936 THE RESPIRATORY SYSTEM. 
The outer surface of the lung (facies costalis pulmonis) is extensive and convex. 
It is accurately adapted to that part of the wall of the pleural cavity which is 
formed by the costal arches and the intervening intercostal muscles, and it presents 
markings corresponding to these. Thus the imprint of the ribs appear as shallow 
oblique erooves, while the intercostal spaces show as elongated intervening 
bulgings. 
The inner or mediastinal surface of the lung (facies mediastinalis pulmonis) 
presents a smaller area than the outer surface. It is appled to the mediastinal 
se aa and presents markings in accordance with the inequalities upon this (Fig. 
632, p. 934). Thus it 1s deeply hollowed out in adaptation to the pericardium upon 
which it fits. This pericardial concavity comprises the greater part of the media- 
stinal surface, and owing to the greater projection of the heart to the left side, it is 
much deeper and more extensive in the left lung than in the right lung. Above 
and behind the pericardial hollow is the hilus of the lung. This is a wedge- shaped 
depressed area, within which the vessels, nerves, and lymphatics, together with the 
bronchus, enter and leave the organ. Amidst these structures also are some 
bronchial glands. The 
; a tha hilus is surrounded by 
i AT tebe. the reflection of the 
pleura from the surface 
of the lung on to the 
pulmonary root. Be- 
4 Ne hind the hilus and 
aay if a ee S pericardialarea there is 
Nea maior aan on each lung a narrow 
Miliary artery strip of the inner sur- 
face of the lung which 
Clavicle 
Clavicular part of__ 
pectoralis major 
Spine of scapula 
Coracoid— AF ay 
_—Subseapularis 
Brachial nerves 
Axillary vein — [aN THA 2a » PMN || serratus is in relation to the 
aerial A = Sipe. lateral wall of the pos- 
Rib Th 77 RN ; terior mediastinum. 
i On the right lung this 
1D 1V 
Pectoralis _ 
minor 
part of the surface 1s 
ueren ide * Vaa\N depressed, and corre- 
|| cRiorabtintene sponds to the ceso- 
fenaice phagus; on the /eft 
lung it presents a 
broad longitudinal 
eroove, which is pro- 
duced by the contact 
of the lung with de- 
scending thoracic 
aorta, and also, close 
to the base, a small 
flattened area in front 
of this which is ap- 
plied to the cesophagus 
where it pierces the 
diaphragin. 
The portion of the 
inner surface of the lung which lies above the hilus and pericardiac hollow 
is applied to the lateral aspect of the superior mediastinum, and the markings 
are accordingly somewhat different on the two sides. On the left lung a broad 
deep groove, produced by the aortic arch, curves backwards over the hilus, 
and becomes continuous with the aortic groove on the posterior mediastinal 
surface. From this a narrower, deeper, and much more sharply-marked groove 
ascends, and turns outwards over the apex pulmonis a short distance from the 
summit. This is the sulcus subclavius, and it contains the left subclavian artery 
when the lung is in place. In front of this a shallow wide groove, also leading 
up to the front aspect of the apex, corresponds to the left innominate vein. In 
1 Diaphragm 
Fira. 634.—SaGITTaAL SECTION THROUGH LEFT SHOULDER AND LEFT LUNG. 
