1364 



CLINICAL AND TOPOGRAPHICAL ANATOMY 



verse line at the junction of the manubrium and body of the sternum. It is well 

 always to count ribs from this point and never from below, as the twelfth rib 

 varies in size and maj^ be obscured by the sacro-spinalis muscles. The nipple 

 in the male, lies between the fourth and fifth, nearly an inch lateral to their 

 cartilages. The lower border of the great pectoral corresponds to the fifth rib. 

 The seventh, the longest of the ribs, is the last to articulate by its cartilage with 

 the sternum. When the arm is raised, the first three digitations seen of the 

 serratus anterior correspond to the fifth, sixth, and seventh ribs. The ninth rib 



Fig. 1104. — The Arch of the Aorta, with the Pulmonary Artery and Chief Branches 



OF THE Aorta. 

 (Modified from a dissection in St. Bartholomew's Hospital 

 Int. jugular v.^ 



Inferior thyreoid veins 



Transverse cervical a. 



Transverse scapular a. 



Right inf. laryng. n. 



Right com. carotid a. 



Subclavian v. 



Vagus nerve 



Innominate a.-^ ^ 

 Left innominate v. 



Phrenic nerve 



Superior vena cava 



Arch of aorta 



Right bronchus 



Branch of right pul- 

 monary a. 



Branch of right pul- 

 monary V 

 Right pulmonary a. 



Branch of right pul- 

 monary a. 

 Branch of right pul- 

 monary V. 



Right atrium 



Right coronary a. 



Thoracic vertebra 



Azygos vein 

 Intercostal vv. 

 Intercostal aa. 



Museum.) 



Thyreoid body 



Left int. jugular v. 

 Vagus nerve 

 Left com. carotid a. 

 Left inf. laryng. n. 

 Left subclavian a. 

 Lelf subclavian v. 

 Left int. mammary v. 

 Left sup. intercostal v. 

 Phrenic nerve 

 Vagus nerve 

 Recurrent n. 

 Lig. arteriosum 

 Left pulmonary a. 

 Left pulmonary v. 

 Left bronchus 



Branch of left pul- 

 monary a. 

 Pulmonary a. 



Left pulmonary v. 

 ^ ^Left coronary a. 

 Conus arteriosus 



(Esophagus 

 Thoracic duct 

 Thoracic aorta 



is the most oblique. The eleventh and twelfth can be felt lateral to the sacro- 

 spinalis. Owing to the obliquity of the ribs, their sternal ends are on a much 

 lower level than their vertebral extremities. 



'Thus the first rib in front corresponds to the fourth rib behind, the second to the sixth, 

 the third to the seventh, the fourth to the oitihth, the fifth to the ninth, tlie sixth to the tenth, 

 and the seventh to the eleventh. If a horizontal lino be drawn round the body from before back- 

 ward at the level of the inferior an^le of tlie scapula, while the arms are at the sides, the line would 

 cut the sternum in front between the fourtli and fifth ribs, the fifth rib at the nipple line, and 

 the ninth rib at the vertebral coUiinn.' (Treves.) The most frequently broken are the sixth, 

 seventh, and eighth. 'J'he upi)er four and the two lowest ribs are best covered l)y soft parts, 

 and, in the case of the former, the shoulder and arm take off sonie of the violence that would 

 otherwise reach them. The way in wliicli th(! ribs are embedded in the soft parts (fij;. 1106), 

 and the fact that the fragments are often held in place l)y the periosteum, account for the diffi- 

 culty which is often met witli in dctectinf; crejiitus. The intercostal spaces are wider in front 

 than behind. The three upper are the widest of all. 



