The Thorax. 119 



about one inch outside their cartilages. Landmarks for 

 the junction of the ribs with their cartilages. Draw a line 

 from a point half an inch external to the sterno-clavicular 

 articulation, downwards and outwards, to the tip of the 

 eleventh rib. (Fig. 7.) Scapula. The upper border of the 

 scapula corresponds to the upper border of the second rib, 

 or, to the tip of the first dorsal spinous process. The spine of 

 the scapula. corresponds to the tip of the third dorsal spine, 

 or, to the space between the third and fourth spines ; the in- 

 ferior angle is on a line with the lower border 

 of the seventh rib, or with the tip of the sixth 

 dorsal spine. (Fig. 8.) The tips of the spines of the dorsal 

 vertebrae, from the third to the ninth, are on a level with 

 the lower borders of the bodies of the vertebrae next below, 

 and each, roughly corresponds to the head of the rib be- 

 longing to the second vertebra below, thus the spine of the 

 third vertebra corresponds to the head of the fifth rib ; that 

 of the fourth to the head of the sixth rib, etc., whereas, 

 each tip of the spinous processes of the other vertebrae, is 

 about on a line with the lower border of the vertebra to 

 which the spine belongs. The tip of the twelfth rib, how- 

 ever, is on a level with the second lumbar spine. The relative 

 position of the intercostal vessels and nerves is, both from 

 above downwards, and from within, outwards, as follows : 

 Vein, artery and nerve. Internal mammary artery. A line 

 drawn from a point half an inch external to the sterno- 

 clavicular articulation, parallel with, and half an inch from 

 the lateral margin of the sternum and terminating about 

 the lower border of the sixth costal cartilage. (Fig. 6.) 



Deformities of the Chest. Certain effects may 

 result from the action of muscles on defective osseous tis- 

 sue, or may arise from deficient atmospheric pressure on 

 the inner aspect of the thorax, as seen in such diseased 

 conditions as rickets, chronic tonsillar hypertrophy, etc. 



