398 JAMES CRAWFORD WATT 



Between the upper and middle portions runs the musculo- 

 cutaneous nerve, but there is no perforation of the lower part 

 of the muscle by the brachial artery and median nerve, as occurs 

 when the muscle extends as far as the medial epicondyle of the 

 humerus. The medial edge of the upper third of the muscle is 

 connected with the deep surface of the pectoralis major by a 

 muscular band. 



MUSCLES OF THE UPPER ARM 



Biceps hrachii (figs. 7 and 8, Bi) 



Origin. The long head arises normally from the supragle- 

 noid tubercle of the scapula. Its tendon is very thin and 

 narrow. 



The short head is fleshy and heavy, arising by a broad tendon 

 from the coracoid process and the capsule of the shoulder joint, 

 the muscle formed by this head overlapping that of the long 

 head. 



In addition to these two heads two accessory heads are pres- 

 ent on the lateral side, arising from the deep surface of the 

 tendon of the pectoralis major and joining the long head at the 

 level of the bicipital groove. On the lateral surface of this 

 united bundle comes in a tough short tendon from the deltoid 

 tubercle and under the long head there is also a distinct bundle 

 arising from the shaft of the humerus to join the long head. 

 There are thus seven distinct origins for this muscle. All these 

 abnormalities have been noted by Le Double though some of them 

 are extremely rare. 



Insertion. The greater part of the muscle passes into a tough 

 cylindrical tendon passing to the bicipital tubercle on the 

 radius. 



This is a second tendon, however, passing from the super- 

 ficial and medial aspect of the muscle, as a broad fiat band 

 with diverging crescentic edges. It is attached to the ante- 

 rior surface of the medial epicondyle of the humerus, and to the 

 shaft of the radius in front of and beyond the bicipital tubercle. 

 Between these two points the inferior border of this aponeurosis 



