Thorax: first published as 10.1136/thx.8.3.189 on 1 September 1953. Downloaded from Thorax (1953), 8, 189. THE SURGICAL ANATOMY OF THE PULMONARY VESSELS BY J. C. VAN DER SPUY From the Thoracic Surgical Unit, Johannesburg Group of Hospitals, and Department of Surgery, University of the Witwatersrand, South Africa (RECEIVED FOR PUBLICATION SEPTEMBER 29, 1952) Surgical resections of the lung have in recent diately beneath the pleura, or deeply, in an inter- years become common and relatively safe pro- segmental plane. The intersegmental veins drain cedures. Depending upon the extent and nature of also adjacent segments within a lobe and may the disease process, the whole lung, one or two drain adjoining segments of a different lobe. In lobes, or one or more bronchopulmonary segments the latter instance the veins pass subpleurally may require excision. Modern pulmonary re- across the base of a fissure. The perisegmental section depends to a very large extent upon the (intersegmental or segmental) veins course some- precise identification of the primary, secondary, what independently of the segmental bronchi and and tertiary hilar bronchovascular structures, and arteries to reach the subp'eural plane in the it has thus become essential to have a detailed primary hilum and there join a main pulmonary knowledge of the anatomy of these structures at vein. the different hilar levels. PULMONARY ARTERY The aim of this paper is to describe and to illus- The main pulmonary artery divides in front of copyright. trate this anatomy. It is based upon a study of 42 the left main bronchus into a left and a right pul- complete casts of the bronchovascular tree and the hilar anatomical findings displayed during the monary artery (Fig. I). course of 92 partial and 30 whole lung resections RIGHT PULMONARY ARTERY.-The right pul- performed by some members of the Thoracic monary artery has to cross the midline to reach the Surgical Unit, Johannesburg, during the past year. root of the right lung. This it does by passing http://thorax.bmj.com/ The pulmonary vessels and the bronchi are illus- transversely to the right, behind the ascending trated chiefly from such approaches as are used aorta and the superior vena cava respectively, in by the surgeon when dissecting the different front of the oesophagus and immediately above primary, secondary, and tertiary hila. the left atrium and right superior pulmonary vein Each lung, anatomically, is composed of 10 under cover of the arch of the azygos vein. bronchovascular or bronchopulmonary segments. Behind the superior vena cava the right pul- These segments are miniature lobes differing from monary artery divides into an upper and a lower lobes only in their size and in the usual absence of trunk (Fig. I). Of these the superior pulmonary fissures at their anatomical boundaries. trunk supplies the anterior and apical broncho- on September 28, 2021 by guest. Protected A lobar bronchus branches from a main pulmonary segments of the right upper lobe by bronchus at a relatively constant site, and sub- dividing, as it enters the lung substance in front of divides in a more or less standard fashion into its the right upper lobe bronchus, into the apical (Al) segmental bronchi. The pulmonary artery, how- and anterior (A3) segmental arteries (Fig. II). ever, has not this same lobar distribution, and Emerging from behind the superior vena cava, it although the segmental pulmonary arteries follow is, but for the covering given it by the pleura on the segmental bronchi somewhat closely, they tend the root of the lung, completely exposed. to have a variable and independent origin from the The inferior pulmonary trunk proceeds from pulmonary artery. behind the superior vena cava to become sub- The segmental artery, like the segmenital pleural, but only to disappear almost immediately bronichus, occupies a central position within the by passing behind the superior pulmonary vein bronchopulmonary segment. The blood carried (Fig. IV). It is the counterpart of the left pul- to the segment by such a centrally situated artery monary artery. Passing laterally and slightly is collected by perisegmental pulmonary veins; as downwards, under cover of the superior pul- such, they are either placed superficially, imme- monary vein (Fig. IV), it crosses, the anterior sur- Thorax: first published as 10.1136/thx.8.3.189 on 1 September 1953. Downloaded from 190 J. C. VAN DER SPUY face of the right bronchus, between the origins of Arising from the inferior pulmonary trunk, the upper and middle lobe bronchi (Figs. II and slightly above the lower lobe apical segmental III). Then curving downwards, it runs sub- artery, is the artery to the posterior segment of pleurally in the depths of the oblique fissure (Fig. the upper lobe. It passes backwards and upwards III), on the antero-lateral aspect of the basal and is termed the posterior ascending artery (A2, bronchus. Figs. III, Illa, and IVd). Whereas the posterior The inferior pulmonary trunk supplies the segmental artery of the right upper lobe in the majority of cases arises from the pulmonary middle and lower lobes as also, in the majority artery in this situation, it frequently, however, of cases, the posterior bronchopulmonary seg- arises from the superior pulmonary trunk itself ment of the upper lobe via the posterior ascend- of ing segmental artery (A2, Fig. III) and frequently during the latter's subpleural course, from either segment, via its two terminal branches, namely, the apical (Al) also the anterior bronchopulmonary and the anterior ascending segmental artery (A3, Fig. or anterior (A3) segmental arteries (Figs. Ila from the lower lobe apical segmental artery such instances the anterior ascending seg- Ilb), III). In (A2, Fig. IlIb), or even from the middle lobe mental artery is usually accessory to the anterior artery. segmental artery (A3, Fig. II), but in a small per- centage of these cases it is solely responsible for The inferior pulmonary trunk breaks up into supplying the anterior bronchopulmonary seg- the four basal segmental arteries, either just within ment. Occasionally, however, the anterior ascend- the oblique fissure or just inside the lung ing segmental artery may derive its origin from parenchyma. Each basal segmental artery follows the middle lobe artery (A3, Fig. IlIb). its respective bronchus very closely, keeping to its antero-l1teral side. These take off from the The acute angle formed between the oblique inferior pulmonary trunk either singly or via an and transverse fissures forms the point of an anterior and a posterior trunk, the former dividing arrow which guides one to that area of the sub- into the medial (A7) and anterior (A8) basal seg- pleural pulmonary artery, in the depths of the mental arteries, whereas the latter provides thecopyright. oblique fissure, from which the pulmonary arterial lateral (A9) and posterior (AIO) basal segmental supply to the middle and lower lobes and part of arteries (Fig. ILL). the upper lobe is derived (Fig. III). LEFT PULMONARY ARTERY.-The left pulmonary Arising from the postero-lateral surface of the artery, arising in front of the left main bronchus, inferior pulmonary trunk, in this area, one finds ascends slightly in a posterior and lateral direc- the lower lobe apical segmental artery (A6, Fig. tion, arches over the left main bronchus, and then http://thorax.bmj.com/ III). It descends slightly in a backward direction, hooks round the left upper lobe bronchus, follow- lying superior and, as the surgeon sees it, lateral ing a subpleural course throughout (Figs. V, VI, to its corresponding bronchus. To the anatomist, and VII). It more fully establishes its superiority however, the artery is superior and anterior to the over the left superior pulmonary vein (Fig. VIII) bronchus. The reason for this difference is that than does its right counterpart, the inferior pul- the surgeon, in opening the slit-like oblique fissure, monary trunk, which lies directly behind the right displaces the apex of the lower lobe medially. superior pulmonaty vein (Fig. IV). Similarly also, the middle lobe artery (Figs. III, Owing to the different courses taken by the left on September 28, 2021 by guest. Protected IIIa, and IIIb) appears to be superior and lateral and right pulmonary arteries, the antero-posterior to its corresponding bronchus instead of superior and infero-superior relations in the hilum of the and posterior. left lung are vein, bronchus, and artery, whereas The lower lobe apical segmental artery is the same relations in the hilum of the right lung usually single (A6, Fig. III), but at times the apical are vein, artery, and bronchus. segment of the lower lobe summons the aid of a As the left pulmonary artery is about to arch second segmental artery (A6 i, A6 ii, Fig. IIIa). over the left main bronchus it gives off the first of Arising more or less opposite the lower lobe a set ies of segmental arteries for the supply of the apical segmental artery, from the anterior surface left upper lobe. This segmental artery (A3, Fig. of the pulmonary artery, is the middle lobe artery. V), arising from the antero-superior surface of the It may be single, when it divides into two pulmonary artery, passes in front of the upper branches, one each for the medial and lateral seg- division of the left upper lobe bronchus to the ments of the middle lobe (A4 5, Fig. Illa). As anterior bronchopulmonary segment, crossing frequently two separate middle lobe segmental behind the apical-posterior tributary (VI, V2, Fig. arteries are present (A4, A5, Fig. III). VIII) of the superior pulmonary vein. Thorax: first published as 10.1136/thx.8.3.189 on 1 September 1953. Downloaded from THE SURGICAL ANATOMY OF THE PULMONARY VESSELS 191 I= Arter-.- 'fc/ 7 r: 111 711 111 b 11I I.