ANATOMY OF THE DRILL. 



431 



lingual avtery and brandies of glosso-phai-yngeal nerve as in Man, 

 and the well-marked submaxillary gland lies on its surface. It is 

 united to its fellow to form one sheet. It is continuous with the 

 sterno-hyoid. 



The pectoralis major (text-fig. 10 A) is strong and complex, and 

 consists of several parts. The first is strong and thick, and 

 arises from the margin of the sternal end of the clavicle, the 

 entire length of the sternum, the inner ends of the costal cai-ti- 

 lages, and the aponeurosis over the rectus abdominis in the infra- 

 sternal fossa. Its sujDerficial fibres fuse with those of the deltoid. 



Text-fioure 10. 



Muscles of the slioulder-girdle. A : superficial aspect ; H : the humerus on section 

 across the pectoral crest ; C : structures under the pectoralis major and deltoid 

 CM : cleido-mastoid; P.M : pectoralis major ; Su.M : subclavius; T : trapezius ; 

 T.A: thoracic axis artery; C.V : cephalic vein; CI: clavicle; D.F : deep 

 fascia ; R.I : first rib ; T.M : teres major ; L.H.B : long head of biceps ; P.C : 

 pectoral crest. 



The second part covers the inner part of the chest-wall and part 

 of the external oblique aponeurosis, and joins the deep aspect of 

 the first part which is inserted into the capsule of the shoulder- 

 joint and the prominent pectoral ridge on the humerus. A third 

 part arises from the second, third, fourth, and fifth costal carti- 

 lages and intercostal muscles in the intervening spaces, and is 

 inserted into the capsule of the shoulder-joint and deep part of 



29* 



