELS. 2/ 5. Length of interval separating the "eparterial" bronchus from the trachea above, and from the first " hyparterial " branch below, compared with the average length of internodia in the "hyparterial" system; 6. Distances of the various bronchial tubes from the bifurcation of the trachea, expressed in percentages of the length of the bronchial stem ; 7. Diameter of the bronchial stem at various heights, expressed in ]3er- centages of the diameter of the trachea ; 8. Diameter of the several primary divisions, expressed in the same terms ; Measure- 9. Eatio between the diameters of the latter, and that of the bronchial stem ; J^jg and"*"' 16. Absolute initial and terminal diameters of the " eparterial" and of the oompara- • 1 n T • •II- tive), of the "hyparterial systems, expressed in square millimetres ; diameter of 1 1 . Relative terminal diameter of the same systems, expressed in per- tubel?"°^^ centages of their initial diameters ; 1 2. Absolute calibre of the bronchial tree at various heights, expressed in square millimetres ; 1 3 . The same, expressed in percentages of the initial calibre ; 14. Aggregate absolute calibre of the right and left halves of the bron- chial tree, expressed in square millimetres ; I 5. The same expressed in percentages of the tracheal calibre ; 1 6. Table illustrating the relations of the primary bronchi to the number of pulmonaiy lobes. Many of the measurements, which have been enumerated above, were Tabuktioa carried out in specimens, or in metallic casts obtained from some 48 in- Mammalia" dividual species, belonging to fourteen mammalian families, and most of the tables, of which there is a great number, include separate columns for the right and for the left lung respectively. In the section devoted to the human bronchial tree the same analysis is and in repeated with all its detail, in connection with specimens derived from a series "'^"' of individuals. But, in addition, elaborate tables are here constructed, which Compaia- show the absolute, the relative, and the average volume of the pulmonary o7the"seTC^- lobes in the right and in the left lung in different sexes, and at various ages, ™i ^'jj'^^ including the later foetal months. ages, &c. A short chapter is devoted to the approximate measurement of the Estimate of pulmonary respiratory surface ; and a concluding chapter deals briefly with vespiraloiy the subject of the bronchial tree in birds and in reptiles. ^'^^'^■ The human section is a mine of information concerning the measurements Measure- of the trachea, bronchi, and primary bronchial branches. It is unfortunate JJJan? ma"do that these determinations should have been made exclusively on metallic casts, f™™ *^® a kind of preparation capable of great perfection of detail, but liable also to casts. serious errors. Such, in distant outline, is the range of the facts ascertained by Professor Aeby. 28 THE BRONCHI AND PULMONARY BLOOD-VESSELS. II. — Professor Aeby's Theories^ The theories, for which Professor Aeby endeavours to find a basis in his anatomical facts are limited to three, but their importance is far-reaching. They respectively relate to : — (a) The existence of a bronchial stem ; (b) The monopodic branching of the bronchial tree ; (c) The distinction between an eparterial and an hyparterial segment in the lung of mammalia, and the essential asymmetry, in man, of the right and of the left lung. Each of these theories must be considered separately in the following pages. ( 29 ) CRITICISM OF PROFESSOR AEBY'S VIEWS. Pbofessoe Aeby's First Theory: The Bronchial Stem viewed as an Axial Structure. In connection with the remarks to be ventured in this criticism, it must be The dis- pointed out that the theoretical nature of the propositions to be considered partly" limits the range of their discussion. Just as Professor Aeby has sometimes theoretical. failed adequately to support his theories with facts, facts may not be forth- coming to overthrow them, and the conflict may of necessity remain one of opinions. A discussion of this kind is not, however, without some utility, ita uses. since it may draw attention to the debatable nature of propositions which have hitherto passed unchallenged, and to the need for decisive facts. The "Bronchial Stem" of Aeby. — Anatomists in the past had The main been content to look upon the remainder left after the delivery of the upper accordiiK lobar bronchus, as the lowe7- lobar hronchus, on the left side, and, on the right *<> t^e older view. side, as the bronchus destined for the middle and lower lobes. With that view Professor Aeby is unable to sympathize. According to him, each lung possesses a fundamental (" gnmdlegendes") Aeby's axial structure, which he terms the " bronchial stem" ; but the axis in question stem/'" is not supposed by Aeby to be symmetrically placed in the lung. Upon this stem, as an independent basis, he appears to rest the whole system of pul- monary architecture. In most quadrupeds the disproportion existing between the " remainder," Contrast or continuation, of the main bronchus is much more obvious than in man ; {^tween and it is from a consideration of their bronchial tree that Aeby derives his ?tem and DITflillCllfiS strongest arguments in favour of the theory of an axial bronchus. Among obvious ' mammalia, man appears to present the only instance in which the existence InSs, of a "bronchial stem" is difficult to recognize at a glance; in Aeby's esti- less so in mation this is a difference rather in degree than in kind. The excellent illustrations in Professor Aeby's work sufficiently demonstrate how well the axial theory fits the anatomical appearances in many mammals. Even in man a continuation of the main bronchus may be traced for some distance in both lungs, as a tube somewhat wider and more direct than those which branch from it. 30 THE BRONCHI AND PULMONARY BLOOD-VESSELS. The bron- cliial stem cannot be identified in lower part of human lung. Professor Aeby's measure- ments point to same conclusion. Opposite ends of the Mammalian series selected as starting- point by Aeby and by the author. Facts and Reasons opposed to the Theory. — But the description of the human bronchial tree, which will he given in Section II., affords proof that in man any distinct trace of the " bronchial stem " of Aeby is lost below the level of the upper third of the lower lobe. The same conclusion may be also derived from an inspection of the photographic reproductions of human bronchial casts contained in Professor Aeby's book. His own measurements are singularly instructive on this point. The third ventral hyparterial bronchus and the bronchial stem are found relatively to possess a diameter of 5'i mm. and 5-8 mm. in the right lung, and of 5 '7 mm. and 6' 4 mm. in the left lung {loc. cit., p. 74), a disproportion which is admitted to be trifling. It might be suggested that it is unfair to discuss, in relation to one particular case, a theory which was devised for general application, especially since this particular case is jDointed out by Aeby as affording imperfect support to the theory. On the other hand, if the whole mammalian class is to be taken into consideration in ■ connection with the question at issue, it must remain matter of free choice which end of the series shall be selected as the point of departure in the inquiry. Professor Aeby has preferred to start from the inferior representatives of the group, which, it is only right to own, are the more numerous ; and the conclusions which he bases upon them are made to apply, not without considerable strain, to the higher representatives also. I propose, with a view to testing the theory, to reverse this march. But I cannot lay claim to that even familiarity with human and with comparative anatomy which adds so much weight to any views expressed by Professor Aeby. In the field of comparative anatomy I am dealing with data, not my own, but for which I am entirely indebted to that obserrer. Although this circumstance detracts much from their value, the following considerations may serve a useful purpose as suggestions arising from an opposite standpoint, and, at any rate, they may throw some side light upon a train of thought developed by the excluside study of the bronchial system m man. Advantages in studying the differ- ences, rather than .tlie simi- larities in the two groups. In man a long ster- num, a Professor Aeby insists mainly upon the points of agreement which he discovers in the two groups. But, by directing attention to the points of difference and investigating their causes, we may step nearer to a correct appreciation of the stem-like appearance described by him ; and we may perhaps succeed in tracing the diversities in its growth to some definite anatomical and physiological influences, instead of calling' to aid abstract morphological tendencies. Difference in the Thorax of Man and of Quadrupeds. — The contrast between the bronchial tree of man and that of most other mammals, to which attention has been called, is associated with a no less striking contrast in the shape of the thoracic cavity and in the anatomical relations of the heart arid of the lungs in the same animal groups. In man the sternum is relatively long, almost reaching to the lower level of the THE BEONCHI AND PULMONARY BLOOD-VESSELS. 3 I dorsal spine, and the diaphragm, between its anterior and posterior points of horizontal attachment, assumes a practically horizontal position. In a large number of '*^ ™^™' quadrupeds, on the other hand, the sternum is short, the dorsal spine extends peds, ster- far below* the level of the xiphoid notch, and the diaphragm acquires an diaphragm obliquity which may be occasionally of considerable degree. Moreover, the oblique. . . ■ . . Differences heart, resting in quadrupeds along the dorsal surface of the short sternum, is in position situated at a relatively higher level in the thorax than in man, in whom it is tSL^o^f' supported by the central portions of the diaphragm, and occupies the entire ^s*'''. ^'^^ distance between the xiphoid notch and the lower dorsal spine. thorax. Besultiug Difference in Bronchial Tree. — The long, narrow thorax of quadrupeds, instead of being, as that of man, shallow and broad, is flattened from side to side, like the keel of a ship, and would present on transverse section a heart-shaped otitline. The vertebral groove of the thorax acquires Vertebral in them considerable depth and width, and being relatively long, it affords feep^nd lodgment for a large mass of pulmonary substance. Indeed, it may be said long in that in these animals the bulk of the respiratory space is to be found in the peds. dorsal and postero-lateral thoracic regions. To these regions air must be conveyed with directness and in quantity. Hence a Hence the continuation of the main bronchus is decidedly dorsal in position, f^Mth and and its channel is both long and wide. Its plane is almost posterior to that length and • • ... -1-111--I1 * dorsal of the heart, which occupies a mesial position immediately behind the sternum, position of From a stem thus placed , long anterior branches would arise at a considerable yon of angle, for the supply of the anterior parts ; and the short posterior branches, ^^™''^"^' recurring at regular intervals, would further accentuate the axial appearance axial ap- of the continuation of the main bronchus. In man the anatomical conditions are widely different. The heart occupies in man the more thoracic space at the base of the thorax than at any other level, and dOTsai! fills the mediastinum from front to back. Thus the main bronchi and their continuation cannot become posterior to it, but they diverge so as almost to embrace it laterally. In other words, the main bronchus assumes a less dorsal, or, in relation to each lung, a more central position in man than in quadrupeds. This central position of the bronchus, taken in conjunction with the relative Hence, shortness of the human lung, and with the almost circular outline of the shorthand inferior aperture of the human thorax, necessarily leads to a breaking up of ™'^'' the air-supplying stem into diverging tubes of almost equal size. Among branches the latter it becomes next to impossible to demonstrate the existence of any radiate '"^' axial tube difiering in value from other bronchi. It is also of importance ^/^j to note that the same circumstances give rise to a, roughly speaking, radi- ating arrangement of the bronchial divisions. Had not the size and position of the heart prevented the bronchus from assuming, in each half of the chest, a strictly central position, the radiating arrangement would probably have presented absolute regularity, and the * The terms anterior and posterior have here the same valiie as in human anatomy. The trunk is to be imagined in the upright position. 32 THE BKONOHI AND PULMONARY BLOOD-VESSELS. " bronchial stem" of Aeby wMch ceases to be recognizable in the lower third of the human lung, would have become incapable of demonstration at a yet higher level. The ap- Conclusion. — It would thus appear that where it does exist, the a^"Son-° bronchial stem is the result of anatomical and physiological necessities, and chiaiBtem" ^jj^t where it is missed, the disappearance is associated with analogous anatomical changes in the anatomical and physiological requirements. It may, there- ?ogicai^^'°' fore, be held that, far from being the expression of an abstract law of notrf* an^' development the axial feature which Professor Aeby finds to be so character- abstract istic of the bronchial tree of most mammals, is in them associated, as a result, with certain anatomical and physiological peculiarities. The almost entire disappearance of the axial type in man strongly suggests that the question is mainly one of adaptation. Pkofessor Aeby's Second Theoky : MoNOPODic Branching in the Bronchial Tree, instead of Dichotomy. Dichotomy Importance of the Question. — The theory of an " axial bronchial questfon Stem " applies only to the main bronchus and to its primary branches. It than the j^^„ jjg jjgj^ q^ peiected without any preiudice as to the characters of the preceding •' _ ^ ■' . . one. bronchial tree in general. But a rejection of the principle of dichotomy would possess much wider significance and should not be entertained without deliberate consideration. There are reasons for believing that dichotomy prevails on a large scale in the depth of the lung. If this were clearly shown to obtain, the primary divisions themselves might, on renewed consideration, be found not to depart so widely from the type in question as was at first suggested by their general features. limited Statement of Professor Aeby's Views. — The description of scope of the bronchial tree by the German anatomist does not extend bevond the investiga- primary branches derived from the main bronchus. As far as they relate to brOTichiS^ this important, but comparatively limited, portion of the bronchial system, tree. jiig remarks are obviously justified by the appearances. To quote his own words (loc. cit., p. 4) : " The bronchial tree is not polypodic, as was admitted on the strength of the erroneous assumption of a dichotomous mode of division, but strictly monopodic. This is also true of the further branching Existence of the lateral bronchi. Departures from this strict law do not, in general^ tomy at'the occur except in outlying districts ; the contrast between stem and branch periphery gradually vanishing as they acquire equality in size, and outwardly assume by him. thereby the aspect of equivalent parts of a common whole. In the terminal divisions this is probably the rule, but on this point I possess no personal information." THE BRONCHI AND PULMONARY BLOOD-VESSELS. 33 Wider Scope of the Author's Investigation. — The present investigation is not confined to any one portion of the bronchial system, and in using the term " bronchial tree," I refer to the entire set of air-tubes, all of which, from the trachea onwards, have been subjected by me to examina- tion. But, whereas Professor Aeby starts from the anatomy of the primary bronchi, and from them draws inferences as to the probable behaviour of the smaller divisions, I am inclined to seek the genuine type of bronchial Gemune architecture in those portions of the bronchial tree which are in intimate type lo'be relation with the respiratory district. This difference in points of view s°."g^t sufficiently explains a slight divergence in the interpretations awarded to respiratory anatomical facts concerning which there can be no disagreement. '^ ™ ' Tracheal Bifurcation — "Why Unequal ? — The first division occur- The main ring in the respiratory tract, that of the trachea, is an uneven one, and this unequal ; is made to serve Professor Aeby's contention. But the obvious inequality in products of the size of the two main bronchi should not make us regardless of the yet abifur- . . rr-t. . cation, more important fact that they are the products of a bifurcation. Their want of equality, as well as that of the lungs themselves, will be later on Their shown not to rest upon any principle of asymmetrical construction, but to be ^u'e'to ' ^ ultimately due to the unavoidable encroachment of the heart towards the left ^°^j*j ""^ °' side. Similar reasoning is also applicable, on either side, to the primary divisions of the main bronchus, the differences between which are most obvious, — although Professor Aeby was the first to draw sufficient attention to their inequality. Dichotomy at the Periphery. — But the trachea and main bronchi The are after all extra-pulmonary; — and their primary divisions are not con- tubes, tained entirely within the pulmonary boundaries. The behaviour of the ^^?^°^^ bronchial tree within the depths of the lung is a more trustworthy indica- dichotomy. tion of the architectural principle upon which both are built. The further dissection is carried within the lung, the less rarely does even dichotomy occur. At the periphery of the bronchial system perfect bifurcation pre- ponderates, and a multitude of simultaneous and equal bifurcations take place immediately above, or at the level of, the furthest bronchial zone. These may readily be seen in dissections as lobular and sub-lobular bronchioles. Moreover, under the microscope bifurcation is found to be. Dichotomy to a great extent, the mode of origin of terminal bronchioles. broncMoieB. Even Dichotomy Unsuitable for the Lung. — Although, even Exceptions in the peripheral districts, instances of want of symmetry occur, their paucity adds force to the rule ; and it may be advanced that dichotomy is unmistakably displayed both at the tracheal and at the pulmonary extremity of the bronchial tree ; and that it constitutes, so to say, the alpha and the omega of bronchial division. But absolute- evenness of Dichotomy, dichotomy is not to be looked for. Due regard being paid to the shape of and omega the thorax, unevenness is more likely than regularity. The products of a ^^o^g^g^i dichotomy which had been carried through with mathematical precision would system. 34 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Evpn dichotomy impossible in the lung. The law of adaptation OTermles others. Dichotomy, in broader sense, im- plied in " mono- podic branch- ings." Tripodio divisions, &o., exist in appear- ance only. One struc- tural principle should suffice in the lung. Mode of adaptation. Disparity of bifurcated tubes equi- valent to disparity of pulmonary districts. Disparity of angles. have fitted ill witliin the pleural boundaries. Nay, even the more elastic principle of "monopodic branching" requires, in its working, to be allowed some latitude. All so-called principles, or laws, are overruled by a higher law, the law of adaptation. But that principle will best lend itself to a wide application which is least restrictive in its terms. In bifurcation pure and simple, in other words in dichotomy not necessarily even, we possess a principle sufficiently broad to cover every individual irregularity of form, and sufficiently comprehensive to contain even that principle of monopodic branching which Professor Aeby advocates in connection with the primary divisions of the bronchi. Uneven Dichotomy implied in Professor Aeby's Theory, — It is obvious from Professor Aeby's pleading that his objections are addressed to even dichotomy, which means the divisions of a tube into two equal derivatives equally diverging from it. But the words employed by him in describing the mode of division which he recognizes, contains the admission of dichotomy in a broader sense. Does not monopodic branching imply that two tubes are invariably the outcome of division — viz., the parent tube, which he considers to be axial, and the lesser tube, or branch from the stem ? In the course of this investigation it will be shown that dichotomy, in this sense, is a rule without exception in the lung. Professor Aeby admits in one or two instances a tripodic division ; but these exceptions exist only in appearance. It is not contested that, for the larger tubes at any rate, uneven dichotomy is the rule, and even dichotomy the exception. But, were it only as a means of asserting that never more than two tubes originate from the division of any bronchus, and that tripodic and tetrapodic branch- ings do not exist, the use of the term dichotomy is both justified and serviceable. If admissible, the principle of dichotomy would save us from the necessity implied in the adoption of Professor Aeby's theory, of assuming monopodic branching at one level of the bronchial tree and dipodic branching at another. It remains for us, however, to consider whether, dichotomy can be reconciled with the instances which are argued against it. By what modifications is the principle of dichotomy rendered capable of adaptation to the varying requirements of shape and of space ? The answer is simple, but the facts are infinitely complicated. Dichotomy Modified by Anatomical Circumstances. — Two bronchial tubes arise from a common parent tube. Their disparity in diameter is their most obvious feature of contrast. Whether this be called over- growth in the case of the one, or arrested development in the case of the other, the difference is exactly correlated with equivalent difierences in the size of the relative pulmonary districts. Moreover just in the measure as these districts difier in their situation, a difierence will also arise between the direction taken by the parent bronchus and that taken by each of its THE BRONCHI AND PULMONARY BLOOD-VESSELS. 35 derivatives. And lastly, in order to suit the variety in shape of the indi- Disparity ot vidual pulmonary districts, the length of internodium of each of the products >'i*b™°'J"^- of any bifurcation will often display considerable disparity. Varying Interuodia. — It may be incidentally mentioned that, in importance general, the variability in the length of internodia plays a very important part °nte™o- °' in the architecture of the bronchial tree ; and, if duly regarded, may serve as '^'"■^• an explanation for apparent irregularities. A comparison of the right and of the left bronchial system is, in this respect, most instructive ; and it will be pointed out later on that some internodia may become rudimentary in one Vanishing lung whilst retaining a fair size in the other, and vice versd. mtomo la. Varying Angles of Divergence. — It is an almost invariable rule The that of two diverging bronchi the smaller one diverges most from the direction tSie of the parent tube. This observation, which lies at the root of Professor ^^^J'^^^ Aeby's theory of monopodic branching and of an axial stem, is not in my estimation incompatible with the assumption of a pervading system of modi- fied dichotomy,* even when the divergence of one of the two branches is infinitely diminished (as in the case of the bronchial stem of Aeby) and when Vanishing this branch appears both in size and in direction to be the continuation of the divergence. parent trunk. The rule holds good even in the case of the tracheal bifurcation, the left product of which is more oblique as well as smaller than the right. But it sufiers an interesting exception in the case of the left pedori-apical bronchus, to be elsewhere described. Cause of the Disparity of Tubes and Angles. — Unevenness in Belay ot the size and in the divergence of bronchial tubes may be largely ascribed, as branchings already hinted in the remarks made concerning the influence of physiological factors, to the relative delay which occurs in the earlier branchings of the bronchial tree, as compared with its more rapid subdivision at the periphery. It results from this circumstance that tubes of large diameter supply to pulmonary districts which they traverse or approach, lateral tubes of relatively small size, and that the latter arise at a comparatively large angle. In contrast with this delayed branching, and comparative infrequency of Evenness divisions at the root, the internodia become much shorter, the angles of towards divergence less uneven, and the bifurcated bronchi less unequal in size, as periphery. soon as the respiratory zone is reached. Yet, even in the depth of the lung, many of the distributing bronchi which supply sub-lobular and lobular branches, present, as a result of peculiarities of environment and of the Here also, necessity for adaptation, an irregular course. Attention will presently be rant^type^' called to some of these aberrant types. Conclusion. — The foregoing considerations tend, in spite oi primd facie ah bronchi Uichoto- mous. * I warmly acknowledge at this stage the courtesy of Dr. Sheridan Del6pine in com- municating to me some of his unpublished observations on the construction of the bronchial tree, and my indebtedness to him for the suggestion of a view which anatomical observation has enabled me to confirm. causes un- evenness. 36 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Size of district and of bronchia correlated. The use of the term " bronchial stem." appearances, to support the view (i)that all bronchi are dichotomous ; and (2) that in any bronchial pair, the greater size of one bronchus is correlated with the greater mass of lung-tissue which it must supply with air. Thus unevenness of size is not necessarily a negative evidence against dichotomy ; and dichotomy does exist, at any rate in the limited sense that never more than two branches arise from any one division. With these reservations in favour of a pervading dichotomy, the use of the term " bronchial stem " is conceded in respect of its convenience ; just as the expression "bronchial tree," conveying a purely metaphorical meaning, was adopted for the sake of brevity. Professor Aeby's Third Theory : The Eparterial and Hyparterial System. This ' theory analysed into de- finite pro- Iiositions. Statement of Theory. — The subsequent remarks will be more readily understood if the fundamental ideas upon which the theory rests are laid before the reader with some detail. For the sake of greater clearness these views have been arranged in the shape of definite propositions, which, I believe, faithfully represent Professor Aeby's own statements. Two borders, anterior and pos- terior. Two surfaces, parietal and "vis- ceral. A tree-like stem. Eight upper bronchus not ventral nor dorsal. Lobes and bronchi asymme- trical. Difference between the lungs as to site of trans- bronchial passage of pulmonary artery. 1. Surfaces and Borders. — The human lung, in harmony with the arrangement of the " lateral bronchi," presents two borders only, which are relatively anterior and posterior ; and only two surfaces, an external or parietal surface, opposed to the thoracic walls, and an internal or visceral surface, which faces on the one hand the mediastinum, and on the other hand the diaphragm (loc. cit., p. 53). 2. Bronchial Stem. — A continuous bronchial stem, or axis, pervades each of the lungs, and from this stem successive bronchial divisions are derived, just as so many branches might arise from the trunk of a tree. 3. "Lateral Bronchi." — In their origin from the stem the bronchi are either dorsal or ventral, with one exception, that of the right upper bronchus, which is neither ventral nor dorsal, but which supplies ventral and dorsal branches as products of its own division. 4. Bronchial Asymmetry. — The right and the left lung are not, in most mammalia, symmetrical in their lobes, neither are they symmetrical in their bronchial supply. 5. The Pulmonary Artery as it enters each lung, bears a definite anatomical relation to the main bronchus, and to its first branch ; but this relation is widely diiferent in the two lungs. 6. The Bronchus Crossed by the Artery. — On both sides the artery crosses the bronchus from before backwards, at a given point, which is constant. But in most mammalia and in man the passage of the artery occurs on the left side hefore any branches have arisen from the bronchus. THE BEONCHI AND PULMONARY BLOOD-VESSELS. 37 All the branches of the left bronchus are therefore situated below the Left lateral artery ; they are therefore termed hyjparterial. The right bronchus on the "™ypar. contrary is crossed by the artery after delivering its first branch. The ^^^('^ pulmonary artery thus separates the branches arising from the right bronchus chi"epar- into two sets, one of which is hyparUrial, the other eparterial. "Typar-° 7. Instances of Complete Symmetry, in Animals. — In a few *®"'^" mammalia the arrangement is symmetrical on both sides, owing to a presencB symmetrical passage of the pulmonary artery ; and in them both lungs ll^^^^^' possess an eparterial and an hyparierial set of bronchial branches. This system" ... in some arrangement is never seen m man. mammals. 8. Pure Hyparterial Type, — In one genus only (Hystrix cristata, its bilateral the hedge-hog), symmetry of an opposite kind obtains. In this animal Hystrix™ neither the right nor the left bronchus bears any branches superior to the °°'y- pulmonary artery. Both its lungs are entirely hyparterial. 9. Eparterial and Hyparterial Distribution. — In respect of their ventral and dorsal branches the eparterial and the hyparterial districts show a marked contrast. Whereas in the hyparterial the ventral and the dorsal branches arise separately from the bronchial stem, in the eparterial system they coalesce into a single eparterial trunk (the right upper lobar bronchus). 10. Upper Bight and Upper Left Lobe not Analogous. — upper left Inasmuch as in man and in most mammalia the left lung does not possess an •^lenT'to' eparterial district corresponding to the right upper lobe, the superior of the ™'^j'f , two left pulmonary lobes, being hyparterial, is the equivalent not of the right Lower upper lobe, or eparterial lobe, but of the right middle lobe which is hyparterial. i'*^.^ But the left infei'ior lobe exactly corresponds with the right lower lobe. 1 1 . Mixed Type. — The human lungs are an instance of a mixed type Mixed type in which only one lung contains an eparterial district. ™ '°°'°' 12. Eparterial Type. — The presence in some animals of a left Eparterial eparterial bronchus in addition to a right eparterial bronchus gives rise, in teriaUTOcs. them, to the true eparterial type. 13. Hyparterial Type. — The absence of both eparterial bi^jtiches, where it occurs (in Hystrix cristata) constitutes the true hyparterial type, which may be looked upon as the lowest morphological expression in mammalian pulmonary architecture. 14. Lateral and Accessory Bronchi. — In man the right and the Four left hyparterial districts are almost identical, each possessing about four ventral bronchi ; and four dorsal branches, in addition to some accessory bronchi. four dorsal; ' •' and some 1 5 . The Left, a Diminished Lung. — The right human lung pos- accessory, sesses, in its eparterial lobe, an additional district, non-existent in the left poseJrsef lung ; in other words, the left lung is deficient in a true upper lobe, such »<> ep^r- as would belong to the complete eparterial type of lungs. upper lobe. Criticism. — Such, in bare outline is Aeby's ingenious theory, which strong^ 38 THE BRONCHI AND PULMONARY BLOOD-VESSELS, belief in the eparterial theory. If inappli- cable to man, the theory is self-con- demned in mammalia in general. Generaliza- tion "was probably applied pre- maturely to insuffi- cient facts. Complete criticism later. Doubt as to the compe- tence of the pulmonary artery as a test for the bronchi. If prece- dence de- termined by bulk,bronchi and air cells would rank first. A ssiiming equality between may be knawn in these pages as the " eparterial theory." Founded upon anatomical research it is considered by its author to be unassailable; and hitherto the event has fully justified that belief. The difiidence with which I approach its discussion is not due to my entertaining a belief of the same nature, or even any doubts ; but rather to respect for the authority which belongs to any views coming from so distinguished a source ; and especially for the great value of the work in which they are conveyed. Any criticisms now ventured against the eparterial theory are pri- marUy directed against its applicability to the genus Homo. In connection with comparative anatomy my opinions can claim only a secondary value. Nevertheless should evidence arise showing the absolute inapplicability of the eparterial theory in man, its applicability to the mammalian series must become exposed to serious doubt. Professor Aeby's whole endeavour has been to unify the bronchial peculiarities of the mammalian genera under one comprehensive scheme. If in the more limited district of human anatomy the theory should prove to be untenable, it is but logical that the arguments by which he has sought to establish the general fitness of his doctrine should complete its refutation in the field of comparative anatomy. Professor Aeby's Facts Correct, but Incomplete. — The facts advanced by Professor Aeby ia connection with the eparterial theory are, obviously correct : we can only object to his having given us so few, Nay, it was a misfortune that the analytical study of the bronchial system, which he has initiated, should not have been pushed further by him before the generalizing methods of comparative anatomy were brought into play. Facts though correct may be incomplete ; and doctrines built upon them in their immature stage may lapse into the rank of theories when further facts give room for larger constructions. The anatomical facts hereafter to be described possess this completing value. Their conflict is with the theory not with Professor Aeby's laborious conquests in the field of anatomy. The Principle of the Theory questioned. — Although the adequate criticism of the eparterial theory must of necessity be postponed to the section of thig work dealing with anatomical detail, it is possible even at this stage briefly to examine the principle which underlies it. A question at once arises as to the competence of the standard used as a test for the morphological value of the bronchial tubes. Are we sufficiently justified in using the position of the pulmonary artery as a qualitative test ? Is it seniority in development, or is it greater physiological importance, which is considered to raise the pulmonary artery so far above pulmonary structures, and to render it standard-giving ? "Were precedence regulated according to bulk, the bronchial tree, taken together with its parenchymatous extension, would be found in mammalia greatly to exceed in cubic space the vascular, and therefore to be more entitled to the first place among all pulmonary structiu-es. Alternative Terminology proposed. — That the lung is pre-emi- nently an air-organ wc may perhaps not venture to assert, for throughout the THE BRONCHI AND PULMONARY BLOOD-VESSELS. 39 animal series the vascular component is a constant one, whereas the bronchial vascular component is only found in air-breathers. In the mammalian lung we ing systems cannot do less than allot to the aerating mechanism at least an even share of !?®ib™^' importance. But if equal dignity should belong to vessels and to bronchi it chiai"aiid would be as plausible to speak of the left pulmonary artery as " c'pihronchial " chiai" and of the right pulmonary artery as " hypolroncMal " as to couple the Greek t^^^^^ prefixes with the name of the blood-vessel. Practical Considerations. — It may be argued however that theo- andprac- retical considerations such as these are not the best guides, and that in ,'sefui ""''"' questions of nomenclature it is wiser to study convenience. This view also may be pleaded in favour of the terms just jDroposed. For it will be shown in the course of the description of the bronchial tree that the employment of such terms as " epihruncMal " and " hypohronchial," although not indispen- sable, would serve a practical purpose in surgical anatomy. ( 40 ) SECTION II. THE DETAILED ANATOMY OF THE BRONCHIAL SYSTEM STUDIED PROM THE BEONOHIAL OASTS AND PROM DISSECTIONS. THE METHODS EMPLOYED. A BRIEF reference to the methods used in the present investigations will serve as a natural introduction to the anatomical description of the bronchial system. The results were obtained by means of a combination of the methods of dissection and of intra-hronchial injection. The two methods may be con- veniently considered under separate headings. A. — Dissection. i. Dissection of Non-injected Lungs. The speci- Mode of Performance. — For this purpose lungs were used either mens used. fj.ggjj^ Qp after short maceration in water, or after jpreservation in spirit. A successful dissection of the bronchial tree is essentially a work of patience. Difficulty The difficulty varies with the completeness which it is desired to attain in with'cmn- ^'^® preparation, and culminates in the dissection o£ specimens intended to piexity of show all three tubular systems in their mutual relations and in their relation to the pleura. Professor Aeby rightly points out that a lung, when slightly A sodden sodden, becomes easier to dissect. Lungs derived from the post-mortem room lung °^ ^^^ differ much, according to the variety of their pathological conditions, in their favourable, fitness for the object in view. For the rest the usual methods and instruments ^A\\^n°t' of dissection, a dissecting board and a large assortment of pins of various Necessary sizes will answer all requirements. imple- ments. ij. Dissection of Injected Lungs. Curved Dissection Compared with Maceration. — The process of clean- forceps and jjjg ^,y disscction the casts of the injected air-tubes and blood-vessels is one SClSSOffaj cK'Ci of excessive labour and difficulty. It is well to be provided with an assort- THE BRONCHI AND PULMONARY BLOOD-VESSELS. 4 1 menfc of forceps and scissors with varying lengths of blade and different curves. But, even armed with the best weapons, the dissector will scarcely Dissection escape the disappointment of being compelled to sacrificCj for the completion an^ de-' of. his task, many of the finest and most ornamental ramifications of the ^truotive to .... _ , - finer injec- mjection. i had, lor the same reason, and on a very large scale, to submit tions. to this almost unavoidable disfigurement of my specimens. The latter were, however, dissected with ordinary forceps and angular scissors. The alternative method, that of putrefactive maceration, is greatly to be preferred, whenever Maceration, applicable. B. — Intra-bronchial Injections. The Injection-mass. — The only material which can be recommended Fusible is fusible metal. I owe to Dr. Sheridan Delepine the suggestion of this "^'''^' excellent method. Numerous mixtures of wax, paraffin, resins, &c., were tried in vain. Attempts to inflate the lungs permanently by passing through them a continuous current of dried air ended likewise in complete failure. The fusible metal used had the following composition : — its com- position. Tin ..... 2 parts Lead Bismuth . Cadmium The melting-point of this alloy is 158° F. 4 7 I i. Injection of the Lungs, in situ, before opening the Chest. Drawbacks to this Method. — Of this proceeding I have no personal Method experience. It is described by Professor Aeby as being extremely simple, mendl'd by Were it as successful as it is stated to be easy of performance, its results Professor would surpass in respect of anatomical truthfulness those attainable by any its nncer- other method. But, judged by the photographs of specimens prepared by ^e'^u^nt"^ Professor Aeby with its help, it appears to be uncertain in its operation, and failures. it must probably be held responsible for some of those conclusions of that eminent observer with which I am unable to agree. It is only right to suggest that the principle of intra-cadaveric injection may have been less at fault than the manner in which it was carried out. But, under the most favourable circumstances, there are still inherent objections to its use, some of which may be enumerated : (i) Inability to judge of the fitness, or otherwise, of the organs to be inherent iniected. objections J _ to its use, (2) Inability to drain the air-passages from any accumulated secretion, (3) Inability to empty the contents of the pulmonary blood-vessels, and to control absolutely the factor of post-mortem hypostasis. 42 THE BEONCHI AND PULMONARY BLOOD-VESSELS. (4) Difficulty arising from cadaveric coldness in nortlaern climates. (5) Absence of any outlet for tlie pressure of air produced by the injection (if forcible). (6) Inapplicability of this method to the injection of the pulmonary blood-vessels. Fig. I. E F H ]'] ^•'i D ]•] Front view of Beokchial Teee, dissected and peeseeved in the WET STATE. (From a ritotograph.') The side of each square in the frameworlc measures 2 cm. The specimen was obtained from the body of a child affected with old scrofulous disease. Irregular naasses of calcareous matter are seen below the trachea, and in the right pulmonary root. An increase of the peri-bronchial fibrous tissue, and a slightly webbed condition of the bronchi of the right lower lobe are additional abnormal- ities. The relations of the bronchi are somewhat disturbed, owing to the tubes being all pinned to a plane surface ; and to some of them having been forced into unnatural positions. In this manner the right posterior-horizontal bronchus and its branches are shown in square C iv ; part of the left posterior-horizontal's distribution occupies square F v, &c. It may 1)9 I^ spitc of these drawbacks (which, in pioneer- experiments for the serviceable (jletemiinatioii of the normal features of the bronchial tree, were but too in SOTllG ' cases. likely to give rise to erroneous results), its employment for the elucidation THE BRONCHI AND PXJLMONABY BLOOD-VESSELS. 43 of special points may present great advantages, and it is well suited, as a preliminary step, whenever a subsequent injection of the blood-vessels, after removal of the lungs from the thorax, is intended. 11] ^',1 V1.1 VI 1,1 Fig. 2. B C D E F G H mssssssm K JL iij VI. I Vll] D E F G H K Dey Specimen of the Beonchial System: front view. {From a Photograph.) Dissected and pinned in the moist state, subsequently stiffened by drying. The wires of the frameworli cross each other at intervals of 2 cm. The bronchi had been severed from the trachea at the autopsy by jagged cuts. Many of the small ramifications have disappeared, especially on the right side. Moreover the right cardiac, anterior-basic, and posterior-horizontal districts are not displayed to advantage ; and the left pectoral distribution has been raised above its normal level, disclosing the posterior-horizontal distribution. ij. Injection of the Zungs after Bemoval from the Body. Advantages and Objections. — This method has yielded good results Method in my hands, and with sufScient care is capable of complete success. It the^aufhof presents some facilities for manipulation in which the other method is deficient ; but the loss of the natural support afforded by the thoracic 44 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Its defects, parietes adds greatly to the difficulty of its performance and to the danger of a shifting of the specimen, or of a disturbance of its normal relations, during the injection. This danger may be avoided with the help of appro- priate mechanical means. Prepara- tions for a simple and for a com- pound injection. Simul- taneous injections not tried. The ap- paratus. Mode of perform- ance. Tempera- ture and pressure employed. Pressure- gauge not used, but desirable. Aeby uses no pres- sure ; imperfect injections in conse- quence. Modus Operandi. Preliminary Measures. — The lungs are secured in a manner which allows room for expansion, without any disarrangement of their normal relations, and the necessary cannulas and fittings must be fixed into the orifices of the tubes to be injected with metal — namely, in the case of an intra-bronchial injection, into the inferior orifice of the larynx, or lower down into some part of the trachea; in the case of an intra-arterial injection, into the common trunk of the pulmonary artery; in the case of an intra-venous injection, into the inferior part of the left auricle ; and lastly, in the case of a threefold injection, into each of the orifices mentioned. The metallic tube conveying the heated metal is made continuous with the cannula, and the metal is injected under moderate pressure u.ntil a steady resistance is felt. When more than one set of tubes were dealt with, the several systems were injected in succession. Simul- taneous injections were not attempted; but they would probably yield very good results. A previous warming of the lungs, and the application of tolerably strong heat to the metallic tube near its pulmonary end, imme- diately before the passage of the fusible metal, are precautions which I have found essential to the success of the injection. The Injecting Apparatus used by me consisted (i) of an ordinary tall, broad-necked bottle, provided with two tubes (the longer one being metallic and reaching to the bottom) ; (2) of a pressure-bottle, provided with proximal and distal taps ; and (3) of a stomach-pump for the supply of compressed air. The bottle containing the fused metal was immersed completely in water kept boiling, and it was connected, on the one hand, with the pressure- bottle, on the other hand with the cannula. As soon as, by a turn of the tap, the compressed air had been admitted, active pumping was used for the purpose of keeping up and increasing the pressure. The amount of pressure applied at the onset and subsequently, and the amount of resistance which was taken as an indication to cease pumping, were not registered in any way, as they might have been with advantage, but were entirely left to appreciation by muscular sense and by personal expe- rience, which proved to be satisfactory guides. Active Pressure Indispensable. — The employment of pressure is of primary importance. Professor Aeby thought that in the supine subject, the proper weight of the metal, when it was poured into the trachea, was sufficient to inject the bronchial tree. This, doubtless, would be the case with THE BRONCHI AND PULMONARY BLOOD-VESSELS, 45 any permanent fluid of high density ; but, with fusible metal, his results plainly demonstrate that it is otherwise. Some additional pressure is re- quired in order to obtain the necessary velocity and to convey the fased metal into the smaller tubes within the brief delay which precedes the solidification of its surface. The Avoidance of Undue Pressure was partly secured, in Too much my own injections, by the imperfection of the joints in my apparatus, ^^^s^X" and by the elasticity of the india-rubber which formed most of the connec- ^,ia'ed T. T -1 through tions. But every operator must be prepared to learn experience at the cost elasticity of of a few failures, in the direction of either too little or too much pressure. " ™^' "' Failures and Faulty Results. — Eupture of the lung, should it occur, resulting in general escape of the injected mass, irretrievably puts an end to the experiment. But more serious than this form of disaster would be the error of mistaking, after maceration, the cast from an im- Errors to be perfect injection for a faithful representation of the bronchial tree. Errors the sludy'of of this kind I have sought to avoid by comparing the casts with the results isolated of numerous collateral dissections of non-injected specimens ; and by giving jj^^ i^^gj the preference to the method by dissection as a means of isolating the cast, avoided. Maceration removes all collateral indications which might throw light upon deficiencies in the injection. But, where the bronchial membrane is allowed to remain in contact with the metal, tubes which the latter did not reach are still there to tell the tale. Concluding Kemarks. — The process of injection by this rough and Difflcuitiea, ready method demands of the operator quickness and judgment at the time ^^^ ^^^ of injecting, in addition to a laborious preliminary preparation. That the ^^sj^^ difficulties are not excessive even in the case of a triple injection is shown operator, if by the fact that the writer's successful injections, reproductions of which are duiy"pre° contained in this book, were conducted from beginning to end without P*'^^'*- human aid or witness, although in other less fortunate injections the intelli- gent help* which he received was truly welcome. ♦ Mr. Artlett, anatomical-attendant, and Mr. Philpot, museum-attendant, at St. George's Hospital, have both deserved my thanks for their faithful and willing services on various occasions. ( 46 ) THE METALLIC BEONCHIAL CAST. General Eemarks on Metallic Bronchial Oasts. Good Shortcomings and Fallacies in Metallic Casts. — Whether for Ss't"/'"' study, or for demonstration, a good metallic cast of the bronchial tree presents superior to advantages which cannot be surpassed by those of any other method at present prepara- in USB. Certain drawbacks are however insepai'able from these advantages, tions. jj^ ^j^g gj.g|. pjg^Qg casts of the bronchi in general, but more especially metallic casts, fail even to suggest the qualities of lightness, of pliability and of Their mobility, which characterize the air-tubes and the blood-vessels of the lung: "I'^j'y ^'^ they are rigid to a fault. Moreover, whereas in a non-injected lung the The weight mutual relations of the bronchi vary within deiinite limits corresponding to metal may ^^^ State of extreme distension and to that of extreme collapse of the lung, deflect the ^}^q injection of a heavy mass within them is capable of materially altering these relations, if sufficient care be not exercised; and any artificial position of the tubes, brought about in this maimer in a cast, is thenceforth permanent, the pres- , Again, owing to the rapid cooling of the fused metal it is difficult, within qdre^'may the brief delay, to inject enough metal to fill the peripheral tubes without ™^^™'y employing an amount of pressure which may lead to over-distension and some ; unevenness of those tubes which are situated nearer the trachea. Thus on remain the One hand metallic tube-casts are seldom evenly regular ; and on the uumjected. Q^jjgj. t]jg tubes may receive too much, or too little, or none of the metal injected. The last-named is by far the most common defect. Intra- Degrees in Completeness of Injection : its Tests. — An abso- 'ectira not ^^^^ty perfect pulmonary injection would fill the intra-lobular structure as wanted. well as the bronchial branchings. A cast of this nature would be too complete to be of use for the study of the bronchi, inasmuch as the latter would be deeply buried in the midst of their injected lobules, and altogether hidden from sight. A less perfect, but more serviceable degree of injection is that which reaches, but does not go beyond, the lobular bronchioles. Bronchioiar The uniform presence of the casts of the latter in all the parts of a teste '^ bronchial injection may be taken as an adequate test of its completeness. THE BUONCHI AND PULMONARY BLOOD-VESSELS. 47 On the contrary, wherever the bronchioles are missed, the value of those tubes which carry injection can he judged only approximately from their individual appearance. If the surface of a tube-cast be plainly indented other with transverse striae, corresponding to the circular muscular fibres, and if its f™ fub/-^ ^ diameter should present no sudden diminution, excepting at the seat of a ''^''^^' bifurcation, a strong inference exists in favour of the injection of the said tube and of its immediate derivatives having been complete. Nevertheless, sometimes even then, we should bear in mind the possible contingency that one or more of its branches may have failed to admit the fused metal, owing to a tempo- rary obstruction at the orifice. Incomplete Casts. — All metallic casts 'which show only the larger causes of tubes, must be regarded with considerable suspicion. The failure of injection n"'^s°s™^ of the medium-sized tubes in such cases can only be explained (i) by an imperfect supply of metal, or (2) by an imperfect amount of pressure, or (3) by too rapid a cooling of the injection-mass. Any one of these causes, operating singly, would vitiate the experiment, and might lead to the non- injection of one or more of the big tubes, and concurrently to the absence of any trace of the small-tube injection. Unequal Kesults in Right and Left Lung. — It is important inci- Left dentally to point out that the right and the left lungs difier in the readiness jiumore with which they receive a metallic injection, and the two casts are apt to ^re- readily, sent a marked difference in the fulness of their detail. In my own experience the difference has invariably been in favour of the left lung, the bronchi of which have been completely injected even in cases where somewhat impor- tant bronchi in the right lung had failed to be filled. This difference in Suggested behaviour of the two sides of the bronchial tree is probably correlated with the greater length of the left bronchus, and with the smaller distance which separates its apical and basic branches. I have dwelt, at some length, upon this part of my subject, in view Incomplete of its practical importance. It is clear that metallic casts should not be trust- implicitly trusted, unless obviously complete in all their branchings. I have uX'ss'com- not succeeded in obtaining perfect injections of this kind ; but those which P^^ed with I have obtained have been carefully checked by comparison with numerous dissections of the non-injected bronchial tree, some of which were studied in the moist state, and others, after drying. A similar precaution is to be recommended in all cases. General OoNfiGURATioN of the Metallic Cast of the Bronchial Tree. The Great Anatomical Gap in the Cast. — When viewed as a whole, and from a moderate distance, the metallic bronchial cast yields a rough reproduction of the outward shape of the lung. First to attract 48 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Transverse notice, as an apparent defect, is a considerable interruption of outline, nghtrast. corresponding to tlie interval between the right upper lobe, and the middle and lower lobes. A broad transverse gap extends from the outer border of No iudica- the lung to the root, and from the upper lobe to the middle lobe. Comparison in fresh with the dissected specimens clearly shows that this is not a failure of lung. injection, but an anatomical gap. In the fresh lung, this gap is not foretold Situation by any break in the outline of the visceral pleura. The left bronchial cast and m left presents no gap in the situation described ; but its equivalent is found in entf ^'^'^'^' ^liother position. In it the trachea and the pulmonary apex are separated by a much broader interval than is the case on the right side. An inspec- tion of the specimens with triple injection shows that both these gaps are Left gap occupied by blood-vessels. The transverse gap in the right bronchial tree BiooT ' accommodates the right lower pulmonary artery, the upper division of the vesselscon- pulmonary vein, and some of their branches. The vertical gap, in the apex of the left lung, is filled below and inwards by the arch of the aorta, and externally to this by the left pulmonary artery, and by one of the branches of the left pulmonary vein. Eeiatione The Encroachment of the Pulmonary Artery occurs, therefore, diffe?'^ not only at different levels in the two lungs, but on opposite sides of the bronchial tree, viz., on the inner side of the left and partly on the outer side of the right. Moreover, on the left side the gap is not bounded above as in the right cast, by a bronchus following a transverse direction. Separate No Other difference of equal importance is noticed at first sight between of rieM°° ^^® *^° casts. But want of perfect agreement in details becomes evident and left on closer inspection. For this reason it is impossible to give a single sary. description which shall suit both lungs; each lung must be dealt with separately. In connection with the preceding remarks, and with those to follow, the reader should consult the illustrations, more especially those of the metallic cast (figs. 10 and 1 1) and the diagrams (figs. 6 and 9). ( 49 ) EEMARKS ON THE NOMENCLATURE OF BRONCHI AND BLOOD-YESSELS. Significance of the Absence of a Bronchial Nomenclature. — No serious attempt appears to have hitherto been made to construct a systematic nomenclature of the air-tubes. Beyond the point of bifur- cation of the main bronchus into lobar bronchi, they cease to be known by individual names. This absence of a nomenclature may be taken to No uomen- indicate that the need for a nomenclature had not been experienced, arguesno In this afasence lies also a further admission, viz., that the bronchial need felt for J- M • 1 T 1 ■!-> '"® same, distribution had not been made the subject of a systematic study. Bronchial and no tubes are still spoken of as being of the first, second, third, or other order, stiid™'* '" This kind of classification may be theoretically satisfying to the mind : it is Old nota- nevertheless singularly inadequate for the purpose of expressing anatojnical adequate. conditions. Accuracy and clearness of description are not to be attained without the assistance of some more definite terms. Professor Aeby's Classification. — The old classification was not Aebys found sufficient by Professor Aeby in his inquiry into the bronchial system, nomfcci™ and there is special significance in the fact that, just in proportion to the t"™ pro- scope of that inquiry the old nomenclature, or, more aptly, the old system to scope of of notation was modified by him. His investigation being limited to the qlfiry. primary branches of the main bronchus, he did not suggest any departure from the current terminology for bronchi of smaller size. But the early branches studied by him were designated under new and more descriptive names. Had his anatomical description extended further, he would have Definite felt the necessity for a more complicated and a more definite nomenclature, oiogyan Indeed it may be said that in so intricate a study as that of the bronchial indispens- system the naming of individual constituents is not only an object m itself, but dition for also an indispensable condition for the accomplishment of the anatomical task, study!^" We may so far anticipate the description of Professor Aeby's nomen- professor clature as to mention that whilst referring to the several primary branches of ^^^?.'^ the main bronchus to the extent of stating their exact number, he was con- a mere tent to classify them according to certain characteristics into three series, tion of oia In each of these series individual bronchi were distinguished only by a °°®' numeral. In this respect the new nomenclature was not much more than a further elaboration of the old one. And in connection with this fact it 1'.'^ descrip- . . tion like- wiU hereafter be seen that although he had gone so far as to isolate and wise not so THE BRONCHI AND PULMONARY BLOOD-VESSELS. anatomi- cally com- plete. Objections to old numerical method : number, and uneven value of tubes. Specific names rec[uired. Localiza- tion, the principle in their selection. The same applicable to blood- vessels. Lettered notation ; its object. enumerate the various primary branches, their complete anatomical descrip- tion was not attempted. The Present Investigation has for its object to attempt a definite description of the anatomical features of individual bronchi, not only of the primary order but of more advanced series. With this purpose in view, a first objection to the old numerical method of notation is discovered in the multiplicity of the tubes to be designated. But yet greater difficulties stand in the way of the adoption of the old plan, difl5culties connected with the peculiarities of the bronchial distribution. Had the attempt been made to treat each individual bronchus as the local representative of a certain degree of relationship to, or better, of descendance from the main bronchus, values of the greatest diversity, in respect of size, would have been repre- sented by identical numbers ; for a considerable difference in the size of tubes of equal degree of descendance is but the natural outcome of the great differences in the length of the internodia between successive bronchi, and of the prevailing unevenness of dichotomy. Moreover little help would have been offered by this notation towards the localization of the various tubes. The Employment of Definite Names in addition to numerals was unavoidable, for the reasons which I have stated. But the selection of suitable terms was felt to be a responsible duty. Bearing in mind the practical object to be attained, as well as the difficulty which the reader would inevitably experience in mentally identifying the position of any tube of which he was perusing the description, I thought it expedient to notify as much as possible, in the names given to the bronchial divisions, the thoracic region, or the pulmonary district, or the neighbouring organs, which would most clearly define the exact situation of the tubes. With what measure of success this intention was fulfilled the subsequent matter will afford an" opportunity to judge. Whether or not the majority of the names may be found to deserve permanent adoption, they will, at any rate, serve the temporary pmposes of description in this book. Nomenclature of Blood-vessels. — In the nomenclature of the pul- monary blood-vessels the same principle was made to serve. Indeed, with few exceptions the names applied to the bronchi were also applicable to the blood-vessels, or at any rate to the arteries, and their adoption presented among other advantages that of uniformity. Synoptical Tables of the bronchial ramifications have been constructed. They will probably be useful in conjunction with the diagrams, and with the reproductions of actual specimens. A Lettered Notation associated with a number indicating the degree of relationship to the main bronchus has been appended, in the systematic description, to each of the bronchial tubes described. The object of the notation is to facilitate the endeavour to follow, mentally, or on the plates the successive changes in direction suffered by the air channels from the trachea dosvn to any individual tube. Its principle will be explained at the beginning of the detailed anatomical description. ( 51 ) PROFESSOE AEBY'S NOMENCLATUEE AND THE AUTHOE'S ELEMENTAEY NOMENCLATTJEE. Pkeliminaey Observations. The Three Classifications. — Reference has been made, in the The old preceding pages, to three nomenclatures or classifications : ( i ) the old tion^ '^^' classification, (2) Aeby's modification of the old classification, (3) the new f^^Xhe classification devised by me. Of these, the last two only require special Authors, notice ; and I now propose to take them jointly into consideration. nisk of a Confusion in Ifames. — The object of a nomenclature being Danger of to provide the means of better distinguishing from each other the bronchial "nlhlf'"" tubes, and of thereby facilitating the study and description of the bronchial •>a"»'^^' .^ system, our first duty is to avoid any measure capable of adding fresh com- takes in plications to that study. The danger of aggravating existing confusion is incidental to all new nomenclatures, but more especially to a nomenclature of the bronchial tree. The danger in this case is of two kinds. There is a risk of a confusion in the names, and there is also a risk of a confusion between the tubes to which the names refer. Thus the names themselves might be multiplied unnecessarily ; or such Various of the older names as could have done good service might be rejected, whilst beavoided less suitable terms might be put in their place ; or again a given name '" "■"^ _ possessing, in an earlier nomenclature, a certain meaning, might be introduced mendature into a later one with a different significance, and thus objects essentially different might run a risk of being thought identical or alike. These are but a few of the faults of which a new nomenclature is capable. Risk of Mistaking Identity of Tubes. — Quite as serious is the Confusion confusion which, apart from any doubt connected with the terminology, may tnbrs^due affect the names in their appKcation to the tubes. It must be remembered *° *™l[ ^.^_ that, between the various bronchial tubes, there is much resemblance. To sembianco determine, in the actual specimen, which tube is meant in the nomenclature under a given name may be a task of some difficulty. The risk of confusion grows and becomes complex, when a second nomenclature is added. Necessity of Reviewing Aeby's Nomenclature. — Some of the a previous dangers to which I have hinted may be obviated by obtaining a full prelimi- of Aeby's nary acquaintance with the nomenclature which it is desired to supersede tu™^"'''*' needed. 52 THE BRONCHI AND PULMONARY BLOOD-VESSELS. bsfore venturing to suggest any other in its place. It is therefore necessary that I should give a complete account of Professor Aeby's nomenclature, before I proceed to propose my own. In connection with the latter it will be my endeavour to avoid any chance of a misapprehension as to which tubes Some ob- in the specimen correspond to the names. But, with regard to Professor the latter. Aeby's classification, I cannot entertain the same confidence, feeling some hesitation as to the identity of some of the tubes to which he makes allusion. I shall call attention to this uncertainty wherever it exists : in all other cases it will be understood that any doubt as to identity is excluded. Comparative Study of both Nomenclatures. — The preliminary considerations into which I have entered will probably suffice to explain the advantage likely to accrue from the comparative study of the two nomen- clatures. The simplest and the most effectual way of comparing them is to view them simultaneously ; and, with this object, I have arranged them side Synoptical by side, in the shape of synoptical tables. (See pp. 54, 55.) Moreover, in merit of Order to guard against the danger of any mistake in identifying the tubes in ando^f question, and to further facilitate reference, I have likewise brought into diagrams, juxtaposition diagrams representing the two schemes of the bronchial tree (see "next page), my own and that of Professor Aeby. Pkofessok Aeby's Nomenclature of the Bronchial Tree, studied FROM THE Diagram. Professor For greater clearness in the exposition of Professor Aeby's views I have dia^ara. Ventured to reproduce, from his work, the diagram representing the front aspect of the bronchial tree in man. Tbe"bron- The Diagram, (fig. 5) gives special prominence to the "bronchial '^Y'^^,, stem" (of Aeby). The trachea, the main bronchus of each lung, and the shaded for bronchial stem, which is but the bronchus continued, are all readily identi- recognition. fied in the drawing. The annular shading which represents the cartilages of the trachea is continued downwards along the main bronchus to its extremity; and this tube is represented as axial. The shading, which is confined to this one tube, has presumably no significance beyond facilitating the recogni- tion of the bronchial stem ; and does not convey the meaning that any difference in the structure of the bronchial walls exists between this tube and its branches. No statement suggesting such an interpretation is made by Aeby. The Pulmonary Artery. — The important difference in the situa- tion of the right and of the left pulmonary arteries is also made con- spicuous : it will be noticed that the vessels are here represented in section at P. and P. Lateral Bronchi. — Two sets of branches are seen to arise from the stem. They are lettered in two series as v. i ; v. 2 ; v. 3 ; and v. 4 ; these tenaiven- are, in both lungs, the Tiyparterial ventral Iranches : and as d. i ; d. 2 ; d. 3 ; Fig. s- Pbofessoe Abby's Diagram of the Bronchial Tree ; feont view. B. ff.: Main bronchi, arising from the trachea, and, in either lung, continued into the bronchial stem. c. i Cardiac bronchus (not represented in the left lung). c?„ dj, d^ d, : Hyparterial dorsal branches, evenly present on both sides. ep. . Eparterial bronchus, found only in the right lung. Its ventral and its dorsal divisions are shown. «„ Uj, v^ V, : Hyparterial ventral branches, evenly present on both sides. P. P. : Situation of the right and of the left pulmonary artery after crossing the bronchial stem. Fig. 6. ax. b. Author's Rough Diageam.* (For more accurate detail constdt diagram fig. g.) The aorta and, below this, the left pulmonary artery are seen above the left bronchus. — Below and to the left of the left pulmonary artery are seen (i) the left upper lobar bronchus, (2) its ascending branch, the pectori -apical, and (3) its descending branch, the cardiac. — Immediately above the right pulmonary artery, is the right upper lobar bronchus, or pectori-apical. To the inner side of the artery arises the cardiac— The letters a., ax.,p., indicate in both lungs respectively the apical, the axillary, and the pectoral distributions. — p. h. points to the extensive posterior-horizontal district ; some distance lower is seen the small lesser posterior-horizontal bronchus. — a. b., ax. b. represent the anterior- and the axillary-basic districts ; c. ; r. c, the cardiac and the retro-cardiac branches. The posterior-basic distribution is shown behind the anterior-basic bronchi. * Details are not snfSciently faithful in this diagram, which was not drawn by myself : but it will give a rough idea of the position and distribution of the larger tubes. THE BEONOHI AND PULMONARY BLOOD-VESSELS. S3 and d. 4 ; these are the hyparterial dorsal branches. All these hyparterial trai and branches receive from Aeby the name of " lateral bronchi." brauches. The Eparterial Bronchus. — The left bronchial stem carries no other Eparteriai branch. But the right bronchial stem gives rise to a large bronchus (Ep.) ^'"°°'=''"^ ; immediately above P. ; and lower down, and towards the middle line, to a smaller one C. The important branch (Ep.) is, in Aeby's terminology eparterial. It divides its ventral into anterior or eparterial ventral branches, and into posterior, or eparterial branchea dorsal branches. Disparity of Left Lung. — If, in the diagi-am, the outline of the Absence bronchus (Ep.) be temporarily covered, so that its origin and its branches be (j,;p.)"and' hidden from view, the right bronchial tree will have the appearance of being p) '" ^"^^ almost identical with the left. The members of the ventral and of the dorsal series in both would then correspond with each other almost exactly, with the sole exception of the branch 0, which does not appear in the left bronchial tree. "Cardiac Bronchus" of Aeby. — The origin of the branch (C) is origin of seen to be neither ventral nor dorsal, and therefore excludes it from the two bionXus series previously mentioned. It is described as the " cardiac bronchus," being ^g^t°.°j g^. the only air-tube upon which Aeby bestows an individual name. dorsal; Occasional " Cardiac Lobule." — It is not suggested by Aeby that its con- bronchus (0) is otherwise than constant — on the contrary special prominence aiobuie is awarded to it, owing to its constancy, to its size, and to the circumstance i^ometnnea that in some animals it forms the basis of a separate lobule in the right lung, to it ; It must be noted however that no cardiac branch is described by him as from left forming part of the left bronchial tree. '"°^' Accessory Bronchi. — In spite of its constancy, the cardiac bronchus it serves is made in Aeby's nomenclature, to serve as the type of an inferior class of ly^f^"^'''' air-tubes. These are the accessory bronchi (" neben-bronchen "), so termed on "Accessui-y . nni .. T bronchi;" account of their apparently less regular and less constant situation. In theii- contrast with this exceptional instance, the accessory bronchi are stated to be- Src'hLi' subiect to variations, in their number and position, in the several mammalian ?'**• "f , J ' ■*■ ; ^ lower lobe, classes. But, in most of the latter, they are specially abundant in the lower to inner part of the bronchial tree ; and they occur always on the inner side of the etem ; tUeir bronchial stem (loc. cit., pp. 6 and 7) and most frequently possess a down- ^"^^^ ward direction. wards. The Bank of Accessory Bronchi. — As far as I have been able They are to gather the meaning of the remarks of the German author, these tubes do secondar ^■ not possess the value of typical primary bronchi ; they are rather to be but. by regarded as the dorsal and the ventral branches of the latter, — in other may arise words, as " secondary bronchi." Whenever, as in the lower portions of the but°do'n™t' bronchial tree, they arise directly from the bronchial stem, this is the result even then of a transfer (Uebertragung). Neither their origin from the stem, their typical ■ number, nor even their size, should be allowed to establish a confusion '"^^ '' ( 54 ) NOMENCLATURE AND ORDER OF THE PRIMARY BRANCHES OV THE MAIN BRONCHUS, OR ITS CONTINUATION, COMPARED WITH PROF. AEBY'S NOMENCLATURE. RIGHT LUNG. AUTHOR'S NOMENCLATURE. AEBY'S NOMENCLATURE. 1. Upper-lobar Bronchus (or Rt. Pectori-apical B.) 2. Middle-lobar or Cardiac Bronchus 1. Eparterial Bronchus. 2. First Hyparterial Ventral Bronchus. 3. Posterior-horizontal Bronchus 3. First Hyparterial Dorsal Bronchus. 4. Retro-cardiac Bronchus 4. Cardiac (Accessory) Bronchus. 5. Anterior-basic Bronchus 5. (?) Second Hsrp arterial Ventral Bronchus. 6. Lesser Posterior-horizontal Bronchus 6. (?) Second Hyparterial Dorsal Bronchus. 7. Axillary-basic Bronchus 7. (?) Third Hyparterial Ventral Bronchus. 8. (?) Third Hyparterial Dorsal Bronchus. 9. Posterior-basic Bronchus 9. (?) Fourth Hyparterial Ventral Bronchus. 10. j» jj 10. (?) Fourth Hyparterial Dorsal Bronchus. N.B. — A query placed before some of the names given hy Prof. Aehy signifies ', ( 55 ) NOMENCLATUEE AND OEDEIl OF THE PRIMARY BRANCHES OF THE MAIN BRONCHUS, OR ITS CONTINUATION, COMPARED WITH PROF. AEBY'S NOMENCLATURE. LEFT LUNG. AEBY'S NOMENCLATURE. 1. 2. First Hyparterial Ventral Bronchus 3. First Hyparterial Dorsal Bronchus AUTHOR'S NOMENCLATURE. (Left Pectori- 1. Upper-lotaar Bronchus/ apical B. (or Bronchus Impar)\ \ Cardiac Bron- chus. 3. Posterior-horizontal Bronchus. / Retro- cardiac Bronchus. 5. (P) Second Hyparterial Ventral Bronchus 5. Anterior-basic Bron- chus. 6. (?) Third Hyparterial Ventral Bronchus . 6. Axillary-basic Bronchus. 7. (?) Second Hjnparterial Dorsal Bronchus . 8. (?) Third Hyparterial Dorsal Bronchus 0. (?) Fourth Hyparterial Ventral Bronchus 9 8. Posterior-basic Bron- chus. jj )) j) / Lesser Pos- terior- horizontal Bronchus. i 10. (?) Fourth Hyparterial Dorsal Bronchus. 10. a dovht as to the figure whicJi should he prefixed to them in the synopsis. )) )) ») 56 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Mostly anterior, maybe absent behind, in animals. Subordi- nate posi- tion in man. In diagram ventral bronchi are external; dorsal bronchi arc internal. Aeby'a description of their origin. between them and the genuine " typical bronchi/' enumerated in the nomenclature. Accessory bronchi are most usually given off from the anterior aspect of the bronchial stem. In some animals they are altogether absent behind, although still occurring anteriorly. Accessory Bronchi in Man. — In man (loc.cit.,-p. 53) accessory bronchi play a very subordinate part. Their only important and constant representative is the cardiac bronchus found in the right lung. Position of Lateral Bronchi at their Point of Origin. — It will be noted that the origin of the ventral bronchi is depicted as lateral ; and that d.^ on the right, and d.^ on the left side, are rather internal than dorsal in their origin. In this connection the following passage from the German book, although occurring in the section devoted to Mammalia, deserves to be quoted (loc. cit., p. 6) : — " The two rows of lateral bronchi are never exactly opposite each other. The origins of the ventral bronchi always drift outwards and backwards, and they approach so closely those of the dorsal branches, that only a narrow strip of the bronchial stem intervenes. This is for the reception of the chief artery after it has arched backwards with rapid curve, over the fii'st ventral bronchus." Short Analysis of Aeby's Bronchial Tree.— In conclusion the bronchial tree of man, according to Aeby, consists of the following parts : 1 . Bronchial Stem ; 2. Eparterial Bronchus and its ventral and dorsal branches — occurring in the right lung only ; 3 . Hyparterial Bronchi occurring evenly in both lungs and classified into : a. Four Ventral Hyparterial Bronchi, 6. Four Dorsal Hyparterial Bronchi ; 4. Accessory Bronchi, of which one only, the Cardiac Bronchus, (which is not found in the left lung) possesses any considerable size. Author's diagram more com- plete. Essential differences. No arti- iicial dis- tinctive marks. The Authoe's Nomenclatuee, studied feom the Diagram. Chief Points of Difiference. — The diagram (fig. 6) is more compli- cated than Aeby's diagram, owing to the introduction into it of branches other than the primary. Thereby it is made to appear more different from the latter than it is in reality. Even, however, if we disregard the smaller branches (not all of which are as faithfully depicted as I could wish), and if we confine our attention to the primary divisions, — a few essential differences between the two diagrams still remain : I. No shading or other distinctive mark has been used in the author's diagram for the pui-pose of distinguishing one bronchus from THE BRONCHI AND PULMONARY BLOOD-VESSELS. S7 another, all bronchi of same size presenting, in the human lung, identical structure. 2. The aorta, which possesses important relations to the left bronchus The aorta and to the pulmonary artery, has been shown, in section, in connection with the latter. 3. The origins of the various bronchi, in relation to the surfaces of The the main bronchus (or of its continuation), do not occupy the positions origins which are allotted to them in fig. 5. different. 4. The names appended to the tubes in the diagram are altogether dis- The names tinct from those employed by Aeby. differ. Chief Points of Agreement. — If we put aside these differences some Identical general agreement may be traced between the series of branches respectiYely both dia- depicted in each diagram. grams. Thus in the right lung : — 1. The Upper-lobar Bronchus corresponds with Professor Aeby's Their new " eparterial bronchus," and carries anterior, as well as posterior, righri'ung ; branches. 2. The Middle-lobar (Cardiac) Bronchus arises at the same level as, although more anteriorly than the bronchus described in Aeby's diagram as first hyparterial ventral. 3. The Posterior-horizontal Bronchus occupies the position of Aeby's second hyparterial dorsal branch. 4. The Retro-cardiac Bronchus likewise tallies with Aeby's cardiac branch, — excepting in its mode of origin, and in the name which it receives. 5 . The second hyparterial ventral branch of Aeby is represented here by the Anterior-basic Bronchus, allowance being made for the peculiar position given, in the German diagrain, to all the ventral branches. 6. In the Lesser Posterior-horizontal Bronchus may be recog- nized the second dorsal branch of Aeby. 7. The Axillary-basic Bronchus corresponds to the third hypar- terial ventral branch. 8. The third hyparterial dorsal branch has a representative in the Inferior Dorsal Bronchus, a secondaiy branch not specially lettered in the diagram. 9 and 10. The anterior and the posterior divisions of the Posterior- basic Bronchus respectively correspond to the fourth ventral and to the fourth dorsal branch of Aeby. In the left lung : — I and 2. The TJpper-lobar Bronchus, which Aeby designates under inieitluug. the name of first ventral hyparterial bronchus, differs widely So THE BRONCHI AND PULMONARY BLOOD-VESSELS. fi'om the right upper lobar in serving as joint origin for the PectoriTapical Trunk and for the Cardiac Trunk. I have termed it Bronchus Impar. 3. The Posterior-horizontal Bronchus is the equivalent of the first dorsal in the other nomenclature. 4 and 5. The Anterior-basic Bronchus may be taken to be the bronchus which Aeby describes as the second ventral ; although in his diagram the latter takes its origin from the outer side of the " bronchial stem." The Eetro-cardiac Bronchus arising from it, and corresponding to Aeby's '' cardiac bronchus " in the right lung, is not mentioned by him in connection with the left. 6. Arising next in the descending series, the Axillary-basic Bronchus claims the position of the third ventral in Aeby's diagram. 7. The Lesser Posterior-horizontal is the second dorsal branch according to Aeby. It is a branch from the posterior-basic bronchus. 8. The third dorsal branch is represented by the Posterior-basic Bronchus. 9 and I o. The anterior and the posterior divisions of the Posterior- basic Bronchus, as in the right lung, represent the fourth ventral and the fourth dorsal branch of Aeby's bronchial stem. The correspondence thus shown to exist between the two nomencla- tures is, for easier reference, set forth in a tabular form on pp. 54, 55. ( i9 ) CLOSER INSPECTION OP THE BRONCHIAL CAST. MODES OP DIVISION OP BRONCHI, General Radiating Arrangement. — The general plan of the bronchial Badiatiou distribution is, in a broad sense radiating (see figs. 4 and 7), since the amaiiroot extensive sub-pleural surface of the lung, for the greater part convex, to a large in "ll^'T • 1 siiri£ic6. derives its supply from a comparatively limited region, the pulmonary root. This may be seen most plainly from the posterior view of the cast where the early branches are within sight. No True Centre of Badiation. — There is, however within the lung, no precise centre of radiation. The divergence of the larger bronchi occurs in various directions : upwards, outwards, backwards, forwards, and down- All brouclii wards. If we trace them from their periphery to their origin, they are seen towards^ to converge towards a short vertical line, namely, towards that segment of ^.^'*r'.^'^''" the main bronchus (or, strictly, of its continuation) which is included between (the brea- the origin of the upper-lobar bronchus and the origin of the three basic tinued). bronchi. Secondary Systems of Badiation. — Inasmuch as in each lobe Eadiation the supplying bronchus gives rise to a roughly radiating system, the lobea. regularity of the general radiation first mentioned is broken up to a certain extent. Again, & fan- shaped arrangement is commonly seen in the branchings Pan-shaped of individual primary bronchi. The most striking instance of this kind is tions— e.^., seen in the left posterior-horizontal distribution. *^** °\ '^'* Peripheral Sub-lobular and Intra-lobular Badiation. — horizontal. Lastly, a radiating arrangement is faintly indicated, at the great convex ?':'^"'u'?"J'"^ surface of the lungs, by the direction of the sub-lobular tubes perpendicular perpendi- to the free surface. And within the lobules in every situation, the tendency surface, to radiation is dimly represented by the intra-lobular bifurcations. Intra- Individuality of Primary Bronchi. — The closer they are placed bifurcation. to the root the more individuality do bronchi display in their shape and in ^^ isolated their direction. Whereas from the general appearance of the cast of any j'*^' °f * peripheral bronchus, isolated from the other tubes, it would be impossible is capUe to tell the exact position which was occupied by it in the bronchial tree, in recognSedi 6o THE BRONCHI AND PULMONARY BLOOD-VESSELS. the case o£ a large bronchus, thus isolated, identification would be comparatively easy to the expert. Constancy Constancy in Primary Bronchi. — It may also be stated of the tubes^^ larger tubes that their position and arrangement are constant in man. The probably same constancy, which is capable of demonstration in them, most probably small ones, also prevails, as a rule, in the smaller tubes as far as the periphery. Indi- vidual peculiarities would however occur more frequently within this district than at the pulmonary root. Tiie Abnormalities are not absolutely restricted to the smaller bronchi, smaller rpj^g latter, in addition to the chances which arise from mere numbers, are tubes more ^ ^ ^ ' exposed more exposed to external pressure and possess less resistance. But irregu- inginflu- laritics are occasionally also found in the larger tubes from causes which Abnoi-ma- ^^^'^ ^o^" hitherto been traced. None but these coarser abnormalities would litiesin produce any obvious modification in the outline of the bronchial tree. I tubes have observed abnormalities in the middle-sized branches, but their import- encTtiie "' ^^^^ ^^^ "°^ been such as to mar the general features of the specimen, taken outline of ag a whole : and as to the smallest tubes, peculiarities in their arrangement bronchial .,„., tree. would be hardly perceived at first sight. Bronchi Advantages Special to the Mode of Origin of the Primary neaTaspos- Bronchi. — The origin of the larger tubes at the pulmonary root, from a sibie to vertical line instead of from a point, constitutes a decided gain with regard district; to the distribution of air. In this manner bronchi originate nearer to supply is their respective peripheral districts than they could have done if the therefore division of the main bronchus had taken place at a central point within the more direct. ■*■ ... long pulmonary boundary. Although the actual distribution of air to the pulmonary parenchyma is not a part of the functions of the large tubes, it is essential that the air should . be transmitted through them to the smaller tubes with the least possible friction and with directness. Secondary Secondary Bronchi. — In like manner the earlier divisions from the tar between primary bronchi, constructed for the same purposes as the latter, and obeying and have ^.j^g game rules, are relatively few, and their internodia are relatively long. Thanks nodia. to this arrangement the periphery is approached by few and rapid strides. No lobules The Central Frame^work gives the Bronchial Directions. — aiTsefrom Thus, although passing between lobules, the primary, the secondary, and primary, sometimes the tertiary division from the main bronchus bear no lobules of (sometimes their own. Lobular bronchioles do not arise until by a more rapid progress tubes!^ of bifurcation the larger tubes have broken up into a central framework, Peripheral shaped into almost as many directions as are, with growing complexity, directions ^.gprgsented at the periphery, shadowed Parietal Sub-pleural Bronchioles. — The sub-lobular bronchioles in the . framework, which are situated at the parietal surface of the lung preserve, almost Also those unmodified, the leading directions supplied in this manner by the central tally placed framework; and the same may be said of some of the less superficial ohioies. bronchioles. FOITE PEAGMENTS OP THE BRONCHIAL CAST OP A CHILD, IN WHICH SEVEEAL DEEP-SEATED LOBULES HAVE TAKEN THE METALLIC INJECTION ; CLEANED BY MACEEATION. (From an enlarged Photograph.) The specimens illustrate the varieties in the mode of division of bronchi, the alternation of their planes of bifurcation, the varying apertures of their angles, and their very open, arch-like, bifurcations at the periphery. Beourrent bronchi and lobules are also seen. The empty angular spaces were probably supplied by recurrent tubes, analogous to the upward-pointing bronchiole seen I " vertically below the main angle of A. A good instance of a T-shaped bronchus is to be noticed on the observer's right-hand side of the same specimen, in its upper part. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 6 1 Central Bronchioles. — But the case is very different with those central lobules which make up the inner bulk of the lung. The deeper lobules are ^™y° '° °® arranged with endless variety of axis, and their supplying bronchioles greatly in assume in consequence the most varied directions. The mode in which this variety is attained may be briefly explained. Conversion of Directions ; its Mechanism. — While long inter- Eepeated nodia and few bifurcations are the special means adopted for transmitting yong"*' the tracheal air, through the airless root-zone, to the distant periphery, re- ?^°''' peated bifurcation and short internodia are the rule whenever, within a short (some distance, considerable change of direction is needed. Internodia may even l?vanisii- become so short as to be difficult' of recognition, and at first sight may '^"Jj^'^* altogether escape observation. ing angles. The Angles of Divergence. — In addition to these variations in the means of length of the internodium, and of the frequency of bifurcation, the aperture tronchila^ of the angles of divergence varies in accordance with the situation of parts, directions without however going beyond a definite size. An aperture of i8o is often approached but never exceeded. In this manner air-tubes are enabled, by the help of two or three bifurcations with large angle of divergence, to furnish lobular bronchioles possessing the same direction as their own original direction, and also bronchioles of exactly opposite direction. Among the many varieties of direction assumed by the deeper bronchial Special ofiF-shoots there are two specially deserving to be noted : conversion. 1 . Becurrent Bronchi and Bronchioles. — Of this large class no Becurrent better examples exist than the tubes supplying the lobules which fill up the apmoach- inter-bronchial angles. Most of the lobules in question receive their bron- ™g deep chicle not a tergo, but a fronte. In other words bronchioles supplied to a/rmte lobules of this kind arise from their parent-tube at a point further removed direction from the pulmonary root than the lobule for which they are intended, contrary to -,.,.. T on. tue original Their course is therefore exactly opposed m direction to that of their one. parent. 2. X-shaped Bronchi represent another important type of somewhat j-shapcd irregular distribution. This is well illustrated by the behaviour of bronchi the^ntlrow supplying the often narrow intertubal intervals. These intervals and the ii»tertubai jTjr ./ o ^ ^ „ , . . spaces; inter-bronchial angles both afford excellent instances of the many inequalities of position and of space, which exclude from the bronchial system the universal application of any rigid geometrical law. A bronchus entering laterally a long narrow interspace will bifurcate incuis-de- under difficulties. Instead of forming an acute angle, its two branches ^^t'lfg^^""" will probably take diverging rectilinear directions — their aperture will be haviour of 1 80°. The centripetal branch, meeting with a cul-de-sac, will be curtailed trai an™ in development and fail to attain more than a sub-lobular size and will end bramsiT™' in two lobular bronchioles ; the centrifugal branch, free to extend outwards, may acquire a size and an importance such as to obscure the dichotomous character of its origin. 62 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Recur- rent and X-sliaped bronchioles also at the surface (see mesial surface of Apex), and like- wise at opposed septal sur- faces. Mode of termination of super- ficiiil T-shaped branchlels. T-shaped bi'on- chiolos in contact "with large vessels and bronchi. The conditions to which the preceding paragraph refers may be difficult to realize from a written description, but a glance at the figures l, lo and 1 1 will clear up any obscurity. The Same Varieties seen at the Pulmonary Surface, and at Septal Surfaces. — Reversal of direction is not exclusively confined to bronchi supplying interspaces where respiratory tissue is thickly massed, and where space is not available for the regular, wedge-shaped, development of the lobular groups. Recurrent tubes and lobular masses may also be seen in injected specimens of the bronchial tree in various superficial situations. A striking instance of the recurrent type, in a super- ficial position, may be readily recognized in the apex-region of the metallic cast, where the surface of the lung faces the trachea. The "r~shaped bifurcation is invariably found along the opposed surfaces of interlobar septa ; and by noticing the position of these X "Shaped ends in a metallic cast, the position of the interlobar septum may readily be traced, without fni-ther help. But the same peculiarity is also noticed at the parietal surfaces of the lung. Indeed the appearances presented by the fine superficial terminations of a metallic cast are almost characteristic. The tubules, as they approach the surface with perpendicular direction, divide into two delicate branchlets. The angle formed by the latter varies between 90° and 180°, being larger than is witnessed at other bifurcations. In this manner the branchlets become almost or absolutely parallel with the pulmonary surface. These appearances are best seen in specimens in which the injected metal has not reached the infundibula. X-shaped Tubes found in Deep Situations. — The same mode of termination is observed likewise in many situations within the depth of the lung, not only along the interlobar fissures, but wherever the lobules abut against a resisting surface — e.g., in contact with the larger vessels and bronchi. The "bron- chial stem" bipinnate, according to Aeby, but not strictly so. This is disproved by h-s segregating the "acces- sory bronchi." A pHori improba- bility. The Bipinnate Arrangement, alleged by Professor Aeby. — Reverting to the primary bronchi we are enabled by an inspection of the metallic cast to test the accuracy of Professor Aeby's description of their mode of origin and main direction. The " bronchial stem" is alleged to be bipinnate, its branches arising in two directions, ventrally and dorsally. This statement is however slightly qualified by Professor Aeby, who points out that these two directions are not followed with absolute accuracy by the branches at their origin from the stem (c/. p. 56). A careful observation will show that the departures from the arrangement described are relatively numerous and considerable. We have on this point Professor Aeby's own admission. He is compelled to form a special class of " accessory bronchi,'" in order to accommodate bronchi, whose origin is obviously neither ventral nor dorsal. Neither is it a ^priori probable that branches should be given up only in two directions. It will be readily seen in the cast that THE BRONCHI AND PULMONARY BLOOD-VESSELS. 6^, branches also arise, as necessity requires, on tlie outer and on the inner side of the bronchial stem which he describes, as well as dorsally and ventrally. Analogy in Mode of Branching of Bronchial Stem, and of its Analogy Derivatives. — A special case will perhaps be pleaded for the " bronchial "^stlm" stem " itself, as a tube distinct from all other bronchial tubes — and not *°^ p"' ... mary necessarily constructed on the same plan. But, on comparing its behaviour bronchi, with that of later divisions in the bronchial tree, it is possible to trace between it and the latter considerable analogy. General Uniformity in Sequence of Bronchial Branches. — All Habitual the component parts of the bronchial tree show a marked tendency towards in direc- uniformity in the order of origin of their branches. An invariable rule si"|!J.essive cannot be framed ; but, in spite of the great variations occurring in the bifurea- length of the internodia, it is possible to recognize a regular system, deter- mining the relative direction of successive bifurcations. Alternation of Bifurcations at Right Angles. — According to the The piaues prevailing arrangement each bifurcation occurs in a plane perpendicular to give^bifur- that o£ the preceding bifurcation, alternate bifurcations thus taking place in "J^'P^A the same plane. This order would obviously facilitate the even distribution angles to of lobules on all sides of the bronchial tubes. But this arrangement is occasionally modified to suit the irregularities in the configuration of the lungs ; and I shall have occasion in describing the bronchial tree to point Occasional out the more striking exceptions to the rule. ^'"'^^ ^°^^' In the mode of subdivision of the right main bronchus tolerably plain Branches vestiges of the alternation in question will be recognized in the metallic main''"^ cast. The first bifurcation, which gives rise to the upper-lobar bronchus, bi-onchus. lies in the transverse plane of the body. The plane of the second bifurca- tion (from which the cardiac bronchus takes its origin), is sagittal. But The the third bifurcation, giving off the posterior-horizontal bronchus, is irregular horizontal, in also occupying a sagittal plane. The retro-cardiac bronchus is produced by a transverse bifurcation, and the anterior-basic by a sagittal bifurcation. The sagittal plane is, however, repeated by the lesser posterior-horizontal at the lesser its origin, and by the larger bifurcation of the lower end of the bronchus horizontal into axillary-basic and into posterior-basic branches. Analogous conditions Jfo^g'""'^' will be found in the left half of the bronchial tree. The Uniform Alternation unnoticed by Prof. Aeby. — Prof. inAebys Aeby's classification of the primary bronchi as ventral and dorsal branches, p'^-fSy" is not capable of being reconciled with the facts iust described. According branches 1 • 1 i? 1 1 1 ■ -I • are sagittal, to that theory the primary branches ol the bronchial stem would all be given except off in the sagittal plane of the body. But the exceptions which he admits terFaP' and in favour of the " Eparterial " bronchus (described as arising from the 1^'^''^^°" external surface of the bronchial stem), and of the " cardiac " (retro-cardiac) bronchus (which is given off internally), go far to invalidate the theory which he proposes ; and they afford a strong argument in support of the view that the primary bronchi follow, in their mode of origin, the same rules which 64 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Alterna- tions more regular with diminiBli- ing size of bronchi. determine the relations of successive bifurcations throughout the bronchial tree. Moreover, if we remember that the alternation of planes acquires increasing regularity as the tubes decrease in size and increase in number, and that it becomes almost invariable in the case of the bronchioles, we are the more justified in venturing to draw the early bifurcations into the general scheme, and to regard their few irregularities as, numerically speaking, insignificant. ( 65 ) CONCLU'DING EEMAEKS ON SOME IMPOETANT FEATUEES COMMON TO ALL BEONOHL In concluding tte general remarks devoted to the bronchial tree, the follow- ing statements may bo put forward. (i) More or Less Even Dichotomy is the mode of division of Dichotoniy bronchi in general. In this respect they are imitated by the blood-vessels ° ™"'' "' of the lung ; or at any rate by the pulmonary artery. (2) The Pulmonary Arteries are Faithful Attendants upon the The pui- bronchij resting upon them, as it were, for support and for protection from ^"eryTc- pressure, and conveying venous blood into the immediate vicinity of the air- companies sjipply, by which it is to be refreshed. Leaving aside details which will be fully given in subsequent pages, it will suffice to point to the constancy of this association, and to the assistance which it affords us in identifying any vascular branches as belonging to the pulmonary artery. (3) The Bronchial Tubes do not anastomose. Each lobe there- Absence of fore receives from the main bronchus a distinct air-supply. The same anasto-'^ principle of separate supply extends, within the lobe, as far as the infundi- ^°^^^- bula. This absence of anastomosis is physioloL'ically of great moment. It Possible , , , ., ... ^ , .° "^ ° . eddies or does not, however, exclude a possibility that air-currents may pass from one overflow bronchus to another, at least at the periphery. The bronchial distance °ntoneigii- separating two neighbouring lobules (and a fortiori two neighbouring infundi- bom-ing hula) from their common trunk of origin, is small, and occasional interchange especially of air between them is easily conceived, nay, may be looked upon as pro- phery! bable, whether as a result of diffusion, or by mere overflow due to uneven Lobes con- , . tain iso- tensions. . lated respi- Respiratory Districts. — At the root of the lung the conditions are T^.'^'y '^'^- very different, since the primary, secondary, and tertiary branches from the Possible main bronchus radiate towards the periphery for considerable distances, cJJangr without bearing any lobules. Within each lobe, large groups of lobules within the being served by separate bronchi are thus kept in practical isolation from but not eaqh other as regards their air-supply. Each of these sublobar groups may t.hem^ex- be considered as forming a separate respiratory district, within which the "^P* ^"^ tidal air, or the bronchial contents in general, may, perhaps, be capable of patho- interchange from lobule to lobule. Definite support is given to this assump- conditions. E 66 THE BRONCHI AND PULMONARY BLOOD-VESSELS. tion by the anatomy and the pathology of various morbid processes. Only in extreme pathological conditions does a similar overflow occur between tubes of sublobar, or even of lobar magnitude. A knowledge of the situation, within each lobe, of the respiratory disti'icts of which it is composed, is likely to be valuable to the clinical Their physician. But an attempt to define their anatomical boundaries would enumei-a- ^j^jj advantage be postponed until a full description of the bronchial would be tree had supplied a sound basis for the subdivision of each lobe into its premature. , t , lobular groups. ( ^7 ) THE MAIN BEONOHI. What is, steictly, to be understood undee the Teem "Main Bronchus " ? Doubt as to the Limits of the Main Bronchi. — The origin of the Their bronchi occurs opposite the' inter-vertebral disc separating the fourth and the obvious fifth dorsal vertebrae (Quain). Almost identical statements are given on this point by all anatomists. But there is a lack of agreement, nay some degree their lev- of confusion, as to where the main bronchi terminate. To this question we "g'^buuf shall presently revert. Provisional Subdivision. — In order to facilitate description, we may assume, temporarily, that each bronchus presents the following parts : — (i) An Extra-pulmonary Portion; ' (2) A Non-branched Intra-pulmonary Portion ; (3) A Branching Intra-pulmonary Portion, (i) The Extra-pulmonary, or extra-pleural, portion bears the same Extra-pni- relation to the pleura as the trachea itself, being a mediastinal structure ™°5iaZ '^^ situated altogether outside the membranous sac. The length of this portion tjoai por- is very different on the two sides of the chest, as may be seen from the drawing (fig. 1 1) of the posterior aspect of the metallic cast. The empty pericardial sac is there shown from behind, and the line of pleural reflection occurs on the right side a little external to line G, and on the left side nearer to the line B than to the line D. Measured horizontally, according to the scale in the drawing, this portion extends outwards, on the " right side " for a distance of its extent 19 mm., and on the left side for a distance of 30 mm., from the vertical and'^on"tho' line bisecting the tracheal bifurcation. '^f' ^i^e. (2) The Intra- pleural portion at first bears no branches. This is a very intra- brief interval, measured, on the left side, by a horizontal distance of 5 mm., tion'^tfirlt and on the right side, by a yet smaller fraction. Indeed, on the right side, branchless. this portion does not, strictly speaking, exist, since the separation of the upper lobar bronchus from the main trunk is already foreshadowed by a transverse furrow on the posterior pspect of the extra-pleural portion. 6?, THE BRONCHI AND PULMONARY BLOOD-VESSELS. be-ins at ^^^ "^^^ Branched Portion, or rather tliat portion whicli is situated the origin below the first branch, is the only one which gives matter for doubt. ot branches. The Oldest View. — So long as anatomists paid no attention to the intra- endTaUhe piil^ionary bronchial tree, and were content to describe the right main first bifur- bronchus as dividing into three lobar bronchi, and the left main bronchus as Oil ion dividing into two, the point did not arise for consideration. According to this oldest view the bronchus came to an end by the fact of its undergoing divi- sion. The application of the term " main bronchus" to either of the tubes beyond that point would have been inconsistent with the principle of dicho- tomy, then recognized. Professor Contrary View held by Professor Aeby. — With this view Professor tinuesThl' Aeby's theory is in complete opposition. Not only does he not admit so early bronchus ^ termination of the main bronchus. He considers that this tube is continued to the base, without losing its chief characters, as far as the base of the lung ; and he chiai gives further emphasis to this opinion by employing the term " bronchial ^^^" stem." This expression is felicitous not alone because it avoids the obvious inconsistency in terms which would have been implied in the use of the name " main bronchos," but because it asserts his rejection of the lobar principle in bronchial nomenclature. ■ Lobation Pulmonary Lobes as a Sasis of Bronchial Classification. — rejected 'by According to the old style, at the point where the main bronchus came to an Professor gjj^,j^ ga,ch lobo was supplied with its own bronchus. Perceiving the varieties basis of which esist among mammalia in respect of lobation, and the variability of the tion. " lobation in each species, Professor Aeby preferred to deal with the bronchi in lieasonsfor their "naked condition," entirely discarding: the lobes as a basis of description. retamiugit, iit ... ■, • -, -r -, • t n -i especially i venture to uphold an opposite opimon, to which 1 have previously reierred la man. ^^^^ ^ ^^^ ^^^ ^^ Suggest that it is wise not to dissociate the bronchi from the lungs in respect either of their study or of their nomenclature. For the special purpose of human anatomy, in its connection with surgery and medicine, the retention of the lobar basis of nomenclature is not only appropriate but indispensable. This necessity must be considered entirely apart from the theoretical question and does not bear with the slightest weight upon its solution. It constitutes a strong additional reason for upholding the use of the old terminology in these pages. The left Subdivision of Main Bronchi reconsidered. — The Left Bron- to^chus chus.- — ^Holding fast by the lobar principle of bronchial nomenclature, we bihmatioii ^^^ ^* ®^^^ *° choose between the old and the new view as to the length of the main bronchus. On the left side, at least, there is no room for ambiguity. This lung has but two lobes ; and the main bronchus hkewise supplies but two branches, one for each lobe. It comes to an end at the level of that bifurcation, as was formerly taught. It is therefore clear that a branched It has only r j.t t j-j i it twopor- portion 01 the leit bronchus does not exist. The latter consists of two THE BEONOHI ANJD PULMONARY BLOOD-VESSELS. 69 portions only, an extra-pulmonary and an intra-pulnionary portion, both t:ons,pxtra- branchleSS. putaonary. The Right Bronchus. — Some complication exists, however, on the The three right side. The three lobar bronchi do not, as it was long ago thought, arise broneh'i ^^ simultaneously. A first bifurcation sets free the upper lobar bronchus — and ?»' s™"'- the large tube, which remams, subsequently divides into the middle and the ^he iuter- lower lobar bronchi. This tube may, or may not, be described as the " con- 7'^^™^ tinuation of the main bronchus." Accuracy would be best served by restricting by what the use of the name to the undivided bronchus, and denying it to its offshoot. ^0^,^? In respect of simplicity and of uniformity there would also be an advantage Better not in viewing the right bronchus as coming to an end with the first bifurcation tiwims, in the same manner as the left. Moreover the inferior segment in question, '^"' ^y * , separate which soon divides into the middle and the lower lobar bronchi, may well name, claim a separate name by reason of its size and of its important relations. Bronchus Intermedius. — ^I would suggest for it the term "inter- "Bronchus mediate stem " (bronchus intermedius), which is conveniently short, and conveys medius." some reference to the somewhat central position of the tube, and to its character as an internodium between the upper and the middle lobar bronchus. The right main bronchus would thus bifurcate into the upper lobar bronchus, and Bifuicatioa the bronchus intermedius. "The bronchus intermedius in its turn would break ° up into the middle lobar and into the inferior lobar bronchus. Objection to a Misapplication of the Term "Main Br on- No finality chus." — The alternative plan of continuing to the intermediate portion the of the ttrm designation of main bronchus, besides involving possible ambiguity, is open bronchus" to the serious objection that this would serve as a precedent leading to much if inisap- confusion in the further nomenclature of the bronchial tree. Thus, within the lower lobe, it would be difficult to refuse the name lobar bronchus to that branch of bifurcation which might appear to be the strict continuation of the main tube ; the same difficulty would arise at the second bifurcation ; and no logical excuse could be advanced against the application of the term " lower lobar " to a very small linear descendant of the great lobar trunk. We are therefore justified in refusing to extend the term " main Two sec- bronchus " to any portion of the bronchial system situated below the in°the°ri Jht origin of the first branch from that trunk ; and, on the right side of the bimchus, chest as well as on the left, we must speak of the main bronchus as consist- left. ing of two parts only, an extra-pleural and an intra-pleural part, to the exclusion of a third, or branched, portion. Description of the Main Bronchi. Taking leave of the question of nomenclature, we now turn to a descrip= Modem tion of the main bronchi. What progress has been made, during the last ourlinow- f ew years, in our knowledge concerning them, may be gathered by com- }^g^®,^^ paring the account contained in the last edition of Quain'a " Anatomy " with bronchi. ;o THK BRONCHI AND PULMONARY BLOOD-VESSELS. Previoiis errors. the following extract from an edition, not twenty years old, of another well- known text-book of anatomy : * " The right bronchus wider, shorter and more liorizonial than the left is about an inch in length, and enters the right lung opposite the fourth dorsal vertebra. The vena azygos arches over it from behind ; and the right pul- monary artery lies below and then in front of it. The left bronchus is smaller, more oblique and longer than the right, being nearly two inches in length. It enters the root of the left lung opposite the fifth dorsal vertebra about an inch lower than the right bronchus.'' (The italics are not contained in the original; they indicate statements which have been found inaccurate and have been corrected in later editions of this excellent manual.) Right bronchus is more in- clined than the left. Causes of the old mistake, readily avoidable. Corrected statement. Points of Difference between the Two Bronchi. — Whilst both bronchi agree in possessing a direction downwards and outwards, considerable difierences exist between them in the following respects : ^ I. Inclination. — The right bronchus departs from the horizontal to a greater extent than the left, — not less than the left, as stated by Sappey and by the great majority of anatomists previous to Aeby. The old miscon- cef)tion as to the relative inclination of the bronchi is traceable to two causes: (i) the neglect of intra-pulmonary dissections; (2) the practice, apparently prevalent among former anatomists, of following the upper border only as a guide to the position of the right bronchus. This upper border rapidly ceases to belong to the main bronchus and becomes the upper border of its first, or upper lobar branch ; whilst the lower border is hidden from view by the pleura before it has strongly diverged from a direction parallel to the same upper border. The confusion due to this mistake is removed by the most superficial dissection, which brings into view the lower border of the lobar branch, and the angle between it and the main bronchus ; in this manner I happened to recognize the true anatomical relations inde- pendently of Professor Aeby's description, which had not then come to hand. A glance at fig. 1 1 will enable the reader to appreciate the meaning of the preceding remarks : it will also enable him to perceive the corrections required for the italicized statements on this page. It is clearly shown by the cast, that the main bronchus, or rather its continuation, does not enter the lung at the level of the fourth dorsal vertebra, but lower. At the same level as the termination of the trachea, which corresponds to the fourth inter-vertebral disc, a bronchus does enter the lung ; this is however the upper lobar, not the main bronchus. This circumstance may likewise, at least in some cases, cause us to qualify the statement that the vena azygos arches over the main bronchus. Would it not be often more correct to speak of the vein as arching over the upper lobar bronchus ? * " Anatomy, Descriptive and Surgical," by Henry Gray, by T. Holmes. Fifth edition. 1869. Edited THE BRONCHI AND PULMONARY BLOOD-VESSELS. 7 1 2. Curvature. — ^In this respect the main bronchi, and their continua- c-siiaped tions within the lung present not only differences, but contrasts. To these rigM ° Professor Aeby has drawn attention ; and, in order to follow him, I must, g't^™"'^'"''' for the present, adopt his terminology, and speak in terms of the "bronchial stem." The right bronchial stem, rectilinear near its first part, gradually assumes a faint curvature with concavity inward. The shape of an elongated letter Q would express the direction of this curve ; but so slight is the the latter, that, in order to detect it, a careful inspection is needed. The left bronchial stem, beyond its first portion, which is straight, or and nearly so, is said by Aeby to present a double curve somewhat resembling curve of that of the letter g- With that description I cannot entirely agree. I have J.jf'ai'stem succeeded in recognizing a very distant resemblance to that letter in the according outline of the bronchial stem, not however from the anterior aspect, but from behind. When viewed from the front, the outline would be that of a reversed S whose curves would face in the same directions as the retiring angles of a Shape of letter 2- But it is necessary to add that the degree of curvature is quite according ' insignificant as compared with that which belongs to the ordinary capital *" rafted' letter. The old-fashioned elongated ^ (duly reversed thus : ? ) is much *ape of "* ^ reversed f more nearly a correct representation of the bronchial curve. Even in this letter the middle third only can be fairly compared with the curve in question. Thus, whilst similar to the right bronchus in its lower part, the left .Additional bronchial stem performs an opposite excursion in its upper part. Nor is this convexify all. In addition to the downward and inward bend of that portion of its ^^"JP'?'''^ course which is immediately above the upper lobar bronchus, the left bronchial stem, according to Aeby, is also, in a slight degree, bowed from front to back, with concavity backwards. The origin of these curves is easily explained, in connection with the relations of the left bronchus to the heart and to the large vessels. 3. IJength. — Professor Aeby (loc. cit., p. 65) gives for the non-branched portion of the bronchi the following average lengths : Right bronchus, 2 1 ' I mm. Left bronchus, 49 mm. The average given for the right bronchus is stated to be depressed slightly below the usual standard by the occurrence, among Professor Aeby's specimens, of a case of very high origin of the right upper lobar bronchus. Sappey's averages (loc. cit., p. 430) are : Honchi For the right bronchus, I S to 1 8 mm. to "various For the left bronchus, 30 to 35 mm. observers. But, in exceptional cases, 10 to 12 mm. for the right, and 40 and 45 to 50 mm. for the left, have been recorded. Quain {loc. cit., p. 265) gives for the right bronchus, a length of i inch (25 mm.), and for the left bronchus, a length of nearly 2 inches (50 mm.). 72 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Diiimetui" of the bronolii according to Tarious obseiTers, My own measurements agree with those of Professor Aeby. 4. Diameter. — Measuring the transverse diameter at the origin of the bronchi, Aeby finds : — Eor the right bronchus, 167 mm. For the left bronchus, 1 4- mm. These figures closely resemble those obtained by Sappey for the mean diameters, viz. : For the fight bronchus, 1 6 mm. For the left bronchus, 1 2 to 1 4 mm. The dis- proportion between initial size of right and of left bronchus explained. Marc See* gives values slightly differing from these, viz. : In 18 males, on- an average 14 mm. In 12 females, „ 12 mm. In 1 8 males, „ i i '6 mm. In 12 females „ mm. Diameter of riarht bronchus Diameter of bronchus left The left bronchus equal, in calibre, to half the trachea ; the calibre of both bronchi much in excess of the tracheal calibre. The diameter of the right bronchus, in persons older than twenty years, varied between I7"75 and 17'5 mm. The diameter of the left bronchus, in persons older than twenty years, varied between 7 and I3'5 mm. At its origin the right is much the wider of the two bronchi, the difference according to Aeby being almost in the proportion of 3 to 2. The sectional surfaces are stated by him to be equal to 2 2 2 sq. mm. and 1 5 7 sq. mm. respectively. This is a greater difference than can be accounted for by the difference in size between the two lungs. The following circumstances appear to me to assist in its production. In the first place the orifice of the right bronchus is not entirely lateral, but is also partly inferior to the trachea. And again, by reason of the early origin of its upper lobar division, the upper and the lower surfaces of the right bronchus,, instead of being cylindrical, are caused to diverge almost from the beginning. Relative Size of Trachea and of Bronchi. — A knowledge of the relative size of the trachea and of the bronchi is of much theoretical interest. According to Professor Aeby (loc. cit., p. 71), if the diameter of the trachea be taken as 100, the diameter of the right bronchus would be repre- sented by 70, and that of the left, by 49' 3. The aggregate lumen of the two bronchi would thus considerably exceed that of the trachea ; whilst the smaller bronchus would practically be equal to half the tracheal calibre. In all cases examined by him Professor Aeby (loc. cit., p. 79) found the aggregate calibre of the main bronchi to exceed that of the trachea by about ^. * "Da Calibre relatif de la TrachSe et des Bronches," JBtdl. de VAcad. de Mid., 2me Serie, vol. vli. p. 408. THE BSONCHI AND PULMONABY BLOOD- VESSELS. 73 The figures obtained by Marc S6e (loc. cit.) for the bronchi have been given above. For the trachea his measurements led to the following results : — Diameter of trachea In 2 1 males, on an average 1 8 mm. In 12 females „ 14' 5 mm. In 8 subjects examined by Marc See the calibre of the trachea was Maro s^e's inferior to the sum of the calibre of both bronchi (of these subjects 5 tions. had extensive pulmonary tuberculosis, the others were adults with normal lungs). In 1 1 other subjects the tracheal calibre was superior to the joint bronchial calibre. Aggregate Calibre of the Bronchial Tree. — Prom the observa- AccoidiDg tions which I have quoted Marc See concludes that, normally, the calibre of calibre of ° the two bronchi equals that of the trachea ; that likewise the branches of ^\^. i"°°- •^ . ' . cmal sys- any bronchus have an aggregate calibre equal to that of its parent-tube ; and tem is that the respiratory channels therefore represent a cylinder. Pathologically by'a^^^° ^ the equilibrium may be upset in favour of the bronchi, as in phthisis, or in •'yii'^iier ; favour of the trachea as iu emphysema. Professor Aeby (loc. cit., p. 75) contends that, this alleged equality according is never found. The rule is that the products of any division of the bron- by an ' chial stem exceed in capacity that of the parent stem, and that the rela- co™'*^*^ tion would be represented graphically not by a cylinder but by an inverted cone. Calibre of the Trachea. — The same is, according to him, also true The of the tracheal calibre (loc. cit., p. 68) when its diameter is compared at caUbrT various levels. Thus the sectional area of the lower extremity being taken likewise, to be 100, that of the upper end is 52*2 per cent., that of the middle third 63 "5 per cent., and that of the lower third, 83 "5 per cent. Exception to Aeby's Rule. — An important exception to the rule irregu- occurs however in the bronchial tree, at the level of the eparterial bronchus. b™nohiai ° Since in man no eparterial bronchus is to be found on the left side, the ^^^'^JS, "' . ^11 T • • • 1 • ^^^ "Epai-- variation in question is not referable to any division m this tube, but teriai" occurs in its continuity, and, according to Aeby, may be taken to mark the site of the suppressed bronchus. ■ The exception consists in the aggregate capacity of the right eparterial Instead of bronchus and lower bronchial stem being not larger, but smaller than that expansion, of the bronchial stem prior to division. In like manner, at a corresponding ^t^Jj,^"^'""^ level, the lefb bronchus generally presents a narrowing ; this being an level, even exception to another rule, viz., that the calibre of an internodiwn preserves bronchus, a cylindrical value. It is however to be noted that Professor Aeby, in fnte°"f^ia, determining the' superior measurement, selects not the section of the main are usually bronchus situated immediately above the eparterial bronchus, but the orifice of the bronchus at the tracheal bifurcation, an orifice which is apt to be considerably wider than the bronchus itself. 74 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Relations of the Main Bronchi at the Root of the Lung. — This important subject will be much more conveniently treated in connection with a description of the blood-vessels in Section III. and to that section the reader is therefore referred. The Beonchus Intermedius or Continuation of the Eight Main Bronchus below the Origin of the Upper Lobar Branch. The directions followed by the continuation of the main bronchi have already been mentioned under the heading of the latter ; and they will be further noticed in the course of the detailed account of the bronchial tree. This is however the place for a brief description of the diflferences which occur in the mode of termination of the right and of the left bronchus. Joint origin In the Lieft Lung, the origin of the upper lobar division, or hronchus upper and ifnpcir, which marks the end of the main bronchus, also defines exactly the idwer lobar beginning of the lower lobar bronchus. Between the two last-named bronchi. . . . . bronchi there is no transition, the latter being the direct continuation of the former tube. On the Bronchus Intermedius. — In the right lung, on the contrary, a con- aninter-*"' siderable inbeiTal separates the origin of the upper lobar bronchus on the nodiiim QJJ0 hand, and the joint origin of the middle and lower lobar bronchi on the the upper other. Inasmuch as this transitional section of the length of the main middle air-tube belongs neither to the upper lobe nor to the lower lobes, it has the brom:hi value of an internodium inserted between the great lobar bronchi, for the The purpose of increasing their distance. I have already proposed for it the bronchus term hronchus intermedius. Not existing in the left lung, this is an odd dius an odd structure ; it is not, however, odd in the sense of obviously disturbing the produced' Symmetry of line, or of constituting a numerical addition to the branches of i'^s^ourof ' *^® bronchial tree ; for it is nothing more than the continuation of the main the main bronchus drawu out, as it were, at a given spot. Indeed it may be pointed out that, in the left lung, at a lower level, an analogous drawing-out takes Analogous place in the length of the lower lobar bronchus, causing a short internodium diumlin the ^° precede the origin of the posterior-horizontal bronchus, whereas, on the left lower right side, an interval can hardly be recognized between the level of origin bronchus, of the cardiac bronchus and that of the posterior-horizontal. The It will be shown hereafter that the hronchus impar (left upper lobar impafmore hronchus) does constitute a numerical addition to the branches of the bron- truiyodd. ghial tree, and therefore deserves, in a much more definite manner, to be qualified as odd. Length of Dimensions and Direction. — Measured from the retiring angle below bronchus ^^g origin of the upper lobar bronchus to the similar angle below that medius. of the middle lobar bronchus, the intermediate stem, in the metallic cast under consideration, has a length of 2-5 cm. Its direction is identical with THE BEONCHI AND PULMONARY BLOOD-VESSELS. 75 that of tlie main broucliiis. Viewed from beliiucl it is however readily seen that its lower extremity swerves outwards from the straight downward- and-outward course. A similar outward tendency may also be observed in the middle and inferior lobar bronchi ; but in them it is much more deve- Vll] "I J Peepaeation of the Chief Beonchi, dissected in the moist state, akd allowed to dry aftee being packed full of deibd sponge, and stiffened with wiee. Feont view, taken peom the bight. {From a Pliotof/rajyh.) The side of each small square measures 20 mm. Several of the bronchi having given way, or shrunk in drying, the specimen im- perfectl)' illustrates the branchings of the bronchial tree. But the main bronchi, their mode of origin and of termination, and their general relations are olearlj' seen. The bronchus iutermedius traverses square C iv ; and the bronchus imp.ar lies across square ¥ iv. loped. The irregularity in question is a strong argument in favour of the Outward view that the "bronchial stem" of Aeby does not preserve beyond this level '^*'^'^<=''™- the value of an axial structure. The intermediate stem is cylindrical and CyHudrical possesses a considerable calibre, although, as far as the unaided eye can °'^^' judge, this is rather less than the aggregate calibre of the two bronchi derived fi-om it. 1^ THE BRONCHI AND POLMONAllY BLOOD-VESSlSLg. Posteriorly an intia- piilmonary and a sub- pleural part. Its mesial surface above is exti-a- pleural. The lower lobe covers its pos- terior sur- face. The lower branch of the pul- monary artei-y crosses it in front ; lower down the cardiac bronchus covers it anteriorly. Belatious. — The relations of the intermediate stem are of importance. At its origin it is not entirely included within the pulmonary pleura. Its oblique posterior surface is divided into two parts, a larger, distal, intra- pulmonaiy, and a smaller, mesial, sub-pleural portion, by the vertical line of reflection of the pleura. In fig. ii, which represents the posterior aspect of the metallic cast, the actual conditions will be readily recognized. The pleural membrane has been divided along the line of its reflection, and may be seen (in square (G iv) ) extending vertically across the oblique course of the stem. It will also be seen that the mesial surface of the stem is in its upper part, entirely extra-pleural, in other words mediastinal. The pulmonary tissue which clothes, from behjnd, the intra-pulmonary portion, belongs to the inferior lobe ; for it should be noted that, in spite of the origin of the middle lobar or cardiac bronchus being superior to that of the posterior-horizontal bronchus, the distribution of the latter rises higher than any branch from the former. Anteriorly the intermediate stem is not in immediate relation with pul- monary tissue, nor with pleura. The interlobar septum and its pleural lining do not penetrate as far as the bronchial surface, but the latter is in direct contact with the lower branch of the right pulmonary artery, and separated by this from the superior branch of the right pulmonary vein (see chromo- lithograph, p. 1 80). Further down, the mesial half of the anterior surface is also in direct relation with the posterior aspect of the cardiac bronchus, which, in its first part, descends in front of its parent trunk, and in close proximity to it. ( n ) ELEMENTARY SKETCH OF THE MOEE IMPORTANT DIVISIONS OP THE BRONCHIAL TREE STUDIED PROM THE METALLIC CAST. My present object is to convey a general idea of the situation and of the names of the chief air-tubes, without loading their description with any- unnecessary detail. This first stage in the study of the bronchial tree will be much facilitated for the reader by his frequently consulting the diagram fig. 6 at p. 52, and the synopsis of the primary bronchi at pp. 54 and 55. The introduction of an elementary sketch to be followed by a more complete description brings with it the evil of repetition, but there are practical reasons which recommend such a course. The Right Bronchial Tree. Right Bronchus. — This short and wide tube is chiefly remarkable for cwef its directness, for the steepness of its downward-and-outward slope, and for " ^^^ ^^^' the early bifurcation which it undergoes, soon after its origin from the trachea, and before it is fairly buried within the lung (cf. p. i o and p. 70). Upperiobav Upper Lobar Bronchus. — Ihe uppermost division 01 the mam ("Epar- bronchus is entirely devoted to the upper lobe, which receives no other bronchus). supply. Anatomists had known it exclusively under the name given above. Its iiori- until Professor Aeby proposed for it the term " eparterial." The direction direction. of this important tube is almost always horizontal, as is very clearly shown F?™eiiy in fie. 1 1 (see also other drawings and diagrams). It appears to have been for main habitually mistaken, in the past, for the main bronchus, which for this reason p ™° J""" was, until recent years, described as horizontal. The line of pleural reflection line and crosses its origin posteriorly, and the vena azygos from above (see fig. 11, azygoa column G, line iij). This bronchus may arise even higher than the usual level, ^'^^^ "• but in every case it is superior to the pulmonary artery (see chromo- pulmonary ■' artery lies lithograph), below it. The branches of the upper lobar bronchus respectively supply the centre its distri- and the three sides of the apex of the lung (cf. p. 89). ^"""°- Bronchus Intermedius. — This name is applied to the remainder left Broncima by the separation of the upper lobar division from the main bronchus (see n^edius. figs. 9 and 11). It is the continuation of the latter, 78 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Cardiac Middle Lobar, or Cardiac Bronchus. — The branch for the middle crossed ' lobe IS given off at the bifurcation of the intermediate stem, immediately by'iower' tiehind the lower division of the right pulmonary artery (the upper division division of having risen into the upper lobe). This lower division, roughly preserving artery, the transverse direction of the main right artery, crosses, at this level, the descending air-tubes, and partly rests upon the bronchus which is being described. The bronchus lies at first in immediate contact with, and anterior to the lower lobar stem, separating it from the artery. Just below the point where the blood-vessel passes outwards, the air-tube bends slightly supplies forwards in order to supply the middle lobe. Anatomists have hitherto the middle described it solely as the middle lobar bronchus, a name not normally appli- cable to any bronchus in the left lung. There are good reasons, hereafter to be set forth, for using, at least as an alternative, the name cardiac Ironchus, which is based upon its visceral relations. In association with the fact that it arises anteriorly, and is situated below the arterial trunk. Professor Aeby designates this branch as the first hyparterial ventral bronchus. Tjjo Lower Lobar Bronchus. — The other product of the bifurcation of lower lobar ^q intermediate stem, the lower lobar bronchus, is, from the first, situated broncbus , . . . . ' arises be- withm the lower lobe (this lobe rising posteriorly above the level of the last- levei^of"^"^ named bifurcation) ; its undivided portion is restricted to a very short course, its lobe. Posterior-horizontal Bronchus.— This large branch bifurcates borizmtai from the preceding trunk a few millimetres below the level of the cardiac ^"""n^r"^' 131'onchus. It arises from the posterior, or more strictly, from the dorso- lateral lateral bronchial wall, and is termed by Aeby first dorsal hyparterial bron- it" name ; chus. The designation which I suggest instead of the latter was first applied by me to branches of this air-tube, some years ago, in the Gulstonian Lectures on Pulmonary Cavities. (See Lancet aixd British MedicaUournal, 1882.) The direction of this interesting, but unusually short trunk, is sufiiciently indicated its disfri- by its name. It distributes branches upwards to the infra-spinous region, bntion. downwards to the middle dorsal third of the lung, and horizontally outwards and forwards, to its middle axillary third. The Eetro-cardiac Bronchus. — Barely 9 millimetres below the origin cf "cardiac" ^lie posterior-horizontal bronchus, there arises, from the inner surface of the branch of .nii Aeby more continuation 01 the lower bronchus, a downward branch termed by Aebv ^"led"^,!- the "cardiac bronchus," but described by me, with closer regard to its tro-cardiac; anatomical relations, as retro-cardiac. It is destined to aerate the two its distri- bution and posterior thirds of the inner aspect of the lower lobe. The strictly internal Irefa'-^"' origin of this bronchus (see fig. 11, line H, square G vj) excludes it from the teraal. scheme of dorsal and ventral bronchi set forth by Aeby in his nomenclature. He frankly recognizes the difficulty, and he gives to this air- tube a place EeasoDs among the accessory bronchi. Very strong reasons should be adduced before Suiuid not '^^ could Consign to a secondary position so constant and so large a bronchus, be regarded and One distributed to a district peculiarly isolated from other branches of gory. the bronchial tree, The fact that, in some animals, and rarely in man, this THE BRONCHI AND PULMONARY BLOOD-VESSELS. 79 district is constituted into a separate retro-cardiac lobe (Herz-lappen, lobus Occasional infracardiacus, Aeby), (azygos lobe, lobulus impar, Owen), strongly illus- ^^^iXj. trates its claim to be individually considered in any scheme of the bronchial system. The Three Basic Bronchi. — Three large trunks arise at the extremity The basic of the lower bronchus, and divide between themselves the air-supply of the theh^'^'' base, although not in accurately even shares. Their arrangement is in the mutual antero-posterior order ; the axillary-basic occupying the middle place between their dire'c- the anterior-basic in front of it and the posterior-basic behind. All three '°°' bronchi retain the downward and outward direction ; and their joint distribu- tions assume a distant resemblance to a vertical segment of an inverted funnel, with convexity outward. In consequence of this arrangement the They do inner basic surface of the lung would remain isolated as to its bronchial "heinufr'*' supply, — as it was stated above. i'^^'^- Their Origin and Relative Size. — The mode of origin of the three Eepeated basic trunks is riot by simultaneous trifiorcation, but by a rapid repetition of auhdr'°" bifurcation. The posterior-basic bronchus is not only the largest of these but origin. the last, and might therefore claim to contain the continuation and the end of the alleged "bronchial stem." It will be seen that some difficulty exists, even for Professor Aeby, in determining, in man, which of its branches is to Which of be regarded as the ultimate tube. For supporters of the old theory of bifar- "bronohiaT cation, this question does not occur, ^'^"^ " ' Professor Aeby's attention does not appear to have specially dwelt upon This is the even size and importance which all three basic bronchi assume in man. doubtful in But I have elsewhere suggested (see p. 31) that in quadrupeds with short man than sternum, the anterior-basic bronchus would probably shrink into secondary rappds. dimensions, whilst the size of the posterior-basic bronchus would so materially increase as to maintain for it, almost as far as the base, that pre-eminence in calibre, which Professor Aeby considers synonymous with an architectural axial quality. The Anterior-basic Bronchus, or, more fully named, the anterior- Auterior- lateral-basic, larger than the axillary-basic, but not so important as the bronchus. posterior-basic bronchus, takes its origin from the anterior aspect of the continuation of the lower bronchus, about 9 millimetres below the origin Its origin. of the retro-cardiac bronchus, and distributes branches to the anterior and Its distri- to the antero-lateral regions of the base. In Professor Aeby's nomenclature "''°°" this trunk would represent the second hyparterial ventral bronchus. Lesser Posterior-horizontal Bronchus. — Between the level of Lesser origin of the anterior-basic and that of the axillary-basic a smaller bronchus, ^ori™°4] ■ for the supply of the third fourth of the dorsal surface is given off back- its origin wards. This is the lesser, or inferior horizontal bronchus (or second hypar- bution. Urial dorsal bronchus of Aeby). The Axillary-basic Bronchus, the anterior product of the final Axiiiary- bif urcation of the remainder, or continuation of the lower lobar bronchus, origi'u and 80 THE BEONCHI AND PULMONARY BLOOD-VESSELS. distribu- tion. Posterior- basic bron- chus, ratlier larger than the other two. Its branches tlioiight to represent the lower primary branches of Aeby. Its distri- bution superficial and deep. is probably identical with the third liyparterial ventral hroncJms of Aeby (as far as it is possible to guess, in the absence of any individual description of this air-tnbe). Since its distribution is entirely axillary, the signification of the word " ventral," when applied to it, is rather strained. The employment of that term was probably determined by the fact that the bifurcation, which gives rise to this tube, is contained, not within a transverse, but rather within an antero-posterior plane. Posterior-basic Bronchus. — From the posterior-basic, which even in the human subject possessed of a horizontal diaphragm, is somewhat larger than the other two basic trunks, Aeby probably derives the fourth hyparterial ventral hronchus, and the third and fourth hyparterial dorsal bronchi which form part of his nomenclature. Branches from the trunk in question may be pointed out which would suit these designations ; but in the human subject they^ could hardly be placed on a footing of morphological equality with those branches which arise directly from the bronchial stem by means of bifurca- tions contained within the root-zone. The areas of distribution of the posterior- basic bronchus are the posterior-axillary surface, the dorsal surface with the exception of its innermost section (which is within the province of the; retro-cardiac bronchus), and the inferior surface. It likewise, and to a greater extent than the other basic bronchi, furnishes deep branches for the intra- pulmonary tissue. The Left Bronchial Tree. The left bronchus long, and slightly convex downwards bends suddenly down- wards. The car- diac curve occurs in the lower lobar trunk, not in the bronchus. Origin of this tube from the anterior and lateral aspect of bronchus. The Left Bronchus is elsewhere stated to be much longer than the right bronchus, and to present, in its extra-pulmonary part, a very feeble curve, with convexity downwards and slightly inwards. Being less steep than its fellow, it forms a larger angle with the vertical axis of the lung. It endeavours, after penetrating into the hilus, to rectify this strong diver- gence by a somewhat sudden downward bend. Just below the level of this bend begins the important cardiac curve which is concave inwards and slightly forward, and terminates with a gradual outward deflection. This curve was first described by Aeby in connection with the " bronchial stem." I have already ( Bronchus and the Posterior Central Apical, a slightly curved branch ^ggsgi)"'^' which lies behind the anterior central apical but has an opposite direction Posterior CcUtrl*&l and curvature. Both bronchi end by means of the customary sub-pleural apical (viij. forkings. '''''''^- ' The Posterior Apical Bronchus (fig. 1 1 , left upper corner of Posterior square H iij) rises upwards and slightly backwards for a distance of i cm. (y^'e^Jgp) Its inner and its outer branch respectively supply the posterior-inner surface posterior and the posterior surface of the apex. To the first of these the designation tracheal posterior tracheal rightly belongs since this bronchus is contained in the Apical transverse body-plane which also contains the trachea, and therefore directly Bpf™tg faces the trachea. The other, larger, branch with strong outward slope is W- esspe). .-s'i&i'.. ( 96 ) TABLE I. Bkonchial supply TO RIGHT APEX. BIGHT UPPE; Axillary- APICAL tbttnk (ij. e). Bight ascending apical stem {iij. es). Anterior ascending apical (iv. eaa). FOSTERIOB ASCENDING APICAL {iv. ess). Anteeioe tracheal Anterior ascending apical (v. esas). Posterior APICAL (v. esBp). Stebno- TRACHEAli ia,A.%Jtxr.^Li ±B,i%.\ja.r,A.u LU,a.\JU.j^A.u hcaKixj a,aiCA±^ i (vij. esaias). (vij. esaiai). {vij. esaiss). {vij. esaisi) Anterior Superpicial INNER anterior apical apical (vj. esass). {vj. esasa). Middle Tracheal •>™'"''"^^ '< tracheal recukrent Anterior Inner Posterior tracheal (vj. esspi). Apical supra-spinate (vj. easpe). CENTRAL srPEEIOE APICAL APICAL (vij. esasss). (vij. esassi). Inner Innee ascending superior apical marginal (viij. esassis). (viij. csassii). PosTEEiOE Posterior X-shaped TRACHEAL TRACHEAL DORSAL RECURRENT (vij.eSSpis). SUPEA- (Vij. CSSpii). SPINATE (vij.esspep). Intra- Tee- pulmonaet minal branch. branch. Posterior Axiai central teeminal APICAL (Viy. eSBSBBB] (viJj.esBsssi). N.B.— In addition to the above» the Right Apex receives the following bronchi from the Pectoral Distribution :— External Anterior Apioa BfiOyCHTAL SUPPLY TO LEFT APEX. LEFT TTPPEB (BKOWCHUE Left cardiac bronchus (Ij.d). (See Table III.) Axiilabt- (iij. Lept ascending apical stem (iv. ass). Anterior ascending apical (v. a»sa). Posterior ascending apical (v. asss). Apical bteeno-clavicular (vj. assai). Anterior Apical steeno- clavicular claviculae (vij. assaia). (vij. assali). Innee anteeioe apical (vj. assaa). Anteeioe claviculae (v^. aBsaaa). Innee anteeioe apical (vij. assaaa). Inwaed Forwaed T-shaped T-shaped bronchus beonchus (viij. assaiii). (viij. assaiiu). Outee teeminal (viij. asEaase). Innee terminal (viij. assaasi). Descend- Anteeioe ing beanch. BRANCH. Anterior ascending aortic (viij. asBsisa). Posterior ascending AORTIC (viij.asssisp). Antebiob Posterior VERTICAL vertical APICAL apical (viij. asssssa). (viij. asssssp). Anterior vertical Veetical marginal (u. asasBsas). (ix. asBsssai). Innee vertical maeginal (x. asssssaia). Anteeioe veetical marginal (x. asssssaii). N.B,—Th^ meaning oftU lettera used as notation is explained on page 88. ZiOBAB BHOUCHTJS. ( 97 ) PECTOaAt THUKK (ij.a). (See Table II.) Sight axillabt stem (iij. ee). CbNT&IIi AXII1I1AB.T INTESLOBAR (It. eed). AXILLABT STEU (iv.eee). Eetro-axillaet (v. eeep). AxiLLAffiT (v. eeee). Betro-axillabt ivteblobar (vj, eeepd). IlETItO-ASIlIiABT (vj. eeeps). EXTEBXAL IlfTEBLOBAB (vj. eeeed) Sppea- SPINATE (vij. eeepsp). ABCEVDIIfCl Keteo-axiiiaet StrPEA- SUPEA-SPITTATE spiNATE (viij. eeepspp). (viij. eeepsps)* POSTEBIOE AXILLAET APICAIi (vy. eeepse). DEBCENJ>IN'Gi' FOBTEBIOB AXILLABT (viij. eeepsed). Posterior axillary APICAL (viij. eeepses). AnTEEIOE AXILLABT APICAL (vij. eeeeep). Ibtfeeioe terminal (vi'j. eceeepd). and Clavioular Branohes (from the Mid-peetoral); Steruo-olavicular and Apical Parasternal (from the Ascending Parasternal}. IiOBAB BBOWCHUB IMPAE). Left pectori-aficaIi bronchus («. a). APICAL STEM Pectorai, TRriTB: (iij.aa). (See Table II.) Left (eudimentaet) axillart stem (iv. ase). Posterior axillary stem (v. ases). Posterior apical (vj. asess). MiD-APICAI. (vj. asese). Axillary stem (v. asee). Axillary posteeiob Axillary IlfTERLOBAR STEM (vj. aseepj. (vj. aaeee). Inweb posterior APICAL (vij. asesss). I Outer posterior APICAL (vij.asesse). / IirifER MID- APICAL (vij. asesei). Outer MID- APICAL (vij . asesee] Outer ASCENDIva APICAL (v^.aseees). Superior axillary (vij. aseeee). T-SHAPED InWER DEEP MID- PULMOITART APICAL (viij.aseseia). (viij. aseBels). / Outer MID- APICAL (viy. aseseea). Outer posterior APICAL (viij. aseseep). T-SHAPED Outer Outer POSTERIOR POSTEBIOE CENTBAL MARGINAL APICAL (ix, asBseise). (viij. asessep). (viij. asesses). Inner Infebiob Supeeiob Outeb Posterior MID- outer pUTER POSTEEIOB OUTER APICAL MID-APICAL MID-APICAL APICAL CENTBAL (ix. aseseiss). (Ix. aseseeae). (ix. aseseeas). (ix. aseseepe). (ix. aseseeps). HoBizONTAL Ascending Centeal Inneb OUTER OUTEB ASCENDING MID-APICAL POSTEBIOE POSTEEIOB (x. aseseisss), (x. aseseissi). APICAL APICAL "•*" (ix. asessese), (is. asessess)^ Posterior Anterior inner inner Posterior Inner terminal, terminal, xpioal aortic posteeiob recubrent apical (viy. aseBBsi). (viij.ases&ss). Inner Outer terminal terminal (ix. asessBBi). (ix, aBesssse). Posterior Outer terminal. terminal. T-SHAPED POSTERIOR INTERLOBAR (viij. aseeeep). !^UPERIOB AXILLARY (vij. aseeeee). Antebior axillary BRANCH (viij. aseeese)^ Descending Ascending supeeiob supebior axillary axillary (ix. aseeeecd). (ix. aseeeecs). Horizontal Axillary SUPEEIOB apical AXILLAEY BEONCHUS (x. aceeeeese). (x. aseeeeeas). Claviculab and OTHER BEANCHES. G 98 THE BRONCHI AND PULMONARY BLOOD-VESSELS. PoBterlor tracheal (vj. esspi). Posterior tracheal (vij.esspis), Posterior j tracheal I recurrent \(vij.esspii). Apical supra- spinate (vj. esspe). Apical supra- spinate (vij, esspes). T-shaped dorsal supra- spinale (vij esepep). the apical supra^spinate. Both branches are readily seen in fig. 1 1 , square Hij. The Posterior Tracheal Bronchus closely resembles in shape and general direction the anterior tracheal bronchi and gives up early an inward, slightly descending, horizontal branch ending with X"Sl'a'Ped bifurcation, the Posterior Tracheal Recurrent. The branches of this bronchus (ascending and descending) run in a line with the posterior-inner border of the apex. The small trunk continued yields a deep-pulmonary, — and various small branches. After a full curve with concavity inwards, it terminates at the same level as the anterior tracheal bronchi, at the inner apical surface. The Apical Supra-spinate, diverging from its twin-tube, curves in the opposite direction, with concavity outwards and downwards ; the sweep of this curve is a much longer one, this bronchus sending a branch to the extreme outer-posterior surface at the level of the acromion. The branches of this trunk imitate the two bifurcations of the preceding one. But the "Y-shaped Dorsal Supra-spinate Bronchus (seen in fore- shortening in fig. 1 1 at lower part of square H ij) is directed straight backwards, and the deep-pulmonary, instead of being anterior, is lateral. The trunk itself terminates in an anterior and a posterior outer supra-spinate branch of small size ; and these, by their sub-pleural divisions, supply the district above mentioned. The accessory apex bronchi will be described under the respective head- ings of the pectoral, and of the axillary distributions. THE LEFT APEX AND ITS BRONCHIAL SUPPLY. The Left Upper Lobar Bronchus (Bronchus Impar) and the Pectori-apical Stem. A short preliminary description of the behaviour of the upper lobar stem is indispensable for the due appreciation of the relations of the apical bronchi. The Left Tipper Lobar Bronchus arises at a level 3 cm. below the level of the right upper lobar. Its horizontal distance or " longitude " from the infra-tracheal angle is 4-3 cm. It takes its origin from the upper anterior (and, slightly perhaps, outer) aspect of the main bronchus, which, bending downwards at that spot, alters the slight upper concavity of its transverse portion into the inner or cardiac concavity of its intra-pulmonary segment. Direction, Calibre, and Length. — A direction forwards and out- 1-3 cm. wards is assumed by the upper lobar trunk. Its length is only 1-3 cm. but Lett upper lobar bronchus. Site and mode of origin. Direction forwards and out- wards. Length THE BEONCHI AND PULMONARY BLOOD-VESSELS. 99 it possesses a calibre of considerable size. Although not as large as that of Calibre the inferior lobar bronchus, its diameter is apparently equal to that of the lhlt\l° right upper lobar bronchus.* But it should be borne ia mind that the left T?.'"' "rr^r 111 1 • lobar. upper lobar bronchus is not the perfect equivalent of the right upper lobar. Inasmuch as it supplies the cardiac besides the apical and pectoral districts, it must be supposed to contain the elements of a cardiac, as well as those of an apex-bronchus. Reasons for using the Name "Bronchus Impar." — By follow- ing the two branches it is easy to verify the correctness of this assump- tion. One of these, the descending branch, is distributed in a manner and A descend- in a situation analogous to those of the right cardiac bronchus. The other J^f cardfao' branch rises, with a direction which will be presently described ; but it soon bronchus ; gives off, by bifurcation, a large anterior bronchus, which is devoted to the fng'braneij, supply of the pectoral region, and which is at once recognized as the fellow to ^°™ '^'^f"''" the right pectoral bronchus. The other product of this division, after a a pectoral straight upward course, supplies three branches to the apex ; this ttibe is axuiarj'- obviously the equivalent of the right axillary-apical. It is equally mani- l<^f"'\'^a^i, fest that the trunk from which both the pectoral and the axillary-apical arise apical is no other than the fellow to the right pectori-apical trunk. It is now clear that, whereas the right pectori-apical trunk is the upper The right lobar bronchus for the right lung, the same trunk in the left lung is only ^pkaHs a branch of the upper lobar bronchus, and a twin-tube to the cardiac bronchus. ^^« ^"^^"^ The left upper lobe therefore contains an additional, and, judged by not so in ' the standard of the right bronchial tree, an irregular tube. Beyond ^lg_ ' this tube the left upper lobe presents an equality with the right as The left regards the number of internodia and of bifurcations. But the tube under ^^t gon". '''^ discussion is essentially different from the right upper lobar bronchus in its parable ,,. ,.., ,..7. ., , ,. . with the behaviour and m its branches; and, since it is impossible to deprive it right; of the name "upper lobar," it is at least necessary to add to this name natedas^ another which shall express the essential dissimilarity between it and the I'bronchna right upper lobar bronchus. Hence the term " bronchus impar " which I propose for it. The Pectori-apical Stem. — On the other hand, although the left The left lung contains a stem exactly the counterpart of the right upper lobar apica"" bronchus, it is impossible to give to this stem the name " left upper lobar." ^^ tjj°f°Jgi,t It must be known merely as the pectori-apical stem. This difficulty has led upper lobar, me to use an alternative name for the right upper lobar bronchus also. I termed left term it the right pectori-apical ; and by this means I am able to secure a B^,^^th°^'^'"' correspondence in the names which shall express the correspondence which right upper , , -, lobar may exists between the tubes. be termed Differences between the Left and the Right Pectori-apical p^?,'°,"- Bronchi. — There is however a great disproportion between these two bronchi Different in their size, in their direction, in their level of origin, and in their distance direction,"' * Of. p. 21. lOO THE BRONCHI AND PULMONARY BLOOD-VESSELS. and posi- tion of the two pec- tori-apical bronchi. Elongation of left apical in- temodia rendered necessary by low origin of pectori- apical, 'Pectoral trunk (iij. aa). ' .Axillary- apical trunk Mij. as). from the infra-tracheal angle. The left pectori-apical is a short trunk mea- suring only 8 mm. It does not continue the direction of the bronchus impar forwards and outwards, but abruptly rises, almost in a vertical line, and with a slight inclination forwards and outwards. Thereby it serves the purpose of diminishing the vertical distance which exists between the level of origin of the left axillary-apical trunk and that of the right. Nevertheless a vertical distance of 2 cm. persists between these two poiuts of origin ; and inasmuch as the upper level reached by the right apical distribution is practically identical with that reached by the left, the difference must be made up by a lengthening of the ascending branches of the left distribution. Branches of the Left Pectori-apical. — Two large trunks arise from the bifurcation of the pectori-apical trunk : the pectoral stem, "which proceeds straight forwards and a little upwards ; and the axillary apical stem which is almost vertical, preserving the slight forward inclination, but losing the faint outward tendency special to the pectori-apical. The pectoral dis- tribution will be separately considered ; but the apical and the axillary distri- butions cannot readily be treated independently of each other, owing to their common origin from one trunk, but chiefly because they take almost even shares ia the bronchial supply to the apex. General Survey of the Bronchial Distribution to the Left Apex. The left apical bronchus has a smaller distribu- tion than the right. Extent and shape of the distri- bution. Distribu- tion of the posterior axillary, Area of Distribution of the Apical Bronchus. — The apical division of the left axillary-apical trunk plays a much less important part in the bronchial supply of the apex than that which belongs to the right apical. The latter was shown to occupy the whole inner aspect, and also the whole upper-posterior aspect of the apex. In the left lung the apical bronchus is restricted to the inner-anterior corner of the apex. Its branches supply the inner-anterior border and a section of the adjoining inner, and of the adjoining anterior surfaces, not quite amounting to half of each of these surfaces. Of the cubic space of the apex this distribution may be said to occupy the anterior-inner third. The general shape of the distribution is that of a pyramid presenting an anterior, an inner, and a posterior- external side, a base facing downwards towards the infra-apical bronchial interspace, and a summit pointing upwards towards the inner-anterior angle of the apex. Areas of Distribution of the Anterior and Posterior Axil- lary Bronchi. — Both divisions of the axillary stem, but especially the posterior, possess, in the left lung, a predominating upward tendency. To the posterior axillary division belongs the bronchial supply of the following surfaces of the upper apex, viz., the posterior part of the inner surface, the whole posterior surface and outer surface, and the outer part of the anterior surface. THE BRONCHI AND PULMONARY BLOOD-VESSELS. lOI The anterior axillary division is distributed to the lower, or basic zone of and of the the apex, in the outer-anterior and in the superior-axillary regions. txiUaiy. Accessory Apical Supply. — Only one branch from the pectoral dis- The asog. tribution the ascending mid-pectoral comes into relation with the apex, rising ^pproTihee anteriorly as far as its lower or basic boundary at about the level of the *^® ^^^ "* • /.■IT », ,., __. •' the apex. interior border ot the clavicle. But it does not take any part in the air-supply about to be described. Peculiarities of the Left Axillary-apical Trunk. — Strongly con- vertical trasting with the rudimentary ri^t axillary-apical trunk, the corresponding stem ^^1 con" on the left side has a length of i cm. Moreover, instead of being horizontal siderabie outwards, it is almost vertical upwards and slightly forwards. This circum- theaxii- stance enables not only the apical trunk, but also the axillary to arise from a ^^^-^'^^"^ ■ level relatively less inferior than would otherwise have obtained. The manner spurions in which these two trunks originate is in one sense analogous to the arrange- tf'f"™^-- ment at the right apex ; it is a spurious trifurcation. That Professor Aeby Prof. Aeby should select this as an instance of bifurcation in contrast to the trifurcation f^biTurra- which he describes (loc. cit., p. 62) at the right apex is the more astonishing tion i^ere, as, in the specimens which have been examined by me, the left division was cation at so evenly tripartite that it was difficult to determine which two, among the apex!^ ' three apparently simultaneous tubes, were linked together by an abortive The left common trunk. Probably Professor Aeby's specimens presented a different thTmost arrangement of tubes. Nevertheless this is essentially a bifurcation repeated fjjf]™^ '° unilaterally, of the same type as that elsewhere described (see p. 91); and we are enabled to analyse and interpret correctly its deceptive appearances thanks to our knowledge of the faithful analogy existing between the upper right and the upper left lobes, which Professor Aeby had thought to have dis- proved. Studied in the light of that analogy the left ascending apical trunk is consists seen most clearly to be a complete though a diminutive reproduction of the ascg.apioai, right ascending apical ; and it follows that the two other members of the an?v.°lnd^ apparent trifurcation are respectively reproductions of the two axillary divisions posterior m the nght lung. bronchi. A confirmation of these views is readily obtained by a close inspection of The the mode of division of the axillary-apical trunk. The ascending apical is apical ta^s not the direct continuation of this trunk. It tends to form an angle with i'Oiorma.n , angle with the latter by diverging slightly forwards and inwards. Had the axillary- the axil- apical trunk been horizontal, as in the right lung, the size and the morpho- truukaTlc logical value of this angle would have become more obvious ; it would have Juq"^'^'' directly pointed to the morphological identity between the right and the left apical bronchi. Viewed anteriorly, the three trunks in question are placed side by side, Thetrifnt'- and the two angles which separate them have their apices at the same level, deceiving Posteriorly, however, this is not the case. The two axillary divisions arise ^"*®"°^'y- from a short common trunk of origin, directly continuous with the parent the bifur- I02 THE BRONCHI AND PULMONARY BLOOD-VESSELS. cation is recognized. A rudimen- tai-y axil- lary stem is visible. The differ- ences ex- plained by the assump- tion of a horizontal pectori- apical stem having become vertical. The ascending apical ■would be dwarfed by this rota- tion ; the axillary bronchi would acquire greater size. stem, and are decidedly posterior to the ascending apical, whicli tlie said trunk partly Mdes from view. The separate existence of this rudimentary stem is capable of demonstration in the metallic cast (see fig. 1 1 , square C iv), owing to the fact that the furrow dividing its two branches terminates fully 2 mm. higher than the furrow dividing it from the ascending apical trunk. In conclusion the differences noticed between the bronchial tree of the two apices are readily to be explained if we imagine that a lobar bronchus bearing the same branches as the right upper lobar bronchus had been lifted bodily from the horizontal into the vertical position. Certain re-arrangements of direction, of size, of length, and of branching of bronchi would be necessary in order to fit within the pleural space a bronchial district thus rotated ; but no important member of the bronchial system need in the process have been altered past recognition. The greatest sufferer in a process of this kind would obviously have been the ascending apical trunk, for in the right lung, with horizontal axillary- apical stem, this was the only large ascending trunk. In a similar way the axillary divisions would have gained largely in importance as members of the apex-supply ; and they would, of necessity, have usurped part of the posterior and outer territory otherwise monopolized by the ascending apical. These are precisely the conditions observed at the left apex. Subdivision to be adopted. — In view of the importance thus attained by the two axillary divisions, the description of the apex-supply will be sub- divided into three sections respectively devoted to the ascending apical, to the anterior axillary and to the posterior axillary bronchi. Distribution of the Left Ascending Apical Bkonchus. /Anterior ascending apical (v. assa). Posterior ascending apical (v. assg). Apical sterno- clavicular (vj. assai). I Inner anterior apical (vj. assaa). The Ascending Apical Bronchus rises forwards and inwards, for a distance of I "2 cm., as far as its bifurcation into the anterior and the posterior ascending apical. The posterior trunk assumes an almost vertical direction. The anterior, on the contrary, improves upon the forward tendency of the common trunk ; but its two branches subsequently revert to a more upward direction. The anterior trunk and its two branches are seen in fig. i o (in square F iv close to line F). Anierior Ascending Apical Distribution. The Anterior Ascending Apical, a short stem, 8 mm. in length, closely corresponds to the same trunk in the right apex ; but instead of facing inwards, its two branches are distributed forwards, to the anterior surface of the apex. They are respectively named apical sterna-clavicular and intier anterior' apical. They are both very wavy in outline, or even angular, especially the stemo-clavicular. (See fig. i o, squares F iv and E iv.) A descending intra-pulmonary branch, of small size, is supplied by both, or by the anterior branch from each of them. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 103 The Apical Sterno-clavicular contributes its descendiag deep Apical pulmonary branch before bifurcating. Both its branches of bifurcation are ciavMar mainly horizontal. The outer, a Superficial Clavicular Branch, is of (/iJ^s^Kii). „, 11 . . ' Ant. small small importance. ciayiouiar The Apical Sterno-clavicular Branch, bending inwards at a ilsL). right angle, divides into two large T-shaped bronchi respectively directed luward ^ towards the anterior surface and towards the internal surface of the apex. ZtnT^ The Anterior Inner Apical follows a serpentine course upwards, (^"J.-. where its termination does not reach the highest level. (See fig. 10, Anterior squares F iv and P iij.) £ndf ^^ Its Anterior Clavicular Branch is given at the same level as that [^^iia.^ from the sterno-clavicular (see fig. lo, square P iv), horizontally forwards. Antoioi- It is more important than the inner clavicular, and comes into contact inner apical below with the extremity of the ascending mid-pectoral trunk (the latter Anterior tube has been interrupted in fig. lo, near the right upper corner of branch (Wj square I' v). The descending deep intra-rpulmouary is given off from this *^^*^)- branch. The continuation of the trunk supplies deep intra-pulmonaiy branchlets, Outer ter- and one larger ascending, posterior, intra-pulmonary and finally divides into Ss^tse™''' an inner larger and taller, and a smaller outer terminal branch for the supply ^^^^ ^^^'j . of the anterior apical surface, just below the higher distribution of the vertical assaasi). apical and of the central apical bronchi. These two terminal tubes are seen in fig. lO, square Fiij, the inner branch ending on line ij, the outer branch in the middle of the square. Posterior Ascending Apical Distribution. The Posterior Ascending Apical supplies the anterior part of Posterior the inner surface of the lower apex, and the inner fourth or third of the ^^1^'°^ true summit of the lung. Part of this distribution is shown, in fig. lo, (v.asss). occupying a posterior plane, at the boundary between squares E iij, B iv, and P iij, P iv. Its direction is almost vertically upwards, and its length Aortic about 8 mm. It differs from the right trunk bearing the same name, in not (vj. asssi). being in any sense dorsal, and in dividing, not into an anterior and a J^^^^x^^ posterior, but into inner and outer branches, which may be described as aortic W- assss). apical and as vertical apical bronchi, respectively. The Vertical Apical resembles closely the axial apical of the right Eising apex, but lies nearer the internal surface. It is a long thin branch supplying branch^v^. upward branches at acute angles. Its first bifurcation yields posteriorly a y^^t^^i rising intra^apical hrancli. Its second bifurcation supplies to the mesial apical (vij. surface of the apex two trunks known as posterior and as anterior vertical "°°°° apical bronchi, which diverge but slightly at first. The vertical apical and its two branches are shown in fig. lO, chiefly in square Fiij, close, and almost parallel, to line P. 104 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Antr. (viij. asssssa), and postr. vertical apical (viij. ^asssssp). Antr. ver- tical (ix. asssssas). Antr. mar- ginal (ix. asssssai). ^Anterior vertical niarginal(x, asssssaia). Inner ver- tical mar- ginal (x. Aortic apical trunk (vj. asssi). 'Ascg.aortic apical (vij. asssis). ( Aortic I apical re- cun-ent l^(vij. asssii). ' Antr.super- ficial ascg. aortic (viij. asssisa). Postr. supl. ascg. aortic (viij. The Posterior Vertical Apical, after an upright course, during whicli small inward branches are given to the sub-pleural surface, arches backwards and inwards towards the corresponding upper corner of the apex, which it does not quite reach. The Anterior Vertical Apical divides, after a course of i"3 cm., into an anterior vertical and a vertical marginal bronchus. The vertical apical bronchus terminates upwards in a line with the ascending apical stem. The vertical marginal bending inwards horizontally gives rise to two X"S^^P®^ branches distributed to the inner and to the anterior surfaces in the same manner as, but at a much higher level than, the branches from the sterno- clavicular, (See fig. lo, squares E ij and Eiij.) The Aortic Apical Trunk (for this distribution see fig. lo, squares E iij and E iv) in its supply to the lower part of the inner surface of the apex is overtopped by the taller arching branches from the ascending apical and from the ascending axillary. It may be regarded as the displaced and diminished equivalent of the right supra-spinate. Its length is 4 mm. It bifurcates into an ascending portion and into an inward Aortic Apical Re- current Bronchus. The latter presents a strongly hooked descending branch and a small anterior branch, both freely provided with branchlets (seen in fig. i o, square E iv in a posterior plane). The Ascending Aortic Apical divides into an anterior and a pos- terior superficial bronchus, which diverge upwards in the shape of a letter V; and are also well furnished with sub-lobular branches. (See fig. ip, square E iij.) LEFT AXILLAEY DISTRIBUTION. Eudimen- tary axil- lary stem (iv. ase). /Posterior axillary stem (v. ases). Axillary steDj (v. asee). The Rudimentary Axillary Stem (see fig. 10, square Pv; and fig. 1 1 , square C iv) is the continuation of the axillary-apical stem. Viewed from the front, it presents no appreciable length, but immediately bifurcates. Of its two divisions one only, the posterior axillary, preserves the original direction upwards, outwards, and very slightly forwards. The other, or axillary division assumes greater obliquity outwards, forming with the horizontal an angle of 45°, Owing to these directions the former becomes essentially an apex-bronchus, the latter remains to a great extent axillary. The whole of this distribution may with advantage be studied from the posterior aspect of the cast, in fig. 1 1. Distribution of the Posterior Axillary Trunk. Poaterioi- The course followed by this bronchus takes it past the central point of trank^ the apex, a little behind that point. At the level of the centre it breaks up (v. ases). jjj^-Q fgyj. branches (an anterior and a posterior inner, and an anterior and a posterior outer) for the aeration of the central and of the posterior parts of THE BRONCHI AND PULMONARY BLOOD-VESSELS. I OS the apex. These arch in bold curves respectively outwards and inwards, and thus assume a distant resemblance to the lateral leaves of a palm-tree. (See fig. I o, square F ij ; the distribution is best shown however in the posterior view, fig. 1 1.) The Posterior Axillary, in its undivided portion, has a length of 1-3 Posterior \ cm. In the apparent trifurcation of the axUlary-apical stem (seen in square (vj^asess). I F V of fig. I o), it lies slightly behind the two other trunks which, viewed from ^-"^^sS. 1 the front, appear to arise at the same horizontal level with it. Its first bifurcation supplies the strictly vertical posterior apical, a trunk 8 mm. in length; and the mid-apical, i'2 cm. long, which continues the original direction with slightly increased outward bias. Inner postr.s The Posterior Apical, overlapped in fig. 10 by the mid- apical and its asesss). ' I bifurcation in the lower and outer corner of P iij, divides into an inner, and api«a^(^f'| into an outer posterior apical trunk. aseese). ) The Inner Posterior Apical continues the vertical direction as far innerpo8tr.' part of the inner superior margin, and the inner posterior angle of the apex ^^^i (S" (fig. II, column 0, line j). asesssse). The outer branch arches outwards (column B, line j) to the inner posterior half of the summit. The Outer Posterior Apical has a posterior as well as an outward Outerpostr, ascending tendency. It remains posterior to the outer branch of the mid- asesses). apical stem ; and not reaching as high as the summit, it is overtopped by ) branches from that bronchus. At the same level as its twin-tube it yields a Jjsfc^fr f-shaped posterior margirml bronchm, of which the descending branch assists ginai (viij in f ormins: the posterior edge of the inferior lobe (fig. 1 1 , line C). n i.iT-T-i T Asog. onter\ After a further course of i cm. the trunk divides into an ascending posterior outer posterior apical and a horizontal outer posterior apical, which are asesslss)." distributed to corresponding regions. mter wr. ( apical (ix. The Mid-apical Stem is of much more important size than its f^ff^^^f > fellow. Its two arching branches, the inner mid-apical and the outer mid- trunk ■npical (ending in columns B and C of fig. 1 1 above line j), span the entire ^'^■^^^^J" ) lo6 THE BRONCHI AND PULMONARY BLOOD-VESSELS. /■Inner mid- j apical (vij. I asesei). i Outer mid- I apical (vij. vase see). width, and terminate respectively at the inner and at the outer surface of the apex. The inner surface however is only touched by a far-reaching branch, whereas the central apex, and the outer surface in its upper part, are entirely supplied from this source. Viewed from above, this district would take the shape of a pyramid inscribed in the curve of the pulmonary summit, and presenting its apex inwards, and its base outwards. In front of the apex of this pyramid would lie the apical district of the ascending apical bronchus ; and behind it, the smaller inner-posterior apical district would complete the roughly quadrilateral outline of the total apex-district. Inner mid- apical (vij. asesei). /T . deep pul- monary (Tiij- aseseia). Inner mid- apical (viij aseseis). /Outer I central (ix. J aseseise). j Inner mid- apical (ix. I (Central ascg. (x. ttseseisss). Inner mid- apical (x. aseseissi). The Inner Mid-apical is the longer, the more vertical at first, and subsequently the more curved of the two branches. Whilst ascending, as does its parent trunk, almost vertically, it reverses the outward tendency of the latter into an inward tendency with concavity inwards. As the summit is neared, this tendency develops into a strong curve inwards and upwards. (See fig. 1 1, square B ij.) The branches all take their origin upwards, from the outer or convex side of the bronchus, with one exception, that of the X'Shaped Deep Pulmonary (see fig. lo, between squares P iij and G iij), a small branch arising forward from the early part of the trunk and facing the transverse apical bronchial interspace. The next bifurcation provides an ascending Outer Central Bronchus, ending, in fig. 1 1 , at the intersection of lines B and j ; and the ensuing bifurcation an upright Central Bronchus which delivers a small Anterior Mid-apical Bronchus forwards to supply the upper surface not reached by the anterior inner apical. (See fig. 1 1, square B ij, near line 0.) From the level of this bifurcation the mid-apical curves strongly inwards, and when near the inner upper margin divides into an anterior and a posterior branch, one of which (or both) reaches the margin. Descending intra-pulmonary branchlets are given by these bronchi. (Outer mid- apical (viij, nseseea). Outerpostr. apical (viij . i 'Superior outer mid- apical (ix. aseseeas). Inferior outer mid- apical (ix. aseseeae). / Outer postr. I apical (ix. J aseseepe). 1 Postr. outer central (ix. asese eps). I ( li The Outer Mid-apical, which crosses diagonally, in fig. lo, the square G iij, almost strictly continues the outer ascending tendency of the common trunk, but it adds to it a strong backward element. It bifurcates into an anterior or outer 7nid-apical branch and into a larger outer posterior apical branch. In their branching their divisions are symmetrical, but of uneven size and slightly different level. The Outer Mid-apical division, after yielding, near its point of origin, a downward T-shaped branch, divides into a- superior and inferior branch of bifurcation for the upper outer slope of the apex exactly above the axillary apical. The much larger Outer Posterior Apical divides into a,posterior outer- central branch and an outer posterior' apical. The names of these bronchi sufficiently indicate their destination. The terminal branches from the THE BEONCHI AND PULMONARY BLOOD-VESSELS. I07 posterior outer-central are purely superior. Those from the outer posterior- apical are partly bestowed upou the posterior, partly upon the outer upper margin of the apex. Distribution of the Left Axillary Trunk. The upward and outward course of the axillary stem is maintained for Axillary a distance of i • i cm. at the level of its second bifurcation where the two ^'^™" resulting divisions, especially the lower, assume a more horizontal course. The first bifurcation yields an important Axillary Posterior Inter- Axillary lobar which faces the inner branch of the ascending oblique- dorsal trunk, fnterlobar. From the front this is seen in fig. i o, close to intersection G iv. In fig. i r , ^^'*'^ it is hidden from view, except its origin in iv. The axillary stem now divides into an outer almost horizontal trunk the superior superior axillary, and an anterior trunk the outer ascending apical. (See fig. ^^]^}^^ 10, square G iv.) aseeee). The district corresponding to these trunks is analogous to the pyramidal Outer ascending apical district, but the pyramid is here a low one, none of the apical (vij. branches rising to a high level. aseees). The Outer Ascending Apical soon gives an outward smaller Antr. axii- ■ branch, the Anterior Axillary, which is almost horizontal and lies in front cS (vuf of the superior axillary, assisting in forming the upper boundary of the outer asce infra-apical bronchial interspace. (Seep. 108.) apical (viij. The outer ascending apical distributes a "^-shaped Iranchlet towards the ' transverse apical bronchial interspace, & posterior deep pulmoruiry, and forwards a clamcular and an ascending clavicular branch. It terminates in an upper Oaivicnlar and a lower terminal branchlet, below and in front of the anterior division branches^ from the outer mid-apical. The Superior Axillary, at first rising slightly, becomes horizontal, Siip. axy. and gives horizontally outwards a "f'Staped interlobar branch. The trunk, aseeeee). after a further outward course of i cm., divides into an ascending, and a pci^tranter- slightly anterior descending superior axillary. . aseeee*' T^' The Descending Superior Axillary branch inclines slightly down- Descg.supr.^ wards and divides into an upper and a lower surface-branch for the anterior ^^y- (■^- ■* ■*• 81S6G66GCI 1, axillary district. This terminal fork is easily recognized in fig. 10, square Ascg.supr. TT . axy. (ix. Ji IV. aseoeeos). The Ascending Superior Axillary branch divides into the Hori- AxiUary \ zontal Superior Axillary and into the Axillary Apical Bronchus. aseeeleS). I Both these bronchi terminate, at different levels, in the mid-axillary line, by ^p^rf™'*' ( means of anterior and posterior branches of bifurcation. - axillary (x.j ■* aseeeeese). 108 THE BRONCHI AND PULMONARY BLOOD-VESSELS. The Left Infra-apical Interspace.. Left infra- A Well-defined, horizontal interspace, transverse to tlie axis of the body, space, which may be conveniently termed the left infra-apical interspace, is found to ri°ht"^ between the bronchial stems which rise to the apex of the lung, and the stenio- horizontal bronchi destined for the pectoral distribution. This bronchial space ; interspace is well shown in fig. i o, below line iv. It is analogous to the sterno-scapular interspace in the right bronchial tree, but difiers from it in direction, cause of The want of symmetry between the right and the left bronchial interspace ^fferences ^^ bound Up with difierences in the shape and relation of the two pectoral Right apex bronchial districts. On the right side of the chest, the pectoral trunk assists sevmir largely in the bronchial supply to the apex. In the left lung the apex is branches independent of anv aid from the pectoral trunk, having derived its air- from pec- -^ , •' -^ . i. i -n torai trunk. Supply in great measure from behind, at the expense of the axillary ontref distribution. Upper It results that the left pectoral district possesses an almost horizontal oHeft'^'^ upper boundary, one twig only, the ascending mid-pectoral, rising to the S?'^^''?™',. level of the apex-bronchioles and terminating in the middle line of the lung, is hori- between the inner and the outer anterior apical distributions. Extending to the zontal . . . ... on a level outer surface of the lung where it faces the posterior horizontal distribution, horizmi^ai. ^^^om that spot the boundary slopes downwards and inwards — forming the sternal hypotenuse of a triangle, the right angle of which is formed by the sternal border and by the horizontal boundary. The level of the horizontal boundary is the same as that of the right hori- zontal sternal bronchus. The right The greater part of the right pectoral district is above this line, whereas dfstrict'is *^® wholc of the left pectoral district is inferior to it. This important point ™*i"'y may be made out in fig. lo. Line v, in that drawing, is situated a little level. below the level in question. RIGHT AXILLARY DISTRIBUTION. Axillary The Axillary Trunk, short and broad (little more than i cm. in (ii]"?ee). length), is the direct continuation of the upper lobar bronchus. It is the outer division from the tripod described by Aeby (erroneously, as I have endeavoured to show) as a trifurcation of the "eparterial" bronchus. The apex-trunk and the axillary trunk should rather be regarded as bifurcated from a rudimentary intemodium, of the same standing as the pectoral trunk, and with it derived by bifurcation from the tipper lobar bronchus. THE BRONCHI AND PULMONARY BLOOD-VESSELS, I09 This rudimentary trunk has already been described under the name of axillary-apical (E ij). The branches arising from the right axillary spread outwards, under General repeated bifurcation, in the shape of a pyramid having its apex at the axXr^^ apparent trifurcation. The base of the pyramid is represented by the '"strict. axillary and by the outer-posterior apical surfaces of the upper lobe. The Central Axillary Interlobar is a short and relatively stout Axuiary bronchus descending from the axillary immediately before its bifurcation. /iv°eee). So close is this relation that, had this bronchus ever been previously ^xmar' described, it would probably have been regarded as forming part of a trifurca- interlobar tion. Its two branches, sloping respectively forwards, and backwards, end with T'S^^Psd branchlets at the interlobar surface. Further reference will be made elsewhere to this distribution. This interesting bronchus and its branches are displayed in square H iv «f fig. 1 1 . Two slightly diverging trunks of almost equal size, the axillary and the Axillary retro-axillary hronchi, are the products of bifurcation from the main trunk, (™°eee). the faint upward tendency of which is assumed, in more marked degree, by ^'™" its continuation and namesake (v. eeee). trunk The bifurcation in question is seen in fig. 1 0, just below the intersection ^^' '^^^^^' of lines C and iij. Distribution of the Bight Axillary Division. The Axillary Trunk is about 2 cm. in length. From its middle Length of part arises obliquely downwards an External Interlobar Branch. t™k!^ Branchlets are distributed from this bronchus forwards and backwards. The final bifurcation of the axillary takes place in the same plane as the Axillary preceding one, the anterior axillary-apical and the superior axillary being (Vj^eeeee). the results. To the former reference has been made elsewhere (see ^^to™al r ^ interlobar I "Apex'). They both possess a length of about 2 cm. and a symmetrical (vj. eeeed).j termination into an upper and a lower forking division. (Consult diagram fig. 9 ; but note that the axillary apical, as there shown, is too distant from the apex, and not sufiiciently vertical in direction.) The Anterior Axillary Apical supplies a small branch forwards, Anterior and rises for a distance of 2 cm. before bifurcating. The upper of its forked apiraTfvii terminal branches ends near the external surface of the apex at the level of eeeees). the middle third ; the lower third being supplied by the inferior branch. axillary The Superior Axillary presents exactly analogous branches, which elee'ep). provide for the aeration of the middle or external portion of the superior axillary region, the anterior and posterior aspects being otherwise supplied. I 10 THE BRONCHI AND PULMONARY BLOOD-VESSELS. /Eetro- axillary l(vj. eeeps). ( Eetro- I axillary I interlobar \(yi- eeepd). Supra- Bpisate (vij. J eeepspj. V. Posterior I axillary I apical ^vij. 'Ascending supra- spinate (viij. ( Eetro- axillary snpra- Bpinate veeepspp). /Posterior axillary apical (viij. eeepses). Descending posterior axillary (viij. ^eeepsed). Distribution of the Might Retro-axillary Division. (This distribution can be best studied in fig. lo, squares H iij and I iij.) Singular among apex bronchi in possessing a posterior origin and a backward course, the retro-axillary trunk is of same size as its fellow, and likewise delivers a descending branch, the Retro-axillary or Superior Dorsal Interlobar which however quickly becomes horizontal, and with T-shaped bifurcation subtends the interlobar pleural surface. The two arms of the T ^''^ s^^'^ ^^ ^S- lOj above and almost parallel to line iij. The retro-axillary presents slight upward tendency and bifurcates into equal divisions, the supra-spinate and the posterior axillary apical. The Supra-spinate Trunk continues the backward curve of the retro- axillary, and ends after a course of i"5 cm. in an Ascending Supra- spinate and a Retro-axillary Supra-spinate Branch. Both these tubes contribute in the formation of the base of the pulmonary apex. They extend respectively outwards and backwards at the level of the scapular spine. The Posterior Axillary Apical Trunk, moving outwards and upwards, bifurcates into the Posterior Axillary Apical and into the descending posterior axillary. The former is concerned in the supply to the outer posterior border of the apex. The Descending Posterior Axillary, inferior to the preceding bronchus, curves downwards, but previously sends an anterior descending branch to the axillary region. The right axillary distribution, which has briefly been sketched, diifers greatly from the left in the horizontal direction of its trunk and of most of its divisions, and in the more limited share which it takes in the formation of the apex proper. Shortened intemodia and, as a result, apparent trifurca- tions are frequent in this distribution which thus rapidly acquires an extensive periphery. ( HI ) THE PECTORAL REGION. RIGHT PECTORAL DISTRIBUTION. General Survey of this District. The General Shape of the pectoral bronchial district is roughly that General of an elongated pyramid, placed horizontally with its small end towards the of an^ root of the lung. The base of the pyramid corresponds to the anterior part eioog^ild of the surface of the chest, between the clavicular and the mammary leYel. The mesial surface is also posterior and is much bevelled. The lower surface, also bevelled posteriorly, , is like the two preceding, invested by pleura. It forms the upper side of the short or transverse fissure. The outer side of the The sides, pyramid is interrupted by the oblique fissure, or great fissure of the lung. The upper side of the pyramid is continuous with the tissues of the apex, but in the bronchial cast it is formed by the sterno-scapular inter-bronchial space. It will be understood from the previous description that there are but two and the free edges to the pectoral district, the mesial, or sternal, and the inferior thf^°° edge, the former vertical, the latter horizontal, both being sharp. pyramid. I have already stated that, in the right lung, the bronchi supplying the Bronchi pectoral district send upwards branches which take a prominent part in the the apex. ° aeration of the anterior portion of the apex. In this sense the distribution which we are considering is not limited strictly to the pectoral region of the chest. The bronchi of this bronchial district are without exception derived from A single the pectoral stem, which is given off at the first bifurcation of the right upper pectoral* lobar bronchus. The Bronchi of the Right Pectoral Distribution. (This distribution can be followed in fig. lo, column B, where it extends between line ij and line vj — also in the diagram, fig. 9.) The pectoral stem barely exceeds 1*3 cm. in length, but is of substantial Pectoral thickness. Arising from the anterior extremity of the upper lobar bronchus, (if.™). at the seat of the spurious trifurcation, it contributes the first part of the semicircular curve forwards and inwards which carries the termination of the I 1 2 THE BRONCHI AND PULMONARY BLOOD-VESSELS. horizontal sternal bronchus to a point in the anterior pulmonary fringe nearly- opposite to the bifurcation of the trachea. fSterno- The two divisions from this stem lie side by side at their origin, not (fif aTJ. however in a strictly horizontal plane. The outer branch or mid-pectoral is *^'t , sliarhtly superior to the internal or sterno-pectoral bronchus. The same inclined (uj. ae). plane continued upwards and backwards receives the divisions of the axillary stem. This imaginary plane defines the lower boundary or floor of the sterno- scapular inter-bronchial space or sulcus. Distribution of the Bight Sterno-pectoral Trunk. ■Ascending The Stemo-pectoral Bronchus, of same length as its parent, con- sterno- tinues the semicircular curve, and divides into the ascending sterno-pectoral pectoral ^ , - . , . , . ' (iv. aas). and the horizontal pectoral bronchi. 1^8™"'^^ Reference has been made to the Ascending Sterno-pectoral in con- pectorai nection with the apex. Suffice it to mention here that this trunk rises forwards stemo- ' ^^^ inwards for a distance of i • 5 cm. and bifurcates into the sterno-clavicular and (clavicular ^jje apical parasternal bronchus which occupy with their branches the regions Apical ' indicated by their names. Both bronchi run an upward and ? inward course IvTaa^^f and remain within a transverse plane at least as far as the level of the clavicle. (-Horizontal 111 Contrast to its twin- bronchus the Horizontal Sterno-pectoral I °3^J^°.^j addresses itself to the supply of inferior districts. It is exceedingly short ; (v. aaii). and, bifurcating almost immediately, it yields the imur-pectoral trunk, and by pectoral a second bifurcation, i cm. distant from the first, the descendhig mid-sternal. (y. aaia). QontinuinsT its forward and inward curve the horizontal bronchus distributes a Descending ° • i- t • <• I mirt-sternai descending parasternal to the corresponding region of the anterior surface, and \ Hoi-i^ntai Several marginal branchlets to the pulmonary fringe, pectoral rjijje Inner-pectoral Trunk, of smaller size than the horizontal ^v]. aaiii). -^ , , ' Descending pectoral, and not exceeding, in the cast, i cm. in length, proceeds forwards parasternal ^^^ ^ little downwards. After a bifurcation which gives rise to the deep I'aaiiid). imur-vectoral interlobar, it supplies branchlets to the inner portion of the Horizontal , -^ ^ '■ marginal Upper lobe. Inner™""* ^^^ Deep Inncr-pectoral Interlobar deserves mention in connection !peotoi-ai with the Central Inter-bronchial Space (c/. p. 1 2 1 ) of the right lung, of Spinner- which it forms one of the boundaries. Its branchlets are brought into pe^'o™^ relation with the upper division of the pulmonary vein, behind which descends (vj. aaiad). the pulmonary artery. pinner The Descending Mid-sternal is easily identified as supplying the miX^emai l^'^^r extremity of the sternal border. It lies at first nearer the posterior (vij. than the anterior surface of the fringe. Each of its divisions the inner and Outer ' the outer descending mid-sternal, again subdivide. nSdistemai From the inner division arise (i) a small T-shaped bronchus for the peri- (y\)- cardial surface, and (2) marginal branches for the fringe of the lung. THE BRONCHI AND PULMONARY BLOOD-VESSELS. I I 3 The outer division provides anterior and posterior branches which, ap- proaching the fringe, may be termed sub-marginal. Distribution of the Bight Mid-pectoral Trunk. A slightly ascending direction forwards and outwards rapidly removes the Mid- Mid-pectoral from the vicinity of its twin trunk the stemo-pectoral. After ^v" aea). a course of i'5 cm. it bifurcates, giving rise to the mid-pectoral apical, and ^4' , by a second bifurcation to the outer pectoral. apical The Mid-pectoral Apical resembles the ascending sterno-pectoral in jl^,*^ being distributed mainly above the level of the pectoral zone. In several pectoral particulars it contrasts with this bronchus. It is entirely an apex-bronchus, (Fv°les). beginning to deliver branches at a height which almost corresponds to the ^]° yf'„j ^. summit of the distribution of the other bronchus. It arises 8 mm. higher and (v. aesa) also fvirther back than the latter, and, being at first vertical, maintains this luner deep situation for a distance of 5 mm. Then inclining forwards and very "™°™)- slightly outwards in its ascent, it supplies an Infra-clavicular horizontal ^''J- . bronchus, which bifurcates into an inner and an outer superficial branch. This apical is the most anterior and the lowermost of all the branches connected with the ylshap^ed supply of the apex ; and, in direction, it is the continuation of the second part ^"^ndi*"^^ of the mid-pectoral apical. The main trunk, now purely apical, ascends ver- (vj.aessp.). tically from this point, giving a posterior and inner T^^liaped bronchus which faces the anterior ascending apical trunk, and, 5 mm. higher up, a Clavi- cular Branch, outwards and forwards. From this point the mid-pectoral apical bronchus, whilst ascending almost Mid- vertically, shows a slight backward and outward inclination, in conformity with apical or the dome-shaped surface of the district, and may be termed from its position anteriOT- the External Anterior-apical bronchus. Its small anterior terminal apical (vij. branch is in the same anterior transverse plane as the middle anterior-apical Clavicular bronchus, a branch from the- anterior ascending apical stem. Its posterior aesssk). '/ lateral terminal branch contributes to the supply of the external surface of Anterior, - the apex in its anterior portion. aesssss), In conclusion this bronchus, although originating from the pectoral stem, 4^™^*' 1 rises to the anterior external surface of the apex, falling short of the greater bronclms height attained by the more central air-tubes of the apex as a result of its aessssp). -* own somewhat lateral position, and of the dome- like formation of the pulmo- nary summit. Whilst not approaching the surface excepting at its upper part, it is the most anterior of the apex-bronchi, being separated from the apical stem and its branches by the broad stemo-scapular inter-bronchial sulcus. peJ.'Jo™?" Its distribution begins at the level of the clavicle ; it is mainly anterior and ^^"^1,,^^;^^^ superficial, and, in shape, pyramidal. reviewed, The distribution of the ascending stemo-pectoral, on the contrary, ^^^^^^ acquires breadth as it ascends, owing to the divergence of its two large with the branches. It supplies the inner. third of the clavicular surface of the lung — stemo-"'^ H ( 114 ) TABLE II.— LEFT PECTORAL DISTRIBUTION. g O O 03 P3 S ^ S a B t^ ^ xn O cfi H "^ " w H 3 f^ S fi B >j o d P S M H S h fr s o " !2i O B Bl -rj H 5 j'^ H -^ >^ -( 03 >< 1^ pq Hi ( 115 ) TABLE II.— EIGHT PECTORAL DISTRIBUTION. '8 & DO cH -r-s ii6 THE BRONCHI AND PULMONARY BLOOD-VESSELS. pectoral distribu- tion, /Middle pectoral (v. aeaa). I Outer pectoral \(y. iieae). /Middle pectoral ) (vj. aeaaa), \ Descending j interlobar V(vj. aeaad) .Middle pec- toral (vij. aeaaaa), Ascg. pec- toral (vj. ■aeaaas). Outer pec- toral (vj. aeaee). Descend- ing inter- lobar (vj. Waed). 'Outer pec- toral (vij. aeaeee). Ascending outer pec- toral (vij. ,aeaees). ^Horizontal terminal ,(viij. ( aeeaeee). 1 Descg. ter- niiual(viij. '^aeaeeed). Pectoral stem (iij. aa). Tinner or I sterno- I pectoral (iv. aai). Outer pectoral '(iv. aaa). < the outer third of the same being furnished with air by the anterior axillary- apical bronchus. After the origin of the apical division the mid-pectoral ceases to rise and is less outwards inclined. At first horizontal it assumes a slightly downward tendency which is continued in its branches and restores them to the original level of the pectoral stem. The bifurcation into the middle pectoral and the outer pectoral bronchus occurs 8 mm. in front of the previous bifurcation. The direction of the outer pectoral is chiefly and almost strictly external, that of the middle pectoral mainly anterior, and the two tubes diverge in a horizontal plane (slightly descending). From each arises, close to the bifurcation, a descending deep pectoral interlobar bronchus, directed towards the central root-space, and forming its anterior upper boundary. (See diagram, fig. 9 ; see also fig. 10, line B, between squares A iv and B iv.) The Middle Pectoral Bronchus, advancing almost straight, with very slight outward inclination is of short length. In addition to the Inter- lobar Branch, it supplies a small Ascending Pectoral Branch for the kmg-tissue situated slightly higher. Its terminal bifurcation takes place at the anterior pectoral surface into an ascending and a descending branch. The Outer Pectoral Bronchus has a longer course, almost strictly outwards. Its branches bear a close analogy to those of the preceding bronchus. The Interlobar Branch is an exact repetition of the interlobar from the middle pectoral, and is situated a little external and posterior to it. But the Ascending Outer Pectoral is not vertical, but inclined very obliquely upwards and outwards. And the two terminal branches are re- spectively horizontal and descending and are directed slightly backwards, approaching at their extremity the slightly superior and posterior distribution of the superior axillary trunk. LEFT PEOTOEAL DISTRIBUTION. (For the study of this distribution consult fig. 10 ; column E, and colamns v and vj.) The Left Pectoral Stem, equal in thickness to the apical, has a length of 1-2 or 2-2 cm., according as it is measured along its upper or along its lower border, and a directly forward course. Its two horizontal divisions the inner, or sterno-peetoral, and the oioter pectoral, both possess at first an anterior direction. The inner or sterno-pectoral immediately turns inwards towards the pericardium. The outer pectoral breaks up before taking any departure from the sagittal direction ; but its outer branch shows a rectangular outward bend, analogous to that seen in the sterno-pectoral bronchus. Via. 10. A B D E V G 11 I ^\ aMi < ^ ■i« ■■■j^ .. . ^ ^^^i._J?i C^ ij ] 3k.((.\fJ£^^ ^^3^ AUXW//7 i^>?!t= 1 ■ • IP ^fe jW^ mm 3« iii ^/wnAj^v/;^ |W _/ w^^ ^/u Ytl 1 W ^"ht/^'"?'*^ ^ r i ^Vyf\ W^ .^S /^_^« iv ^"^S w C ^^ u sy /^m f^^^p^ M i 1 F ^^ y \Jym.^^^ ^ V \ / /Jr^ w^ Mr -HiO^^ j-rCgf^^^ Crr- \ / / ^^"^ ^^-J / W^ ' iK^^^*sa^^!^^X ^^S^ vj ^^/ w / 'oliOif i m\ ^^ ■V vij ^miWrm n 4 W 1 p V ■ffllWviW / /\ ft ^ 1 »^ viij ni 'U »Y V JL\ \ 1 % ix ^* ^ \ \ 1 8 i ■ ^i \, ^fM^^J/Tv)^ ^w '^ c*/W^^ ™1 1 X **»>^,^ J i^ 3 xj W^ X A ■ B ■ c D E F G ' H I Fig. 10. Drawing feom a metallic cast of the Beonchi. Feont view; peom the left. The soft parts and the bronchial membrane have been dissected away, except the trachea, the origin of the great vessels, and the pericardium, which are shown in situ. EXPLANATIONS OF THE DRAWING. I. Centeal Paets. Above line ilj, between this and the trachea : the divided orifloes of the great arteries, and (at line D) of the vena azygos (raised). Above line iv, below the V. azygos : the termination of the superior V. cava, dividing into right and left innominate veins. Between line C and the V. cava : — the divided branches of the right superior pulmonary vein, and close behind this, within square B v : the inferior division of the right pulmonary artery. 2. Right Beonchial Tree. Right Upper Lobe : In square C iv, behind the right innominate V. : — the three apex-bronchi diverge, the pectoral stem horizontally for- wards, its branches occupying a front plane, — the ascending-apical stem, upwards, — and the axillary stem, shown in weak outline, outwards. Line C passes between the anterior and the posterior ascending-apical,* and the tracheal-apical bronchi. The superficial anterior-apical forms an angle, near the intersection B j with the external anterior-apical, from the mid-pectoraL Square B iv contains the pectoral trunk dividing into its branches. Right Middle and Lower Lobes : In square B vj, behind the pulmonary vein, the cardiac stem gives rise to the mammary-cardiac, the sterno-cardiac and the posterior miammary-cardiac trunks. Square B viij shows, in profile, the parallel-sternal branches, and between these and the pericardium two descending retro- cardiac branches in shaded outline. 3. Left Bronchial Tree. Left Upper Lobe : Square F vj contains the cardiac trunk (from the bronchus impar, which is not in view). The shaded trunk is the posterior- horizontal. Lower down the cardiac branches are seen in profile in column F. In square F "^ the pectoral stem divides horizontally, along line v, into its conspicuous sterno-peotoral, and into the mid-pectoral divisions. The ascending mid-pectoral is cut short. The axillary-apical stem, partly disguised by the latter, bifurcates into the ascending-apical and the axillary trunk ; and this again into the axillary and the posterior- axillary, thus imitating a trifurcatiou. Into square H iij rises the axillary-apical. — Square G iij shows outer mid-apical branches above, outer ascending-apica branches below, and between the latter a twig from the outer posterior-apical. Along line G the inner mid-apical bronchus rises into square F ij, concealing the inner posterior-apical branches. In square E iv a letter H is imitated by branches of the apical sterno-clavicular, behind which are aortic branches of the posterior ascending-apical. Left Lower Lobe: Line G, below the posterior-horizontal (shaded), coincides with the interlobar fissure. In square G vij the anterior-basic trunk bifurcates into the more vertical cardio-basic, and the widely branching mammary trunk. In square G viij a shaded retro-cardiac branch is seen. (The bther basic distributions are better displayed in fig. 1 1.) " The right posterior ascending-apicttl bronchus will be seen if the two posterior branches terminating in square C ]' he followed downwards. Its external outline is hidden by the bronchus anterior to it. THE BROKCHI AND PULMONARY BLOOD- VESSELS. I I / Distrihution of the Zeft Outer Pectoral Ti'unJc. The Outer Pectoral Trunk, immediately before dividing, yields an Outer pec- N upward branch, the Ascending Mid-pectoral Bronchus which, after (""t-ia")"'' 1 bending horizontally forwards, again assumes a rising tendency. This is the Ascendiiig ; only derivative from the left pectoral stem which rises above the boundary of torai (v. the broad horizontal infra-amoal inter-ironcJiial sulcus. It may serve as a ^^ . ' , , .-^ . Horizontal landmark dividmgthis space into an inner and an outer half. The ascending outer pec- mid-pectoral distributes three small deep intra-pulmonary branches, and ends aaaLv' with an upward and a downward fork. tora'uTj The bifurcation of the outer pectoral gives rise to the mid-pectoral and to aaaea). the horizontal outer pectoral trunk. Both move outwards ultimately, but this Pg^°™^ai movement is preceded, in the case of the Mid-pectoral Bronchus, by an mid-peo- initial forward course of 2 cm. which terminates with its bifurcation ; at aaa'ead^. ' this point its inner division continues the forward direction, whilst the outer ^"^.'^p""'' division carries out the outward bend iust begun by the common trimk. ^'^^^ (yij- TTi • ^ 111 1 aaaeaa). y Immediately, or soon after its origin, the mid-pectoral bronchus sends a superficial N Descending: Central Bronchus into the central root-space. This bronchus p'd-pec- r p. ipi'£»''i toral (vi]]. faces from above the cardiac trunk. The other branch of bifurcation is the aaaeaaa). Superficial Mid-pectoral which divides at the surface into an upper and outer'(in- a lower forking branch supplying the outer portion of the mid-pectoral ^'^^1°^^^^ region. The latter, or Inferior Outer Interlobar Pectoral possesses (viij. slight inclination downwards as well as a main outward tendency, which is Horizontal \ soon interrupted by the pulmonary fissure. It aerates the interlobar sub- outer pec, .pleural ■ tissue near the anterior surface, at the level of the third interspace aa^ieee). ' 1 , J.1 "1. Posterior ^between the ribs.. mid-pec- The Horizontal Outer Pectoral is sufficiently localized by its name, forai inter- . 11 11 lobar (vij. It is mainly concerned with the anterior surface, but its early branch, the stout aaaeep). Posterior Mid-pectoral Interlobar, proceeds horizontally backwards to ^^^l\^_ the interlobar surface, where it faces with its T-shaped bifurcation the posterior teriobar horizontal distribution. The horizontal outer pectoral divides into the l^^^" Upper Outer Interlobar Pectoral supplying the interlobar tissue close ^^?:j'j7g^)- to the outer fringe of the upper lobe and the Middle Interlobar Outer outer in- 111 11 mi -J?' teriobar Pectoral, similarly distributed at a slightly lower level, ihe interior pectovai interlobar outer pectoral, derived from the mid-pectoral has already been ^^eeee). described. These three bronchi and their lobules form the outer edge of the upper lobe in the pectoral zone. Distribution of the Zeft Ste^-no -pectoral Trunk, The Sterno-pectoral Stem, like a semi-flexed left elbow, bends hori- ^toj^o-P^^''- zontally inwards, so as almost to reach the pericardial surface. Its straight (iy. aai). horizontal portion is continued forwards as Inner Mid-pectoral, a short ii8 THE BRONCHI AND PULMONARY BLOOD-VESSELS. (Inner mid- pectoral (v. aaia). bterno- pectoral (v. aaii). {Stemo- peotoral (vjraaiii). Anterior bronchus of the root (vj. aaiip). /Horizontal sternal I (yij. aaiiii). ( Desceud- 1 ing sternal \aaiiid). Horizontal sternal aaiiiii). Upper para- sternal (viij. aaiUia). /'Upper I (hori- I zontal) ( marginal. I Lower 1 (vertical) ^marginal, ^Descend- ing sternal (viij. aaiiidd), ( Lower I parasternal (viij. \aaiiida). /Lateral J marginal, \ Lower l^marginal. stem with very open bifurcations. From this arise an ascending branch of small size, and a longer, almost vertical, descending branch. Both being superficial, are freely provided with ramifications. Beyond the angle (of 90°) which it forms with its previous direction, the second portion of the sterno-pectoral stem pursues its inward course for a distance of 1 7 cm., and gives an Anterior Bronchus of the Root to the internal or mesial surface just opposite the termiaation of the left main bronchus. In this situation the upper division of the pulmonary vein, en- closed between the main bronchus behind, and the elbow of the sterno- pectoral stem in front, rises into the horizontal inter-bronchial space which exists between the apical and the pectoral zone, and which I have termed the infra-apical sulcus. The ascending branch from the anterior bronchus of the root at this level is among the structures which lie in front of the vein. The final bifurcation of the sterno-pectoral gives origin to the horizontal sternal and to the descending sternal. Both trunks soon bend forwards at right angles with their previous directions and each of them, just before the bend, bestows a branch upon the neighbouring pericardial surface of the lung. The Horizontal Sternal bifurcates into a small Upper Parasternal which lies to the right of the inner mid-pectoral bronchus between this and the sternal distribution, and into a continuation of the trunk. This ultimately breaks up into an Upper, almost horizontal, and a Lower, almost vertical Marginal Bronchus. From the Descending Sternal arises likewise a Lower Parasternal which extends nearly to the lower boundary of the sternal distribution, and bears several branchlets. After some undulations, such as are common among the bronchi of the in- jected left lung, the descending sternal yields a Lateral Marginal Branch, and it terminates with a marginal bifurcation at the lower projection of the sternal fringe. All the branches which have been described may be traced with tolerable ease in fig. 10 in the vertical columns D and E, ( 119 ) THE CARDIAC REGION. BRONCHIAL SUPPLY TO THE RIGHT CARDIAC DISTRICT, OR RIGHT MIDDLE LOBE. General Remakes concerning the Middle Lobe. General Shape and Relations. — ^Whereas the right upper lobe is The middle situated, for the greater part, externally to the axis of the intermediate gr^at part bronchus, the middle lobe is, at a lower leyel, in a large measure internal to internal . . . -, to axis of the same axis continued. bronciius Viewed from the front the general outline of this lobe is triangular. The diuT"^ sternal and basic borders are gently curved, but the upper and outer boun- Triangular daries are rectilinear, and they converge towards a point situated in the ^ axillary region. The inner and lower margins are thin, the upper and outer possess considerable thickness. The anterior surface may be regarded as the base of a very shallow Surfaces, irregular pyramid, of which the apex would be formed by the attachment of the middle lobe to the pulmonary root. The upper surface, forming part of the short, or transverse, fissure is of Pissm-es. less extent than the inferior and outer surface, which forms one of the boun- daries of the lower half of the great oblique fissure, and is in contact with the lower lobe. The inner or mesial surface is analogous to the inner surface of the pectoral district. In cases of normal development all these surfaces are lined by pleural This lobe membrane. It follows that, on all sides, the middle lobe is isolated from the ex°c'ept'at remainder of the lung, excepting at its attachment to the root. The pedicle '"o^t. formed in this situation is tolerably broad and thick and surrounded by a rather loose fold of pleura. It contains the cardiac bronchus and blood- diacstem. vessels and some glands, embedded in areolar tissue. The super- Bronchial Supply .^-The middle lobe is entirely aerated through the mai-y-car- branches of the cardiac stem. The apparent trifurcation of the latter stem at gterno-^ the upper and posterior part of the lobe is really a bifurcation into an outer '^'^^^f^- or superficial mammary-cardiac trunk, and an inner, very short, although deep mam- stout, stem, the sterno-cardiac, which immediately divides into an anterior, diaZiivide inner, sterno-cardiac and an outer, posterior, deep mammary-cardiac trunk. *y^i'^™' The supply of the lobe is divided between these three trunks. supply. 120 THE BRONCHI AND PULMONARY BLOOD-VESSELS, Supply to the outer comer; to the sternal, and to the mammaiy half. The Outer Corner is served by the mammary-cardiac. A vertical line, drawn through the anterior surface, roughly divides the Sternal or Inner Half, supplied by the sterno-cardiac, from the Outer Half, which receives its supply from the deep mammary-cardiac. The latter, by its inner posterior cardiac branch, encroaches posteriorly beyond the imaginary middle-line and extends downwards to the extremity of the inferior fringe, which is not reached by the sterno-cardiac bronchi. The Inner Border is parallel with the sternum, and the inner surface is in contact with the pericardium. These anatomical relations are turned to account in our nomenclature. The presence of the nipple not far from the upper outer boundary of the lobe is also a useful landmark. The Eight Cardiac Bronchial Distribution. Cardiac stem (ij- a). Its rela- tions. The pulmonary artery and vein. [Mammary- cardiac / (iij. ae). I Budimen- 1 tary inner- I cardiac (iij. aa). 'Posterior mammary- cardiac ( (iv. aad). I Sterno- cardiac ''(iv. aai). (This distribution is seen, in distant foreshortening, in columns A and B of fig. lo, being in- cluded between the horizontal lines v and ix. It is more clearly displayed in the diagram, fig- 9) The Cardiac or Middle Lobar Stem originates 2-8 cm. below the lower angle of origin of the upper lobar bronchus. Although undoubtedly ventral, it does not arise absolutely from the anterior surface of the bronchus intermedius. It is slightly internal as well as anterior. This circumstance assists in the production of the mesial position of the cardiac lobe in relation to the lower bronchial stem. But to the same result the inward curve of the sterno-cardiac and of the deep mammary trunks contributes yet more largely. For a distance of 2 cm. the cardiac stem remains parallel to, and in posterior contact with, the descending bronchial stem. The lower, horizontal, division of the right pulmonary artery lies here across the anterior aspect of both these tubes, on its way to the various bronchial districts. The artery itself is situated behind the obliquely ascending upper pulmonary vein. Perhaps in consequence of these relations, the lower bronchial stem swerves faintly backwards at this level, whilst the cardiac stem presents a slight anterior concavity. The bifurcation into the forward tending mammary-cardiac and the Rudimentary Inner-cardiac Stem occurs immediately after the bend taken forwards by the cardiac stem. The inner- cardiac stem divides at once into a horizontal inward branch, the sterno-cardiac, and into the more posterior branch, descending obliquely forwards and slightly inwards, the posterior mammary -cardiac. Distribution of the Bight Mammary-cardiac Trunk. The Mammary-cardiac Trunk, in its unbranched portion, has a length of 1-5 cm. and describes, in a horizontal forward direction, the same curve as the upper half of an elongated letter S ; the second half of the curve THE BRONCHI AND PDLMONAKY BLOOD-VESSELS. 12 t is imperfectly, and witli varying curvature, carried out by each of its two branches. The inner or Superficial Mammary-cardiac Division preserves a superficial ^ main direction forwards, and, after distributing branchlets to the surrounding SrdTc'"^^" tissue, divides into two branches which bend downwards, near the anterior S^i ^^^- \ , ' Outer / pulmonary surface, as Inner and Outer Terminal bronchi, and supply mammaiy- the upper part of the outer half of the lobe. (fv* ee). j The Outer Mammary-cardiac Bronchus completes the letter S Outer \ with a long bold anterior curve extending to the axillary angle of the middle ^rSao"^ I lobe. During this course small branches are given to the periphery. A ^ac^dmg ) bifurcation of this trunk takes place close to its origin, setting free the interlobar J ascending interlobar, which helps to supply the upper septal surface of the middle lobe. The Ascending Interlobar branch is analogous in position to two Three ascg. other interlobar bronchi between which it lies intermediate, namely, the ascending interlobar from the sterno-cardiac, and the ascending interlobar from the posterior-horizontal. All three rise to the same level — and their horizontal distance from the bronchial stem behind is almost the same (2 '2 cm.). They thus form the anterior outer boundary of a Central Central Boot-space defined above by the descending interlobars from the axillary ™°'-»P»=«- and from the sterno-pectoral, and behind by the ascending mid- dorsal distri- mteriobarsf bution from the posterior-horizontal. The space in question and the bronchi Ascendiog just enumerated are seen in fig. 10 and fig. 1 1, when inspected side by side. ""' " °'^*' Diagrammatically, they are also shown in fig. 9. d''*"t°"'"k' (it. aaii). , . Ascending Distrihutio7i of the Bight Sterno-cardiac Trunh. interlobar (iv. aais). At the end of its horizontal inward course, the Sterno-cardiac sterno-"'" 1 Trunk furnishes a similar Ascending Interlobar Bronchus; and, f*^''!^°;j-> I bending downwards at a right angle, it breaks up into its anterior, or I'osterior ) superficial sterno-cardiac, and into its posterior parasternal division. (vj. aaiip). j By its first bifurcation the Superficial Sterno-cardiac gives rise to Superficial < the anterior parasternal. This bronchus distributes small branches to the diac r-vij- upper part of the parasternal surface of the cardiac lobe. Anterior A subsequent bifurcation marks the origin of the Anterior Peri- parasternal cardial, a very short trunk, with vertically diverging arms, for the supply aaiida). of the upper third of the sternal margin and internal surface of the middle Superficial s 1 1 stemo- lODe. cardiac I Descending slightly inwards, the continuation of the sterno-cardiac divides £^J- jj^-, \ into the Marginal Sterno-cardiac (which bifurcates into the first and Anterior f second Parallel-sternal Cardiacs), and into the Third Parallel-sternal (viij. Cardiac. ?^"'^'^)- '' Marginal These parallel air-tubes form a symmetrical row extending outwards etemo- from the sternal margin. They do not reach to the lower extremity of the ^iiddddY ( 122 ) TABLE III.— LEFT CARDIAC DISTRIBUTION. W H iJ l3 M f^ E? aj ^ B > 4§^t f^ b^ 2 n S !z f5 ^ R d r^ a a M rrt . H 1 I " S ^H g m iii 124 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Thii-d lobe, but correspond, in the non-dissected lung, to a bulging usually seen at sternal the lower part of the inner pulmonary border, and terminating a little way ^.SiifdddeS'^' ^t)ove the lower anterior angle. The parallel bronchi are readily seen in the sternal diagram (fig. 9). They are also seen, in profile, in squares B vij and B viij bulge over „p c ~ . „ theparal- offig. 10. lei-stemais. ^ fourth or Outermost parallel-sternal bronchus is supplied by the fteriOT p°^^i. Posterior Parasternal. This trunk divides into a Deep Posterior sternal cvij. Parasternal branch and into the fourth parallel-sternal. The Fourth ; aaupa). '^ ' Foiu-th Parallel-sternal, in its downward course, furnishes the posterior surface sternal (vij. '^i^h a posterior superficial branch, ^aaaipe). Distribution of the Bight Posterior Mammary -ea7'diae Trunk. Posterior The Posterior Mammary-cardiac Trunk is of short length mammary- . " . t t • cardiac (i-2 Cm.), and descends obliquely forwards and slightly inwards. Lymg ■ " behind the sterno-cardiac, it almost subtends the right angle described by posterior the latter. It divides into the inner ^posterior cardiac and the descending mammxiry-cardiac. cardiac (v. aadd). Descending The Inner Posterior Cardiac, a long and vertical bronchus, occupies cardiac the posterior plane of the lobar distribution, and almost bisects it into (v. aa a). ^^^ lateral halves. It corresponds to the interval left between the more f'lnuer . posterior anteriorly placed descending mammary-cardiac and the superficial parasternal ; (vj.aaddd). — ^1^^ it is parallel, in a slightly posterior plane, and external, to the fourth ^"'f'^^. sternal-parallel bronchus. Its terminal bifurcation occurs a little above the postenor '^ cardiac lower end of the " parallel " distribution ; and its two terminal branches, the ^ inner and outer lobular, undertake, unassisted, the supply of the lower angle, lobular Or lobule, and of the lower margin of the middle lobe. In squares A ix, B ix cardiac""^ of fig. 10, line B Separates the two small tubes. *^^^- .. The only branch of bifurcation from the inner posterior cardiac, viz., Outer the Outer Posterior Cardiac, is given up high, and does not extend posterior bfeyond the middle third of the lobe. It delivers backwards a small interlobar cardiac branch. aaddde). The Inner and Outer Lobular branches do not require any special /The T"® ,. description. descending ^ mammary- cardiac ( (yj. aadaa). The Descending Mammary-cardiac Trunk assumes a downward, ^teriobar foi'w^^^! ^^^ slightly outward course. l(vj. aadae). Its first branch, the External Interlobar, given backwards and Semai oiitwards to the interlobar surface, presents the usual T-shape bifurcation. marginal After a course of I '2 cm., the trunk bifurcates into the Upper External aadaae). Marginal, which distributes small branches to the outer margin and to the external Outer anterior surface of the cardiac lobe in its upper part ; and into the marginal Inferior External Marginal, or continuation of the descending mam- ■' " mary-cardiac, which supplies the outer external margin and the inferior THE BRONCHI AND PULMONARY BLOOD-VESSELS. 12? external margin, and gives branchlets to the lower surface of the cardiac lobe in its external half. Both bronchi are, in their first portion, covered by the superficial mammary- cardiac distribution ; and in a similar manner, the branches of the upper external marginal are imbricated over the longer branches of the inferior external marginal. The descending branches of the latter bronchus, although not parallel, are arranged in lateral order, — somewhat resembling, in their mutual relations, the row of parallel-sternal bronchi described above. BRONCHIAL SUPPLY TO THE LEFT CARDIAC DISTRICT. General Survey of the Left Cardiac District. Shape and Disposition. — The anterior surface of the cardiac distri- Elongated bution has an elongated triangular shape with almost horizontal base ghapfoniie upwards. The inner, or pericardial, and the outer, or interlobar, surfaces slope ai^terior backwards. If we could imagine this district disconnected at its upper part gggg^ from the. upper lobe, the free surface th\is formed would be horizontal and biance to the whole might be roughly compared to an inverted pyramid. This verted resemblance is more obvious in the metallic cast than in the fresh lung ; for, Py™™^> although no interruption of surface defines, in the lung, the boundary marked between cardiac and pectoral distributions, a wide horizontal gap exists in the '^^f^ ^^T' depth between the origin of the pectoral and the origin of the cardiac stem, horizontal analogous to the equally important gap situated below the apex and just inter-bron- abpve the horizontal range of the pectoral ramifications. The upper level above this of the cardiac region is the same in both lungs ; but, externally and above, '^ "°'' the left distribution does not extend as far as the right ; and in its lower, pointed part it does not possess the same breadth as the right middle lobe. General Plan of Bronchial Supply. — If a vertical sagittal plane be imagined, passing through the length of the left upper lobe, in this plane would lie the anterior and the posterior cardiac bronchus, the cardiac stem, and the ascending as well as the horizontal division of the pectori-apical bronchus. The general direction of the cardiac stem may be expressed by the words " downwards and forwards ; " but its course cannot be figured by a straight line ; for it possesses considerable curvature. The ordinary curved Bifurcation pi'inter's bracket roughly represents the aperture of the great bifurcation of "^par""'*"^ the left upper lobar bronchus. The bracket must be imagined to have its resembles a centre at the angle of bifurcation of the bronchus impar, and to face, or open the cardiac forwards. One of the limbs would be constituted by the ascending pectori- lu^l- umb. apical stem, and by its continuation the axillary-apical stem ; the cardiac stem would correspond, in general outline, to the lower limb of the bracket. The Cardiac Stem, projecting forwards from the termination of the Cardiae short bronchus impar, immediately bends downwards, and very slightly out- ° ™ ^'^' 126 THE BRONCHI AND PULMONARY BLOOD-VESSELS. I* Anterior- cardiac ) (iij. da). i Posterior- cardiac l^Ciij. dd). wards (see diagram, fig. 9). During its descent, it bifurcates into the anterior and the posterior cardiac. Whilst the anterior cardiac assumes a horizontal direction forwards, its terminal branches become at first vertical ; and sub- sequently they slant, in undulating fashion, forwards and downwards. The continuation of the cardiac stem as posterior-cardiac, taking a second bend, passes from the vertical into the oblique direction and thus becomes parallel with the anterior-cardiac divisions. At the same time its outward tendency is modified into a slightly internal one ; and the extremity of the cardiac lobule receives its termination. It remains, throughout its course, posterior to the branches which it delivers. Stemo-car- diac trunk (iv. dai). Mammary- cardiac trunk (iv. dae). 1Mammai-y- cardiac (v. daea). Interlobar branch (v. daee). (Horizontal, (vj. daeae) and Descend- ing cardiac mammary ,(vj. daead). Inner, (vij. daeaaa) and Outer / euperiicial j mammaiy- I cardiac (vij. \daeaae). (Inner, (vij. daeadi) and Outer de- scending mammary- cardiac(vij. vdaeade). {Inner, (v. daii) and Outer stemo- cardiac (v. dale). (Inner stemo- cardiac (v]. daiid). Anterior pericardial (vj. daiii). Distribution of the Left Anterior-cardiac Trunk and of its Branches. (For this distribution and the following, consult diagram (fig. 9) ; also, in fig. 10, the columns D, E, F, G, between lines iv and x.) Arising from the cardiac stem, 2 '3 cm. from the origin of the latter, the Anterior-cardiac Trunk bifurcates, after a course of r3 cm., into an inner or sternal, and an outer or mammary division. The Mammary-cardiac, the smaller and shorter division, is almost horizontal in its distribution, and supplies the anterior external part of the base of the pyramid which has its apex at the cardiac lobule. By means of the Interlobar Branch, which arises upwards and outwards from its first portion it also supplies the external face of the cardiac district. It bifur- cates into a descending mammary-cardiac and a horizontal mammary-cardiac bronchus. The Horizontal Mammary-cardiac Bronchus assumes greater lateral extension than other branches of this distribution, and is devoted to the anterior surface of the outer corner of the cardiac district, to which it supplies an Inner and an Outer Superficial Mammary-cardiac Bronchus. The Descending Mammary- cardiac, slanting forwards, at first behind the horizontal branch, divides into an Outer and an Inner Descending Mammary-cardiac which supply the outer half of the middle third of the cardiac district. The Sterno-cardiac, a larger trunk than its twin-tube, undertakes the supply of the sternal half of the district in its upper two thirds. By a bend analogous to that of the mammary cardiac it alters its original forwards • and outwards direction into one forwards downwards and inwards ; and its two main divisions, long parallel air-tubes, ultimately become vertical. From both divisions several short branches are distributed on both sides. The Inner Sterno-cardiac approaches the surface, and before bending downwards it gives an important outward rising X'Shaped bronchus, the Anterior Pericardial, sufficiently described by its name. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 27 Having reached the surface, the termination of the trunk divides into a Superficial,, Superficial and a Deep Marginal Branch, both of which end above the i^l'^lf^^ lower third of the cardiac district, at the sternal fringe. descending The Outer Sterno-cardiac divides, at the same level as the preceding, marginal [ into a superficial and a deep branch. Their position justifies their name of Jaildd). J Descending Cardiac Parasternals; their distribution is parallel and superficial, \ external to that of the marginal branches. ^^ ^^^^ I descending ) parasternal I Distribution of the Left Posterior-cardiac Tnonh and of its Branches. C'^ daied). J The Posterior-cardiac is a slightly larger trunk than the anterior cardiac ; it forms the direct continuation of the cardiac stem. At first possessing some outward tendency, it subsequently moves forwards down- wards and inwards, and for a length of 3 to 3*5 cm. carries no branches. Small bronchi are distributed by it to the posterior part of the cardiac district, in its middle third. But the two divisions arising from its main bifurcation are destined, as their name indicates, for the supply of the cardiac lobule. A few millimetres above this bifurcation an important branch, the Posterior Posterior Pericardial, is given inwards, for the internal sub-pleural dis- (jy. ddi). trict facing the pericardium. This is a T-shaped bronchus, each of the arms cardiac of which also terminates with a "[""Shaped bifurcation. By its posterior extre- /""adal mity this small distribution is in relation with the inferior pulmonary vein, Anterior and no great interval separates it from the upper extremity of the inferior (t- wn!' (ij.) The upper part of the distribution is stunted, and the symmetry of wards. branching lost ; guianties. (iij.) The mid-axillary trunk and distribution are deflected slightly downwards ; (iv.) The right ascending and descending mid-dorsal branches, instead of being oblique and far-reaching, as in the left lung, are vertical and com- paratively short. THE EIGHT POSTBRIOR-HOEIZONTAL DISTRIBUTION. (This distribution may readily be studied in the diagram (fig. 9) and in fig. 11.) General Observations. — The first large air-tube which is supplied onginof to the lower lobe is the posterior-horizontal stem. It arises slightly below itareiations the level of the cardiac stem, from the posterior (and slightly lateral) aspect ^^^^^l^' of the inferior lobar bronchus. The latter name becomes applicable to andbron- the continuation of the bronchus intermedins from the level of the cardiac medius. stem downwards. But no appreciable vertical interval exists between the right cardiac and the right posterior-horizontal bronchial origins ; and the right inferior lobar bronchus does not therefore, practically speaking, begin above the level of the posterior-horizontal, as in the left lung. For a ^^^^^°^^^ short distance above the level in question the intermediate bronchial stem, as mterme- stated elsewhere (see p. ;^6), and as may be gathered from the diagram (.hreo° (fig. 9) and from fig. i r, &c., is surrounded posteriorly by the pulmonary [JjJ^°''*'"y tissue of the inferior lobe ; but its anterior surface is not buried within the latter, nor in the pulmonary tissue of the middle lobe, but corresponds to the bottom of the transverse fissure. This fact may be demonstrated by raising the overhanging flap of the upper lobe. For a distance of 3 cm. down- interior wards from the same level, the lower lobar bronchus bends very slightly ° '^^^ ''"• backwards previous to breaking up into the basic branches. The posterior-horizontal distribution corresponds in both lungs to the Situation upper posterior and to the upper lateral part of the lower lobe, in tne rigiit of the lung it forms an horizontal elongated zone bevelled anteriorly. The dorsal '^*™ ■ part of this zone is supplied by the posterior-horizontal branch of the stem, the remainder by its mid-axillary horizontal branch. 130 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Posterior- horizontal stem (iij. dp). f Mid-axil- lary hori- I zontal f (iv. dpe). I Posterior- horizontal l(iT. dpp). The Posterior-horizontal Stem is remarkably short (only 0'6 cm.) and stout, being almost equal in diameter to tbe cardiac stem. Its direction is backwards and outwards. But this becomes converted, after bifurcation, into the outward direction and gentle downward slope of the deep mid-axillary horizontal trunk, which is destined for the middle third of the axillary region. The rather smaller posterior-horizontal division, measuring only 6 mm. in length, arises straight backwards, with very slight upward tendency : it will be described further down. Its horizontal and ascending branches occupy a higher level than the branches from the mid-axillary horizontal : this circum- stance gives rise to the downward and forward slope of the interlobar surface. /Horizontal or central axillary interlobar I (v. dpea). Mid-- axillary horizontal ,(v. dpee). /Superior mid- axillary bronchus (vj. dpeee). , inferior mid- axillary bronchus \(y\. dpeed). 'Superior mid-axil- lary (vij. / dpeeee). ] Axillary mammary ^dpee ( 'Lower mid-axil- lary (vij. dpeede). Posterior horizontal axillary .dpeedp). Right Mid-axillary Horizontal Distribution. The undivided portion of the Mid- axillary Horizontal trunk measures I cm. in length. A slight curvature modifies its direction to one outwards and slightly downwards and forwards. Remaining within the plane of the previous bifurcation, it divides into the continuation of the same trunk, and into a smaller but important bronchus, the Central or Horizontal Axillary Interlobar. This bronchus advances straight forwards, almost vertically beneath the descending axillary interlobar from the axillary trunk, but at a much lower level than that branch, and terminates in two small branches fashioned to the respective surfaces of the upper and of the middle lobes, which they are destined to face. A little further the mid-axillary horizontal gives rise to a superior (slightly anterior) division which follows the original direction and into an in- ferior (somewhat posterior) division. Both are distributed to the axillary region. The length of the Superior Mid- axillary bronchus is 1-5 cm. Its divisions are — an upper posterior and a lower anterior branch, termed respec- tively the superior mid-axillary and the Axillary Mammary. They are distributed to the districts indicated by their names. The length of the Inferior Mid-axillary is 17 cm., and its direction outwards and downwards. It supplies a small Central Descending Branch to the space situated above the unbranched origin of the large basic bronchi ; and it divides into the Lower Mid-axillary which is distributed below the superior mid-axillary ; and into the Posterior-horizontal Axillary branch which bifurcates repeatedly and supplies the lower part of the middle third of the posterior axillary region. The general drift of the mid-axillary distribution is slightly downwards and outwards. In the left lung this distribution rises much higher, not being materially curtailed by the great fissure, thanks to the almost vertical slant of the latter; but it also remains more posterior than in the right lung. Pi so a o M (A an o M K o O pq M .3 g^ Hi a o (5 60 C5 Iz; 1—1 I a w o iz; o l-H Pi !^ 1^ I o p< o Ph bo ■? ■ '« a g ? 1 5 i I I fao I g.a s .9 .a O d [Q U OJ m OJ 13 s 5 rS ■a ^ 'cj ■f^ _o ^ i 0^ a 2 rJd > 'i 43 -t3 1 o r^ Oi 1 a o CD be o s 1 t-t i S 13 ■^ S -S ^ -3 £ -s 'g 1 1 ^ g § g a § -g 53 ° S .S S " I S ra ft ^ +3 0) ^ ° ft £ 'tS S S «4 ^ M " a g S £ 23 @ 8 I I ■§ a> o o Hi THE BRONCHI AND PULMONARY BLOOD-VESSELS. I 3 l Bight Superficial Mid-dorsal Distribution. The two divisions from the superficial horizontal are at right angles to Horizontal 5-5 each other, one being yertical, the other horizontal and transverse. Both ™''d^ppe)! these directions are also perpendicular upon the sagittal direction of the Vertical de- parent trunk. They are brought about by means of the rectangular curve mid-dorsai exhibited by each of the bronchi in question at its origin. The liorizontal jj' F^ ' . mid-dorsal trunk distributes branches to the upper part of the mid-dorsal mid-dorsal district ; the vertical descending mid-dorsal, to the lower part. Vei-ticaf^ ) The Horizontal Mid-dorsal Trunk, after a brief course of 6 mm., ascending . , .', ' mid-doreal gives off by bifurcation the vertical ascending mid-dorsal, for the supply of the (vj. dppes)., posterior upper fringe of the lower lobe : and continuing horizontally outwards 'Interlobar n p. i-i. . T 7 -, 1 1 • 1 ,, branch (vii. tor 2" 5 cm., bifurcates into an upper ana a lower branch which supply the dppeea). upper half of the middle third of the posterior axillary region (the lower n^Sldorsal half being supplied by a posterior branch from the mid-axillary horizontal). C^J- The Vertical Ascending Mid-dorsal gives up, by bifurcating almost gpper 1 immediately, a Mid-dorsal Interlobar Bronchus. A short distance ^ranch. I further down aris3s from the same trunk, upwards and outwards, the branch, j Ascending Oblique Dorsal, which supplies the outer part of the posterior- Mid-dorsai\ upper fringe. Finally the vertical ascending mid-dorsal divides into two ter- (vij. | minal lateral branches, provided with branchlets, for the respective supply of VOTtfcai the anterior and of the posterior aspect of the thin pulmonary edge. dm-faUvi" A similar interlobar branch also arises from the horizontal mid-dorsal dppess). bronchus prior to its final bifurcation. Ascending >> ^ •■ T n oblique The Vertical Descending Mid-dorsal does not exceed 6 mm. m dorsal (viij length. It presents considerable analogy with the vertical ascending mid-dorsal, vertoi ) It bifurcates into a small anterior branch, the Deep Descending Mid- ^^I'^J^'^'j. dorsal, which approaches the posterior aspect of the lower lobar bronchus, dppesss). , and into the Superficial Descending Mid-dorsal, in continuation of the Vertical do- original direction. The latter divides into a small Mid-dorsal Vertebral mid-dorsai Marginal, of T shape, and into the Mid-dorsal Oblique. This branch ^^^' ^^V^^^ curves downwards and outwards and bears small superficial branches at a descending distance of 2-3 cm. below the horizontal mid-dorsal. (vj.dpp^d). Deep- -,..,. . , descg. mid- The dorsal part of the posterior-horizontal distribution is much more dorsal (vj. restricted than in the left lung. It does not extend upwards as high as the J.^ 7" ' .... . . Mid-dorsaP level of the upper lobar bronchus, and mferioiiy it is curtailed owing to the inner mar- powerful development of the lesser horizontal mid-dorsal, a branch which, in fppddi)!''' the left lung, is of insignificant size. SbUqtT^*' (vij- dppd Ippdde). TABLE IV.— LEFT POSTERIOR-HORIZONTAL DISTRIBUTION. am ^ p^ H U 15 0) o o TABLE IV.— RIGHT POSTERIOR-HORIZONTAL DISTRIBUTION. 134 THE BRONCHI AND PULMONARY BLOOD-VESSELS. THE LEFT POSTERIOR-HOEIZONTAL DISTRIBUTION. (For a study of this distribution consult the diagram (fig. 9) and fig. 11.) General Survey of the District. Differeuoes Viewed from behind, this distribution presents considerable symmetry, riMu'^Ind ■*-* consists of a honzontal -portion which extends, with widening area, from left. the parent stem near the vertebral border to the upper part of the second f.^i™?" third of the axillary and of the posterior axillary space ; and of a dorsal veiopment. portion represented by two long oblique branches. These arise from the same trunk as the horizontal bronchus, but from its posterior aspect, and equally diverge from the latter. Their own total divergence slightly exceeds Horizontal ^qO^ gy. ^j^gir branches, which are remarkably symmetrical, the ascending and oblique and descending mid-dorsal oblique bronchi form the vertebral border and of the aerate the posterior surface of the two middle fourths of the lung. In other tubes^'*^ words they span posteriorly the upper f of the lower lobe, and they extend Ascending from the axillary line to the aortic border of the lung. The thin upper edge scendinK ^^ *^® lower lobe and more than the upper J of the same are exclusively niid-dorsal supplied by branches from this distribution. The latter gains in thickness bronchi. from above downwards, as far as the anterior horizontal axillary branch. This Kelativeex- is the level of its maximum thickness, below which it wastes to a thin inferior district. edge. At this lower level the lateral branches from the basic trunks under- its varying take, morc anteriorly, the chief share in the bronchial supply. thickness. Upper and lower edge. rp^g JJrojjchIAL SuPPLY TO THE DISTRICT. p . ,; .^ The left posterior-horizontal, a short and thick stem, possesses interesting horizontal anatomical relations. Mesially it lies close to the vertebral border of the 3 em(.ij.p;. -^^^g ^nd to the adjacent descending aorta ; anteriorly it is in contact with to the pul- the descendmg trunk of the pulmonary artery which separates it from the edge'smd bronchus impar, or left upper lobar bronchus. The latter is situated more fh^"'^'"'t*° anteriorly and o'9 cm. higher; whereas, in the right lung, the difference in and left level between the corresponding two bronchi is 3' 2 5 cm. Prom above it is artery &o. approached by the almost vertical interlobar fissure, from, which it is separated by the descending pulmonary artery — and more internally by the end of the arch of the left pulmonary artery where the latter breaks up into descending pulmonary artery and into its apex-branches. Deep The thickness of the tube is considerable in proportion to its small length horizontal of Only 8 mm. ; but its diameter is abruptly bisected into an anterior and a iiudimeu- posterior half. The anterior half only is continued as a single tube as " deep tary super- postcrior-lwrizontol trunk." The posterior half subdivides on the spot, and terior-hori- without the intervention of an intemodium, into the ascending and descending l^i'-pp). tnid-dorsal oblique bronchi. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 35 This is probably the most perfect instance of an. apparent, but spurious Ascending \ bronchial trifurcation to be found in the human lung. The real nature of Xiquo7f!. the division is revealed by the following test. When viewed exactly from EPs)- behind, the dividing tube does not present a continuous tripartite stellate ing mid- line of intersection, but two separate lines, mutually perpendicular, and oSfque situated at separate levels. Analogy also strongly points to the conclusion C'^- pp'^)- that this is merely a double bifurcation. In the right kmg, the diverging ^.ff^^ca"* bronchi, which are vertical instead of oblique, arise, by bifurcation, from a tion; definite stem capable of being measured. If from some cause, sav from a test for its , , ' t/ spunous- more posterior position and greater length of the posterior-horizontal stem ness. analogous to what is seen in the left lung, the trunk in question had, on the Analogy right side, become reduced to rudimentary proportions, the two bifurcations rigbtiung, which are in the right lung quite distinct, and separated by an internodium, might, in this lung also, have become contiguous or even confluent. Zeft Oblique Mid-dorsal Distribution. Unlike the anteriorly placed deep posterior-horizontal, which divides, Fan-shape, after a branchless course, into secondary trunks opposite the wide aperture of the angle formed by the divergence of the oblique mid-dorsal trunks, the latter distribute peripheral branches very early (within 2 or 3 cm. from the angles). Viewed from behind, the cast of this symmetrical angular distribu- tion, filled in at the periphery by the later branching of the deep trunk, closely resembles an expanded lady's fan, the fully extended sides occupying the vertebral border, and the knob-like handle being represented by the posterior-horizontal stem itself. It results from the posterior position of their origin and from their slight and imbri- forward inclination that the oblique mid-dorsal trunks and divisions form t^irSs"- from behind an imbrication for other dorsal bronchi, especially for the more tribution. anteriorly placed horizontal group, for the small inferior mid-dorsal horizon- tal and for the early divisions of the posterior-basic stem. The Ascending Oblique Mid-dorsal Trunk slants upwards in a Ascsndmg line which would probably, if continued, touch the acromion or the coracoid ^jlj^aorsai process ; and under cover of the scapula it bifurcates into branches which (^- ppse). . , Ascending supply the upper fringe of the lower lobe and terminate below the lower aortic posterior border of the pulmonary apex. Previously, however, at a distance ^^' ^^^^J- •of 6 mm. from its origin, the trunk supplies an ascending aortic bronchus which rises vertically along the aortic border of the lung. The first part of this tube is visible in fig. 1 1 , but as in many other cases, the bronchus has been interrupted in the drawing in order to display other structures. With these exceptions the whole posterior-horizontal distribution is well shown in fig. II. By means of anterior and of posterior branchlets the vertical Ascending Aortic Trunk supplies the sub-pleural surface facing the first part of the 136 THE BRONCHI AND PULMONARY BLOOD-VESSELS. (Ascending aortio (yj. ppsss). Posterior sub-plenral brancli (vj.ppssp). 'Upper ascending sub- apu- lar (vj. / ppses). ^ Lower ascending sub-scapu- lar (vj. 'ppsee). Stiort snb- pleural dorsal branches. Descend- ing oblique mid-dorsal (iv. ppd). /Descend- I ing aortic (y. ppdd). Descend- \ ing oblique mid-dorsal V(v. ppde). (J-' ■ dorsal I ranch (yj. ppdep.) I Descend- ing aortic V(vi.ppded). (Descend- ing oblique (vj. ppdedV Horizontal sub-pleural (vj. ppdee). descending aorta, and also conies into relation with the posterior aspect of the arch and of the descending division of the left pulmonary artery. Lying behind, and parallel to the ascending- apical stem, it forms the posterior boundary of the broad quadrilateral inter-bronchial space which constitutes the vertebral end of the interlobar space. A T-shaped Posterior Sub-pleural branch is supplied backwards by the ascending aortic, close to its origin. The continuation of the ascending obligue mid-dmsal bifurcates, 2 cm. beyond its origin, into the upper and loxver ascending sub-scapular IroncTii. No departure from the original direction is made by the Upper Oblique Sub-scapular which gives iipwards and forwards an interlobar branch (opposite the axillary interlobar) and bifurcates into marginal branches which terminate just below the middle of the posterior surface of the pulmonary apex, forming the fringe of the lower lobe in this situation. The Lower Ascending Sub-scapular slopes rather less steeply upwards and outwards and gives posteriorly three successive short sub-pleural branches. The Descending Oblique Mid- dorsal forms with its fellow-branch an angle of i io°. It has an unbranched length of i'2 cm. only. Its bi- furcation gives rise to the descending aortic Ironchus which follows vertically the inner border of the lung. In close analogy with the ascending aortic, the Descending Aortic yields a f -shaped Sub-pleural Dorsal branch, and its continuation bi- furcates just behind the origin of the lesser posterior-horizontal into two small terminal hronchi, external and internal, which bear deep branches as well as superficial dorsal ones. The continuation of the descending oblique mid-dorsal supplies upwards and outwards a small Horizontal Sub-pleural bronchus which distributes sub-pleural branches to the district contained in the great angle, and a descending oblique hronchus which supplies an anterior and a posterior branch and ends with a terminal fork immediately behind the level of the inferior dm'sal horizontal bronchus. ^Superior mid-axil- lary hori- eontal (iv. pea). Inferior raid-axil- lai-y hori- zontal V(iv. pep). Anterior superior mid-axil- lary hori- Left Mid-axillary Horizontal Distribution. Of the two divisions from the deep posterior-horizontal stem, a short trunk measuring r2 cm. in length, the Superior Mid-axillary Hori- zontal not only is the higher but also, slightly, the anterior. It bifurcates, after a course of 8 mm., into a posterior and an anterior upper mid-axillary horizontal branch, which present very little divergence from the horizontal direction. Each of these delivers, close to its origin, an interlobar branch directed forwards. The Posterior Upper Mid-axillary rises slightly outwards, and supplies to the posterior surface two small branches. It is situated at a THE BRONCHI AND PULMONARY BLOOD-VESSELS. 13/ slightly higher level than its fellow-branch. The branches of its terminal zontai distribution are on a level with those of the outer pectoral bronchus, and ^ostltioi would dove-tail with the latter, but for the intervening fissure. SaSi- The anterior iipper mid-axillary, inferior to the preceding, and horizontal, lary '^ori- is on a level with the angle of origin of the pectoral and cardiac bronchi, and (v. peas), reaches the surface at the mid-axillary line, or a little in advance of this line, opposite the interval between the outer pectoral distribution above, and the outer mammary distribution below. The Inferior Mid-axillary Trunk, which is, in direction, slightly inferior posterior, likewise divides into s, posterior inferior mid-axillary horizontal and laryhori- au anterior inferior mid-axillary horizontal. }°y^\ -i The Posterior Inferior Mid-axillary Division is horizontal, and posterior after a course of i-6 cm., gives by bifurcation an Oblique Descending j^^'^^i Branch. It finally bifurcates, in company with, and a little above the laryhori- latter, at the mammary level, in the transverse posterior axillary vertical ^y pgpe) plane. ^ST^^' Before finally bifurcating each of these tubes gives a Sub-pleural mid-axU- Dorsal and a small Deep Dorsal Branch. zo?tai°" The Anterior Inferior Mid-axillary Horizontal assumes a down- (v. pepd). ward and forward direction : it approaches the septal surface to which it dis- \^ie^r ^ ^ tributes two Interlobar Branches. Its terminal branches reach the axil- J^?"^^ lary surface behind the mammary distribution. zontai \ (yj. pepee). Descend- ing oblique (v].peped).J Anterior \ inferior ] mid-axil- lary hori- 1 zontai (vj. ) pepda). Interlobar branches (vj. pepde).. ( 138 ) THE RETRO-CARDIAC DISTRICT. Pkeliminakt Eemaeks. Situation. District larger iu right thau iu left lung. The bronchus, termed by Aeby "cardiac." The district included between tlie downward and outward slope of the three basic bronchi and the posterior part of the inner surface of the lung is termed the retro-cardiac district and the bronchus supplying this district, the rdro-carcUac stem. In the right lung this district is more extensive than in the left, and it includes the inner posterior corner of the base. In the left lung it is limited to the region first mentioned. The right retro-cardiac stem was termed by Aeby the cardiac stem, a name more appropriately reserved for the right middle lobar bronchus, and for its left equivalent. Arising strictly from the inner surface of the lower lobar bronchus, it could find no place in the classification of bronchi into ventral and dorsal : it was therefore described by Aeby as an accessory bronchus. This designation is misleading ; — it is fortunately unnecessary in the nomen- clature here adopted. The existence of a retro-cardiac stem in the left lung appears to have been overlooked by Aeby. In this lung it is not a primary, but a tertiary branch from the lower lobar bronchus, arising not above the origin of the anterior-basic stem as in the right lung, but from the cardio-basic branch of this stem. THE EIGHT EETRO-OAEDIAO DISTEIOT. Eetro-car- diac stem (iv. ddi). 'Anterior retro- cardiac (y. ddie).' Posterior retro- cardiac Uv. ddip). /Anterior retro- cardiac Cyj. ddied). ' Posterior pericardial (or retro- peiicardial) Qvj. ddiei). (In connection with the description which follows, the diagram (iig. 9) and fig. 1 1 (columns G and H, between horizontal lines v and vij) should be consulted.) The Retro-cardiac Stem is rather smaller in calibre than the poste- rior-horizontal. It runs a vertical course, with slight inward convexityj for a distance of i"5 cm., and then bifurcates into the anterior and the posterior retro-cardiac. It originates from the inner surface of the lower lobar bronchus, mid-way between the origin of the posterior-horizontal and that of the inferior posterior-horizontal. The Anterior Retro-cardiac assumes a thoroughly downward and outward direction under the influence of the neighbourhood of the peri- cardium. After a course of i'3 cm. it gives up inwards an important sub- pleural branch of bifurcation, the Posterior Pericardial a T"Shaped bronchus extending its branches upwards and downwards in rectilinear order. THE BRONCHI AND PULMONARY BLOOD-VESSELS. I39 The continuation of the anterior retro-cardiac supplies a deep external branch for the tissue of the lower lobe, and ends by bifurcation for the supply of the inner surface and of the underlying pulmonary tissue of the base. The Posterior Retro-cardiac, whilst remaining in the original Posterior sagittal plane, swerves backwards, with anterior concavity, so as to be slightly Jarifec posterior to the pericardium. (^- ^^v')- It divides into an outer, deep ; and an inner sub-pleural branch. The inner, sub- latter is analogous to, but smaller than, the posterior pericardial, — the outer ^„"e™deep branch, or continuation of the posterior pericardial, is distributed in a manner branch, analogous to that of the anterior retro-cardiac bronchus. LEFT EETRO-OAEDIAO DISTRIBUTIION. The liCft Retro -cardiac Stem, not originating directly from the lower Eetro-oar- lobar bronchus, would not be included in a nomenclature confined to the (v%adp). consideration of the primary bronchial branches. In size however there is little to choose between this bronchus and the right retro-cardiac, which is a primary division ; — and the pulmonary district on the left side is but little smaller than that on the right. We are therefore justified in undertaking their description in this place. The ascendants from the bronchus in question are (i) the cardio-basic stem, (2) the antei'ior-basic or cardio-mammary basic stem and (3) the lower bronchial stem. Its descendants may be described as follows : The Retro-pericardial Ketro-car- , arises inwards within a few millimetres of the origin of the stem. Its two f^^dadpd) branches, anterior and posterior, descend at an acute angle. It is not there- inferior fore a 'J'-shaped bronchus such as the posterior pericardial which is to be pericardial seen, in the metallic cast, a little above it, or as the pericardial branch from pericardial) the descending aortic bronchus behind. At a distance of i'5 cm. from its (^'- "^^pO-/ origin, the retro-cardiac stem subsequently divides into Superficial and Deep Retro-cardiac Bronchi. Both these air-tubes acquire considerable length, and, like their parent Supei-ficial trunk, present some undulation. The superficial trunk is also anteriorly d^^°>^'"" placed. They each divide into an anterior and a posterior branch. dadpdi). The anterior division from the superficial retro-cardiac is long and extends cardL^Crij. to the anterior lower border of the lower lobe, to a point situated 2 cm. "^^'^P'^^)- above the anterior-basic angle : the posterior branch is much shorter. In the oi°Sese^tL case of the deep retro-cardiac the conditions are reversed. The posterior antenorand branch is here the longer of the two, although it does not quite reach the branch; vertebral border of the lung ; the inner or deep branch is shorter. Both trunks supply short outward branches for the deep pulmonary tissue, and intra- and the superficial retro-cardiac also furnishes a small sub-pleural branch bmnchlets resembling the retro-pericardial branch. ( I40 ) TABLE v.— LEFT RETRO-CARDIAC DISTRIBUTION. X M ■< O 'A Hi P A< Ph n n i^i j o 1^ & H Hi 'V M V 03 Hi o Pi M O P3 o <1 s (3 ^ -*3 .2 V m rci ^ ^ >, .>■ \ s ^ ^ 1 •^ 1 t M ) t4 !5° ^ a » ^ 5 3 •m -« •^ .'^ } 02 M fl 6 p; -a 73 n o o H P< " "2 ■9 ^ N ■2 >, -a - o M i Eh M 'a M ■« Si. o H I 2 '^ 2 ta a o ■s n o P^ ( 142 ) THE BASIC REGION. REMAEKS CONCERNING THE RIGHT AND THE LEFT PULMONARY BASE. The base a couven- tioDiil turm, usually meaus lower part of lower lobe. The term justified by the shape of the district, and by its possessing special bronchi, the three basic tranks. The lesser posterior- horizontal, The " Pulmonary Base " is an imaginary division of the lung, usually described for clinical rather than for anatomical purposes, and not corre- sponding to any outward line of separation, or to any perceptible land- mark at the pulmonary surface. In spite of this absence of any delimitation, we all agree in understanding by the term " base" the broad lower extremity of the lung, including its inferior third. On each side the " base " mainly consists of part of the lower lobe, and, in speaking of the " pulmonary base," most clinical observers probably have in their mind the "base of the lower lobe " only. Yet the lower horizontal third or even fourth of the lung com- prises part of another lobe, the middle lobe in the right, the upper lobe in the left lung. These lobes reach as far as the anterior pulmonary basic edge, which in varying proportions they help to form. The bronchial and the vascular supply of these inferior segments of lobes which are mainly situated higher up, have nothing in common with the bronchi and blood-vessels of the base of the inferior lobes, and we may, at any rate for the present, leave the higher lobes entirely aside. Turning to the bronchial tree as shown in the metallic cast, and confining our attention to the lower lobes, we discover both in the shape and in the mode of the bronchial distribution some justification for the use of the term base. The Shape of the bronchial district in question is analogous to that of the lower part of the lower lobe itself, which is described in the introduc- tory section as roughly resembling the lateral half of an inverted cone. The Bronchial Supply to the lower horizontal third of the lower lobe is mainly derived from the three large terminal trunks of the bronchial system. These define the " base " as a special region in the bronchial tree, with much greater precision than this can be done from ordinary anatomical or clinical considerations. I therefore submit that they can, with great propriety be termed the three " basic bronchi." I have distinguished them as the anterior- basic, the axillary-basic, and the posterior-basic stems. To their number, as contributing to the basic supply, might also be added a fourth, the inferior, or lesser posterior-horizontal bronchus. The retro-cardiac distribution, which THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 43 has already been described, should also be mentioned as taking a share in the and tho aeration of the base, although its origin which differs in the two lungs, is dtao°aiso' only in the left lung truly basic. The relations of these several tubes, on the *^^'^'' right and on the left side, are very clearly shown in the drawing (fig. 1 1 ) representing the posterior aspect of the metallic bronchial cast. General Survey of the Bronchial System of the Eight Base. Relative Situation of Aeby's " Bronchial Stem." — The "bron- The chial stem" described by Professor Aeby coincides, in its lower part, with the stem"'^'^'*' posterior-basic stem, and ends in one of the branches of the latter. Assuming "^y®": " antenor, for a moment the correctness of Aeby's views, which I have ventured to ultimately criticize in the introductory section, and the existence of a " bronchial stem,' to tracheal of which there seems to be insufficient evidence in man, I would point out P'*°®- that the " bronchial stem " would, at no part of its length, become anterior to the plane of the trachea ; but would preserve to the last the outward and downward slope which eventually carries its termination into a position entirely posterior to the plane of the trachea. The same observation would also apply to the left " bronchial stem." This difference in planes may be partly ascribed to the influence of the Reasons thickness of the bodies of the vertebras which keeps the trachea well in front ^ ^' of the posterior thoracic plane, partly to that of the concavity of the posterior part of the thoracic cavity, which permits the lung to extend backwards. Relative Position of Basic Trunks. — Thus, at the base, the down- The pos- ward continuation of the main bronchus is decidedly posterior to the tracheal po"teriOTto olane, and posterior also to the bulk of the lung. Indeed the only bronchi tracheal -*■ , . . , plane and which occur in the bronchial tree behind the posterior-basic, are the posterior- to most horizontal, and the inferior or lesser posterior-horizontal ; and of these two ™°" ^ distributions the former does not belong to the base. We are now enabled to determine the position of the basic bronchi and Antero- their mutual relations. These air-tubes are at first arranged in strict antero- order"f'tho posterior order, and possessing the same inclination outwards and downwards, three basic they form a broadening plane, slanting in the same direction as that of the of the lesser lower lobar stem. This may be seen at a glance, in fig. ii. A similar horizontal, arrangement will be described in the left lung. There however the inferior posterior-horizontal is not in strict line with the other basic bronchi, neither is it as large as in the right lung, owing to the greater size acquired in the left lung by the posterior-horizontal distribution. In the right lung the order in which these bronchi occur, is, from before backwards : (1) The anterior-basic stem (2) The axillary-basic ,, (3) The posterior-basic ,, (4) The lesser posterior-horizontal stem. 144 THE BRONCHI AND PULMONARY BLOOD-VESSELS. The four Of these the first and the last diverge by an equal quantity from the line oocu'r at o^ ^^^ lowsr lobar stem, which, in the interval betweeil them, bifurcates into different j^g terminal trunks, the axillary-basic and the posterior-basic. On close inspection the anterior-basic is found to originate a little higher than the lesser posterior-horizontal, and the bifurcation just mentioned takes place. about I cm. below the origin of the latter. Analogy Mode of Distribution of the Basic Bronchi. — Considerable analogy between esdsts in the mode of distribution of the anterior-basic and of the axillary- antenor ■,.... . and axil- basic, the former distribution being more extensive than the latter. Their ary- asic, •j^j.^j^^^jj^j^gg take place in two parallel, transverse, vertical planes, occupying together the anterior, half of the base. The axillary-basic distribution is limited to the lateral portion, whilst the other extends from the inner border Sze^of ^^ ^^^ ^^^® ^° ^^® anterior axillary line. The bronchial district belonging to posterior- the posterior-basic will be described later. It is larger than either of the two tribution. preceding ones, and almost comprises the entire posterior half of the base. GrENEEAL SUKVEY OF THE BRONCHIAL SYSTEM OF THE LeFT BaSE. A"bron- Apparent Trifurcation of Lower Lobar Bronchus. — The exist- even more ence of any definite bronchial stem is yet more difficult to imagine in the left doubtful in lower lobe than it is in the right ; for the main bronchus appears here to than in terminate barely 2 cm. below the lower edge of the posterior-horizontal stem "^ ■ in three almost equal, and at first, almost parallel, trunks, which, in close antero-posterior order, continue the long downward and outward cardiac curve of this bronchus, and for a short distance also its slight backward bend, basic* Their three origins might, on superficial observation, be mistaken for a bronchi perfect trifurcation. A side view, however, shows that the anterior trunk and almost Originates at a slightly higher level than the others ; moreover it protrudes equal. relatively more from the main axis than does the posterior trunk. This is seen even more plainly from the inner aspect than from the outer. Here, therefore, Spurious ig another instance of a bifurcation, unilaterally repeated, closely simulating a trifurca- .•<.,. tion. trifurcation. The axil- Relative Situation of the Basic Bronchi. — The middle stem, or lornddes" axillary-basic, which is a little smaller than either of the others, is, both as with the regards axis and direction, the apparent continuation of the lower lobar lobar bronchus. The posterior-basic, owing to its bulging backwards, is out of line bronchus, ^j^j^ ^^^ bronchus, and, in that respect, is less entitled to be regarded, as it seems to be by Professor Aeby, as the continuation of the " bronchial stem." Nevertheless its superior size may in itself constitute a sufficient claim. At first Gradual Divergence — Even during their short unbranched course of toee'tibes^ about I Cm., the three trunks begin to lose their absolute parallelism. The gradually three angles begin to vary, the posterior-basic trunk remaining almost vertical, THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 45 the axillary-basic diagonal, and the anterior-basic displaying least obliquity, with more of the horizontal than of the vertical bias. The Three Distributions are likewise almost parallel, their sub- The three divisions occurring within transverse planes succeeding each other from before butions ex- back wards. But, owing to the occurrence of antero-posterior bifurcations, yeree^y°^ in addition to those which are transverse, each of the three distributions ajidare . ' almost par- gradually acquires thickness from above downwards. The thinnest of the aiiei; thin three upright wedges thus formed is the axillary-basic, the thickest is the broad 'he- posterior-basic, which indeed forms the larger half of the base. The whole ^°^^^^y^' arrangement may, not inaptly, be compared to the common bellows, the sides resemble 'and ribs of which, at first almost parallel, diverge more and more from the mou "hei- plane occupied by the nozzle. ^^^' Some Differences between the Eight and the Left Base. The spurious trif urcation observed at the left base presents with that seen at the right base the following features of contrast : (i) It occurs decidedly higher (by about 8 mm.). (2) Its slanting antero-posterior plane does not face purely upwards and outwards, as does the right, but upwards, outwards, and slightly backwards. (3) Therefore, when viewed exactly from behind, the overlapping profiles of the two anteriorly placed trunks may still be seen, instead of being as in the right lung completely covered by the posterior trunk. (4) Whereas the right basic trunks stretch outwards and downwards stiffly, the left basic trunks form together a long flexible spray, drooping with unequal curves, and thus gradually increasing their mutual distance. (5) In consequence of their higher origin, the left basic trunks possess greater length, and they appear yet longer than they otherwise would appear, owing to their rather smaller diameter. As may be observed in fig. 1 1 , the left lesser posterior-horizontal is not only of smaller size but, at its origin, is more horizontal than the right. Lastly, the retro-cardiac is not, in the left lung, a primary branch from the lobar bronchial stem, as it is in the right, although on both sides of the chest the same districts are supplied by these bronchi. ( m6 ) THE ANTBRIOR-BASIO DISTRICT. RIGHT ANTERIOE-BASIO DISTRIBUTION. The District Supplied. (The description given of this distribution may be best followed in the diagram, fig. 9.) The right The Anterior-basic Trunk arises, with strictly ventral origin, from the basi"dis- front of the lower lobar stem. In this respect it is in harmony with the trict left anterior-lbasic. The two districts have not, however, identical shape and than the extension. The right distribution is smaller than the left by the whole retro- ciudiu'i' the Cardiac district, which derives its bronchus directly from the lower lobar stem, retro-car- j^ ^Qgg j^q^ therefore extend its ramifications to the inner pulmonary surface diac, and ■*■ ^ •^ being kept beyoud the anterior border of the lower lobe. Moreover, inasmuch as the more o^- ^° right and the left anterior-basic districts underlie the septal surface of the fissm-raud ^^"^'^^ lobc, they are influenced in their shape by the direction of the great by tbe fissure. Wheroas the left fissure, in its lower part, is almost aiitero-posterior, diaodis- the right is nearly transverse (with slight obliquity upwards and backwards). tnct. j^ results that, instead of facing inwards with its septal surface, the right distribution faces anteriorly. And since the cardiac lobe claims more than half the anterior-basic surface, the portion of this surface occupied by the anterior-basic distribution is much reduced. The left anterior-basic ramifications will be found to extend to the inner basic angle, of which they constitute the exclusive supply. In conclusion, the right anterior-basic distribution is less complicated and smaller than the left, and more restricted in its parietal sub-pleural extension. Eight Antekioe-basic Distribution. Its distri- The anterior-basic distribution resembles more faithfully than the left the se^mbSesthe axiUary-basic distribution, not only in the arrangement of its parts, but also axillary- in the direction of its bronchi. Like the axillary-basic, the right anterior- tribution. basic trunk and its derivatives follow a straight course downwards and In the left outwards, wMch is almost identical with the direction of the main bronchus resfm- '^ 3,nd of the lower lobar stem, whereas the direction of the left anterior-basic kss."^ '^ trunk and of its branches is complicated by various bends and curves. THE BRONCHI AND PULMONABY BLOOD-VESSELS. 1 47 The Anterior-basic Trunk originates at a very acute angle from the Anterior- front of the lower lobar stem, about 8 mm. below the lower level of the retro- (v!'ddd!l)! cardiac trunk. Its direction is altered from that of the parent trunk only to the extent of a slight obliquity forwards. In calibre it is about equal to the posterior-horizontal stem at its origin. Its distribution occupies a slice of the base parallel to the septum and extending from the anterior axillary line between its middle and its lower third, to the anterior fringe just external to the cardiac lobe. The first bifurcation, into the cardio-hasic and the lateral anterior-hasic oarfio- trunks, occurs after a course of 1-5 cm. Within a few millimetres from their jjj°i7J' .... aadaa). origin each of these bears a large "7""^^^?^^ interlobar Iranch, the directions Lateral of which however are not identical. basic (vj. The Cardio-basic Trunk is the longer of the two divisions, and is l'!gt^''ed destined for the extreme anterior base. It diverges slightly inwards from the posterior original direction. Its final division into inner anterior-basic and outer anterior- (vij.'^*' basic bronchi takes place at a distance of 2'8 cm. from its origin, but its first cardfo-' branch is the Posterior Pericardial, a T"sliaped branch, occupying basic tnmk I a position intermediate between that of the pericardial branches from the dddadd). ) cardiac distribution and that of the retro-pericardial branch. The Inner Anterior-basic, and the Outer Anterior-basic. — inner an- v The two divisions of the cardio-basic trunk are provided with small branches, (viij. most of which are destined for the deepest tissues. Those from the internal ou'teran''-' division, also supply the anterior edge of the base. Each bronchus sub- terior-basic sequently bifurcates into an inner and an outer terminal fork, which carry dddaddo). I numerous branchlets. The Lateral Anterior-basic Trunk is directly continuous with the Lateral an- direction of the common trunk. ,The X-shaped Interlobar Branch, arising (vw'ddae)' from its anterior surface, faces towards the cardiac lobe which lies in front of j-siaped it. This trunk is much shorter than the cardio-basic, measuring only i-i cm. branch fvij. I down to its chief bifurcation into the external mamraary and infra-mammary ^^^^■<'^y bronehi. In Table VI. it is termed infra-mammary. mai-y (vij. The External Mammary Bronchus assumes a lateral direction External ' inclined barely 20° below the horizontal. By its smaller anterior branch it mammary partly supplies the surface external to the nipple. By its larger, posterior dddaede). branch, which likewise possesses an upward and a downward terminal branch, mammary it becomes associated with the axillary branch of the axillary-basic and assists C™J- in the supply of the upper part of the lower third of the anterior-axillary region. The Infra-mammary Bronchus divides, after a course of i'2 cm.. Anterior into an anterior and an external branch. In general direction and in arrange- m^^y (?x! ment of branches this distribution resembles the more internally placed External'''' f cardio-basic distribution. But the infra-mammary branches do not reach the infra-mam- base ; they are supra-marginal, not marginal. The arches in which they dddaedde). - ( 148 ) TABLE VI.— LEFT ANTERIOR-BASIC DISTRIBUTION. S (fl ficial Mammary bronchi divide symmetrically, each into an upper and Desoend- a lower terminal fork. The two branches from the external bronchus are mar^trank larger and further reaching than the internal branches, and they come i^-^^^)- , respectively into anterior contact with the anterior inferior mid-axillary- daadi) and] horizontal, and with the upper mammary-axillary bronchus. scending ) mammary f (tj. daade).J The descending mammary or Infra-mammary District occupies the inner de- \ anterior surface of the lower lobe for a vertical distance of nearly 4 cm. mamimfy between the preceding district and the basic zone. ^\-ir\ The Descending Mammary Trunk after an unbranched course of interlobar 8 mm. divides, whilst still in the depth of the lung, into an inner and an alartii). oiitcr trunk. l^iei^ . , , , . 1 1 1 1 D supr., (viii, The inner trunk is rather more important than the outer by reason 01 daadida). the size and extent of its branches. A small Interlobar Bronchus is the Jfor Mra-" product of its first bifurcation. After this it divides almost immediately, by mammary a second bifurcation, into a Superior Infra-mammary Bronchus dis- daad'idd). 152 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Inner and outer ter- minal bran- ches from each of these. Deep in- tra-puhuo- nary (vij. daadee). Outer de- \Boending mammary (vij. daaded). Inner and outer ter- minal ex- ternal in- fra-mam- mary bronchi. Cardio- basic stem (iv. dad). (Oardio- basic stem (v. dadd). Ketro-car- diac stem (v. dadp). Cardio- I basic (vj. daddi). Jeep i cardio- basic I (rj. dadde). •Supra- marginal cardio- basic (vij. daddia). Cardio- basio bronchus (■"]■ ,daddid). tributing an inner and an outer terminal fork to the surface, and into an Inferior Infra-mammary. This bronchus, whilst still under cover of the former, divides into two diverging bronchi of good size, which ultimately become superficial after deli- vering deep and sub-pleural branchlets, and terminate by contiguous forkings 3 cm. above the fringe. The Outer Descending Mammary follows with less symmetry the pattern just described. It supplies outwards a deep intra-pulmonary (vij. daadee), but no superior branch. It bifurcates like its fellow into outer and inner External Infra-mammary Terminal bronchi ; the outer bronchus comes into anterior relation with the lower mammary-axillary bronchus. Zefi Cardio-hasic Distribution. The Cardio-basic Trunk, imitating in a reverse direction the initial curve of the mammary, presents at first a posterior and inferior convexity. Before this curve is completed the trunk undergoes a bifurcation in the same plane as the plane of bifurcation of the anterior-basic stem and of its mammary division, that is, in a direction almost parallel to the interlobar septum. The two resulting trunks are the cardio-hasic continued, and the Retro- cardiac. The latter has been made the subject of a separate description (see p. 1 3 9). It assumes a direction downwards, which is that of the early portion of the curve mentioned above. The Cardio-basic Trunk almost immediately returns to the original outward and downward direction of the anterior-basic stem. This direction it preserves for a few millimetres only ; for another sharper bend downwards, forwards and inwards, brings it closer to the anterior border of the lower lobe and to the septal surface which it then follows, at a slight depth within the lung, as far as the anterior angle. The latter is exclusively supplied by its branches. The bifurcation of the cardio-basic trunk takes place about I'S cm. from its origin, and gives rise to a superficial and to a Deep Cardio-basic Trunk. The latter, smaller and much less branched than its twin-bronchus, is external and posterior to it, and preserves this relation. It does not become superficial, having for its special duty to supply the deep pulmonary tissue intervening between the descending and hitherto branchless trunks of the axillary and of the cardio-basic distributions. The distribution of the Superficial Cardio-basic is entirely symme- trical. A superior smaller division, the Supra-marginal Cardio-basic, arises anteriorly, which carries an inner and an outer hranch. These are not destined to reach the extreme base, but they extend their terminal forks down to a level one or two centimetres above the fringe. The supra- marginal cardio-hasic is itself covered above by the termination of the infra- THE BRONCHI AND PULMONARY BLOOD-VESSELS. I S3 mammary branches, and it furnislies an imbrication for the basic distribution inner and below. branch The cardio-basic bronchus divides into its outer and its inner terminal f™"i ^^^ supra- branch at the same level as the supra-marginal.' These branches distribute marginal several branchlets to the neighbourhood, and end at the extreme base by tasio. terminal angular arches, i cm. in height, and about i cm. broad at their inner and lower extremity, or base. A succession of these arches lines the whole lower "g'J^Jninai fringe of the lung. Both limbs of each of them bear laterally sub-lobular branch. bifurcating branchlets, and finally become sub-lobular themselves. arches. ( 154 ) THE AXILLARY-BASIC DISTRICT. EIGHT AXILLA.RY-BASIO DISTEIBUTION. Situation of the district. General resem- blance to the ante- rior-basic, district. Smaller size of the right axil- lary-basic region. The District Supplied. (The diagram (fig. 9) will facilitate the study of the bronchi to be described.) This thin slice of the inferior lobe, included between the anterior-basic dis- tribution in front and the posterior-basic behind, is parallel to the former rather than to the latter. Moreover it is planned on the model of the ante- rior-basic, and its branches display an arrangement symmetrical to that of the anterior-basic trunk. For reasons already stated (see p. 146) the left axillary distribution is, just as the left anterior-basic, rather larger than the corresponding distribution on the right side. Indeed the right axillary-basic is reduced to the most simphfied expression of what we recognize as a basic trunk. It consists of a single trunk of origin, bifurcating into a single lateral and a single basic trunk. The former is intended for the upper part of the lower axillary third, and the latter for the axillary border. Axillary- basic trunk (vij. dddedd). 'Axillary- basic (viij. dddeddd). I Eetro- I mammary- basic (viij. Mddedde). 'Axillary- basic (ix. dddedddd). ( External I superficial branch (ix. Uddeddde). Deep branches The Bkonchial Supply. The Axillary-basic Stem is the anterior and smaller member arising from the final bifurcation which occurs 8 mm. to I cm. below the origin of the anterior-basic stem. Of rather smaller size than the latter, it remains strictly posterior to it, and posterior likewise, lower down, to the infra-mam- mary division. Near the base it emerges from under cover of the external infra-mammary bronchus. Its axillary branch is, in like manner, strictly posterior to the external mammary, branch for branch. The axillary -basic stem pursues a branchless course for i"S cm., and bifurcates into a trunk possessing an identical direction, the axillary-basic continued, and into the axillary-retro-mammary trunk, which is parallel in direction to the external mammary, and therefore almost horizontal. The Axillary-hasic Division gives rise to an external superficial branch, which forms part of the system of imbricating branches observed around the whole surface of the lower lobe. It also distributes small deep brandies to the THE BRONCHI AND PULMONARY BLOOD-VESSELS. I 55 pulmonary tissue and bifurcates into an inner and an outer terminal. Both ""^ '°ii™ latter bear sub-lobular twigs and end at the fringe with arches similar to those terminaia described above. 1^^! The External Superficial Axillary-basic supplies the lower axilla ''*^^'=- and ends in supra-marginal arches. mammary- The Retro-mammary-axillary Division, following the example of ?^-*'"y the external mammary, breaks up after a course of i '2 cm. into an anterior dddedde). and a posterior branch, the posterior branch being the larger one. Each subse- ^.anch°' ) quently divides into an upper and a lower superficial hronchvs. This distribution posterior f and that of the external mammary (which are depicted too low in the diagram) Each of are covered at their origin by the last ramification from the axillary division *''®^® ^^^^ of the posterior- horizontal stem. They form, below this, the next imbrication ; and a lower and the same process is repeated downwards by a succession of imbricating guooessive rows of air-tubes, each of which is of rather more acute angle than its pre- imbrica- , o J. tions from deceSSOr. above down- wards. LEFT AXILLARY-BASIC DISTRIBUTION. The Left Axillaey-basic District compared with the Same District ON THE Right Side. (The description of this district should be foUowed on the diagram (fig. 9) in conjunction with fig. 10 and with fig. 11. The bronchi are best displayed in the drawing last named.) The differences noticed between the left axillary-basic distribution and the Differences corresponding right one relate chiefly to size and to position. Whereas the 1^ position. right distribution was seen to be included between two almost strictly trans- verse planes, slight obliquity of the anterior and posterior boundaries is found on the left side, owing to the posterior position of the lower bronchial stem at the point where it divides into the axillary-basic and posterior-basic trunks, and owing also to the fact that a more anterior point of the basic fringe is reached by the left than by the right basic division. Thus the left distribution is rather more posterior in its axillary and rather more anterior in its basic section than the right. In addition the extent of surface supplied by it both Extent of in the axilla and especially at the base, is more considerable ; and the bron- greatei' on* chial ramifications are correspondingly more complicated. The exact paral- "^^ '«f'- lelism observed on the right side between the axillary- basic branches and metrymih those of the anterior-basic trunk, are here, owing to the sinuous course of the ^a^"^'. latter, not so perfect. tnbution. ( 156 ) TABLE VII.— LEFT AXILLARY-BASIC AND LESSER POSTERIOR-HORIZONTAL DISTRIBUTIONS. <^ M W t^ ii < m O "< M S a " t= M Ph H 7 A* " S H Q P M q ^ 3 5 1-^ c ^ O qEH h1^ p£j ■ ^ ^ o frj H g-i H ■BH 5 ^.^8 S S ° 3 S- O H ri gj M H O rr( izi O «•== ^ 158 THE BBONCHI AND PULMONARY BLOOD-VESSELS. Bbonchial Supply to the District. Axillary- basic trunk (iv. dde). IEetro- mammary- axillary (v. ddee). Axillary - basic (v. dded). Three Buooessive bifuroa- tlong in tli3 same plane. (Upper, (vj. ddeea) and Lower retro-mam- mary-axil- laiy (vj. ddeee). From the former a superior and am inferior branch ; from the latter, a descending intra-pul- monary, and an in- ternal and an external peripheral bronchus. /Anterior superior axillary- basic ("vj. dde da). Posterior inferior axillary- basic (vj. ,ddedd). The an- terior superior axillary- basic gives a lateral branch, and inner and outer teiTuinals. Lateral inferior axillary branch (vij. ddedde). From this a deep re- The Left Axillary-basic Trunk, in its non-branched portion, mea- sures I '5 cna. It ends in a bifurcation situated within the main transverse plane of the district. Of its two divisions, the outer and rather smaller Retro-mammary- axillary Trunk, adopts an inclination so much more outwards than down- wards, that its upper branch is little removed from the horizontal. This trunk has a length of i'5 cm., and it divides into a superior and an inferior hrarich, the latter being slightly posterior also, and its fellow slightly anterior. The plane of this bifurcation is the same as that of the preceding bifurcation and as that of the following one, for both divisions supply a small branch directed upwards and another, downwards, which are continued within the same original plane as the two previous bifurcations. The Upper Retro-mammary-axillary division from the preceding trunk, is contiguous with the external mammary, which it approaches from behind and from below. It bifurcates into a superior and an inferior branch ; and these bear small deep intra-pulmonary branches ; as it draws near to the surface, the inferior branch becomes more and more anterior. The Lower Retro-mammary-axillary gives a descending intra- pulmonary bronchus bearing recurrent branchlets and divides into an internal and an external peripheral bronchus, to be distributed at the junction of the middle and of the inferior axillary thirds. The Axillary-basic Trunk, rather larger than its fellow, con- tinues the direction of the common trunk, with a very faint increase in the forward tendency of the latter. For the relatively long interval of 2 "2 cm., it remains undivided. Its bifurcation gives origin to an anterior superior and to a posterior inferior axillary-hasie bronchus. These show little divergence in their direction, for they are both intended for the outer-anterior region of the base where the posterior division becomes external and super- ficial ; but the anterior superior branch does not supply true marginal, but supra-marginal arches only. Both divisions have a branchless course of I • 2 cm. ; and both are provided with an early lateral branch, bearing a deep recurrent branchlet. The Anterior-superior Axillary-basic distributes its lateral branch to the anterior axillary region at the level of the infra-mammary branches. Its own division into an Inner and an Outer Terminal bronchus occurs at the lower extremity of the infra-mammary distribution. The terminal bronchi extend to within 2 to 3 cm. from the base forming supra-marginal arches. They provide a last imbrication for the branches of the inferior-axillary-basic. The Lateral-inferior Axillary Branch from the posterior-inferior axillary-basic is of some importance both in size and in position. It takes THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 59 an outward direction towards the axillary fringe, which it does not quite onn-ent, reach. In addition to the Deep Intra-pulmonary Recurrent given Sibricating high up, it supplies three superficial imbricating bi^anches and ends by means Siohes!^ of supra-marginal arches. The Posterior-inferior Axillary-basic Trunk continues a branch- Anteio- less course for 2 "3 cm., and divides behind the imbrication of the supra- ba5c'(viij. marginal distribution, into outer and inner branches which, becoming ^^^j^^*^' superficial, terminate in arches at the fringe. These branches may con- basic (viij. veniently be termed the Antero-lateral-basic and Axillary-basic Bronchi. ( i6o ) THE LESSER POSTERIOR-HORIZONTAL DISTRICT. EIGHT LESSEE POSTEEIOE-HOEIZONTAL DISTEIBUTION. Preliminary Eemarks. Description defen-ed owing to difference of origin between right and left bronchi. Origin of this stem in the right lung. (Fig. 1 1 gives a good idea of the position and main branches of this distribution.) For reasons of symmetry and of clearness of description the right lesser posterior-horizontal distribution must be considered in this place, although somewhat out of the order indicated by its bronchial origin. In the left lung the bronchial trunk in question originates from the posterior-basic stem, and will be described under that head. In the right lung its origin occurs above that of the posterior-basic stem and almost on the same level as that of the anterior- basic, which arises from the opposite side of the bronchial stem. For purposes of classification we may therefore admit that the lesser inferior- horizontal arises immediately below the anterior-basic, and from the posterior surface of the remaining stem which bifurcates into the axillary- and the posterior-basic trunks. The district now under consideration occupies the upper third of the lower half of the lung and it is mainly superficial. Its bronchi are a repro- duction, at a lower level (by 3 cm.), but with almost complete parallelism, of the horizontal mid-dorsal and of the vertical-descending mid-dorsal bronchi from the posterior-horizontal trunk. The Bronchial Supply. Lesser posterior- horizontal trunlt (vj. dddep). ^Inferior posterior- horizontal dddepe). Inferior descending mid-dorsal (vij. Vaddepd). The Right Lesser Posterior-horizontal Trunk is not itself horizontal, but during its short course of I'3 cm. proceeds downwards and outwards in a direction posterior and parallel to that of the lower lobar stem. The Inferior Posterior-horizontal and the inferior vertical-descend- ing mid-dorsal are the divisions arising from the bifurcation. The former assumes an outward direction with very slight inclination downwards, and soon gives by bifurcation an obliquely ascending deep intra-pulTnonary branch. Continuing its course it divides into terminal branches behind the posterior axillary region. THE BRONCHI AND PULMONABY B1,00D-VESSELS. l6l The Inferior Vertical-descending Mid-dorsal has an unbranclied Ascend- ^ length of 1*3 cent, and moves downwards and slightly backwards. It jngdeep bifurcates into the inferior oblique mid-dorsal and the Inferior Inner pulmonary Marginal Mid-dorsal. The latter divides into an anterior and a posterior addepes). ) branch and each of these repeatedly bifurcates, so as to supply the surface of ii^ff"?' '^ •' . ' rr J postenor- the blunt vertebral edge of the lung at this level. horizontal The Inferior Oblique Mid-dorsal is of rather larger size than the arde'epe). , superior branch of the same name, of which it closely imitates the superficial inferior outward descending course, and the branchings. It gives a descending branch, mid-dorsal which is posterior to the posterioi'-basic division, and bifurcates outwards, at ^ddLde). a point i'< to 2 cm. below the inferior posterior-horizontal stem. Infr. inner . . . . marginal The distribution which has been described furnishes the highest layer mid-dorsal of the successive imbrications produced by the descending dorsal bronchi, dddepdi). inasmuch as the right posterior-horizontal distribution, situated above it, Anterior does not to any material extent overlap its branches.* posterior branch * For an account of the left inferior or lesser posterior-horizontal distribution, see p. 167. 5^°™/ ( l62 ) THE POSTERIOE-BASIC DISTRICT. EIGHT POSTERIOE-BASIC, OR DOESI-BASIO DISTEIBUTION. The District Supplied. (The right posterior-basic and its branches, as far as they have been successfully injected in the metallic cast, come into full view in fig. ii.) Extent of The distribution of the posterior-basic stem occupies the whole posterior IS IS no j^^jj ^^ j.j^^ 1^^^^ ^^^ possesses therefore considerable breadth as well as depth, unlike the much more limited sections belonging to the other basic stems. First In contrast with the latter, the dorsi-basic stem undergoes its first bifurcation B»^ttel."'° according to a plane which is almost sagittal, thus extending its ramifications backwards beyond the transverse plane which passes through the trachea and the right main bronchus. The dorsi- Of larger size than either of the other basic trunks, and corresponding in ^lwod*by ^^ direction with the axis of the " bronchial stem," the posterior-basic trunk Aebyasthe claims according to Professor Aeby to be considered as a continuation of the tionofthe latter. Even if that view should be adopted, it will be desirable to apply Btem°'''''*' to this stem the name posterior-basic, which defines its function as the main supplying tube to an important pulmonary district. The Bronchial Supply. Posterior- The Posterior-baslc Stem is strictly posterior to the other two basic basic stem gtems, and it remains, on the whole, part of the oblique, outward-inclined dddedp). and outward-facing plane which contains them ; but within that plane it swerves very slightly backwards. This tendency becomes more apparent in its posterior branch. The first bifurcation occurs 3 cm. below that which ■Lateral g^'^® ^i^e to the axiUary-basic trunk, and its products are the lateral dorsi- I (viif ''*^''' ^"^^^ ^i'^^io^ which is the direct continuation of the stem, and the dorsi- , dddedpe). hosic division, which diverging slightly backwards, probably corresponds to orsi asio ^^^ i}^ij.^ " hyparterial" dorsal branch, in Aeby's nomenclature. It provides dddedpd). tiiQ dorsal supply of the base as far as the neighbourhood of the vertebral margin, where the retro-cardiac distribution completes the circle of basic branches. THE BBONCHI AND PULMONARY BLOOD-VESSELS. 1 63 Bight Lateral Dorsi-basic Distribution. The Lateral Dorsi-basic Trunk, rather larger than its fellow, has Lateral an unbranched course of i cm. The branch arising from its first bifurcation, ^^^' ^'° the Inferior Retro-axillary, is comparatively small. It is analogous to, i^^^^^^' ) although originating at a lower level than, the retro-mammary branch of the retro-axii- axillary-basic ; and it distributes its superior and inferior branches, belonging d^ed^e). to the same level as those from the retro-mammary, to the outer-posterior Superior „ . . .,,.».,,. and inferior Buriace 01 the lung, where it comes mto contact with the inferior oblique branches mid-dorsal distribution. JXr!''" Five millimetres lower the lateral dorsi-basic divides antero-posteriorly Axillary into a smaller anterior trunk the axillary dorsi-basic, and a posterior slightly (x. ddded- more diverging trunk, the lateral dorsi-basic continued.* literal The Axillary Dorsi-basic Trunk supplies the axillary and the ^"'^^■^*^,''' retro-axillary region of the base. It has a length of i '5 cm. and gives an ppdp). anterior T-shaped intra-pulmonary branch of small size, and bifurcates into a superficial and a deep division. The Superficial Axillary Dorsi-basic bifurcates, at a distance snperflcial,^ of I '5 cm. from its origin, into a shorter anterior and a longer posterior pedeeVand bronchus, both of which subsequently divide into terminal branches, which ^^^ \ do not reach to the extreme base, but are imbricated over the basic divisions dorsi-basio from the deep branch. peded). ^ The Deep Axillary Dorsi-basic after a course of 1-5 cm. bifurcates Descend- into an internal Descending Intra-pulmonary division, presenting pu^^'J.nai-y no large branches, and destined for the supply of the central parts of the axillary base ; and into the continuation of the ajdllary doi'si-bastc. This trunk, with (xij. ddded- \ the exception of a few short superficial and deep branches, extends uninter- Marginal ruptedly downwards and outwards to the neighbourhood of the axillary ^■^^"^'^^g;^ fringe, there bifurcating into an anterior and a posterior division distributed (xij. ddded- to the axillary fringe. FronSe ' latter . The larger Lateral Dorsi-basic Trunk presents an arrangement aXdeep" analogous to that of the axillary dorsi-basic. It supplies the retro-axillary p^^j^*"'* fringe and the outer dorsal fringe. From its point of origin it extends terminal downwards outwards and slightly backwards, and it divides into a sitperficial and a deep branch. fiS^^ddded- The Superficial Lateral Dorsi-basic bifurcates into an anterior pedpe),and and a posterior bronchus, both of which supply supra-marginal arches im- lateral bricated above the deep distribution. (x^Mded- The Deep Lateral Dorsi-basic likewise gives rise to an anterior pedpd). * The lower portion of the posterior-basic distribution is incomplete in the metallic cast, owing to imperfect injection. The description given has been completed with the help of fresh dissections, and of dried specimens of the dissected bronchial tree. ( i64 ) TABLE VIII.— LEFT POSTERIOR-BASIC DISTRIBUTION. ^ O Cti ^ OS'S te y ^ OJ C!J 03 rt '^ PS H SS f=^ ( I6S ) TABLE VIII.— RIGHT POSTERIOR-BASIC DISTRIBUTION, 13 ij Org BOSS'S w a 2 c< 03 m o Hi o Eh M . o o ^--^ Ah S ■■ JO". CQ ^ S o S 92 CD 13 4J if rS O 02-9 01 O k/ (U 1-5 ■a w OS © i 03 CO 'vS O OS ^, ;3 o2 I S fi "^ -5< S f"^ 02 & Efl -q i^ TS n ■^ 2 I So f^ o. ■ c3 o ^ 'd IH Ph -^J ID H H tH 'g izi W 2 qT3 pedpdp). From each Bight Dorsi-hasic Distribution. of the latter and a peri- The Dorsl-basic Trunk, which diverges backwards from the main mTrSuai direction of the lower lobar stem, undertakes the aeration of the greater part bronchus, of the posterior base, being assisted slightly on the outer side by the lateral dorsi-basic, and at the inner or vertebral border by the retro-cardiac. It also takes a chief share among the basic trunks in supplying the central base. For a distance of 8 mm. it bears no branches. The first branch is given off, by bifurcation, straight downwards. It may I'Oentrai- -^6 appropriately termed the Central-basic Trunk. It bifurcates into an (ix. inne?- and an outer division for the supply of the intra-pulmonary tissue. The Dorti-^asii letter is also largely supplied by the deep branches from the retro-cardiac ^J'i^^i^V distribution. dddedpdp). Inferior ^ Socond bifurcation occurs 8 mm. lower down into the Inferior Dorsal r°'^ddd d T^^^^ (which probably corresponds to the fourth hyparterial dorsal bronchus pdpp). of Aeby), and into the continuation of the dorsi-basic. The latter does not (x. ddded- alter its outward downward and backward direction. The inferior dorsal which ^pdpd). arises from its posterior surface shows an inward and backward tendency : (xj. ddded- it divides into an inner, and into a more superficial otiter branch, and supplies Onto I'lJe? *^^ inner posterior fringe and neighbouring surface. 1 ?°' ddd *d '^^® Dorsi-basic Trunk divides into an Outer Superficial Branch Ipdppe). and into the continuation of the trunk. The outer branch again divides into oufer'dorsai ^^ inner and an ototer bronchus, which supply the parts above the base. (xj. ddded- The dorsi-basic finally bifurcates into a Deep Anterior and a Posterior (i)orai-basic Dorsi-basic. pdpdd^^*^ These bronchi present an arrangement similar to that which has been Anterior described at other parts of the basic fringe. deep dorsi- basic (xij. ddded- Ipdpdda). Posterior dorsi-baaic LEFT POSTERIOE-BASIC DISTRIBUTION (xij ddded- pdpddp). The Disteict Supplied, This distribution can be readily studied in &g. 1 1 ; it will be noticed that the lesser posterior- horizontal trunk has been curtailed in the drawing.) textent and The whole posterior half of the base is supplied by the dorsi-basic trunk diSt '''* which, by means of the lesser posterior-horizontal, also contributes to the aeration of the posterior middle third of the lung. In general shape this THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 6/ distribution almost exactly resembles the inferior lobe, and the same pyramidal outline repeats itself also in its subdivisions. In consequence of the posterior divergence of its first portion (nearly equal to the anterior divergence of the cardio-basic trunk), the Posterior- Leftpos- basic Stem is, at the beginning of the lower third of the lung, the most *trm''"''''°' superficial of all the large bronchi (with the exception of its own branch, the 0^- ^'^P)- lesser posterior-horizontal). Alone, the lower ramifications from the posterior- horizontal distribution intervene between it and the posterior surface of the lung. Its great divisions, originating at this posterior level, must either descend vertically or else develop a forward tendency. Both these directions are represented (chiefly the latter) in the branchings from the left posterior- basic stem. It will be remembered that the right posterior-basic, in its own trunk and in all its branches, possesses a downward outward and backward movement. The left bronchi on the contrary^ present an outward and slightly forward tendency towards the axillary base ; whilst a few, more superficially placed, descend vertically. Left Lesser Posterior-horizontal Distribution. The Inferior or Lesser Posterior-horizontal Trunk arises Lesser 4 mm. below the origin of the posterior-basic stem, and exactly behind the horizmtai bifurcation of the left descending aortic bronchus, from the posterior surface (^- ddpe). of the stem. It takes its course almost horizontally outwards, keeping at a distance of 3*5 to 4 cm. below the posterior-horizontal trunk, and remaining under cover of the descending oblique from the latter. Both absolutely and relatively it is a little lower than the right lesser posterior-horizontal at its origin, being given ofi" by the posterior-basic stem, instead of arising from the joint axillary-dorsal stem. It is of small size, and gives only small and unim- branches portant branches downwards and anteriorly. fnd'fOT*"^" Together with the external mammary and with the mid-axillary bronchus, wards, the lesser posterior-horizontal helps to form the floor of a Central Lozenge- Central shaped Bronchial Interspace, of which the inferior bronchus and its shape^^' apparent trifurcation form the inner wall, and various X'S'^a'Ped interlobar and J.^^aVs"^ac" deep bronchi the anterior and outer walls. The terminal bifurcation of this bronchus takes place in the posterior axillary region somewhat below the middle of the lung. Left Posterior-basic Bronchial Supply. The chief bifurcation of the posterior-basic stem occurs 2 cm. below the Descend- origin of the previous trunk, and gives rise to the descending oblique dorsal, and dorsal '^"'' I to the slightly larger dorsi-basic division. The latter supplies a pyramidal ^"^islSo I distribution, including the inner vertebral border and deeper parts, and the trunk I l68 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Large ex- whole inferior border and lower basic surface, as far as the middle axillary tent of the -i • latter's dia- ^'■"■^^ ti-ibution. The remainder of the posterior base, — viz., the outer and upper portion, distribution is provided with bronchi by the descending oblique dorsal, a trunk inclined deTendiDK ^owuwards and outwards, with slight forward tendency. oblique dorsal, Zeft Descending Oblique Dorsal Distribution. The Descending Oblique Dorsal Trunk preserves the same direction as far as the lower axillary region, although it does not reach the basic margin. Posterior But it previously gives rise after a course of I'S cm. to the Posterior dOTsafob^ Superficial Dorsal Oblique. This short trunk bears the same relation to Jjj"? C^'i- the outer base as the inferior aortic bronchus bears to the inner. It descends ddpdep). I Deep dor- for 8 mm. exactly behind the deep oblique branch, and bifurcates into two (vij". ^'^^^ superficial divisions provided with several sub-pleural branchlets. The upper Udpdee). ciivision takes an outward direction towards the lower axillary region ; the I branch lower, Or descending, descends almost vertically, but does not reach the edge of dd^Jdepe). *^s l^ng. In the angle thus formed between these terminal branches, the deep Ib^^^hr^"^ portion ultimately comes to the surface about 3 cm. above the fringe. Udpdepd).''" The Deep Dorsal Oblique Trunk, whilst still under posterior cover deep^"""^ of the superficial division, divides into an copper (or outer) and a lower deep dorsal dorsal ob- oUiquc. After giving a deep intra-pulmonary bronchus forwards, the Upper ( ddpdeee)?" Deep Dorsal Oblique again divides into an anterior and a posterior branch. deep"dorsai '^^® destination of these bronchi has already been mentioned, Branchlets oblique from them are furnished respectively to the sub-pleural and to the intra- >ddpdeed). pulmonary tissue. At a distance of 3 mm. below the descending dorsal oblique bronchus there arises from the posterior aspect of the trunk of the dorsi-basic an important minor trunk destined to supply the vertebral portion of the posterior pulmonary surface. The district in question is included between the lower (Inferior limit of the distribution of the vertical descending aortic bronchus (derived from aortic'fiJi^f tte posterior-horizontal trunk) and a level 2' 5 cm. above the lower fringe of DOTsfbasic *^® ^^^S- ^or the bronchus supplied to this district the name of Inferior trunk (vij. Descending Aortic is almost indicated by the anatomical relations. It Inverted ramifies in a fan-shaped manner downwards, thus covering the posterior fan-shaped pulmonary surface from the scapular to the vertebral line, and leaving the outer metrical half of the posterior surface to the descending oblique dorsal bronchus. tion'of"the Between the vertebral border of the lung and the direction of the dorsi-basic ^Sndin ^^^^^' Continued downwards, outwards, and slightly forwards, a space is left, iioi-tic. the outline of which is triangular when viewed from behind. This space is filled by the almost completely symmetrical and equilateral-triangular outline of the inferior descending aortic distribution. The small bronchial trunk in question THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 69 being at first absolutely vertical, forms at once an angle with the direction of the dorsi-basic trunk. The branches of bifurcation of the inferior descending aortic are inner de- symmetrical and equal. The Inner Descending Aortic diverges slightly aortic'rviij. | from the perpendicular, and ends above the inner posterior angle of the lung, outo^d2 completing a curve formed in succession by the main bronchus, by the inferior scending lobar bronchus and by the dorsi-basic, and resembling, when viewed from be- ddpddde). J hind, a very open letter Q. In the concavity of this curve, which constitutes c-shaped as it were the inner edge of the bronchial tree, may be seen the pulmonary facing the vein, the left pericardial surface, and quite anteriorly some of the sternal and §?^*'"' cardiac bronchial tubes. From the concavity of this curve no inward branches are given excepting minute branches from the descending aortic bronchus. The inferior pulmonary vein descends to the level of the bifurcation of the descending aortic : the inner division of this bronchus opposes to the vein a small Anterior T"Shapecl Branch, facing which, on the Ketro- anterior side of the vein, is found a similar branch from the inferior peri- ^.shaped cardial bronchus. bronchus. Other unimportant twigs are given off from the inner division, among them is an upper inward branchlet symmetrical with an outward branchlet from the outer division, and two inward branchlets intended for the lower part of the mesial border of the lung. The inner descending aortic finallv Marginal T •! T • 1 c • T 1 • 1 -T 'nner aortic supplies marginal arches which iumish the interval between the marginal branches. branch from the superficial dorsi-basic and between the termination of the posterior angular bronchus at the inferior angle. The Outer Descending Aortic Bronchus is almost vertical. It Outer do- supplies outwards a sub-pleural branchlet symmetrical with the small inward aortic (viij. branch from its fellow bronchus ; and it bifurcates after a course of i cm. '^'Jp'i'i'i'')- into a vertical sicpra-marginal hranch and an oUique branch, both of which are superficial. The Vertical Supra-marginal Bronchus lies parallel to and 5 mm. Vertical > to the inner side of the inner division of the superficial dorsi-basic trunk, and mar^nai thus separates this bronchus and its distribution from the inner border of the '^dp'^dded^' lung. It terminates in the same manner as other supra-marginal bronchi, Oblique and partly imbricates over the marginal branch from the superficial dorsi-basic ddpdddee). trunk. The Oblique Branch has a brief course downwards and outwards, supplying the sub-pleural tissue in the inferior mid-dorsal region. Zeft Dorsi-hasic Distribution. The ensuing bifurcation of the dorsi-basic division of the posterior-basic stem gives rise to the deep and to the superficial dorsi-basic trunks. The dorsi-basic trunk, in the interval of i'3 cm. separating the origin of the descending aortic and the present bifurcation, has a direction parallel i^; 170 THE BRONCHI AND PULMONARY BLOOD-VESSELS. peep axil- to a line drawn from the posterior-horizontal stem to the lower extremity ba'sio ("viij. ^^ ^^^ posterior axillary line. ddpddee). rp^e Deet) Axillary Dorsi-basic Division follows the same direc- ( Superficial -^ ,.-, , ■•i!j.i_ a* axillary tion, and may therefore be looked upon as the continuation o± the poaterior- ^virj!"^"^'" basic stem. It traverses the depth of the outer portion of the lower lobe in dpdded). fj,QQ|; Qf ^j^Q descending oblique distribution, and emerges above the posterior axillary fringe, to which it is distributed. Deep axil- The first bifurcation of the deep axillary dorsi-basic trunk gives rise to lary dorsi- the Central annular dorsi-basic bronchvs, and to a continuation of the deep ddpddeee). axillary dorsi-basic. The length of the undivided trunk above this bifur- ^ anguiai cation is I cm. ; and between this and the subsequent bifurcation there dorsi-basio ^g g^^ unbranched length of 1-3 cm. The final breaking-up of the trunk is ddpddeed). thus delayed until it has almost reached a superficial position in the posterior axillary region, 'inner, (x. In its deep portion the deep axillary-basic gives rise to two or three stout ddpddeeei) ^^^ ^^^^^ Intra-pulmonary Branches ; it finally divides into an Inner Outer ter- a,nd into an Outer Terminal branch, which supply the tissue above the I minal deep . '■ '- !: mi 1 axillary- axillary fringe, and are therefore supra-margmal. Until close to the supra- ddpdd-^' marginal region they are covered by the imbrication of the inferior deep eeee). dorsal oblique bronchus. Central The internal branch of bifurcation, or Central Angular Dorsi-basic, dor"'ba ic ^^ covered from behind by the superficial dorsi-basic, "the general outline of (ix.ddpdd- which it repeats in a much more anterior or central plane. After a vertical course of i " 5 cm. it bifurcates into widely diverging branches. Posterior The branch to the posterior inner angle, or Posterior Inner Angular, aneSar which bears several deep intra-pulmonary branchlets, divides into an Infe- (x. ddpdd- rior-basic bronchus and into an Angular Marginal bronchus. The Posterior latter furnishes a marginal arch for the posterior extremity of the inner (rdtdd- fringe of the base. ^ eede). The smaller, shorter, Posterior Central Bronchus extends outwards basi"°^" and downwards for the supply of the central zone above the posterior-outer (''J-.^^P'^'^' pulmonary margin. It is anteriorly in relation with the central branches Angular from the retro-cardiac bronchus, and parallel with them. It ends in sub- (LY^ddpdd- pleural basic branches. keedii). Superficial The Superficial Axillary Dorsi-basic Trunk and its distribution dorsSsio ^i® within a plane which passes through the inner posterior basic angle C^"],- and along the posterior axillary line. After a course of I "4 cm. this trunk divides into an outer and an inner branch, the former being slightly larger than its fellows. Superficial The Outer division, or Superficial Dorsi-axillary-basic, is destined fa^^-bSio ^°^ *^® posterior axillary, and lateral dorsal fringe. Immediately above its fWd dd ^if''^'^°^*^°'^ ^* supplies to the posterior pulmonary surface a branch of small ^ede). size, which does not descend as far as the extreme fringe. It then divides THE BRONCHI AND PULMONARY BLOOD-VESSELS. 171 into two branches, inner and outer, respectively termed the Retro-axillary Superficial Marginal and Lateral Dorsal Marginal, which terminate by means of truok (ix. small bifurcating branches at the surface. . ^to."^'*^'.'' The inner division, or Superficial Dor si-basic Trunk, bifurcates after axillary descending for 2-2 cm. vertically downwards, with slight inward bias. It ^"fdpdd divides into an anterior and a posterior branch. Each of these immediately ^^^^^^y ) bifurcates into two bronchi, inrier and outer. The distribution is thus con- dorsal mar- verted into a small pyramidal group which occupies the inner posterior angle ddpdd- of the base, and part of which is overlapped by the fringe of the descending t**"*®^' . ■ aortic distribution. dorsi-basio The branches from the posterior branch, or Marginal Superficial ddpddedd). Posterior-basic, in addition to sub- pleural twigs, give rise to marginal Marginal arches for the fringe, and supply the fringe nearly as far as the angle, posterior- This distribution comes into contact with that of the posterior angular p^^'^^^J"^"^' bronchus. Central The branches arising from the Central Superficial Posterior-basic poBterio* likewise supply branchlets to the intra-pulmonary tissue, and terminate at the p^deila)!^ , basic surface in front of the marginal distribution just described. ( 172 ) Large size of the pulmonary vessels: Peculiari- ties of the bronchial tree, con- nected therewith. They ex- clude the parenchy- ma from the root- zone. They mo- dify the course of bronchi : SECTION III. THE ANATOMY OF THE PULMONARY BLOOD-VESSELS, STUDIED PROM THE METALLIC CAST AND FROM DISSECTIONS. GENERAL REMARKS ON THE PULMONARY BLOOD-VESSELS; THEIR RELATIONS TO EACH OTHER AND TO THE BRONCHL A. — General Relations of the Blood-vessels to the Bronchial Tree. When the simple bronchial cast and the compound metallic cast of the bronchi and of the pulmonary blood-vessels are placed side by side, a striking contrast is presented by the unfurnished aspect of the first and by the fulness of the second. Indeed the great size of the injected blood- vessels is the first thing which arrests attention in the compound cast. Allowance must be made for the greater ease with which the walls of the blood-vessels, as compared with those of the bronchi, yield to the internal pressure exerted during injection. But even after this deduction, the calibre of the pulmonary vessels remains unusually large in proportion to their length, and reminds us of the fact that the amount of blood passing through them, to and from the lung, at each cardiac contraction, is exactly equal to the amount propelled into and derived from the general systemic circulation during the same interval of time. Some of the peculiarities of the bronchial tree may be traced to the pre- sence within it, and to the large calibre of the pulmonary ai'teries and of the pulmonary veins. In the first place these vessels so fill the interspaces left between the primary and the secondary branches of the main bronchus, that no room remains at the root for any pulmonary parenchyma ; and in consequence no lobular bronchioles arise from the central internodia of the bronchial tree but their origin is relegated to more peripheral zones. In some situations the large size of the vascular trunks and the claim which they make upon the intra-pulmonary space bring about the deflection THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1/3 of a large bronchus, or some important alterations in the structure or in the shape of the bronchial tree. The following are striking instances of this kind: (1) The left main bronchus, longer than the right bronchus owing to the e.g., of iLh passage over it of the aorta, is still further elongated in order that it may bronchus afford support to the arch of the left pulmonary artery. Professor Aeby even goes so far as to suppose that the left upper lobe has been entirely sacrificed to the superior position of this vessel ; a view which I cannot endorse. (2) The right cardiac, or middle lobar, bronchus by the unusual course and of the of its first portion, which descends in contact with the lower lobar bronchus, "^diao and by the curvature of its second portion, clearly bears witness to the lateral ^''U'loiius. pressure from the transverse portion of the pulmonary artery, and of the superior pulmonary vein in front of the artery. (3) The large vacant space seen in the metallic bronchial cast, in the different upper part of the middle third of the right lung, is mainly devoted to the the right large blood-vessels and strictly deserves to be termed "the intra-pulmonary i'"ft°yesf vessel-space." This gap is analogous to the space which intervenes between sei-spao^ " the apex of the left lung and the trachea ; but in consequence of the different them, course adopted by the pulmonary artery in the two lungs, the " vessel-space" occurs in different situations on the two sides, above the upper lobar bronchus on the left side, and on the right side below this air-tube. (4) Again the left main bronchus shows a slight depression of its oblique" 0™^**,"'^ axis, near the pulmonary root, and a posterior sulcus at its termination, mainbron- These correspond to the position of the arch of the left pulmonary artery on the nectedwith one hand and to that of the left descending pulmonary artery on the other. narvaiS" B. — General Relations of the Pulmonary Arteries to the Bronchi. The relations existing between the arterial channels and the air-tubes are ■*■ single extremely simple and very constant. Each bronchus is invariably accompanied companies by a single arterial branch. The association once established between them chua. ™"' is never dissolved. Their directions undergo the same variations, and their bifurcations occur simultaneously. The only exceptions to this otherwise Their bi- absolute uniformity are those which occur at the root of the lung before the aresimui- arteries have succeeded in modifying their original direction in accordance **'^<'°''^- with the very different direction presented by the larger bronchi. riautstri- The arterial distribution is therefore a duplicate of the bronchial tree, and dupi™ate°' to describe the bronchial divisions is almost equivalent to describing the of ^^^ . arteries. For this reason a separate diagram of the arterial ramifications T^ereia- will not be found necessary. tiveposi- But with regard to the relative positions assumed by each of the paired teryand tubes, it is impossible to formulate a general rule applicable to all cases, as no°The"^ this has been attempted by Professor Aeby (loc. cit., p. 4) and by Quain same (vide supra, pp. 16, 17). 174 THE BRONCHI AND PULMONARY BLOOD-VESSELS. The aspect of the bronchial surface with which the accompanying artery is contiguous varies with the different districts of the same lung, and within the same district often varies with the individual bronchi. These relations will be in every case described in detail. There is however a rule capable of Fig. 12. Dissection of the Beonchi, op the Pulmonaey Aeteey and of the Pul- MONAET Vein, deied. Right Lung — pkont view. (From a Photograph, — considerably reduced.) The descending pulmonary artery is seen in the front plane, at the middle of the specimen. The details are not sufficiently clear to supply more than a general idea of the kind of dissections to which reference is made. The arte- general application to those bronchi which possess a partly membranous wall the^mlS-^ The artery is always associated with some portion of their cartilaginous surface branous and not with the membranous portion. sides of ^ bronchi. THE BBONCHI AND PULMONARY BLOOD-VESSELS. 175 0. — General Relations of the Pulmonary Veins to the Bronchi. In direct opposition to the mutual behaviour o£ arteries and of bronchi, The veins the relation of the pulmonary veins to the air-tubes is one of constant sepa- distance Fig. 13. Dissection op thk Beonciii, of the Pulmonaet Aeteey and of the Pul- MONAEY Vein, deied. Left. Lung — feont view. {From a Photograph, — eonsideraily rediiced.) In this as in fig. 12 the photographic method has done scant justice to the specimen, the details of which are obscured. In both figures the venous branches may be recognized, in many places owing to the angles which they form with the direction of other vessels. ration. Instead of clinging to the bronchial tubes, the veins usually ramify from the as far from them as it is possible. They generally select the middle of the i^^^gj^^. interspace which intervenes between two or several bronchi. terspaces. 176 THE BEONCHI AND PULMONARY BLOOD-VESSELS. Their mutual divergeuce persists. They ap- proach the lobules at au angle. Again instead of shaping their course in distant imitation of that of the bronchi, they retain their original divergence. In passing from one interspace into another their branches are of necessity otherwise than parallel to the bronchi. Nay, even during their course within the interspaces want of paral- lelism is the rule. The smaller veins approach the peripheral districts at an angle with the corresponding bronchi. Even when entering the lobule the two directions do not blend, and the venules are separated from the bronchiole by a considerable proportion of the thickness of the lobule. A study of the behaviour of the intra-lobular vessels within the lobule belongs to the province of histology and cannot be attempted here. But the description given of them by Sappey (loc. oit., p. 470) favours the view that an analogous divergence exists between the most minute arterioles and venules. D. — General Eelations of the Pulmonary Veins to the Pulmonary Arteries. The veins remain in- dependent of the arteries. They are not parallel, nor similar. Two rules regulate their mutual re- lations. Conclu- sions. The veins connect di- vergent bronchial tracts. The intra- lobular arteries are The mutual relations of the two sets of vessels within the lung, exclusive of their mediastinal portion, may be inferred from that which has been said concerning their individual relations to the bronchi. Throughout the lung the two blood-vessels follow an independent course. Between them there is neither symmetry of distribution, nor regularity of distance. They are rarely parallel. The veins do not, as in the systemic circulation, constitute a repe- tition of the arterial pattern. It is therefore impossible to gather from a description of the course followed by the pulmonary arteries more than an approximate idea of the direction taken by the pulmonary veins ; and a separate diagram of the venous distribution is almost indispensable for refer- ence, when specimens are not available for study (see fig. 1 8). The chief features of contrast between the pulmonary arteries and the pulmonary veins may be summed up in the following rules : ( 1 ) The two vessels are situated on opposite sides of the same bronchi, the artery clinging to the side of the bronchial wall, the vein keeping aloof. (2) The arteries and the veins are not parallel, and they almost always cross each other at a considerable angle, often approaching, and sometimes equal to 90°. I cannot endeavour to discuss in these pages the important physiological considerations which a study of these relations has suggested ; but within the range of pulmonary anatomy I have arrived at the following conclu- sions : (i) Inasmuch as the veins, occupying the bronchial interspaces, dis- tribute their branches in various directions to two or to several bronchi, they establish an elastic link between the divergent bronchial tracts ; and their ramifications throughout the lung constitute a connecting system for the pul- monary elements. (2) From the persistent connection of the pulmonary arteries with the monary vein is con- THE BRONCHI AND PULMONARY BLOOD-VESSELS. 177 bronclii, and from the fact that they enter the lobule in close association, it notably may be inferred that the same relation is continued yet further, and that the ^th ttJe** arterial element accompanies the bronchial element as far as the depth of bronchj- the lobule. With regard to the pulmonary vein, a continued divergence venules ara would be suggested by the very distant behaviour of that vessel throughout dissociated, the lung. Thepul. (3) At the surface the pulmonary vein is found to be intimately con- nected with the pleura ; in its intra-pulmonary part it supports a continuous ^^e pfeTH-a*^ framework of connective tissue which extends between its branches ; and yi"* ^^^ lastly, close to the surface of the lobule, it undergoes division into two or monary more venules, which are at first superficial to the peri-lobular sheath, but anTwith*' which ultimately make their way into the lobule. ^^^ P^i'i- 1 • cT-i- lobular In these three successive stages of distribution, the pulmonary vein may membrane ; be regarded, in a limited sense, as peri-pneumonic, as sustentacular, and as pnOTmonio, peri-lobular. The pulmonary artery on the contrary may be truly described sustentaeu. as intra-pneumonic, as companion to the bronchus, and as intra-lobular. In peri-iobu- other words, in addition to its vascular duty of conveying arterialized blood tion to its to the heart, the pulmonary vein would appear to discharge a supporting functions function in connection with the inter-bronchial and with the peri-lobular The pui- fibrous framework. The pulmonary artery would be, on the other hand, ™tCTyfgj.e. exclusively at the service of the blood-aerating function. strioted to (4) According to all usual anatomical notions the term "artery" is function of synonymous with greater strength and elasticity than is understood under ^^^P"^*''°°' the term " vein." This difference in favour of the arteries is not perceptible wau and within the lung, although it may be claimed for the pulmonary artery in its aie^Mtoon- extra-pulmonaiy, and in its intra-radicular portions. The pulmonary vein is spicuous in on the other hand remarkable for the toughness and for the elasticity as puimonai-y. well as for the independence and for the unsupported condition of its rami- ^^5^"^™ ficationS. more (5) Lastly, it may be argued, at least from a vascular standpoint, that in the the lung is a more direct extension of the pulmonary vein than of the ^^™^' pulmonary artery. Its connection with the left auricle is much more close viewed as a and much more extensive than with the right ventricle ; and whereas the ™tg"sion pulmonary artery acts only as a loose link between the heart and the lung, from the the pulmonary veins firmly connect the two organs, as though by tight-drawn especially 1 . , from the ligaments, left auricle. The veins viewed as liga- E. — Differences between the Pulmonary and the Systemic meuts. Artekies. The pulmonary artery is the only artery in the body which conveys venous The pui- blood. In spite of this contradiction in terms, it is, in its extra-pulmonary artery con- portion, and as far as its secondary divisions within the lung, unequivocally qus blood. 178 THE BRONCHI AND PULMONARY BLOOD-VESSELS. but other- wise re- Bembles the aorta at first. Its smaller branches differ from other arteries ; they have thinner, softer, loss exteusile and elastic walls. The pul- monary capillaries resemble them rather than the veins. The pul- monary artery is purely res- piratory in function. It is less independ- ent in its course. It has no companion veins. It does not anasto- mose. arterial in its structure and surroundings. Its origin from the right ventricle and its close resemblance to the aorta leave, on this point, no room for doubt. Nevertheless, it differs slightly from other arteries in the behaviour of its smaller branches. Its ramifications become intimately associated with the air-tubes ; and, leaning upon them for lateral support, they appear to the naked eye to lose thickness of walls at an unusually rapid rate. Not only are the smaller branches thinner, they also seem to be of slightly softer texture, less extensile, and less elastic than systemic arteries. In connection with this observation special interest attaches to the well- known fact that the pulmonary capillaries are unusually delicate, and narrow. These features would seem to point to their being structurally more closely allied to the pulmonary arterioles than to the venules. In its distribution the pulmonary artery presents other peculiarities which distinguish it from systemic arteries : ( 1 ) It is exclusively devoted to the respiratory function : its branches possess no other destination but the respiratory tissue ; and the structures at the root of the lung, the pulmonary stroma, the pleura, and the bronchi (with the exception of the respiratory bronchioles)- all remain outside the sphere of their distribution. (2) In becoming closely associated with the bronchi, it loses that inde- pendence which is common to most arteries, except the nutrient arteries of bone. (3) In its systematic dissociation from the veins to which it corresponds, it departs from the usual arterial type. (4) Lastly, unlike the majority of systemic arteries, from its origin to its termination it presents no anastomoses. F. — Differences between the Pulmonary and the Systemic Veins. Direct re- lation of the pvilmo- nary veins to the heart. Rhythmical contrac- tion. Early sub- division. Very wide angles of divergence of its branches. The pulmonary veins stand in a more direct relation to the heart than any other veins except the cardiac veins. The four main pulmonary venous trunks are in effect diverticula from the cavity of the left auricle, and take a share in its rhythmical contractions, being supplied with a coat of cardiac striated fibres. In contrast with the pulmonary artery, which loops round into the pulmonary root, and whose breaking up is long delayed, the pulmonary veins, whilst still within the root, succeed in providing a complete set of diverging branches destined for the various parts of the lung. But in effecting this, the veins lose the appearances common to most systemic veins when undergoing division. Their general arrangement distantly resembles the divergence between the fingers of an outstretched hand. The radiating lines along which they extend to every point of the periphery meet centrally, close to the auricle, in the two short pulmonary veins on either side of the heart. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 79 In their subsequent distribution the pulmonary veins assert the same tendency to early and wide-spreading ramification, in striking contrast to the behaviour of the arteries which are restricted to the rigid system of lobular distribution and of dichotomy. The great length and the independent position thus assumed by veins of Great comparatively small calibre necessitate in them greater thickness and tough- and^^"!^* ness than belong to most veins. In the possession of these qualities they *'''^ t'ji'^'^- may even be said to out-strip the arterial branches of corresponding size. wall. Yet more striking are their capacity for extension under linear traction, Great ex- coupled with great resistance to ultimate disruption, and their remarkable anTeks-'' power of recoil. *icity. The pulmonary veins do not anastomose during their course from the Noanasto. periphery to the root of the lung ; but anastomoses occur between their ^°^^^^ ''' smaller branches in the peripheral districts ; and in this manner a connection i<'requent is established between neighbouring lobules, the arterial supply to which is amstor™ absolutely distinct. ""'='^«' In addition to this, during their intermediate course, and even within the Their an- zone of their secondary divisions they undergo extensive lateral branchings, and w?de- and these place in communication large pulmonary districts which are con- ^^an'^chTf tiguous, but otherwise separate. connect the Moreover it should be remembered that the bronchial venules (corresponding districts. to bronchi smaller than those of third and fourth order: Sappey, loc. cit., p. Theyre- ceive some 456) empty themselves into the pulmonary vems as well as the pulmonary of the venules derived from the lobules of the lung. venules. All these circumstances render it highly probable that the pulmonary veins The puimo- act not only as a medium of vascular connection, but as important factors in binds to- binding together the different districts of the lung and the different com- pui^fonary ponents of its tissue. districts ^ andtissucs. The more definite points of contrast between the pulmonary and the Summary systemic veins may be summed up as follows : differences (i) The pulmonary veins possess no valves. the^utoo- (2) They do not accompany the arteries, but almost invariably keep at a nary and distance from them. mio veins. (3) They are single, most probably not exceeding in number the pulmonary arteries, but in many situations appearing to be fewer than these, inasmuch as one peripheral venule often receives blood from two or more neighbouring arterioles. (4) Their total capacity was considered by Winslow, by Santorini, by Haller and others (see Quain, vol. ii. p. 278, 1 876) to be less than that of the corresponding arteries, instead of greater. (5) Alone among veins they convey to the heart arterial blood. They derive their blood from two sets of capillaries which are in vascular connection respectively with the right and with the left ventricle, and which respectively ISO THE BRONCHI AND PULMONARY BLOOD-VESSELS. contain blood described as arterial and venous. It is obvions however that the ordinary meaning of the word venous cannot be applied to that portion of the bronchial blood which has been almost in direct contact with an abundant stream of air in the smaller bronchioles. Any contamination arising from the bronchial venous blood is both slight in extent and limited in kind, much carbonic anhydride not being included in its impurities. (6) The pulmonary veins at their origin are contractile, (7) The scheme of their distribution and the mechanism of their circula- tion are different from those of the veins of any other organ. 1^ w Eh O o <1 125 O 4^ a « (B o > PH .s 1 ■S is O H O n tn S 'd ii 1*1 «- f" I. o ' a l n o .2 ■d * S .9 V is a| 9 vo § IS ■ g pq 1 a pq pq "^ --pq o og .S bO -d S 50 bp^'2 "3 a ^< cu I. J3 a ft " = s iio ^ o b ■■B U SB §*< i § If p c3 g i % a '■' bo (B 5 II N cS T c ^- •H n I §. Was. i ■X, - O fij ^2 O O wS r-' H [I, CO '^b o D a:! O Lm OQ <; o o m 3 Q Q 3 a. ( i8i ) DISTRIBUTION OF THE RIGHT PULMONARY ARTERY. BROAD SKETCH OF THE EIGHT PULMONARY ARTERY AND OF ITS GREAT DIVISIONS WITHIN THE LUNG. The Extra-pulmonary Portion of the right pulmonary artery is long extra- longer than the corresponding portion of the left pulmonary artery, owing ^oi"™*"^ to the common pulmonary artery being entirely to the left side of the middle line. It is crossed in front by the first portion of the aorta. In direction Eeiation to it is nearly horizontal. Immediately before entering the lung, the artery is y°/^^^^^^ situated behind the superior vena cava. As it enters the Lung it lies in front of the bronchus intermedins intra- and of the cardiac or middle lobar bronchus, being in immediate contact with por™™"^ the latter. At this stag^ it presents a very slight obliquity upwards ; and it divides, whilst still in front of the bronchi into an ascending and into a itsascend- descending portion for the upper lobe and for the lower lobes respectively, ^^cen^ng'^' Before its division, it lies immediately above the superior pulmonary vein, divisions. which occupies a slightly anterior plane ; but the internal ascending branch to veins. of the latter passes vertically in front of the termination of the main arterial trunk. It is behind this vein that arise the upper lobar pulmonary artery and the inferior axillary trunk. Chief Branches, and their Directions. — Whilst the pectori-apical The pec pulmonary artery ascends in front of the upper lobar bronchus, to the inner the'peo-* ' side of the apical trunk, delivering on its way the pectoral artery, and whilst *°^^^*^'' the inferior axillary pulmonary artery very slantingly approaches from below pulmonary the district of the same name, the descending division, which may be regarded as the continuation of the main artery, pursues an outward and Descend- downward course, at a level slightly beneath that of the horizontally placed monary pectoral stem of the upper lobar bronchus. The artery is here in close con- ^'^'^'^y- nection with important air-tubes and blood-vessels. Immediately in front is the superior pulmonary vein tending upwards and outwards in a direction almost at right angles to that of the artery. Behind is that portion of the its import. continuation of the main bronchus which we have termed the intermediate ti°ng^ *" bronchus ; and, a little lower down, the two bronchi into which the inter- mediate bronchus divides. Of these the inferior lobar bronchus remains 182 THE BRONCHI AND PULMONARY BLOOD-VESSELS. It is, at first, not parallel to bronchus. Three divisions from it : descending, posterior- horizontal, cardiac. The in- ferior pul- monary artery supplies retro-car- diac, ante- rior-basic, inferior dorsal, axillary- basic, posterior- basic trunks. Alone the last-named is posterior to its bronchi. posterior to the artery, and the cardiac or middle lobar bronchus is slightly internal as well as posterior to it. In this portion of its course the descending artery, retaining some of the outward tendency which enabled it to cross the bronchus, is not yet quite parallel with the latter. Descending Trunk. — Behind the oblique lower border of the supe- rior pulmonary vein, the descending artery undergoes a slight downward bend which renders it thenceforth parallel to the lower lobar bronchus, and it gives rise to three trunks : ( 1 ) A middle, descending trunk ; (2) An outer, posterior-horizontal trunk ; (3) An anterior and inner, almost horizontal, but slightly descending trunk. Of these divisions the first is the downwards continuation of the inferior lobar pulmonary artery, from which the other two arise almost in the shape of uplifted wings. The cardiac, or middle lobar artery, is the anterior division ; — the other division has already been named. The Arteries of the Base. — Greatly diminished as a result of its branching, the descending or inferior pulmonary artery continues its course in anterior contact with the inferior lobar stem. It gradually becomes slightly external to it, and distributes a retro-cardiac, an anterior-basic, and an inferior dorsal branch. Finally, it divides into an axillary-basic and a posterior-basic trunk. The former preserves its anterior and outer rela- tion to the bronchus. The latter becomes at once posterior, and in this relation its branches accompany the branches of the bronchial trunk to their termination. DETAILED ACCOUNT OP THE DISTRIBUTION OP THE EIGHT PULMONARY ARTERY. ARTERIAL SUPPLY TO THE UPPER LOBE. l^hree large arteries : Ascending- apical, pectoral, inferior axillary. -Variations in size, The Right Upper Lobe is supplied with venous blood by three large arterial trunks, which are analogous to the three great divisions of the upper lobar bronchus. The names proposed for them are, ' ' ascending-apical artery;" "pectoral artery;" and "inferior or ascending axillary artery." These arteries become associated with the bronchi respectively bearing the same names. In this respect the arrangement is constant ; but in other particulars variations occur. The Size of the arterial trunks is apt to vary in accordance with difEer- ences in the mode of supply of peripheral districts, a peripheral district equally distant from two trunks being sometimes supplied by one, and some- times by the other. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 83 In the Mode of Origin also abnormalities are seen. According to andia the usual arrangement a large pectori-apical trunk originates from the upper °"®'"" surface of the right pulmonary artery immediately after its entrance into the lung, namely from that part which may be called the transverse portion, and from this trunk or from the transverse portion just external to it, arises the inferior axillary artery. The latter arrangement obtains in the specimen depicted in figs. 19 and 20. But in the preparation represented in figs, i 5 and 16, the three arteries have distinct origins, the first two arising side by side, and the inferior axillary, which is unusually large, springing from the extremity of the transverse portion just before its downward bend. From a comparison with other dissections, the arrangement last mentioned appears to be abnormal. In the following description we shall adhere to the first type. The Eight Pectoei-apical Abtery and its Branches. The Pectori-apical Artery rises vertically behind the inner ascend- Pectori- ing trunk of the superior pulmonary vein, but owing to the inward swerving trunk. of the latter, the artery quickly becomes a little external as well as posterior to the vein. It is in contact posteriorly with the horizontal upper lobar bronchus, and externally with the origin of the inferior axillary artery, a vessel to which it may give origin. The pectori-apical trunk is a very short Pectoral one, and divides almost immediately into the pectoral and the ascending- Ascending- apical trunks. t?unk. Distribution of the Fecto^'al Artery. The Pectoral Artery, when arising from a common trunk with the Pectoral ascending apical, is directed from the first outwards and forwards. In specimens where the pectoral artery independently arises from the transverse portion of the pulmonary artery the direction is at first upwards. Imme- Mid-pec- diately before reaching the neighbourhood of the pectoral stem, to which it stemo- is slightly superior, it divides into an outer and an inner trunk, respectively arteries^ termed the mid-pectoral and the sterno-pectoral arteiy. In the situation and relations of the main arterial trunk is foreshadowed CTsuai the behaviour of most of its branches. They he above and on the inner bronoW. aspect of the air-tubes to which they are attached. To this rule there are two exceptions which will be presently mentioned. The Mid-pectoral Artery passes outwards ■ across and above the Mid-peo- pectoral stem, immediately behind its bifurcation, and applies itself to the upper surface of the mid-pectoral bronchus. But the branch destined for the outer and inferior division of this bronchus reaches the aii'-tube from the outer side, having obliquely crossed the mid-pectoral bronchus. With this exception the arterial branches are internal as well as superior to the bronchial. Stemo- pectoral artery. Usual relation to bronchi. 184 THE BRONCHI AND PULMONARY BLOOD-VESSHLS. The Sterno-pectoral Artery divides into .branches whicli apply themselves to as many bronchial tubes. Each artery adheres to the inner aspect of the correspondiag bronchus. A slight deviation from this rule is observed in the case of the inner pectoral artery, which courses strictly along the upper surface of the air-tube and follows also in its ramifications the upper bronchial border. Relation of ascending axillary- apical artery. Eelationa of arteries and bronchi within the apex. Internal ascending pulmonary Three parallel vertical vessels. Origin of superior axillary artery. Superior axillary- trunk, better termed : Eetro-api- cal artery. Posterior axiUaiy- apical artery : Ijosterior and internal to bronchi. Supra- spinate pulmonary artery. Its bran- ches are Distribution of the Eight Ascending-apical, or Axillary-apical, Artery. The Ascending-apical Artery follows the course and the distribution of the ascending-apical bronchus, to which it is internal and very slightly posterior. The posterior relation of the artery to the bronchus becomes more marked at a higher level, the inclination of the bronchus being slightly forward, that of the artery strictly vertical. It results from this arrangement that the arterial branches are not only internal but posterior to the bronchial branches throughout the apical distri- bution ; and further that the lateral arterial branches pass behind and never in front of any vertical bronchial tubes ; and lastly that in any branchings occurring horizontally the artery would be posterior and superior to the bronchus. The internal ascending pulmonary vein which was at first situated in front of the pectori-apical artery, has, in its upward course, curved backwards, and now approaches the inner side of the ascending apical artery, being but slightly anterior to it. Thus, rising from the upper border of the pulmonary root, and within one transverse plane, is seen a row of three parallel and contiguous vessels : — a pulmonary vein, innermost ; a pulmonary artery in the middle ; and the pectori-apical bronchus externally. The Bifurcation of the ascending axillary-apical artery into apical artery and superior axillary artery takes place at a higher level than the bronchial bifurcation. The superior axillary arterial trunk is, in consequence, separated by a considerable vertical distance from the first part of the axillary bronchial stem, and has much less obliquity upwards than this bronchus. It should not be mistaken for an exact vascular equivalent of the latter. Its distribution is entirely restricted to the posterior apical bronchial district. It may therefore with propriety be termed the retro-apical artery. The Retro-apical Artery, taking its course outwards, and very slightly backwards and upwards, delivers, before joining the retro-axillary bronchus, the ascending Posterior Axillary-apical Artery, which accompanies the bronchus of the same name and all its branches along their inner and posterior aspect, and the almost horizontal Supra-spinate Pulmonary Artery. The latter, passing behind the posterior axillary-apical bronchus, gains access to the posterior and upper border of the supra-spinate bronchus. Its branches THE BRONCHI AND PlJLMONABY BLOOD-VESSELS. 185 accompany the divisions of the bronchus, preserving throughout the same posterior anatomical relation to them. ^o^ toXe bronchi. Distribution of the Might Pidmonary Axillary Artery. The Pulmonary Axillary Artery may be of smaller or of larger size Pulmonary than the retro-apical artery, according to the share which it takes in the ^^^^^ arterial supply to the axillary bronchial district. Usually being restricted to Course and the supply of the lower portion of that district, it is of smaller diameter and ite^lT °* it occupies an anterior plane. Its main level is about 3 cm. lower than that ^""j^^ of the retro-apical artery. The pulmonary axillary artery takes its origin by artery, the side of the pectori-apical arterial stem, from the upper surface of the transverse portion of the pulmonary artery. Passing upwards and outwards beneath the pectori-apical bronchus (a lymphatic gland intervening between them), it is received in the angle formed by the bifurcation of the superior pulmonary vein into the ascending apical vein and into the posteriorly placed superior dorsal vein. Beyond the fork thus produced it approaches by degrees the under and posterior surface of the axillary trunk, which it joins nearly at the point of bifurcation of that bronchus. The artery bifurcates behind the bronchus, and its branches are posterior and inferior to the air- its bran- tubes as far as their termination. In the diagram (fig. 1 7) and in the chromo- posterior lithographed diagram one of its branches is erroneously depicted in front of ^ tronchr the corresponding air-tube ; and in addition an interval occurs between the vessels and the bronchi which does not exist in the specimens. Variation in Origin and Distribution. — ^Whenever the pulmonary Variation axillary artery acquires greater development than the superior axillary trunk, and in its this is due to its undertaking the partial supply of the retro-axillary bronchial ^51^^*1;"^ district. It may even (as in fig. 1 6, square G iv) entirely .supersede the t'on. superior axillary artery. In this case it forms the posterior division of a short arterial trunk (square G v) which arises from the transverse portion of the pulmonary artery close to the beginning of the descending portion. This short ascending trunk, not found in other specimens, bifurcates into an inner posterior division, or retro-axillary trunk and an outer anterior division or pulmonary axillary trunk. The short common axillary pulmonary trunk, when present, forms the Complete upper arm of a complete arterial cross the long arm of which is represented cross by the descending pulmonary artery, the anterior arm by the cardiac artery g"™®** '" and the posterior arm by the posterior-horizontal artery. specimens. The Belations of the arterial branches to the air-tubes differ in the two ^^^ y^tro- . .,, 1 . 1 ,1 apicalbran- districts. The superior axillary trunk, or retro-apical artery approaches the ciiesare corresponding bronchi from the inner side ; its branches remain internal to to bronchi ; the latter. In their vertical portions they become anterior and in their hori- y|o°^°*®V zontal portions, superior to the bronchi which they accompany.* The same cai, and superior if * This relation is not accurately shown in the diagrams. horizontal. i86 THE BRONCHI AND PULMONARY BLOOD-VESSELS. The nxiUary branches are pos- terior and inferior to bronchi. tendency is also observed in the distribution of a retro-axillary arteiy origi- nating abnormally from the transverse portion of the pulmonary artery. On the contrary the pulmonary axillary arterial branches, which normally join their bronchi from the outer side and from below, become posterior as well as inferior to the latter. ARTERIAL SUPPLY TO THE RIGHT MIDDLE LOBE. Contact between Biiperior pnlmonary vein and descending pulmonary artery, at level of transverse fissure. From what has preceded it is clear that the rising inferior pulmonary vein and the descending pulmonary artery are in contact in front of the intermediate bronchus and of the beginning of the middle and inferior lobar bronchi. Inasmuch as the vein is in this situation nearly horizontal in direc- tion (although in the diagrams it appears to ascend), and inasmuch as the descending pulmonary artery sends out two almost horizontal lateral branches, the surface of contact between the two sets of vessels is much extended, and the line of contact is almost horizontal. This line exactly corresponds to that of the short or middle interlobar fissure which joins at its posterior extremity the great fissure. The two vessels are thus respectively covered by the upper and by the lower layer of the septal fold of the pleura. Under a different name the same fold may be traced posteriorly into the longitudinal fisstire as far as the posterior surface of the intermediate bronchus. The cardiac or middle lobar artery. Its bran- ches are su- perior and external to bronchi, The Cardiac or Middle Lobar Pulmonary Artery originates at a slightly lower level than the cardiac bronchus, which, in its beginning, is covered by the transverse portion of the pulmonary artery and by the obliquely ascending superior pulmonary vein in front of the latter. The origin of the cardiac artery is situated exactly below the vein. The arterial branchings faithfully correspond with those of the bronchus, lying above the latter, and slightly external to them, in contrast with "the sterno-pectoral arterial supply, which is inferior and internal to the air-tubes. The distribution in question is readily seen in figs. 1 5 and 1 9 and in the diagrams. ARTERIAL SUPPLY TO THE RIGHT LOWER LOBE, Descending Owing to the great obliquity of its upper surface, the lower lobe, in its pulmonary posterior part, attains a higher level than the middle lobe, and its first arterial trunk, the posterior-horizontal artery, is fractionally higher than the cardiac artery. The Right Descending Pdlmonaky Aeteey and its Beanches. Its direc- tion The Descending Pulmonary Artery is the sole source of venous blood for the lower lobe. From the point where its transverse portion comes to an end, at the bottom of the transverse fissure, the artery takes a direction THE BBONCHI AND PULMONARY BLOOD-VESSELS. 1 8/ downwards, outwards, and slightly backwards almost coinciding with that o£ the inferior lobar bronchial stem. Want of parallelism between the two tubes occurs only in the lower half of the lower lobe. Here the pulmonary artery and becomes more and more external instead of anterior to the bronchus, and ™^*''°"^- finally, in the posterior-basic division, entirely posterior to it. The Branches of the descending pulmonary artery, enumerated from its above downwards, are: (i) The posterior-horizontal artery ; (2 and 3), arising ''™°<='"'^- by a common trunk of origin, the retro-cardiac and the anterior-basic arteries ; (4) the lesser posterior-horizontal ; (5) the axillary-basic and (6) the posterior- basic artery. Distribution of the Bight Posterior-horizontal Artery. The Posterior-horizontal Artery is true to its name, and diverges Postenor- horizontally backwards and outwards from the external and posterior aspect artery."^ * of the pulmonary artery at the point where the latter bends downwards. It therefore continues the level, although not the direction, of the transverse portion of the trunk. It is situated exactly opposite the cardiac artery which takes its origin from the anterior and inner side of the large artery at its bend, with an obliquity downwards and forwards. The stout horizontal trunk, measuring in length from 2'5 to 3 cm. finds itself placed in front of, and at a higher level than the bronchus with which it is associated. It bifurcates almost immediately into a smaller posterior and a larger lateral division. The Vertical Descending Mid-dorsal Artery, a short trunk for the vertical supply of the middle third of the vertebral border of the lung, takes at first mM°doimf a horizontal direction backwards, and crossing from above the posterior-hori- ^"^'^ry. zontal bronchus attaches itself to the upper surface of the air-tube to which it belongs. It ultimately descends along the vertebral border of the latter. The artery in its course gives a branch upwards which accompanies the vertical ascending mid-dorsal bronchus. The Larger, Lateral Division may be regarded as the continuation of the posterior-homontal artery, of which it maintains the direction for a short distance. Before it has acquired a length of 2 cm., it bifurcates horizontally into a posterior and a lateral trunk, destined respectively for the sub-scapular Horizontia and for the mid-axillary districts of the bronchial tree. mid-dorsai The posterior, or Horizontal Mid-dorsal Artery passes horizontally ita backwards and outwards to the angle formed by the horizontal mid-dorsal, ^^"^0^^ and by the ascending oblique dorsal bronchus ; and bifurcating within the" posterior bronchial bifurcation, it supplies companion arteries to the opposite sides of Mid- the two air-tubes ; these arteries gradually become posterior. "'o^ter'^ The Lateral or Mid-axillary Posterior-horizontal Trunk iiorizontai joins the bronchus of the same name and follows its divisions, remaining itsbran- throughout superior, and sometimes becoming anterior to the bronchial tubes. "^^'^ ^^<^ 1 88 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Common origin of retro-car- diac and of anterior- basic arteries. Their branches are anterior and exter- nal to the bronchi. Lesser posterior- horizontal. Its bran- ches are superior to the air-tubes. Axillary- basic artery. Its bran- ches are anterior to the bronchi. Distributions of the Right Lesser Posterior-horizontal, Betro-cardiac, and Basic Arteries. The Retro-cardiac and, the Anterior-basic Arteries arise by a common short trunk situated half-way between, and a little externally, as well as anteriorly to, the two bronchial origins. In this situation it bi- furcates; and the two arteries, diverging equally from the perpendicular direction of their common trunk, apply themselves to the anterior and ex- ternal aspect of the corresponding bronchi, for the ramifications of which they supply arterial branches preserving to the end the same relation. The Lesser Posterior-horizontal Artery. — This is a stout hori- zontal vessel, which arises a very short distance below the level of the preceding trunk, and distributes its branches in contact with the upper wall of the corresponding bronchial tubes. The Axillary-basic Artery. — Of the two terminal divisions of the descending pulmonary artery the asillary-basic is the more direct continuation of the arterial trunk ; — but in size it is much inferior to the posterior-basic. It is, at its origin, superior, and it becomes also anterior to the axillary-basic bronchus. Its divisions remaia throughout the distribution anterior to the bronchi which they accompany. Posterior- basic artery. Posterior relation of this stem and of its divisions to the air-tubes. Lateral dorsi-basic artery. The Posterior-basic Artery represents the lowest as well as the most posterior extension of the pulmonary artery. It departs from the lateral position previously occupied by the arterial trunk, and becomes pos- terior to its accompanying bronchial tubes. This is an important peculiarity, which readily distinguishes the posterior-basic distribution from that of other basic arteries. There is however one exception to the posterior position .assumed by the arterial branches : The Lateral Dorsi-basic Artery passes in front of the correspond- ing bronchus. But its branches ultimately show a tendency to become posterior. Fig. 15. Deawing peom a metallic cast of the Beostchi, Pulmonaet Aeteeibs and Pulmonaey Veins— obtained in a SOMEWHAT OBESE, FEMALE SUBJECT; ISOLATED BY DISSECTION. (Qf. fig5. 1 9 and 20,) FEONT view, EEOM the EIGHT. (The side of each square represents 20 mm.) EXPLANATION OF THE DEAWING. Many peripheral tubes are soft and twisted, not having heen filled with metal. The left auricle is distorted from pressure of injection. Below the auricle, on either side of the aorta, a strip of pleura indicates the line of reflection of the membrane ; above it, part of the aorta, of the common pulmonary A. and of the superior V. cava are in view. Left Lung. In square F vj, the lower division of the left superior pulmonary V. gives rise to the pectoral veins (line v) as weU as to the superior and inferior cardiac veins ; the veins occupying the interspaces below the corresponding bronchi. In square F vi j, the three left basic veins separate the anterior-basic bronchi above (arteries superior) from the posterior-basic B. below (arteries posterior). In squares F v and iv, to the inner side of the pectoral bronchi and arteries the superficial internal ascending pulmonary vein rises to supply the inner apex. A small portion of the transverse pulmonary V. is seen in middle of square F iv, in front of the ascending-apical B. Eight Lung. In the middle third the superior pulmonary vein and the descending pulmonary artery are in close contact. In the upper lobe the veins are relatively more in view. In the middle and lower lobes the arteries to a great extent cover from the front and from above the other structures. A cross-shaped division of the vessels occurs repeatedly in this specimen : e.g., at intersections E iv and C iv, also at C V (large arterial cross). Below the innominate artery are seen the sub-pleural sterno-pectoral V. ; at line iv, the pectoral arteries and bronchi; at line v, the mid-stemal pectoral V. ; at line vj, the cardiac arteries an bronchi (the ascending branch of the central cardiac Y. separating their two sets at point D vj). Along line D, crossed by lineiij, are grouped the ascending-apical artery, bronchus, and V. — and below line iv rises the ascending mid-pectoral V. At junction C iv the axUlary-pectoral Y. is seen in front of the axillary bronchus and artery, the divisions of which occupy the external portion of the upper lobe. At junction C v, the horizontal vein appearing to belong to the middle lobe probably belongs to the upper. Below this vessel, the posterior-horizontal artery, bronchus, and V. are easily found. At junction vj the anterior-basic artery is seen below the cross-shaped mammary-cardiac A. It soon divides into its lateral anterior- basic, and its cardio-basic trunk. The pointed termination of the latter is much anterior to the posterior-basic bronchi seen on either side of it. At junction B vij the axUlary-basic artery and bronchus appear below the lateral anterior-basic trunk. At junction vij a large venous trunk from the inferior pulmonary Y. divides into its branches, anterior- and axillary-basic. The retro-cardiac vessels and bronchi are situated above the artist's subscription ; and externally to the same, in a posterior plane, descends the posterior-basic vein. Fig. ij. Pulmonary arteries, dotted; puhwnary veins, shaded; bronchi, blank; Hack patches indicate lymphatic glands. A B C D £ E G H i m^^ 'ffci jy. ^ )j- f 1 B^"' "-"^ K™^ ^milllMrt ij ^S i s M. ¥9i ^^^ 5i<^ ii.i bV n ^^^Bm^ ^B f% i iv , H -MKr^ W//M// \ |. i ' t "^P ^& P CNyTTwrV V A ^^ 1 m ■ V • Ti^^^ MOT pi ^5P^*-^^^ vi ■ % ^^^ JJ W^ y vil ff^-y^SCTwWfcR*BM 1^^^^^ 1 r ^' It»|^^ vii] ^^^^S^jt^Slt, W^S^a' B^^^nsi mfjnf V ix IBs '^" 1 if ( ill 1 i 1 |! 7/ IM 1 b ■Jlj) j^%j. Mi iij K '! X 1 j 1 — . X A B c D B F a H I ( i89 ) DISTRIBUTION OF THE LEFT PULMONARY ARTERY. General Remarks on the Mode of Disteibution of the Lekp Pulmonary Artery. The extra-pulmonary course of the left pulmonary artery has already been Extra- described. Having risen in front of the left bronchus, and partly arched poJ-uon*-"^ over it, the artery enters the upper part of the root of the lung at its posterior aspect, with a direction forwards, outwards, and slightly downwards. The supply to the apical region of the upper lobe is given at the higher intra- level reached by the artery. Subsequently the diminished arterial trunk ^"^^a™"^ descends behind the large bronchia, following a course to be hereafter described, and after supplying, at the upper level of the middle third of the bitnc™'to lung, the cardiac trunk, it terminates lower down in a manner similar to the right in that of the inferior lobar bronchus. lobe. Inasmuch as the upper lobe does not receive its supply from a large Upper lobe single trunk, analogous to the upper lobar bronchus, but from three trunks, by^three the lobar nomenclature is of less avail for purposes of description than in the ^"sti^"' right lung, and we must adopt a regional nomenclature in its stead. The apical, the pectoral, and the cardiac regions, each receiving a separate artery, will be described in succession. Of these arteries, the two upper arise in close proximity to each other ; the third, at a considerable distance further down. AETERIAL SUPPLY TO THE LEFT UPPER LOBE. (Consult for the study of this distribution the diagrams 14 and 17 and figs. 16 and 20.) A separate name need hardly be given to the broad, massive. Sessile SessUe Trunk which serves as origin to the arteries of the apex (but which is origin ° sometimes nothing. more than a mere bulging of the wall of the pulmonary artery). Indeed all appearances of a special trunk may be absent, and the may be several vessels may originate separately and in close succession, from the °'^^™*' smooth convexity of the posterior part of the arch of the pulmonary artery. When present the trunk is situated on the left side of the pulmonary its situa- arch immediately beyond its downward bend. It is apt to display, in the present'"^" injected specimen, a transverse furrow. The upper and lower segments defined by the latter, are destined respectively for the supply of the pectoral 190 THE BRONCHI AND PULMONARY BLOOD-VESSELS. region and of the inner-anterior gi'oup of apex-bronchi and for that of the outer and posterior group. Arterial Supply to the Inner and Central District of the Left Apex. The Left Pectori-apical Trunk and its Apical Branches. Pectori- apical trunk. 1 Ascending- apical trunk ; Pectoral trunk. The superior segment of the sessile trunk, although it does not accom- pany the bronchus bearing that name, may be termed the pectori-apical artery since it divides into the ascending-apical and pectoral trunks. The direction of this important vessel is almost horizontally forwards and slightly outwards and downwards. Its bifurcation occurs at the foot of the ascending- apical bronchial trunk. Ascending- apical trunk. Anterior ascending- apical artery. Its divisions are internal to bronclii, and above slightly anterior. Posterior ascending- apical artery. Its divisions are pos- terior. Distribiition of the Left Ascending-apical Trmilc. The Ascending-apical Trunk, the larger of the two branches of bifurcation, rises into the apex with a direction upwards and forwards, and adheres to the posterior and inner side of the ascending- apical bronchus. It divides in faithful imitation of the bronchus, and its divisions follow the inner side of the bronchial branches. The Anterior Ascending-apical Artery is, in its relations, ana- logous to the vessel of the same name in the right lung ; but, instead of lying tolerably close to the outer wall of the trachea, it is separated from it by the aggregate thickness of the trunk of the left pulmonary artery, of the aortic arch, and of the subclavian artery. The artery moves for a short distance forwards, in order to reach the inner border of the corresponding bronchus, which it approaches from behind. As it rises, it becomes strictly internal to the bronchus, and in its upper divisions slightly anterior to the corresponding bronchial branches. The Posterior Ascending- apical Artery is situated almost imme- diately behind the posterior ascending-apical bronchus, and its smaller branches preserve the same name and assume the same direction as the bronchus, accompanying its divisions from behind. Arterul Supply to the Posterior and Outer District of the Left Apex, The Left Axillary Pulmonary Artery. Posterior The Left Axillary Pulmonary Artery arises from the lower ^l^^ segment of the sessile trunk and distributes branches within the posterior from the ^one in which it originates. The posterior apical bronchus (from the pulmonary posterior axiUary stem) and the other branches of the axillary stem receive artery. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 191 their attendant arteries from this source. The arterial branches remain in j,^^ contact with the inner posterior side of the bronchial divisions. arteries are isterDal and pos- Siimmary. — "What has been said concerning the arterial distribution thebronchi. to the left apex may be briefly summed up as follows : Beiations The arteries arise at a higher level than the bronchi, and posteriorly and bronchi internally to the latter. ^-^-^^^^ They generally preserve a posterior relation to the air-tubes. Some of Arteries the outward branches become external to the bronchial ramifications. But EronohTJ^ ° the majority of the arteries are internal as well as posterior. ^^^° jj There is however one exception to the otherwise constant rule as to the mtemai. posterior position of the arteries : f ''th'^''T The Outer Ascending-apical Artery, a branch of small size, The outer arises from the pulmonary artery immediately below the sessile trunk, and ascending-; 1. J J J ^ ' apical curving underneath the axillary bronchial stem (the interlobar branch of artery. which receives from it a posterior arteriole), reaches the anterior surface Jr^j^pijes of the outer ascending-apical bronchus, the distribution of which it accom- are anterior , to till3 panics. bronchi. The Pulmonary Veins. — It is the rule for pulmonary veins not to Relations occur on the same side of bronchi as the arteries, and the veins within the arteries the left apex are almost exclusively anterior. The space in front of the puimonaiy ascending bronchi is reserved for the distribution of the upper transverse pul- ™"'^- monary vein. The posterior branches from this vein, reversing the course followed by the arteries, traverse the apex from before backwards, and thus reach its posterior surface, to which they are distributed. ARTERIAL SUPPLY TO THE LEFT PECTORAL DISTRICT, The Pectoral Artery, almost equal to the ascending-apical, its Pectoral twin-vessel, continues the course of the pectori-apical trunk {vide supra). ^^ ^^ ' The direction of this important artery is sagittal from behind forwards ; its direo- and although some of its branches are deflected upwards or downwards, the rXtiras trunk is strictly horizontal. Applying itself exactly to the upper surface of The the pectoral bronchus, the artery becomes anterior to the bronchi in all its arteriefare descending divisions, and posterior to the bronchi in its ascending branches, anterior to Some of the branches show an inclination towards the inner side, others to- bronchi; wards the outer side of the corresponding bronchial tubes. i^® Series In the injected specimen the artery occupies a conspicuous position, but =-™ . its origin is anteriorly hidden by the rising trunk of the mid-apical pul- monary vein ; and the transverse-apical vein (from which the latter origin- ates) lies across its first part. Having emerged from behind the vein, the artery comes well into view The from the front, and assumes a slightly ascending direction. It bifurcates branches remain superior to the bronchi. 192 THE BRONCHI AND PULMONARY BLOOD-VESSELS. twice in rapid succession, and it furnishes each of the pectoral bronchi with a companion artery, which remains superior to the air-tube. The pectoral distribution being mainly horizontal, ample room is afforded below its level for the ramifications of pectoral veins. AETEEIAL SUPPLY TO THE LEFT CAEDIAC REGION. Cardie artery. The left cardiac district equivalent to the right middle lobe. External relation to air-tubes (occasion- ally in- ferior). The Cardiac Artery, a bulky and short trunk, springing horizontally forwards from the antero-lateral aspect of the pulmonary artery, at the level of the cardiac bronchus, supplies all the blood to be distributed to the cardiac district, which is the equivalent of the right middle lobe. If any doubt were possible as to the relative value of the right and of the left cardiac districts, it would be set at rest by comparing the almost identical behaviour of the arterial supply to this region on the right side of the chest, and on the left side. The short cardiac arterial trunk almost immediately splits into an iuTier and an outer division. The inner division is inferior and posterior, the outer division is superior and anterior. The upper level of the cardiac artery is faintly superior to that of the posterior-horizontal artery, and to the level of the cardiac bronchus. The artery is strictly external and parallel to the bronchus, and this relation is preserved with great constancy throughout the distribution. Any departure from the rule is almost invariably in the sense of an inferior position of the arterial branches. Inner or posterior cardiac artery. Its relation to the bron- chi is ex- ternal and inferior. The Inner or Posterior Cardiac Artery is slightly lower than the outer. This is due to the fact that it has to cross beneath the anterior division of the cardiac bronchus and subsequently beneath the cardiac vein, situated between the bronchi, before it can reach the outer surface of the posterior cardiac bronchus, its companion air-tube. Throughout its ramifica- tions it remains external and slightly inferior to the bronchial twigs, the vein lying near the inner side of the latter. Anterior cardiac artery. Stemo- cardiac artery ; external relation to bronchi. Mammary- cardiac artery; The Outer or Anterior Cardiac Artery is much shorter than its fellow, to which it is superior as well as anterior. It immediately bifurcates into an inner and an outer trunk, respectively termed the sterno-cardiac and the mammary-cardiac artery. The Sterno-cardiac Artery crosses inwards above the mammary- cardiac bronchus and applies itself to the outer side of the sterno-cardiac bronchus, supplying each division of the latter with a separate companion- artery. The Mammary-cardiac Artery, much shorter than the preceding, finds itself almost at its origin in contact with the outer bronchial wall which Fig. i6. Dbawinu from the same specimen as pig. 15 : the vAEiors tubes will be eecognizbd by the same FEATURES AS IN FIG. IS- (CJf. figS, I9 and 20.) BAOK VIEW, FROM THE LEFT. (The side of each square represents 20 mm.) EXPLANATION OF THE DRAWING. The thoracic aorta is interrupted in the drawing. Two thin strips of membrane have been preserved in the specimen, indicating the position of the pleural reflection. The arch of the aorta (above which are the left carotid and subclavian arteries) is seen to rest upon the arch of the left pulmonary artery. The position of the descending portion of the latter is well shown. — The right pulmonary artery comes into view beneath the bifurcation of the trachea and is continued into the great vascular gap (column v). Eight Lung. Square G v ; A common axillary pulmonary A. supplies (in this specimen) a large retro-axillary as well as an axillary arterial trunk. Between the retro-axillary and the ascending-apical A. (in column F) lie the upper lobar bronchus (with axillary and apical divisions) and the intervening axial apical vein. In front of the retro-axillary A. are the corresponding bronchus and V. In square H v : tips of the axillary -pectoral vein, superior dorsal vein, and ascending oblique dorsal vein. Square G vj contains in a group the posterior-horizontal arteries, bronchi, and veins ; affords a glimpse of the descending pulmonary A. ; and at line G shows the vertical descending mid-dorsal A., and further inward, the interval between the superior pulmonary V. and the posterior-horizontal division of the inferior pulmonary V. In square G vij the transverse-basic venous trunk divides, covered from behind by the posterior-basic artery and bronchus ; and the posterior-basic vein descends towards point H viij. The smaller posterior veins are seen near line G. Left Lung. Column D, at the apex, shows the posterior ascending bronchus, and its aortic branch beneath the corresponding vein which separates them from the anterior ascending-apical bronchi and arteries in column 0. Line D traverses, below point D iij; the posterior-apical A., a branch from the axillary A., which latter is seen at and below line iv. (The posterior ascending-apical A. appears in square D iij, but the common apical trunk is partly concealed.) In squares C iv and v, the posterior-apical bronchus and the axillary bronchus, (with superior arteries) diverge above and below line iv. At their angle are seen their veins — together with larger veins showing through from the front. In square C v, the axillary-apical bronchus diverges vertically upwards from the pectoral B. and A. The pectoral veins, below, ramify between pectoral and cardiac planes. In square C vj, the inferior cardiac V., in column C, forms the upper side of the angle contained in square C vij, and the stout outer mammary -cardiac A. and B. are in view. The inferior lobe is imperfectly injected, and is seen in proiile ; it may be noticed however that the anterior- and axillary- basic arteries lie chiefly in front of, and the posterior-basic arteries chiefly behind their respective bronchi. In square D vj the posterior-horizontal A. arises in front of and above, and the vein below and behind the bronchial trunk. Fig. i6. Pulmonary arteries, dotted; pvhnonary veins, almded; hronchi, blank; black patches indicate lymphatic glands. ABODE FGH THE BEONCHI AND PULMONARY BLOOD-VESSELS. 193 it is destined to follow. Its ramifications faithfully accompany those of the same mammary-cardiac bronchus. i-elatio», ARTERIAL SUPPLY TO THE LEFT LOWER LOBE. The Left Descending Pulmonary Aeteky. In connection with the description given of the upper lobar arterial supply, and before entering upon that of the lower lobe, it is necessary to refer briefly to the anatomy of the main arterial stem. Since the left pulmonary begins its downward course immediately below The name the summit of the arch, and before any branches have arisen from it, the ing^pulmo- name " descending pulmonary" applies in the left lung to the whole intrar- '^i^jZ'^^' pulmonary portion of the artery, and the sessile apical trunk, where it exists, from an may be regarded as one of its branches. The outer ascending-apical artery ''^''^*^®' and the cardiac trunk undoubtedly take their origin from it, although they are included within the upper lobe. The direction of the descending pulmonary is at first slightly out- Direction wards and very slightly forwards as well as downwards. At the level of the descending cardiac origin, it becomes more vertical. The lower lobar bronchus having ^"j^y""^ assumed from its origin, a more vertical course than that which belonged to The cai- the main bronchus, it results that the pulmonary artery, which was posterior po'^steriov-'" to the plane of the main bronchus above, becomes external to the inferior i^onzontai ■^ . . arteries lobar bronchus. In this manner it comes to lie between the latter and arise at the fold of pleura which lines the bottom of the great fissure. This yet belong' observation renders intelligible the fact that the cardiac artery and the jg^fg*'^^'""' posterior-horizontal artery should originate from the same trunk within the This fact same horizontal plane, and yet should belong to separate lobes. The position „, assumed by the artery is but slightly lateral. Below the level mentioned the agreement name "inferior lobar artery" becomes applicable to the arterial trunk. ai-teriesand In the left lower lobe the arrangement of the bronchial tree is copied |'™°«i'"i bv the pulmonary artery with greater accuracy than in the upper lobe. The ^°^^; agreement between the bronchial and the arterial divisions is not limited to l^^^^ a similarity of origin. In position the two sets of branches are also closely posterior- associated from the first, owing to the intimate relation existing between the district. main artery and the main bronchus special to the lower lobe. In the Differences •^ ^ ^ between posterior-horizontal district, however, some discrepancies are found. the right and the left Distribution of the Left Posterioi--horizontal Artery. distribu- tion: The leading features of difference between this arterial distribution and The left the right posterior-horizontal distribution, are due on the one hand to the trunk greater size of the left district, and on the other to the fact that the descending j^^^'j^^ pulmonary artery, from which the arterial supply is derived, is not anterior, bronchial; N 194 THE BEONCHI AND PULMONARY BLOOD-VESSELS. posterior- horizontal. Th8 posterior- horizontal arterial stem is su- perior and external to the bronchial. 5t may even as in the right lang, but posterior (as well as external) to the lower lobar mmtary or bronchus. Instead of being rather longer, as on the right side, the left absent. arterial trunk is much shorter than the posterior-horizontal bronchial stem, descending Sometimes it does not provide all the arteries for the district ; but one or two pulmonary of the latter may arise independently directly from the descending pul- posteriorto monary artery. Nay, a collective arterial trunk may be entirely absent, or bronchu''s, as in the specimen depicted in fig. 20, only represented by a faint bulging of butanterior jt^q posterior Wall of the pulmonary artery. It should be understood that although the descending pulmonary artery is posterior to the main left bronchus above the level of the posterior-hori- zontal bronchus, the latter passes behind and to the mesial side of the artery, which is thus included between the posterior-horizontal bronchial distribution behind, and the upper lobe, thus forming the floor or groove, of the longi- tudinal fissure. Where it exists, the common posterior-horizontal arterial stem arises on the outer and anterior side of, and a little above the corresponding bronchial stem and divides in a manner analogous to the latter. But in any case, whether arising jointly or separately, the following arteries ai'e supplied to the district : (i) A Deep Posterior-horizontal Artery, which shows a marked tendency to an independent origin (see fig. 20, square vj). This artery at its origin is anterior and superior to the bronchus of same name, but gradually allows the air-tube to become anterior. The relation of the arterial branches to the bronchial is thus posterior and superior. Where, as in the speci- men (fig. 20), the deep air-trunk bifurcates almost immediately, the two attendant arteries may originate separately from the descending pulmonary artery, and the branches of the lower division or Inferior Mid-axillary Artery, may remain anterior to the corresponding bronchial branches. (2) An Ascending Mid-dorsal Oblique Artery arises, either as a branch of bifurcation from a rudimentary superficial posterior-horizontal stem, or as an independent branch from the descending pulmonary artery, In either case it adheres to the anterior and external face of the ascending bronchial stem and bifurcates later than the latter, well within the diverging bronchial angle. Its branches show a tendency to become posterior to the air-tubes to which they correspond. The ascending aortic bronchus may receive a separate artery arising from the mesial aspect of the arterial stem. It may however in other cases be the first branch of the descending mid-dorsal oblique artery. (3) The Descending Mid-dorsal Oblique Artery and its branches become in all cases posterior to their accompanying bronchi, but the road by which this position is gained differs according to the two types already described. In the first type the artery originates from the rudimentary superficial trunk, and descends along the outer side of the bronchus, lying at first across posterior- horizontal artery. Its bran- ches are posterior and supe- rior to the bronchi. The bran- ches of the inferior mid- axillary artery are anterior. Ascending mid-dorsal oblique artery, anterior and exter- nal to its bronchus. Its bran- ches be- come pos- terior to the air-tubes. Varying origin of the ascend- ing aortic bronchus. Descend- ing mid- dorsal oblique artery, posterior to the bronchus. Its normal origin from a i-udi- THE BRONCHI AND PULMONARY BLOOD-VESSELS. 1 95 and between the deep posterior-horizontal bronchus in front, and the ascending mentarj' mid-dorsal oblique vein posteriorly. trnnk!*"*^ In the second type, in which no common arterial trunk exists, the vein other mode last-mentioned and the artery exchange sides. The vein becomes anterior TheTXry and deep, ascending between the deep posterior-horizontal and the descending Js a branch oblique bronchi — and the artery becomes entirely posterior and arises high scending up from the pulmonary artery, and immediately supphes a small ascending art^°and aortic branch mentioned above for the supply of that bronchial district. supplies Its subsequent course is at first vertical (see fig. 20, square D vj), ingnortic posterior and at right angles to the direction of the posterior-horizontal " ™''' bronchus. Having reached the upper level of the descending mid-dorsal branches bronchus, it bifurcates into a Descending Mid-dorsal Oblique and a throughout Descending Aortic Artery. To both sets of air-tubes these arteries are '^°^^^^°'^ posterior throughout, but to the former, slightly superior also. bronchi. In conclusion it may be stated of the left posterior-horizontal distribution Jhe^arterfes that the arteries are, almost without exception, posterior to the air-tubes in arepos- 1 • 1 T • 11 1 ni !■ •■ • 1 terior m their branchings, although some of them are at their origin anterior to the this dis- bronchi. *"^""°"' Arteeial Distkibution to the Left Base. Distribution of the Left Anterior-hasic Artery. The Anterior-basic Artery arises from the anterior aspect of the Anterior- descending pulmonary artery at the level of origin of the bronchial trunk, guperior^'^ viz., I '6 cm. below the cardiac artery. It curves slightly inwards and and ex- forwards to reach the superior and outward surface of the bronchus, and does bronchi. not subsequently forsake this surface throughout the distribution. The Retro-cardiac Artery. — In cases where the retro-cardiac Therotro- bronchus originates from the inner division of the anterior-basic, the artery tmy may' belonefing to this division after beinsr superior, becomes internal ; it is thus ^"se from 1- .11 1-11 1 • 1 • r- ■ 1 *"^ inner brought into contact with the retro-cardiac bronchus, to which it furnishes anterior- . • _j. ■ 1 1 basic divi- an anterior arterial supply. sionorfrom But the origin of the retro-cardiac bronchus may not take place from the *ede- , , ° , '' . . Bcendmg inner division, but higher up from the stem of the anterior-basic bron- pulmonary chus. In such a case it is joined by a special artery derived from the ^nd^is re- descending pulmonary artery. This artery, passing underneath the anterior- spectiveiy basic bronchus, becomes external and slightly anterior to the retro-cardiac cHaior bronchial tube. bronchial. Distribtition of the Left Axillary-iasic Artery. The regularity of the relations existing between artery and bronchus in The axii- the axillary-basic region obviates the necessity for a lengthy description. arteriaT'" The Axillary-basic Artery arises laterally and slightly posteriorly from branches 196 THE BRONCHI AND PULMONARY BLOOD-VESSELS, anterior the descending pulmonary artery, which, at this level, is lateral to the riortotho bronchial stem, or slightly anterior. It is joined from below and from bronchial. ^,3]^^^^ j^y ^]^q axillary-basic bronchus ; and remaining slightly anterior, but chiefly superior to the bronchus, it accompanies the air-channels without any material modification in its relations. Distribution of the Left Fostcrior-basic Artery. Thepos- This large trunk may arise above or below the level of the origin of *®.fi°l'^''^'° the axillary-bronchus. In the former case it applies itself from the first to the posterior surface of the posterior-basic bronchus. But, when it happens origm^^ to originate below the axillary-basic bronchus, it lies in front of this air-tube, relation to ^s terminal trunk of the pulmonary artery. In such a case it would imme- the bronchi, diately join the outer side of the posterior-basic bronchus, to which it ulti- mately becomes posterior. The length of the artery is never considerable ; it varies slightly, how- ever, in these two types of distribution. The arterial branches arise relatively higher than the corresponding air-tubes and join these from above. They almost invariably are posterior and external to the bronchi. Inferior The Lesser Posterior-horizontal Artery is merely one of the posterior- g^rlv branches from the posterior-basic artery ; it rests upon the posterior horizontal •' -i-iii artery. surface of the posterior-horizontal bronchus. The Eight and the Left Pulmonaey Aeteries contrasted. Left pui- '^^^ ™°^* striking features of the left pulmonary artery are its vertical monary coursc and absolutely posterior position. In both these particulars it strongly artery more ■ n i • 1 1 vertical coutrasts With the nght pulmonary artery. posterior. ^^ ^^^ other hand, within their lower two thirds, the two arteries acquire Similarity much similarity. Viewed from the outer side, just below the upper third, they thirds. both present two lateral branches and a downward continuation — which are re- spectively the posterior-horizontal, the cardiac, and the descending pulmonary arteries. The OB- '^^® *^° posterior-horizontal arterial distributions are not quite symmetrical, terior-hori- Qn both sides, however, a descending branch is apt to cross the posterior arteries ; surface of the bronchial stem and to assume a position more internal and more points of posterior than that occupied by any air or blood-vessel in the lung. Snera™ ^^ *'^® region of the pulmonary base the arterial supply shows tolerable agreement equality on both sides. in the basic ■'•' - . . ■ t i ■, supply. Lastly, and most important, the two cardiac arteries unmistakably agree 'n^'the Mt ^^ their behaviour. Their origin is symmetrical on both sides ; and takes place cardiac directly from the pulmonary artery. It is interesting to find that the level of conespond. Origin of the left cardiac artery is slightly inferior to that of the right cardiac. The morphological value of these trunks runs therefore little risk of being THE BRONCHI AND PULMONARY BLOOD-VESSELS. 197 overlooked, and the left artery is not likely to be mistaken, as happened in the case of the left cardiac bronchus, for an unimportant branch in an " hyparterial " upper lobe. By inference, the arteries distributed within the upper third of the two Inferen- lungs are equivalent, if not simila.r — and it is difficult to resist the further infer- arteries in ence that inasmuch as on both sides they are closely associated with the bronchi ^ppei^°otes in their ramifications — these bronchi also are, if not morphologically identical, are also at least morphologically analogous. In the pectoral region the practical identity existing between the two sides The pec- _ may be seen at a glance. Elsewhere it lies under disguise. But by careful butions are scrutiny more and more instances of resemblance are brought to light. j^™„|.i^g^i_ Indeed resemblance is the rule, even in the upper third of the lung ; it is want of agreement which is exceptional. In conclusion, the general resemblance exhibited by the right and by the The ar- left arterial distributions is sufficiently strong to act as a crucial test for the gembiancea 'correctness of the doctrine of similarity of the two bronchial systems — and it cientpr^of might alone be argued as an adequate proof against the theory of bronchial against asymmetry, advanced by Professor Aeby. bronchial theory ( 198 ) THE PULMONAEY VEINS. Mode of Origin and of Distribution, and General Eelations of the Pulmonary Veins. {Important general remarks occur on pp. 175-180.) Isolated The pulmonary venous system, unlike tlie pulmonary arterial system, is not a and spedai ^^re copy of the bronchial tree. In a diagram representing the venous rami- charaotera fications (see fig. 1 8) it is difficult to recognize any trace of the general monrr?"^' arrangement special to the other tubes. With these the veins show no tendency ''"''^' to associate, but they remain solitary from one end of their course to the other. They are not even parallel to the bronchial tracks, but they seem to seek for themselves a path entirely different from that of other vessels. Indeed it is rather direction than distance which separates them from the bronchi and from the pulmonary arteries. They are This estrangement is noticeable even at their origin. The artery and the neverparal- ijronchus enter the lung from above ; the vein approaches it from below. The lel to, but o ' ^ ^ ^^ J? i.1, 1 4- fli cross and two sets of vcssels cross each other within the root 01 the lung : at me bronohiai ^ periphery they cross and cross again, as though their initial divergence could tracts. ^g^g^, ^g rectified. Even between the lobular vessels the divergence is as Similar be- marked as elsewhere. The thin end of the lobule serves for the entrance of the lobules, the bronchiole and of the arteriole ; but the venules pass in at its sides, two or more venules entering each lobule. The left The Left Auricle, giving rise directly to the two pulmonary veins of ^ewedasa '^°^^ lungs, maybe regarded as the common parent- trunk of each set of veins, common and of both sets together. As a trunk of origin, it combines functions resem- trunk or ° o ' i j. ii. ■ i,j. j bling those which belong to the common pulmonary artery and to the right ana oriein. Jstabifsh ^ to the left pulmonary arteries. Unlike the arteries, the veins, which converge establish - - • -i i direct reia- fi'om all parts of the pulmonary peripheiy, do not become unified untii they are tween heart merged into the heart. Through them the heart and the lung are placed in andcontri- tli^ect relation; and they are the chief agents in bringing about the mutual bute to support which these two organs afford to each other. mutual The Pulmonary Pleura ahd the sub-pleural and interlobar tissues Sab°\ ^®^^ important relations to the pulmonary veins (c/. p. 1 76 and p. I 77)- The veins and closo Connection subsisting between the sub-pleural connective layer and the venules ; > V > M ^ .la" M t^ •rt •h v-S ; M r ; o (-( H <^ QQ 1-4 i -^ > i n ^ t> • >" "m •r—> . t> '■> • « a ^ PS O 'A O h-l gn.9 THE BEONCHt AND PULMONARY BLOOD-VESSELS. 1 99 pulmonary venules could probably be demonstrated at any point of tlie pul- at pul- monary surface. It is however specially obvious in two situations : (i) At Mng^Ld tlie pulmonary fringe, venules of relatively larger size become absolutely sub- ** ™^^i^l pleural, and extend almost as far as the sharp edge of the fringe. They clearly add strength to the frail pulmonary structures and to their investing membrane. (2) The whole mesial, or mediastinal surface of the lung is connected not only with venules, but with large sub-pleural veins. To these veins, along a great portion of their length, the pleural membrane is inti- mately adherent; it thereby becomes relatively fixed, and loses pliability whilst it gains in resistance. In extreme inflation of the lung these lines of attachment would become visible as slight depressions between freely bulging portions of the pleura. That this peculiarity should be restricted to the mesial surface is partly the result of the anatomical disposition of parts, the TUeir vessels assuming directions which are nearly perpendicular to most of the and'T'sfo- other surfaces. But the arrangement described may also be connected with logical sig- definite physiological purposes. It is, for instance, conceivable that the ^ ''*°'^*' entire pulmonary framework, if requiring to be fixed by limited attachments, would most readUy be fixed at the expense of the surface which is nearest the heart, and which is least affected by the respiratory movements of the thorax. The Main Pulmonary Veins, of which there are two on either side. The main arise directly from the auricle, where their entrance is not guarded by any ^ei"sT*'^ valve. Both veins take their origin from the upper-posterior corner of the *;=>?■ auricle in close mutual proximity, one being slightly posterior as well as in- ferior to the other. In the drawings this relation is disturbed as a result of the intra-auricular pressure set up during the injection. They immediately diverge. The Descending or Inferior pulmonary vein follows a direction Descend. downwards and outwards, and the Ascending or Superior pulmonary vein •"f^j.°oy assumes an upward and outward course. ascending, It is noteworthy that the three pulmonary lobes of the right lung are not pulmonary' represented in the venous distribution by three vessels ; both lungs alike ^^^°' ^ , . , . , •' ' ^ No third possess two mam pulmonary vems only. rein in the Prom their early divergence it may at once be gathered that the two pul- "^^^ ^"°f • monary veins on each side are meant for different parts of the same lung, and veins never are not a mere reduplication of the venous path, such as normally occurs at i,o"ya,i^y'eg . the systemic periphery. Pulmonary veins differ from systemic veins in being their total single. Moreover, they do not possess valves, and their aggregate calibre has thanThe^^^ been found not to exceed, but to be rather less than the aggregate calibre of *'^''*™l- the pulmonary arteries. ( 200 ) DISTRIBUTION OF THE RIGHT PULMONARY VEINS. VENOUS DISTEIBUTION TO THE EIGHT UPPER LOBE. The l-igbt superior pulmonary vein. rorward curve. Spiral course backwards and up- wards. Eelat-ion to the fissures and to the central in- ter-bron- chial space. It rests upon the cardiac, de- scending pulmonary, and pos- terior-hori- zontal ar- teries, andbeneath the hori- zontal bronchial tubes of the upper lobe. Its branches. Eight Superioe, or Ascending, or Anterior Pulmonary Vein. (Consult for the study of the venous distribution the diagram (fig. i8). Also the diagrams (figs. 14 and 17), and the drawings (figs. 15 and 16, 19 and 20).) The Right Superior, or Ascending, or Anterior Pulmonary- Vein originates from the upper and anterior corner of the auricle with a direction upwards and outwards, and slightly forwards at first, but subsequently backwards. The short forward curve which it presents at its entrance into the lung is caused by its crossing at right angles in front of the descending artery and bronchi. Beyond this point the vein moves spirally upwards, encircling, from the front and from the outer side, the descending vessels, and ending as superior dorsal vein in contact with the upper pleural fold of the great fissure. Although it terminates in the great fissure, its course lies along the groove of the transverse or short fissure. It occupies the upper half of the great central inter-bronchial space of the right lung, which has been described above and which is well displayed in fig. 9. The outer part of the spiral curve (the curvature of which is not well given in the diagrams) rests, from before backwards, upon the cardiac arterial trunk, upon the descending pulmonary artery, and upon the posterior-horizontal trunk, these three vessels being confluent in this situation. This is also the site of the downward bend of the descending pulmonary artery. The venous trunk is thus included between the broad arterial surface below and the horizontal pectoral bronchia above. In this situation it delivers upwards, between the pectoral and the axillary bronchial stems, its largest branch, the ascending-apical vein, which rises, with slight divergence, to the right side of, but not in contact with, the apical bronchial stem. The only other branch arising from the upper surface of the spiral is the important inner superficial ascending vein. The lower and anterior surface of the spiral curve furnishes in succession the cardiac veins, the pectoral mid-sternal, the mid-pectoral, and the external, or axillary pectoral vein. THE BRONCHI AND PULMONARY BLOOD-VESSELS. 20 1 The Anatomical Relations presented by the ascending or superior its rela- pulmonary vein are the following : ^'""^ *° In front of its origin lies the beginning of the ascending vena cava and the tie vena right auricle. '^™' Above and slightly overlapped by it, the right pulmonary artery pursues the ptU- its course downwards and outwards. ^^'^ *"■" Behind it, glands are found along the inner border of the intermediate the bron- bronchus ; — and at, a higher level, the cardiac bronchus, which lies in front of medius, the bronchus intermedins, and the descending pulmonary artery present a the cardiac ■,. , , . . , D JT J J 1 bronchus, slight anterior concavity which receives the backward concavity of this part and the de- of the veia — ^just as the two semiflexed and opposed index-fingers may be pu^^nf^v made to cross and to interlock. At this spot however the vein has already arteiy. given up its earliest branches, viz., the inner superficial ascending vein and the inferior deep veins which descend to the middle lobe, behind and below the cardiac arteries and bronchi. Thus there is no horizontal part to this trunk and its subdivision begins Itssubdivi- almost before it has reached the pulmonary root, and at a point immediately early. external to the vertical outer border of the superior vena cava. The Early Branches of the superior pulmonary vein take four principal Early directions, branches: their ( 1 ) vertically upwards ; directions, (2) obliquely upwards and outwards along the depth of the middle or short interlobar fissure, and for some way along the great fissure ; (3) downwards and outwards; (4) forwards and inwards. The divisions corresponding to these directions are : their names. ( 1 ) The superficial inner ascending trunk ; (2) The oblique continuation of the venous stem ; (3) The cardiac veins, an anterior or horizontal cardiac vein; and a pos- terior, descending, deep cardiac vein, two vessels arising jointly or separately from the lower surface of the pulmonary vein close to the auricle. (4) The pectoral mid-sternal vein, the lowermost, and in its origin the most anterior among the vessels and bronchi of the upper lobe. The Ijater Branches have already been mentioned. They consist of: Later branches : (5) The mid-pectoral vein ; (6) The external or axillary pectoral vein ; (7) The ascending-apical trunk ; (8) The termination of the trunk as superior dorsal vein. pleural. 202 THE BRONCHI AND PULMONAHY BLOOD-VESSELS. Venous Supply to the Bight Inner-apical District. Supei-aciai The Superficial Inner Ascending Trunk is the most superficial ™°'^'',. and the most internal of all the vessels of the root. It is strictly Yertical. -ascending ^ ^ _ _ »' vein ; its It is of large diameter and presents in its undivided portion a length of 2 cm. superfloiai It lies between the superior vena cava internally — the sterno-pectoral position. bronchus and artery externally, the right pulmonary arteiy and its pectori- tious. apical division posteriorly. Anteriorly and along its inner side it is covered by the pulmonary pleura at the line of reflection from the pericardium. Its branches are : (a) an anterior, horizontal, sterno-pectoral vein ; (h) a larger ascending trunk. Sub-pienrai (^0 ^he Sub-pleural Sterno-pectoral Vein, arising slightly sterno-pec- above the level of the artery and bronchus of the same name, and at first toral vein, . .,,. nnci -i ^^ ^ -i remains ^"^ Contact With the internal face oi the artery, gradually becomes separated ■B-hoiiysub.- from them, because not following their somewhat downward direction, and because remaining wholly sub-pleural. Its branches diverge widely along the mediastinal surface of the lung, and are intimately connected with the pleural membrane. They extend to the extreme pulmonary margin. See diagram (fig. 1 8 , /S'. P.). The sub-pleural branches just described may be taken as typical of the branches behaviour of the peripheral veins in various situations, but especially at the iix^Sie pul- mesial, mediastinal or pericardial surface. The sustentacular character of ™l°°'^a^ the pulmonary vein is here emphasized by its close connection with the sub- pleural tissue. The vein serves as a support for the pleura itself, and renders impossible a loosening or a shifting of the membrane beyond defi- nite limits. A complete system of sub-pleural branches of the same kind lines the mesial surface from above downwards. Sub-pieuiai (^) '^^® Sub-pleural Ascending-apical Trunk, or continuation ascending- of the trunk, shows a slight leaning backwards in its vertical ascent. After a course of 6 mm., it divides into the sub-pleural anterior ascending-apical vein and into the suh-pleural posterior ascending -apical vein. Both these its rela- vessels are posterior to, and form angles with, the arteries and bronchi of corre- tions. spending name. The sub-pleural ascending-apical trunk lies upon the anterior surface of the pectori-apical artery (at the level of its bifurcation), in front of the outer border of the vena cava. Sub-pleural '^^® Sub-pleural Anterior Ascending- apical Vein (as well as anterior the posterior vein, in its first portion) rests upon the inner surface of the apical vein, ascendiug-apical artery and faces the convexity of the first bend of the aorta, at its posterior part. The ascending vein shows comparatively slight back- ward tendency. It remains sub-pleural mainly, and supplies the inner sur- face of the apex. Its apical vein ; Fig. i8. a. b. p. a. P- p. h'. ax. h. p. h. p. V. ax. V. EorGH DiAGEAM OF THE CHIEF PULMONARY VEINS AND OF THE UPPER PART OF THE LEFT AURICLE; FRONT VIEW. The left auricle (of which the lower half is not shown) and the superior and inferior pulmonary veins are readily recognized. Between the two latter, on either side, are seen the cardiac veins (lower on the right side than on the left). The right mammary-cardiac branch, corresponding to - and the veins meet most of the bronchial tracts at considerable angles. The rule that arteries and veins occupv different aspects of the bronchi Veins and 1 . n..,, ,, artenes on also receives very constant confirmation m the lower lobe. opposite The basic veins of the right lung do not always follow the plan of distri- tron^ohi. bution which has been described. Variations are specially observed in the yariabiUty mode of grouping of the vessels at their origin. But the leading features of origin or the peripheral ramifications will be found, in most specimens, to coincide with ^o^pJ^g_ those which have been detailed. ( 214 ) DISTRIBUTION OP THE LEFT PULMONARY VEINS. Pjreliminaey Eemaeks on some of the Differences between THE Eight and the Left Pulmonary Veins. Two left veins, superior and in- ferior. Occasion- ally a sin- gle trunk from the auricle. Differences between right and left veins due to asymmetry of heart. Left auricle the least asymmetri- cal cavity, yet it is not central, not trans- verse. tiot hori- zontal, Hence the left veins are shorter, higher. The left lung normally presents two pulmonary veins analogous to the right superior and inferior veins, and these veins occupy the same relative positions in connection with the lung and with the heart as on the right side. The two veins originate in close proximity to each other from the upper outer corner of the left auricle, the superior vein being anterior to the inferior. Occasionally as in the specimen from which the drawings in figs, i 5 and 1 6 were made, they leave the auricle in the shape of a single large trunk, which does not divide until it has entered within the pulmonary root. Important difierences may be observed as regards shape, direction, and mode of branching, when the veins are compared on the two sides. Most of these differences find their explanation in the asymmetrical position of the heart ; and to this subject it is essential to devote a few words. The degree of asymmetry of position is not the same for all the cavities of the heart, it varies with each of them, and it is probably least in the left auricle. Nevertheless even here will be found a very marked departure from bilateral evenness of parts. The middle line of the left auricle does not coincide with the mesial line, or tracheal line continued, but lies a little to the left of it. Again the transverse vertical plane of the auricle is not parallel with the transverse vertical planes of the body but is set with slight obliquity back- wards, and towards the left. Lastly the transverse axis of the auricle is not perfectly horizontal, but is directed slightly upwards as well as backwards, towards the left. The discrepancies between the two sets of pulmonary veins are exactly those which might be theoretically inferred from the anatomical disparities just mentioned. (i) Because the left auricle is brought nearer to the left pulmonary root than to the right, the left pulmonary veins are, in an equivalent measure, shorter than the right veins, and generally present no horizontal extra-pul- monary portion. (2) On the left side the veins take their origin at a slightly higher level than on the right side ; and THE BRONCHI AND PULMONARY BLOOD-VESSELS. 2IS (3) They also arise in a plane slightly posterior to that of the origin of posterior, the right veins. (4) A steeper course of the left veins is another direct consequence of the steeper. almost immediate contact of the left pulmonary root with the auricle. The differences presented by the left veins in respect of their mode of Mode of distribution are to a great extent governed by the peculiarities of the left fafalnced'' pulmonary artery and of the left bronchus ; and these have already been ^^^ Ti-^"^ stated to depend ultimately upon the one-sided situation of the heart. monary The left main bronchus, which in its first part is to a very sKght extent ourveofieft posterior to the right, ceases after its entrance into the pulmonary root to bronchus, incline backwards, and even displays a slight tendency forwards. The right different bronchus on the contrary moves steadily backwards downwards and outwards. ofTght'"'^'' Again whereas the right pulmonary artery occupies a very prominent bronoiius. place among the structures lying in front of the tracheo-bronchial plane, the trunk of the left pulmonary artery is from the first posterior to the left Left pui- bronchus and is not visible from the anterior aspect of the root of the left ^He^'^ot lung. visible in It follows that on the left side nothing intervenes between the superior The left pulmonary vein and the front of the bronchial tree ; but that the right pXonary superior pulmonary vein is lifted by the pulmonary artery from direct contact vein in close .,,.111,. •/ 1. ,1 J contaotwith With tne large bronchi. bronchial On the other hand the right inferior pulmonary vein is, to say the least, ^^j/j^^ ^^^ not posterior to the lowermost bronchial divisions ; but the left inferior pul- right, the monary vein is at first decidedly posterior to the planes of its distribution, monary and therefore, instead of following, as the right, an almost straight outward [^rior^to"^' tendency in its main branches, exhibits in their first part, a forward and bronchi. outward direction. This direction is in addition strongly inclined down- Hence a for- wards, not only because the left inferior vein occupies at first a higher level, ward,' and"" but also because it is from the first in the immediate vicinity of the descending ""t'^^i'i bronchi. Left Superior Pulmonary Vein. — In the right lung the mode of origins of origin of the upper lobar and that of the cardiac veins are rendered different "pper, and by the transverse portion of the pulmonary artery, which lies between them. j^J,^^'® • On the left side this cause of disparity does not exist. The long spiral differ curve which has been described in connection with the right superior vein, is transverse not here required ; but the veins of the upper lobe are enabled to pass into ^^\, the successive bronchial interspaces with as much directness as obtains with upper, and respect to the right cardiac veins. TCinsfaiike Within the interspaces the veins ramify with varying direction according ^'"®'' "'i."''" r ^ •! J a ^ o spaces di- to the course followed by the bronchi. Among the upright air-tubes of the rectiy. apex, interspaces and veins alike become somewhat vertical. The con- ^ns-^^^^^ veyance of the veins to the outlying interspaces in the outer and posterior tersely 2l6 THE BRONCHI AND PULMONARY BLOOD-VESSELS. placed zones of the upper lobe is effected, in the right lung, by the spiral curVe of necessary, ^he Superior pulmonary vein. In the left lung the same purpose is served by the occurrence of a rectangular bend in the vertical course of the chief venous trunk or trunks of the apex. From this bend a horizontal, trans- verse portion extends across the breadth of the lower part of the apex, for the supply of the distant interspaces. The left In addition to the influences which have been enumerated, the absence of veinrLve ^ transverse fissure, and of a separate middle lobe, and the joint origin from a higher single trunk (the bronchus impar) of the pectori-apical and of the cardiac because no bronchial supply enable the cardiac veins to arise at a much higher level (more fissure than 2 cm. higher) on the left side than on the right. The left cardiac exists. veins arise immediately beneath the apical and pectoral veins. Thus the great distance which separates the ascending-apical branch and the inferior cardiac branch of the right vein is reduced in the left vein to insignificant propor- The left tions. The veins, for the left upper lobe, to use a homely but practical illus- veinsaii tration, arise in a tuft from the upper and anterior aspect of this vein, tuff; The instead of occupying at their origin an area of divergence of 180°, as on right veins the right side. with great ° divergence. Differences The differences in shape between the two superior pulmonary veins are- anddlrec- readily gathered from the foregoing description. The right vein which arises Trji-i ht ^^™°®* horizontally outwards is broad and almost cylindrical in aspect, vein broad Upon its origin rests from above and from behind the transverse extra- zoatai"" pulmonary portion of the right pulmonary artery. The left The left vein, which arises almost vertically, with faint direction forwards laiaiir'" ^^"^ outwards, is parallel, but not in immediate contact with the first or coniform, descending extra-pulmonary portion of the right pulmonary artery. Its shape is that of a somewhat irregular inverted cone, the apex of which is branched, whilst the base is free from any branches. Its reia- The direction of the left vein crosses (as occurs in the right lung) the tionstothe t j.- r j.r i j; i o 6/ pulmonary au'ection ot the left pulmonary artery, but between these two structures the artenes. j^^in bronchus intervenes. A slight lateral contact does however occur high up, between the inner ascending-apical vein and the first part of the left pul- monary artery, and between the same vein and the termination of the common- arterial trunk ; — and at its summit the superior pulmonary vein rises nearly into the angle formed by the bifurcation of the common pulmonary artery, and occupied by the left bronchus. f^rior""ui • ^^^ '^^^^ Inferior Pulmonary Vein is not only more posterior and monl)^ ' higher in its origin, and more forward and more abrupt, in its downward Grfater ''°"^®®' ^'^^ ^^^ relative size and the arrangement of its branches' are also siz^orthe ^^*^®^ different from those of the right inferior veins. Owing to the- teSHori- ^''^^^^"^ ^^*^^* °f *^e left posterior-horizontal district, the left vein is zontaivein. relatively larger than the right. The inferior division of ' the left inferior THE BRONCHI AND PULMONARY BLOOD-VESSELS. 217 pulmonary vein is for the same reason absolutely smaller than the right Smaller inferior division. The three trunks which in both lungs arise from this Mt inferior division are not in the left lung arranged in the shape of a regular tripod, but j^^j^fgrfor in parallel finger-like order, forming at first a compact flattened prolongation vein, of the inferior division, and continuing its direction. Divergence, however, ^angl^* soon occurs between these trunks, but mainly upwards and downwards within {"^nt of its the original, vertical, axillary-vertebral plane. VENOUS DISTRIBUTION TO THE LEFT UPPER LOBE. The Left Supeeioe, ok Ascending, or Anterior Pulmonary Vein. The Superior Pulmonary Vein is the only channel through which Superior the left auricle receives the arterial blood derived from the left upper lobe, vein!™*'^^ Its undivided portion, of coniform shape, and of nearly vertical direction, has shape, a length of about 2 cm. The first important structure with which it comes and^Sirec- into contact is the left main bronchus, at its termination, and the bronchus **""■ . impar, both of which it crosses anteriorly. Its oblique right border is leftbron- separated by an interval of barely i cm. from the inferior border of the right bronchus pulmonary artery, which is parallel to this border. Its left border is in close j™pai", relation with the two divisions of the bronchus impar, the cardiac veins lying, pulmonary at their origin, along the anterior inner surface of the cardiac bronchus, and j^ ^"^^l. the pectoral veins arising almost in contact with the pectori- apical trunk, veins, and passing below the pectoral bronchus. The superficial posterior ascending bronThr'^^ trunk, one of the upward continuations of the vein, extends upwards between the apical arterial trunk on the left, and the anterior part of the arch of the left pulmonary artery on the right. The apical trunk, the other and more direct continuation, is in relation with the artery of the same name, and with the pectoral artery. The vein terminates above on a level with the angle of bifurcation of the to commou common pulmonary artery which is situated, on its right side, at a slight aiie'ry.'^*'^ distance. The Branches of the superior pulmonary vein, although arising in close Branches : proximity to one another, are readily distinguished into three sets in connection with their varying directions : (i) The ascendiag-apical trunk follows, as its name indicates, a vertical ascending- course in continuation of that of the parent stem. °'^"'* ' (2) The pectoral trunk which almost immediately subdivides, is directed pectoral, nearly horizontally outwards. (3) The cardiac vein or veins show from the first a strong downward and and cardiac forward tendency. The two cardiac veins may arise from a common trunk, ™°^" ^.. and this trunk may give origin to the pectoral vein. In this case the cleavage mary divi- of the superior pulmonary vein would take place primarily into two, an upper superior pr apical, and a lower, or pectori-cardiac division. In more normal specimens P"-^""*'"^ 2l8 THE BRONCHI AND PULMONARY BLOOD-VESSELS, The pec the cardlac supply separates singly, as the lowest detachment ; and the upper sometimes division or remainder of the superior pulmonary vein contains the elements fte "owe™ °^ *^® pectoral as well as of the apical supply. In the coloured diagram the normally in abnormal arrangement has been depicted. the upper. I'he Venous Distribution to the Left Apex. Apical The Left Apical Venous Trunk. — This vessel is much superior in trunk. gJ2ie to the other two divisions from the superior pulmonary vein, and transmits Relation to ^^ entire blood supply from the apex. It arises straight upwards from the bronchus termination of the vein, at the upper level of the bronchus impar and of the descending main bronchus, and it is almost from the first in contact with the external artCTv^and Surface of the arch of the left pulmonary artery, the second portion of which to apical descends outwards behind it. In its unbranched vertical course of 2 cm. it artery and .,» tt- ■• bronchus. IS therefore surrounded as it were on its inner and posterior aspect by the leit Length. pulmonary artery, and externally it is separated from the apical bronchial stem Highest, \yj tiie corresponding arterial division. It is the highest, the most anterior, tenor and and the most internal of all the tubular structures contained in the pulmonary structure ^oo*- I* divides into a larger, apical, and a smaller, posterior stib-pletiral of root. ascending-apical vein. Posterior '^^® Posterior Sub-pleural Ascending-apical Vein, rising above sub-pieural the arch of the left pulmonary artery, passes backwards, and subsequently apical vein, outwards, to the interval between the ascending-apical and the axillary Occasion- postei'ior-apical bronchi, where it ascends and distributes branches. During suVpieurai, t^^ greater part of its course this vessel is superficial and sub-pleural. It but deep, may, however, forsaking its sub-pleural situation, follow an abnormal course, through the thickness of the apex. In this case it is a mere branch from the transverse portion of the apical trunk, and the sub-pleural supply is derived from the anterior-apical division of the same trunk. Backward Under normal conditions the backward curve of the posterior sub-pleural tw7veiD,to ascending vein takes place immediately above the convexity of the arch, and inner side t^g ygi^ \{q^ across the inner side of the apical arterv, or more strictly of its of apical .11 ii-i 1 ■ artery at its ascendmg-apical branch, which separates the vein from the posterior ascending- ongm. apical bronchus. Apical The Apical Venous Trunk, little diminished in size by the delivery lengtti'and of the preceding vein, continues its upward course for a distance of i'8 cm., direction, fj^^ during that interval presents most important relations. The bifurcation pectoral which gives origin to it occurs just above the level of the pectoral bronchus, toMra ^ ' °PP°^i*® ^^^ ^^^S^ transverse infra-apical inter-bronchial space into the moiith apical in- of which it is Conveyed by its inclination outwards and upwards. The hori- to'pecti^rai ^°°t*^ pectoral artery makes its way forwards across, and in contact with the artery, inner surface of the vein. The posterior surface of the vein is separated from l^te^r^ *^^ preceding vein by the left apical artery, which moves close up to its to stemo- posterior outer side. The internal, or stemo-pectoral division of the pectoral pectoral ^ artery, THE BRONCHI AND PULMONARY BLOOD-VESSELS. 21$ artery, touches its anterior outer surface on its way outwards and forwards, to pleura, The inner surface is situated immediately beneath the pleura and faces the ^"'^ *° ... •' J^ common terminamon oi the common pulmonary artery, from which it diverges pulmonary outwards. *'^^'> Immediately above the level of the horizontal pectoral artery it bifurcates Eeotangu- into two large divisions, forming with each other a right angle, viz., the ^tion!"' transverse-apieal trunk which proceeds horizontally outwards, and the anterior ascending-apical which continues the previous direction upwards, occupying an intermediate position between the ascending-apical bronchi and -the sterno- pectoral distribution. Distribution of the Left Transverse-apical Vein. The Transverse-apical Trunk lies in contact, at its origin, with Trane- two arteries. It rests upon the horizontal trunk of the pectoral artery, which trunkanses bifurcates, beneath and in front of it, into its inner and its outer branch ; and ™.footaot ... ' ' with peo- posteriorly it leans agamst the vertical ascending-apical artery. In other toraiand words, it is wedged into the right angle formed by the ascending-apical and by apical "^' the pectoral artery. Pursuing its course outwards, it passes in front of the ";'^«T- ascending-apical bronchial trunk, which is coupled with the ascending-apical front of artery ; and immediately in front of the interspace between this bronchus and apicS ^' the axillary bronchus, it divides into its branches, the central- apical vein, the artery and 7 -77 . T , . . 7 . bronchus. pulmonary axillary vein, and the posterior-apical vein. The Central-apical Vein rises upwards and slightly outwards in Central. the interspace between the outer ascending-apical bronchus from the axillary ifjga^^"' trunk, and the inner anterior-apical bronchus from the apical trunk. It is tenor and antenor and external to the distribution of the latter air-tube. to the The Pulmonary Axillary Vein is the direct continuation outwards ^™'^'''>'- f. 1 . i^ulmonary of the transverse-apical trunk and passes in front of, and beneath the axillary axillary bronchus, distributing anterior and inferior branches to its two xt u an- divisions, the outer ascending-apical and the superior axillary bronchus. teriorand The Posterior-apical Vein proceeds straight backwards, at first to the' almost horizontally ; and, immediately in front of the posterior-apical ^°'^^^}' bronchus, it divides into two veins which extend respectively into the apical vein, interspaces occurring between the posterior-apical and the axillary, and andmodefof between the posterior-apical and the vertical apical distributions. These division, veins also are anterior and slightly external to the corresponding bronchi. chesS-e' anterior and exter- Distribution of the Left Arderior Ascending-apical Trunk. broncM'^^ The Anterior Ascending-apical Trunk, rather smaller than the Anterior transverse-apical, rises for a distance of 8 mm. within the infra-apical inter- apicS ^' space, at its inner extremity, and divides into an anterior sub-pleural ascending *™"k- and an tipper transverse-apical vein. 520 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Anterior sub-plenral ascending Upper transverse- apical at a higher level, more superficial and more anterior than the transverse trunk. Its bran- ches are in- ferior to the apical air-tubes. The Anterior Sub-pleural Ascending-apical Vein, remaining sub-pleural, supplies the highest members of the series of sub-pleural veins which are associated with the inner mediastinal surface of the pulmonary pleura. It also furnishes veins to the two bronchial districts between which it is placed. The Upper Transverse-apical Vein adopts, as its name indicates, a course analogous to that of the transverse-apical trunk, but at a higher level, immediately under the zone of the smaller peripheral apical ramifica- tions. It is directed outwards and forwards, and is not therefore parallel to the larger transverse trunk, the course of which is either strictly outwards, or even slightly inclined backwards. Thus it is not only much less deeply situated, but its branches are directed towards the anterior, and towards the antero-external regions of the apex at the clavicular level. Its ramifi- cations are chiefly devoted to the service of the apical sterno-clavicular, and of the inner anterior-apical bronchial districts and they remain inferior to these bronchi, whilst also bestowing branches upon those air-tubes which rise from the pectoral distribution as far as the upper zone of the infra- apical bronchial interspace. General analogy be- tween light and left veins. In the right hmg the transverse channel is below the pectoral zone, through which the ascending veins rise. The posterior sub-pleural apical and the axil- lary veins are respec- tively alike. A Comparison between the right and the left apical venous supply enables us to trace between the two distributions a general analogy in spite of much divergence in details. The most striking difference between them is that in the right lung the transverse supplying channel is inferior to the pectoral bronchial range, but that it is superior to the latter in the left lung. Hence it follows that the veins ascending to the right apex pass upwards between the pectoral bronchi, whereas in the left lung they arise altogether above the pectoral zone. Great resemblance exists between the two sides, in respect of the posterior sub-pleural apical and of the axillary venous supply. But, on the left side, the posterior sub-pleural vein does not arise from a " separate division, but from the main apical venous stem, which supplies the transverse-apical, and the anterior ascending-apical trunk, and through this ultimately the anterior sub-pleural ascending-apical vein. The rectangular bifurcations which give rise to the transverse- apical trunk and to the upper transverse vein are remarkable departures from the usual type of division of the pulmonary blood-vessels. Pectoral trunk ; its four divi- , siohs. Varying origin and share in the cardiac dis- tribution. The Left Pectoral Venous Distribution. The Four Pectoral Veins usually arise from the upper division of the superior pulmonary vein by means of a very short trunk of origin. Occa- sionally as in one of the specimens depicted (figs. 1 5 and 1 6) this trunk is given off from the inferior division. In that specimen the pectoral veins are of large size and take more than the usual share in the supply of the cardiac district. Being situated below the pectoral bronchi, in the inter-bronchial THE BRONCHI AND PULMONARY BLOOD- VESkSELS. 22 1 space. between this distribution, and the cardiac, these veins normally partici- pate in the cardiac venous supply. The four veins spread in a horizontal fan-shaped manner, anteriorly and Horizontal outwards, with slight convexity upwards. They originate by means of bifur- branohmg. cations. The first one gives rise to the Mid-sterual and to the Mid- '-Two buc- pectoral and the second to the posterior and to the oioter pectoral vein. furcations". Although this resemblance is not well displayed in the diagram (fig. 1 8), Sub-pieurai the Sub-pleural Sterno-pectoral Vein is in every way analogous to torai vomr that found on the right side. The Outer- and the Posterior-pectoral Veins subdivide in the Mid-stemai horizontal plane situated immediately beneath the pectoral bronchi. Their pectoral^ ascending branches approach the bronchi on the inner side. Their horizontal P^f''- ^^^ ° _ ^^ _ outer pec- branches remain below the pectoral bronchi, and send small vessels to the torai veins. upper boundary of the cardiac bronchial zone. iSSor™ The left posterior-pectoral corresponds to the right superior-dorsal vein, andinter- but is stopped in its backward course, by the longitudinal fissure. It delivers bronchi. a Posterior Interlobar Pectoral Vein opposite the descending pul- monary artery. The left pectoral venous trunk lies in the angle between the cardiac trunk and the pectori-apical bronchus, being exactly in front of the origin of the latter. Venoios Supply to the Left Cardiac Begion, The Cardiac Venous Trunk, as short as the preceding, overlaps The car- from below the inner aspect of the cardiac bronchus. Its two divisions, the trunk.^"""^ superior and the inferior cardiac vein have difierent downward obliquity, the superior closely approaching to the horizontal direction. The Superior or Deep Cardiac Vein, remaining at first superficial Superior or with direction forwards, swerves faintly outwards to a position almost imme- diac trunk. diately below that of the anterior cardiac bronchus. Its Sterno-cardiac Stemo-oar- and its Mammary-cardiac branch respectively approach the inner and internal, the inferior aspect of the corresponding bronchi, and supply their bronchial ^^'^^^'^' districts. veininfe- The Inferior or Sub-pleural Cardiac Vein immediately divides bronchi. ^ into a siih-pleural cardio-sternal branch, analogous to that found on the right inferior side, and into an inferioi' cardiac branch which follows the inferior and inner trunk. aspect of the corresponding bronchi. raUardi)"- sternal, and inferior Eemakks on the Left Upper Lobar Venous Supply. ^^^^ In reviewing the venous distribution of the left upper lobe, it is important Review of to remember that this lobe is the equivalent of the right upper and of the lobar^^^"^ right middle lobe. «"tP'y- 222 THE BRONCHI AND PULMONARY BLOOD-VESSELS. Horizontal The Spreading of the venous distribution in horizontal tiers is a striking M^-^'^^^ feature of the left upper lobe. It is correlated with the peculiarities of the bi-onchiai bronchial tree, and of the arterial distribution, and with the existence of apical, in- three transverse inter-bronchial spaces, — the apical, the infra-apical, and the tofra?''^*'' iiifra'-pectoral interspace. To these might be added a fourth, the infra- torai, and mammary, corresponding to the interval between the superior and the inferior mammary, cardiac broncM. ■^'tii-^^™h ^* results from this disposition, and also from the close proximity of the are closer, superior pulmonary vein to the bronchial tree, that several of the venous paraiieUo branches possess, in this part of the lung, a course more parallel to, and, in first'tha'^* many cases, less distant from the air-tubes, than is to be observed in any in other other part of either lung. This closer relationship is however restricted subse- entirely to the early venous trunks. As they approach the peripheral zones, th^'f^i ^^^ undergo subdivision, they conform to the two rules which have been the two found applicable to all other veins, viz. the rule that the veins occupy the nousdis^"' bronchial interspaces, and from this independent position send branches tnbution. more or less transverse to the direction of the arterio-bronchial tracts ; — and the rule that they select that side of the bronchi which is opposite to the bronchial surface followed by the pulmonary artery. The as- One of the very rare exceptions to the latter rule, is presented by the apt^weins ascending-apical veins, the behaviour of which has been fully described. a striking exception. VENOUS DISTEIBUTION TO THE LEFT LOWER LOBE. Left Inferior or Posterior Pulmonary Vein. The inferior The peculiarities of origin, of size, and of direction of the inferior pul- vein'™*'^ monary vein have already been given with sufficient detail (see p. 2x6); and it has been pointed out that its superior division, the posterior-horizontal vein, its branches Originates in immediate proximity to the left auricle, whereas the inferior tomirail're* division proceeds downwards outwards and forwards for a distance of I "5 cm. lations. before subdividing iato the anterior-basic, the axillary-basic, and the pos- terior-basic veins. The inferior pulmonary vein and its large branches are in close relation with the descending aorta, the pleural reflection passing from the outer surface of this vessel to their posterior surface. Venous Supply to the Left Posterioi'-horizontal District. The pos- The Posterior-horizontal Trunk resembles in all essential parti- teriof-hori- culars the same vein in the right lung. It is somewhat stouter and much shorter than the right vein. It extends upwards outwards and very slightly len th and forwards, for a distance of 2 cm., covered from behind by the small direction, descending aortic branches, as far as the lower border of the descending Tig. 20, Same specimen as fig. 19; left lateral and posteeioe view. (Cy. figs. IS and 16.) (The side of each square represents 20 mm.) EXPLANATION OF THE DRAWING. The middle vertical third of the drawing shows the termination of the common pulmonary A., the arch of the aorta, and the arch of the left pulmonary A., and the sub-tracheal part of the right pulmonary A. The kink in the left descending pulmonary A. is accidental, probably the result of pressure during the injection. The solitary twigs, above and below, belong to the right lung. The origin of the four pulmonaiy veins from the auricle is seen distinctly. Eight Lung. The upper lobar bronchus is foreshortened ; the ascending-apical bronchus, out of sight ; the axillary bronchus and its two large divisions, in view. In the angle to right of trachea, the mid-apical V. divides, far away from, but apparently close beneath the transverse portion of the posterior division of the apical artery, which accompanies the retro-axiUary as well as the posterior- axillary-apical bronchi. At intersection F v : the termination of the superior pulmonary V. as superior dorsal V., below which, the posterior-horizontal arterial and bronchial trunk. Column Tj — contains the posterior-horizontal bronchi and vessels. At line vij, column G, the lesser posterior-horizontal A. is accidentally fused, in the drawing, with the underlying posterior-basic A., which bends downwards at this level. At the same level the inferior posterior-horizontal vein and the descending posterior- basic vein have taken the Injection for a short distance only. Left Lung. In square C v, the apex derives its arterial supply from the axillary tnink (dividing into posterior-apical, and axillary pulmonary arteries), and from the larger ascending-apical trunk arising out of sight between the axillary trunk and the posterior superficial ascending-apical vein. The posterior-apical bronchi are seen in the same square, terminating at line iij, and the axillary bronchi in square B v. Above line iv, the anterior and posterior ascending-apical arteries and bronchi extend to the apex. At junction C iv, a branch from the transverse-apical V. penetrates the interval between the posterior-apical and axillary bronchi. (The veins to the apex are mainly anterior.) Between lines v and vij, the posterior-horizontal distribution is included. The vein may be followed as far as point D vj, beyond which the injection has failed. Just below point D v, originates the superficial arterial supply ; At D vj, begins the deep posterior-horizontal bronchus; the corresponding artery arises anteriorly to it from the descending pulmonary A. In square A vij ends the mammary-cardiac distribution. In square C viij the anterior-basic veins separate the anterior-basic from the axillary-basic bronchi ; the two corresponding arteries are dimly seen in square C vij. Just above point D viij the axUlary-basic veiu intervenes between two posterior-basic bronchi. In column D the termination of the descending pulmonary artery, posterior to its bronchus, covers the breaking-up of the inferior pulmonary V. and of its descending posterior-basic division, the lowermost branch of which ends in D x. Fig. 20. Pulmonary arteries, dotted; left auricle andpdmonary veins, shaded; bronchi, blank; black patclm indicate lymphatic glands. VH] THE BRONCHI AND PULMONAEY BLOOD-VESSELS. 223 mid-dorsal oblique bronclms. Passing to the ventral side of this air-tube, it divides into its chief tributary-veins. Its first branches are given off, however, at a much earlier stage, from its Small aa- posterior aspect, almost immediately in front of the aorta. Their direction is des^diDg*^ respectively upwards and downwards. They bear the names of Ascending aortic veins, and of Descending Aortic Veins. These veins are a little anterior to, internal to and a little nearer the middle line than the air-tubes. They distribute sub- ''™"''^'- pleural branchlets to the vertebral aspect of the lung in its middle portion. The Descending Mid-dorsal Oblique Vein descends in front of. Descending and slightly below the bronchial distribution, which shares with it the same ™bUque'^*^ name. y®i°i A second bifurcation of the continuation of the trunk occurs just below anterior to the level of the deep posterior-horizontal bronchus. The two resulting *''^'^'^°°<=i"- branches take the names of the neighbouring bronchi. The Ascending Mid-dorsal Oblique Vein is inferior and slightly Ascending anterior to the bronchial path ; its branches become more decidedly anterior, oblique"*' Sometimes, as in the specimen of which fig. 16 is a posterior view, the 7®'"'. ascending oblique vein arises independently from the posterior-horizontal anterior to trunk close to its origin. It then replaces the small ascending aortic branch, ^ '■o°o 1, . , ° occasional and it passes upwards and outwards, behind instead of in front of the irregular descending mid-dorsal oblique bronchus. ongm. The Deep Posterior-horizontal Vein is at first inferior and Deep pos- posterior to the corresponding bronchus ; but rising to the level of the bifur- zontai vein, cation of the latter, it passes between its diverging limbs to the front of the teriJ^'thT' air-tubes, and there breaks up into its branches : or it may divide before anterior to ■, ^ . '' thebronohi. having become anterior. The general tendency of the left posterior-horizontal venous distribution Review of is towards an anterior and inferior position of the veins, in opposition to that ^'^ "i'stnct. 1 iTTi -I • veins of the arteries, which pursue a downward and backward course. Very little haveaten- therefore is seen of these veins from behind, although they arise in a plane dowJwards posterior to that of most of the pulmonary vessels and bronchi. When the ^^.^™" ascending mid-dorsal oblique vein takes an abnormal origin from the hori- zontal trunk it remains for some distance posterior, being covered only by the small descending aortic distribution. Another posteriorly placed vein may abnormally arise from the posterior- Occasional horizontal trunk. The small descending aortic branch is sometimes replaced posteSoi"^ by a good-sized vessel, posterior to the artery which descends behind the *"'*°'='i- inner descending aortic branches from the posterior-basic bronchus, and therefore superficial as well as posterior, 2 24 THE BEONCHI AND PULMONARY BLOOD-VESSELS. Inferior division of inferior pul- monary vein. Descending aortic-hasio vein. Eelations and direc- tion of tlie three basic veins. Venovs Supply to the Left Fulvionary Base. The Inferior Division of the inferior pulmonary vein, arising almost in front of the aorta, proceeds for a short distance downwards outwards and slightly forwards, before approaching the innermost of the descending basic bronchi. During this interval it divides into its three basic branches, which keeping at first side by side, resemble the adducted fingers of a hand ; and it also delivers, from its lower portion, a posterior branch, the Descending Aortic-basic Vein, for the supply of the aortic district of the posterior- basic distribution. This vein sometimes is a branch from the posterior- horizontal trunk. Viewed from the front, the termination of the inferior pulmonary, and its three divisions arranged side by side from above downwards, in parallel order, with direction downwards, outwards and forwards, are situated i cm. below the level of the subdivision of the inferior lobar bronchus into its basic branches. The veins pass outwards in front of the posterior-basic bronchial trunk, and behind the inner, or cardio-basic, division of the anterior-basic bronchus. They are within the same vertical axillary-vertebral plane as the lower lobar bronchus ; but their upper border forms with the direction of the latter a considerable angle. Anterior- basic vein. Origin. Anterior retro-car- diac vein, intemaJ to the bronchi. Cardio-basic and infra^ mam- mary veins. The Left Anterior-basic Vein. The Anterior-basic Venous Trunk is the uppermost of the three parallel basic bronchi. Its origin is best studied from the anterior aspect. (See fig. 19, column P, middle of line vij.) The three trunks do not arise simultaneously, but by two successive bifurcations. As in the right lung, the anterior-basic trunk is also here the first product of bifurcation. A small Anterior Retro-cardiac Vein immediately descends from its anterior surface, in front of the angle of bifurcation between it and the still undivided remainder of the inferior pulmonary vein. In fig. 19 this small vein lies obliquely across the Hne of bifurcation and conceals from view its ianer portion. It is separated from the inner side of the retro-cardiac bronchus by a distance of i cm., and converges towards the lower extre- mity of the latter. It probably assists in the sub-pleural supply of this zone. Assuming a slightly less descending course than the axillary-basic, and becoming slightly anterior to the plane of that vessel, the anterior-basic vein divides into its two large branches, the cardio-basic and the infra-rfiamma')~y trunk, below the angle of bifurcation which gives rise to the anterior-basic bronchus. Both these veins pass outwards behind the cardio-basic bronchus but only one of them, the infra-mammary, crosses the infra-mammary-basic bronchus from behind. mammarv, THE BBONCHI AND PULMONAKY BLOOD-VESSELS. 22 5 The Cardio-basic Vein follows the posterior and inner aspect of the The cardio- bronclius and of its branches. l^^f ° ^f\ internal and The Infra-mammary Vein divides almost immediately into a supe- posterior to ,..,,.„.,,.,, •' -"^ thebronchi. nor, liorizontal, and an mfenor, oblique branch. I'he infra- The inferior branch, or Descending Infra-mammary Vein, re- "i^™™ai"y mains below the corresponding, bronchus, the direction of which dgwnwards (i) Descend- outwards and forwards, it follows at a distance. One of its branches is j^f„;°Ht. distributed forwards and downwards to the interspace between this bronchus and the cardio-basic bronchus, the other branch backwards to the interspace in front of the axillary-basic bronchial trunk. The superior branch, or Horizontal Infra-mammary Venous (2) Hori- Trunk, passes between the infra-mammary bronchus in front, and the mammary™" axillary-basic and posterior-basic bronchi behind, and divides into a hori- *'^"°^- zontcd and an asceTiding infra-mammary vein. The Horizontal Infra -mammary Vein passing outwards trans- Horizontal versely, towards the lower axillary third of the pulmonary surface, along Saiy vS™.' the interspace between the descending and the horizontal division of the corresponding air -tube, distributes branches to both these bronchial dis- tricts. The Ascending Infra-mammary Vein is directed upwards, out- Ascending wards and backwards, towards the posterior axillary middle third of the maiy vein. pulmonary periphery. It separates the horizontal bronchial distribution its relation derived from the mammary-basic trunk, from the horizontal distribution, bou^g arising from the axillary-basic and posterior-basic trunks, and is situated bronchial ■ 1*11 1 CllSliJrlCTiSa immediately beneath, and a little in front of the deep posterior-horizontal distribution. To these several districts it supplies branches. Above, it is in close relation, through its branches, with the mid-axillary and to the pleural membrane, and, at the level of the interspace between the posterior- Seriobar"^ horizontal and the basic distributions, with the interlobar pleural fold. pleura. The three large veins which have been described in the preceding para- General re- graphs form a broad, fan-shaped distribution, which occupies a great part of the anterior- the long, oblique, interspace occurring in front of the posterior-horizontal, of ^"T '®"""^ the axillary-basic, and of the posterior-basic distributions, and probably serve the additional purpose of binding together these distributions with that of the anterior-basic trunk. The Left Axillary-hasic Vein. The Axillary-basic Vein, parallel, and in contact with the anterior- Axillary. basic above, and the posterior-basic below, is the upper branch of bi- *^' ^' ' furcation of the remainder of the inferior pulmonary vein, left by the separation of the anterior-basic trunk. Its original direction is soon modified internal and ... , . . , -, -, inferior to into a downward and outward curve, with convexity upwards and outwards, bronchi and P 2 26 THE BRONCHI AND PULMONARY BLOOD-VESSELS. in imitation of the curve rlescrijbed by the bronchial trunk. It lies to the inner and inferior side of the latter. largely Occupying the interspace between the axillary-basic and the posterior- to posterior- basic distributions, it is concerned with the supply of both, but more spe- t'rict'-'^Hs ^^^% o^ *^^ latter. This circumstance explains its large size, which equals of consider- that of the auterior-basic, and exceeds noticeably that of the posterior- able size. , basic vein. llie Left Posterior-basic Vein. Posterior- The Posterior-basic Trunk is the lowermost of the constituents of basic trunk, ^^j^^g pulmonary root, and in its first portion is therefore visible from the andanterior front as Well as from the back of the metallic cast. In its subsequent the'brorichi course it does not penetrate deeply into the lung, but remains in inner and in anterior contact with the posterior-basic bronchus. For this reason, and owing also to the fact that the left extremity of the left auricle is tilted upwards and backwards, the course of the vein is a very rapid one down- wards and slightly outwards. Bi-anohesof Brauches of distribution pass outwards backwards and downwards, to tion.' the lateral, to the posterior and to the central parts of the base of the lung. From its Two veius arise from the first part of the trunk, close to its origin. a'posteriOT I^^^S"^ one of these, the posterior and larger branch, may be considered to branch; arise from the posterior part of the common trunk giving origin to the axillary-basic and to the posterior-basic vein. It has already been described, under the name of descending aortic-basic vein, on p. 224. and a small The Other branch, a small and unimportant vein, arises with direction sub-pieurai downwards and slightly forwards, from the inferior surface of the venous branch. trunk. Its destination is the inner and inferior surface of the pulmonary base. Beyond the analogy which exists between it and the descending sub- pleural branch, supplied in a similar situation by the right posterior-basic vein, it presents no feature of interest. INDEX. Abby'S bronchial stem, zg classification, 49 diagram, 52 eparterial and hyparterial theory, 36- 39 facts, 26, 38 illustrations, 83 theories, 28-39 (monopodic branching according to), 32 views criticized, 29-39, 83 work analysed, 25-28 Alternation of bifurcation, 63 Alveoli, 14 measurement and numeration, 1 5 Anatomy of lungs and bronchi (summary of), 9-24 Aiigles of divergence of bronchi, 35, 61 Apex, right, 89 left, 98, 100 Arch of aorta, 189 of left pulmonary artery, 189 Arches, terminal bronchial, 147, 159, 167, 169 Arteries : see Pulmonary arteries. Auricle, left, 177, 198, 212, 214 Axial character of bronchial stem (Aeby), 29 B BiFUBCATloN of trachea, 33 of bronchi, 65 (axillary-apical), right, 92 Bipinnate arrangement of bronchi (Aeby), 62, 83 Bronchi (main), 10, 67, 69, 74 „ inclination of, 70 „ length of, 71 primary and secondary, 59, 60 arrangement of, 21 common features of, 65 lateral, of Aeby, 52, 56 Bronchi, structure of, 61 recurrent, 61 T-shaped, 61, 62 Bronchial arteries and veins, 23 districts, 86 Bronchial tree of Aeby, 25, 56 stem ,, 29 asymmetry (Aeby), 36 Bronchus impar, 80, 99 intermedins, 69, 74, 77 right main, 69, 70, 77 left main, 68, 70, 80, 82 right upper-lobar, 77, go left upper-lobar, 80, 98 middle lobar, 78 right lower-lobar, 78 left lower-lobar, 81 Bronchi, accessory (Aeby), 53, 56 „ apical, loi aortic (ascending), left, 135 „ apical trunk, left, 104 „ „ recurrent, left, 104 „ (descending), left, 136 „ (inferior-descending), (inner and outer descending), (anterior T-shaped), left, 168, 169 ,, recurrent (posterior-apical), Uft, apical (anterior-ascending) trunk, right, 93 „ ( „ >, ) 1. ieft, 102 „ (anterior inner), right, 103 „ (anterior axillary), right, 109 ,, (anterior mid-), right, 106 „ (axillary-) trunk ; bronchus ; left, 101, 107 „ (axial), right, 95 „ (anterior-, middle-, sterno-tra- cheal), right, 94 „ (ascending posterior), right, 95 „ ( „ >, ), left, 103 „ (central and outer-central), left, ip6 228 INDEX. Bronchi — apical (external anterior), right, 113 „ (inner mid-, outer mid-), left, 106 „ (inner posterior), left, 105 „ (mid-) stem, left, 105 „ (mid-pectoral), right, 113 „ (outer ascending), left, 107 ,, (outer posterior), left, 105, io5 „ (peotori) stem, right, 54 „ left, SS, 99 „ (posterior), right, 95 „ „ left, 105 „ (posterior axillary), right, 1 10 ,, (posterior tracheal and recur- rent), right, 98 „ sterno-clavicular, left, 103 „ supra-spinate, right, 98 „ (tracheal) trunk, right, 94 „ (tracheal recurrent), right, 94 „ (vertical), (anterior and posterior vertical), left, 103, 104 axillary stem, right, 108 „ „ left, 104, 107 „ (descending posterior), right, no „ (descending superior), left, 107 „ (anterior), (ascending superior), left, 107 „ (anterior and posterior), left, 100, lOS „ central interlobar, right, 109 „ posterior interlobar, left, 107 „ horizontal interlobar, right, 130 „ (horizontal mid-), right, 130 „ (horizontal superior), left, 107 „ (inferior mid-), right, 130 Wt, 137 „ (superior mid-), right, 130 .. „ left, 136 „ (lateral inferior), left, 158 „ (vetro-mammary-), left, 158 right, 155 „ (superior), right, 109 „ „ left, 107 basic (anterior-), right, 79, 147 „ „ left, 82, 150 „ (antero -lateral) left, 159 ,, (axillary-), right, 79, 154 „ „ left, 82, 159 „ (anterior superior axillary-), left, 158 „ (central-), right, 166 „ (inferior axillary-), left, 159 „ (central superficial), (marginal superficial), left, 171 „ (oardio-), right, 147 left, 152 Bronchi — basic (external superfi,cial axillary-), right, ISS „ (inner, outer, and lateral ante- rior-), right, 147 , „ (supra-marginal cardio-), left, 152 „ (posterior-), right, 162 _ Wt, 167 cardiac trunk, right, 78, 120 „ hft, 53„8i, 125 ,, (anterior-), left, 126 ,, (mammary-), right, 120, 124 left, 126 „ (sterno-), right, 121 ,, 11 ^«A 126 „ (marginal sterno-), right, 121 „ parallel-sternals, right, I2i, 124 „ parasternals, deep, left, 127 „ (inner mammary-), (inner pos- terior-), riglit, 121, 124 ,, (superficial inner and outer mammary-), left, 126 „ (posterior-), right, 124 Wt, 127 „ (posterior mammary-), right, 124 „ lobular and deep lobular (pos- „ terior), left, 127 „ (superficial mammary-) (super- ficial sterno-), right, 121 central (descending) of root, left, 117 „ ' descending mid-axillary, right, 130 „ apical (outer), left, 106 „ basic (posterior), left, 170 clavicular (anterior), left, 103 „ (infra-), right, 113 „ (superficial), left, 103 „ (mid-pectoral), right, 113 dorsal (ascending oblique), right, 131 (deep), left, 137 „ interlobar (superior), W^/i<, no ,, (inferior), right, 166 ,, (descending), (oblique), left, 168 ,, (posterior superficial), (upper and lower deep), left, 168 „ (supra-spinate), right, 98 „ (sub-pleural), left, 136, 137 dorsi-basic (lateral), (superficial and deep lateral), right, 163 „ (outer superficial), (deep an- terior), (posterior), rigid, 166 ,, axillary (superficial and deep), (descending intra- pulmonary), right, 163 „ (superficial), left, 171 INDEX. 229 Bronchi — dorsi-basio (superficial and deep axil- lary), (central-angular), (posterior inner-angular), Uff, 169, 170 dorsi-axillary basic (superficial), 170 interlobar (anterior-basic and cardio- basic), right, 147 (ascending), right, 121 (ascending deep mammary), left, 151 I (central and external axil- lary), right, 109 (external mammary-cardiac), right, 1 24 (horizontal axillary), right, 130 (mammary-cardiac), left, 126 (outer pectoral), right, 116 (cardiac lobular), left, 127 (mid-axillary horizontal), left, 137 (mid-dorsal), right, 131 (inferior outer pectoral), left, 117 in&a-mammary, right, 147 „ (superior), left, 151 „ (inferior), (external),fe/i, 152 lobular (anterior, posterior, and deep car- diac-), left, 127 „ (inner and outer cardiac-), right, 124 mammary trunk, left, 151 „ (axillary), right, 130 „ (external), right, 147 „ (horizontal and external su- perficial), left, 151 „ (internal superficial), left, 151 „ (outer descending), left, 152 marginal (deep and superficial sterno- cardlac), left, 127 , , (superior and inferior external mammary cardiac-), right, 124 „ (upper, lower, and lateral sternal), left, 118 mid-dorsal (horizontal) trunk, right, 131 „ (ascending and descending), right, 131 (ascending oblique), hft, 13S (descending oblique), left, 136 (descending), right, 131 interlobar, right, 131 oblique, right, 131 vertebral marginal, right, 131 Bronchi — mid-dorsal (superficial descending), right, 131 mid-sternal (descending), right, 112 oblique (descending), left, 137 parallel-sternal cardiacs, 121, 124 parasternal (lower), left, 118 „ (posterior), right, 124 pectoral stem, j-Mc/ji, iii „ „ left, 116 „ (ascending), W^7»«, 116 „ (ascending outer), rJ^/ji, 116 '^ ,, (ascending mid-), rigfAf, 116 ( » 1. ),left, 117 „ (ascending sterno-), right, 112 ( ,. „ ), left, 118 „ (horizontal sterno-), right, 112 „ ( „ outer-), left, 117 „ interlobar (deep inner),rjg'Af, 1 12 „ (inner), right, 112 „ (inner mid-), left, 117 „ (outer), right, 116 „ Uft, 117 „ (middle), right, 113, 116 left, 117 „ (middle interlobar, outer, upper, and posterior), left, 117 „ (sterno-), right, 112 left, 117 „ (superficial mid-), 117 pectori-apical stem, right and Uft, 99 pericardial (anterior), right, 121 „ (posterior, retro - cardiac), right, 138 „ (posterior-basic), right, 147 „ (posterior), left, 127 posterior-horizontal stem, right, 78, 130 „ left, 81, 134 „ „ (anterior infr. mid- axiUary), left, 137 „ „ axillary, right, 130 „ „ (supr. mid-axillary), left, 136 „ „ (inferior), right, 160 „ „ (lesser),WjrAt,79,i6o „ „ » fe/f,82, 167 pulmonary (deep), left, 106 recurrent (deep intra-pulmonary), left 159 „ (tracheal) : see Apical, retro-axillary (and inf ra-spinate), right, no „ (inferior), right, 163 retro-cardiac stem, right, 78, 138 „ left, 82, 139, 152 (anterior), right, 138 230 INDEX. Bronchi — retro-cardiac (superficial and deep), left, 139 „ (posterior), rigid, 139 retro-pericaxdial, left, 139 root (anterior bronchus of), left, 118 „ (descending central, of), left, 117 sternal (horizontal and descending), left, 118 sub-pleural (horizontal) and (posterior), left, 136 sub-scapular (lower ascending), left, 136 „ (upper oblique), left, 136 supra-spinate and (ascending-), right,iio Calibre of trachea and bronchi, 72, 73 Cast (metallic) of bronchi, 46-48, 59-64 Central root-space, right, 121 Classification of bronchi, 49-58 :, „ Aeb/s, 49 ,, „ author's, 56 Comparison between right and left base, 145 „ „ „ „ axillary- basic distributions, 155 Curvature of main bronchi, 7 1 D Diameter of main bronchi, 72 of trachea, 73 Dichotomy, even and uneven, 32-35 Dissected specimens (illustrations of), 42, 43. 75. 174. 175- Dissection-methods, 40 Distributions, bronchial, 86 arterial, 178 venous, 179 District (bronchial) — ■ apex, right, 89 „ left, 98, 100 axillary, right, 108 hft, 104 basic, 142 „ (anterior right}, 146 » ( .. left), 150 ,, (axillary right), 154 „ ( „ l£ff), 15s „ (posterior right), 162 „ ( „ left), 166 cardiac, right, 119 „ left, 125 dorsi-basic, right, 166 „ left, 169 „ lateral, right, 163 descending oblique dorsal, left, 168 infra-mammary, left, 151 District (bronchial) — pectoral, right, 1 1 1 left, 116 posterior-horizontal, right, 128, 129 left, 134 „ „ lesser, right, 160 „ left, 167 retro-cardiac, right, 138 left, 139 Division of the book, 4 of the bronchi (mode of), 59, 65 B EpAETEEial bronchus, 53 theory, 36-39 Epithelium, alveolar, 15 H Hypaetbbial bronchi, 56 theory, 36-39 Infants, lungs of, 1 1 Injection-methods, 41 Injection, mode of performance, 44 Inter-bronchial spaces — sterno-scapular, right, 89 infra-apical, left, 108, 117 central lozenge-shaped, left, 167 central root-space, right, 121 Internodia, bronchial, 35 LOBATION, 9, 48 Lobes of the lung, 9, 29, 37, 68 middle, 119 lower right, 142 lower left, 142 upper right, 89 upper hfi, 98 Lobule (the pulmonary), 12 cardiac, of Aeby, 53 Lymphatics, pulmonary and bronchial, 18 M Maceration, 40 Methods employed, 40 N Neeve-supplt to lungs, 19 „ „ to bronchi, 24 Nomenclature (see Classification), 49, 51, 54, 56,87 Notation (code of), 88 INDEX. 231 Plan of the work, 4 Pleura, 10 (relation of pulmonary veins to), 177, 198 Pleural stomata and pseudo-stomata, 18 Pulmonary anatomy, 9-24 blood-vessels, relations to bronchial tree, 172 arteries, relations to bronchi, 173 „ „ to pulmonary veins, 176 „ differences from systemic arte- ries, 177 „ rigJd and left, contrasted, 196 artery, 16, 48, 52 „ right, 181 „ left, 189 „ ascending-apical, apical, retro- apical, posterior-axiUary apical, supra-spinate, rigife, 184 „ ascending-apical, anterior and posterior and outer ascending- apical, left, 190, 191 ,, axillary, right, 185 hft, 190 „ axillary-basic, right, 188 Wt< 195 „ anterior basic, ri^At, 188 _„ left, 19s „ cardiac, right, 186 „ „ inner and outer, left, 192 „ descending, right, 182, 186 left, 193 „ dorsi-basic, right, 188 „ mammary-cardiac, sterno-car- diac, left, 192 „ pectori-apical, pectoral, mid- pectoral, sterno-pectoral, right, 183, 184 „ pectoral, left, 191 „ posterior-horizontal, descending mid-dorsal, horizontal mid- dorsal, mid-axillary posterior- horizontal, right, 187 „ posterior-horizontal, inferior mid- axiUary.ascendingand descend- ing mid-dorsal oblique, left, 194 „ descending mid-dorsal oblique and descending aortic, left, 195 „ lesser postr. -horizontal, ri^Ai, 188 „ posterior-basic, right, 188 „ left, 196 „ retro-cardiac, right, 188 left. I9S Pulmonary artery, upper lobar, right, 181 parenchyma, 11 veins, 17, 199 „ relation to left auricle, 177 „ relations to bronchi, 175 „ „ to arteries, 176 „ differences from systemic veins 178, 179 „ sustentacular function of, 177 „ differences between right and left 214 „ right upper, 200 „ right lower, 208 „ relations of right lower, 208, 209, 212 „ left upper, 215, 217 „ left lower, 216, 222 „ differences between right and Uft lower pulmonary veins, 216 „ „ between right and left apical veins, 220 „ remarks on the Uft upper-lobar venous supply, 221, 222 „ sub-pleural veins and venules, 199 „ ascending or deep apical trunk; axial-apical, outer-central api- cal, axillary apical, right, 205, 206 „ apical venous trunk, left, 218 „ ascending-apical (posterior sub- pleural), left, 218 „ apical (transverse), (central), (pos- terior), left, 219 ,, axillary, left, 219 „ anterior ascending-apical; ante- rior sub-pleural ascending-api- cal ; upper transverse-apical, left, 219, 220 „ ascending (inner superficial) trunk, sub-pleural sterno-pec- toral, ascending-apical, anterior and posterior ascending-apica right, 202 „ axiUary-basic, right, 211 ., 1, „ left, 225, 226 „ anterior-basic, right, 212 „ ,> „ ; cardio-basic ; in- fra-mammary, ascending, de- scending, horizontal, left, 224, 225 „ aortic-basic (descending), left, 224 „ cardiac, inner-anterior, posterior- inferior, ascending, descending, horizontal, central, sterno-car- diao, mammary-cardiac, outer- cardiac, right, 207, 208 232 INDEX. Pulmonary — veins, cardiac trunk, left, 221 , , superior cardiac ; sterno- and mam- mary-cardiac, left, 221 „ inferior, sub-pleural cardiac ; sub- pleural cardio-sternal ; inferior cardiac, left, 221 „ dorsal (superior), right, 206 „ pectoral (mid-sternal), sub-pleu- ral sternal and interlobar, as- cending sterno-pectoral, mid- pectoral, ascending mid-pec- toral, interlobar mid-pectoral, external or axillary pectoral, right, 203, 204 „ pectoral trunk ; mid-sternal pec- toral ; sub-pleural sterno-pec- toral ; outer and posterior- pectoral ; posterior interlobar, left, 220 „ lesser posterior-horizontal, right, 211 „ posterior-horizontal, superficial, deep ; ascending inid-dorsal, ascending oblique, 210, 211 ,, posterior- horizontal trunk ; as- cending and descending aortic; ascending and descending mid- dorsal oblique ; deep posterior- horizontal, left, 222, 223 „ postr.-basic (descending), right, 211 „ „ „ „ left, 226 ,, retro-cardiac, right, 211, 212 left, 224 „ transverse-apioal trunk, left, 219 (upper), left, 220 „ transverse-basic (deep),ri^7rf, 212 Pulmonary venous supply to — upper lobe, right, 200-207 inner-apical district, right, 202 central and outer-apical, right, 205 pectoral region, right, 203 middle lobe, right, 207 lower lobe, right, 208 lateral dorsi-basic, right, 212 upper lobe, left, 217 apex, left, 218 pectoral region, left, 220 cardiac region, left, 221 lower lobe, left, 222 Pulmonary venous supply to — posterior -horizontal district, hft, 222 pulmonary base, Uft, 224 R Eecueebnt bronchi, 61, 94, 98, 104, 105, 159 Region : see District. Root of lung, 10 Root-space (inter-bronchial), central, 121 Root-zone, 12 Rudimentary bronchial stems — axillary-apical, right, 91, 92 axillary, left, 104 inner cardiac, right, 120 S Scope of the work, i, 33 Sulcus (inter-bronchial), right stemo-scapu- lar, 89 Synopsis of Aeby's nomenclature, and of the author's nomenclature of the primary bronchi, 54, 55 Table I. BronchialSupplytoApex, 96,97 ,, II. Pectoral Distribution, 114,115 „ III. Cardiac Distribution, 122, 123 „ IV. Posterior -horizontal Distribu- tion, 132, 133 „ V. Retro-cardiac Distribution, 140, 141 „ VI. Anterior - basic Distribution, 158, 159 „ VII. Axillary-basic and Lesser Pos- terior - horizontal Distribu- tions, 156, 157 „ VIII. Posterior - basic Distribution, 164, 165 T-shaped bronchi, 61, 62, 94, 98, 104, 105, 106, 107, 109, no, 113, 124, 126, 127, 136, 138, 147, 151 Thorax of man and quadrupeds, 30 Trachea, size, 72 Tracheal bifurcation, 33 „ calibre, 72, 73 Trifurcation (bronchial), apparent, 91, 135, 144 V Veins : see Pulmonary veins. Volume and weight of lungs, 1 1 PRINTED BY BAT.LANTYNE, HANSON AND CO* I.OITDOII AND EDINBURGH