508 



THE MUSCLES 



and at the bend of the elbow the median cephalic vein and brachio-radiahs; 

 deeply the humerus, the brachiahs anticus, and supinator brevis; upon its mner 

 side lie the coraco-braehialis, the brachial vessels, and the median nerve. The 

 semilunar fascia separates the median l)asilic vein from the ])rachial vessels and 

 median nerve. 



Fig. 271.— Deep View of the Froxt of the Upper Arm. 



Pectoralis minor 



Short head of biceps 



Coraeo-brachialis 



Long head of triceps 



Inner head of triceps 



Internal-intermuseular septum 



Long head of biceps 



Insertion of pectoralis major 



Insertion of deltoid 



Brachialis anticus 



Cuter part of brachialis anticus 



Insertion of biceps 



Variations.— The origin of the biceps is remarkably variable. Sometimes one of the heads 

 is deficient. More often a third liead is derived froni the middle of the inner border of the 

 liumorus, and sometimes as many as three additional heads have been found arising troni the 

 humerus. Occasionally it sends slips to the inteinal intermuscular septum, internal condyle, or 

 coronoid process. 



2. BRACHIALIS ANTICUS 



The brachialis anticus — named from its intimate relation with the front of 

 the humerus {braclii>im) — is a thick, somewhat fusiform sheet, curved from side 

 to side to fit on to the front of the humerus, and slightly bifid above. 



