_- 
THE LUNGS. 935 
and a base, an inner and an outer surface, and an anterior and a posterior 
border. 
The apex pulmonis is blunt and rounded, and rises above the level of the 
oblique first costal arch to the full height of the cervical dome of pleura. It 
therefore protrudes upwards through the thoracic inlet into the root of the neck. 
The subclavian artery arches outwards on its inner and anterior aspects a short 
distance below its summit, and a groove (sulcus subelavius) corresponding to the 
vessel is apparent upon it. At a lower level on the apex pulmonis a shallower and 
wider groove upon its inner and anterior aspects marks the position of the innomi- 
nate and subclavian veins. Although these vessels impress the lung they are 
separated from it by the cervical pleura. 
The basis pulmonis presents a semilunar outline, being curved around the base of 
the pericardium. It is adapted to the upper surface of the diaphragm, and conse- 
quently it is deeply hollowed out. As the right cupola of the diaphragm ascends 
higher than the left, the basal concavity of the right lung is deeper than that of 
the left lung. Laterally and behind, the base of each lung is limited by a salhent 
thin margin which descends for some distance in the narrow pleural recess (sinus 
phrenico-costalis) between the diaphragm and the chest wall. This basal margin 
of the lung extends lower down on the outer side and behind than it does in front, 
but it falls considerably short of the bottom of the phrenico-costal sinus of pleura. 
Thus, after expiration, it reaches in the mammillary line the lower border of the 
sixth rib; in the axillary or mid-lateral line the eighth rib; whilst behind it pro- 
ceeds inwards along a straight horizontal line so as to reach the vertebral column 
at the level of the extremity of the spine of the tenth dorsal vertebra. During 
respiration the thin basal margin rises aud falls in the phrenico-costal sinus of the 
pleura, but even after the deepest breath it never reaches the lowest limit of this 
recess. 
The bases of the lungs establish important relations with certain of the viscera which 
occupy the costal zone of the abdominal cavity, the diaphragm alone intervening. Thus 
———— GROOVE FOR SUBCLAVIAN ARTERY 
UPPER LOBE UPPER LOBE 
RRS 
MIDDLE LOBE 
SN 
BASAL LOBE 
W 
N 
BASAL LOBE 
WS 
\\\ 
S 
A B 
Fic. 683.—OUTER OR COSTAL SURFACES OF THE TWO LUNGS. 
A, Right lung. B, Left lung. 
the base of the right lung rests upon the right lobe of the liver ; whilst the base of the 
left lung is in relation to the left lobe of the liver, the fundus of the stomach, the spleen, 
and in some cases to the splenic flexure of the colon. 
59 a 
ie 
