|Henry Gray (18251861). Anatomy of the Human Body. 1918.|
|line would cut the sternum in front between the fourth and fifth ribs, the fifth rib in the nipple line, and the ninth rib at the vertebral column. (Treves).|
Diaphragm.The shape and variations of the diaphragm as seen by skiagraphy have already been described (page 407).
Surface Lines.For clinical purposes, and for convenience of description, the surface of the thorax has been mapped out by arbitrary lines (Fig. 1220). On the front of the thorax the most important vertical lines are the midsternal, the middle line of the sternum; and the mammary, or, better midclavicular, which runs vertically downward from a point midway between the center of the jugular notch and the tip of the acromion. This latter line, if prolonged, is practically continuous with the lateral line on the front of the abdomen. Other vertical lines on the front of the thorax are the lateral sternal along the sternal margin, and the parasternal midway between the lateral sternal and the mammary.
| On either side of the thorax the anterior and posterior axillary lines are drawn vertically from the corresponding axillary folds; the midaxillary line runs downward from the apex of the axilla.|
| On the posterior surface of the thorax the scapular line is drawn vertically through the inferior angle of the scapula.|
FIG. 1216 Front of thorax, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red outline). P. Pulmonary valve. A. Aortic valve. B. Bicuspid valve. T. Tricuspid valve. (See enlarged image)
Pleuræ (Figs. 1216, 1217).The lines of reflection of the pleuræ can be indicated on the surface. On the right side the line begins at the sternoclavicular articulation and runs downward and medialward to the midpoint of the junction between the manubrium and body of the sternum. It then follows the midsternal line to the lower end of the body of the sternum or on to the xiphoid process, where it turns lateralward and downward across the seventh sternocostal articulation. It crosses the eighth costochondral junction in the mammary line, the tenth rib in the midaxillary line, and is prolonged thence to the spinous process of the twelfth thoracic vertebra.