

t 



SURFACE MARKINGS OF THE THORAX 1311 



In the position of expiration the lower border of the lung may be marked by a 

 slightly curved line with its convexity downward, from the sixth sternocostal 

 junction to the tenth thoracic spinous process. This line crosses the mid-clavic- 

 ular line at the sixth, and the midaxillary line at the eighth rib. 



The posterior borders of the lungs are indicated by lines drawn from the level 

 of the spinous process of the seventh cervical vertebra, down either side of the 

 vertebral column, across the costovertebral joints, as low as the spinous process 

 o'f the tenth thoracic vertebra. 



The position of the oblique fissure in either lung can be shown by a line drawn 

 from the spinous process of the second thoracic vertebra around the side of the 

 thorax to the sixth rib in the mid-clavicular line; this line corresponds roughly to 

 the line of the vertebral border of the scapula when the hand is placed on the top of 

 the head. The horizontal fissure in the right lung is indicated by a line drawn from 

 the midpoint of the preceding, or from the point where it cuts the midaxillary line, 

 to the midsternal line at the level of the fourth costal cartilage. 



Trachea. This may be marked out on the back by a line from the spinous 

 process of the sixth cervical to that of the fourth thoracic vertebra where it bifur- 

 cates; from its bifurcation the two bronchi are directed downward and lateralward. 

 In front, the point of bifurcation corresponds to the sternal angle. 



Esophagus. The extent of the esophagus may be indicated on the back by a 

 line from the sixth cervical to the level of the ninth thoracic spinous process, 

 2.5 cm. to the left of the middle line. 



Heart. The outline of the heart in relation to the front of the thorax (Figs 

 1216, 1218) can be represented by a quadrangular figure. The apex of the heart 

 is first determined, either by its pulsation or as a point in the fifth interspace, 

 9 cm. to the left of the midsternal line. The other three points are: (a) the seventh 

 right sternocostal articulation; (6) a point on the upper border of the third right 

 costal cartilage 1 cm. from the right lateral sternal line; (c) a point on the lower 

 border of the second left costal cartilage 2.5 cm. from the left lateral sternal line. 

 A line joining the apex to point (a) and traversing the junction of the body of the 

 sternum with the xiphoid process represents the lowest limit of the heart its 

 acute margin. The right and left borders are represented respectively by lines 

 joining (a) to (6) and the apex to (c); both lines are convex lateralward, but the 

 convexity is more marked on the right where its summit is 4 cm. distant from the 

 midsternal line opposite the fourth costal cartilage. 



A portion of the area of the heart thus mapped out is uncovered by lung, and 

 therefore gives a dull note on percussion ; the remainder being overlapped by lung 

 gives a more or less resonant note. The former is known as the area of superficial 

 cardiac dulness, the latter as the area of deep cardiac dulness. The area of super- 

 ficial cardiac dulness is somewhat triangular; from the apex of the heart two lines 

 are drawn to the midsternal line, one to the level of the fourth costal cartilage, 

 the other to the junction between the body and xiphoid process; the portion of the 

 midsternal line between these points is the base of the triangle. Latham lays 

 down the following rule as a sufficient practical guide for the definition of the area 

 of superficial dulness. "Make a circle of two inches in diameter around a point 

 midway between the nipple and the end of the sternum." 



The coronary sulcus can be indicated by a line from the third left, to the sixth 

 right, sternocostal joint. The anterior longitudinal sulcus is a finger's breadth to 

 the right of the left margin of the heart. 



The position of the various orifices is as follows: The pulmonary orifice is sit- 

 uated in the upper angle of the third left sternocostal articulation; the aortic 

 orifice is a little below and medial to this, close to the articulation. The left atrio- 

 ventricular opening is opposite the fourth costal cartilage, and rather to the left 

 of the midsternal line; the right atrioventricular opening is a little lower, opposite 



