THE LUNGS 



1229 



the thoracic wall in front, laterally and behind, and is marked by grooves corre- 

 sponding to the ribs. The mediastinal surface [facies mediastinalis] is concave and 

 presents a contour adapted to structures of the mediastinum (fig. 994). A special 

 concavity on this surface, known as the cardiac fossa, corresponds to the promi- 

 nence of the heart and is deeper in the left lung than in the right. Above and 

 behind the cardiac fossa is a depression, the hilus of the lung [hilus pulmonis], 

 where the bronchus and pulmonary vessels and nerves togetl>er constituting the 

 root of the lung [radix pulmonis], enter and leave. Near the posterior edge of the 

 mediastinal surface is a groove, which ascends and turns forward over the hilus; 

 the groove of the left lung is adapted to the cylindrical surface of the aorta; 

 that of the right, the vena azygos. A well-marked subclavian sulcus [sulcus sub- 



FiG. 993. — Horizontal Sectiox of the Thorax of a Man, aged Fifty-seven, at the Level 

 OF THE Roots of the Lungs, seen from Above. (J. S.) (Quain.) X 1. 

 A. A. Ascending aorta. A.M. Anterior mediastinum. A.V. Azygos vein. D.A. Descend- 

 ing aorta. E. Eparterial bronchus. I. Superior lobe of lung. L.B. Left bronchus. L.P. 

 Left phrenic. L.P.V. Left pulmonary vein. L.V. Left vagus. (Es. OEsophagus. P A. 

 Pulmonary artery. P.C. Pericardial cavity. R.B. Right bronchus. R.P.A. Right 

 branch of pulmonary arter}\ R.P.C. Right pleural cavity. R.P.N. Right phrenic. 

 R.P.V. Right pulmonary vein. R.V. Right vagus. S. Inferior lobe of lung. Sc. 

 Scapula. T.D. Thoracic duct. 3, 4, 5, 6, 7. Corresponding ribs. 



clavius] extends upward on this surface to the apex, corresponding on the right 

 side to the lower part of the trachea and right subclavian artery, on the left to the 

 left subclavian artery alone. Further forward is a groove adapted in the right 

 lung to the superior cava; in the left to the left innominate vein. The lung is not 

 in actual contact with these several structures, but is separated from them by the 

 mediastinal pleura. The mediastinal surface passes gradually into the costal 

 surface posteriorly, there being no proper posterior edge. Where the mediastinal 

 and costal surfaces meet in front, a sharp anterior margin [margo anterior] exists 

 (fig. 997). In the right lung this runs down in a gentle curve to turn lateralward 

 in the inferior margin. In the left lung the anterior margin is cut into by a wide 

 cardiac notch [incisura cardiaca], which is occupied by the heart in the pericardium 

 as it is pressed toward the anterior thoracic wall. The cardiac notch is separated 

 from the inferior margin by a little tongue of lung substance, the pulmonary 

 lingula [lingula pulmonis]. 



The base of the lung (fig. 994) presents the diaphragmatic surface [facies 

 diaphragmatica] concave and oblique in adaptation to the dome of the diaphragm. 

 It is limited by a sharp inferior margin [margo inferior], which follows the curves 

 of the mediastinal and costal surfaces, and fits into the angle between the dia- 

 phragm and thoracic wall. 



