^KT. 15 a:N ATOMY OF THE EARED AND EAKLESS SEALS HOWELL 71 



MU.SCLEa OF TUB IPPER AHM 



The flexors comprise two single muscles : 



M. biceps brachii (figs. T, 10, 22, 23) was single and took origin, 

 largely by tendon, from the rudimentary coracoid process upon the 

 cranial margin of the glenoid cavity. In both genera it passed 

 through the bicipital groove, between the greater and lesser tuber- 

 osities and was inserted by tendon onto the bicipital rugosity of the 

 radius. 



M. brachialis (figs. 9, 10, 20, 21, 22) was also single, with origin in 

 the Zalophus from the cranial half of the proximo-lateral shaft of 

 the humerus and from the caudo-lateral border of the deltoid ridge. 

 A few of its fibers fused with the supinator longus. In the Phoca 

 origin was from practically the whole of the lateral shaft of the 

 humerus caudad of the deltoid ridge. In both animals the muscle 

 passed deep between the supinator longus and pronator teres to 

 insert by a strong tendon upon the rugosity just distad of the lesser 

 sigmoid cavity of the ulna. Murie and Miller wrote that in EuTTie- 

 topia^ and Arctocephalus this muscle arose by two heads, the two 

 together being very similar to the one in my Zalophus. 



Murie reported a very weak coraco-brachialis in Odohenus, but I 

 am not at all convinced by his text that he was not mistaken in this. 



In contrast to the paucity of flexors, the extensors of the brachium 

 are powerful and specialized. 



M. epitrochlearis (fig. 22) (as of Reighard and Jennings, not the 

 dorsoepitrochlear of some authors) was found in the Zalophus only, 

 but neither Murie nor Miller seem to have encountered a similar 

 muscle during their dissections of eared seals, they, perhaps, having 

 considered it as integral with the triceps. It has, however, all the 

 characteristics of a normal epitrochlear as found in so many mam- 

 mals, save that the great specialization of the long triceps has caused 

 the latter to curve around partly superficial to it. It arose from 

 the fascia and connective tissue investing the medial part of the 

 triceps longus and latissimus dorsi. The fibers ceased in the fascia 

 of the ulnar border of the forearm, and thus the insertion had mi- 

 grated somewhat distad, as have so many other muscles of the 

 anterior extremity. 



The true triceiDs had best be considered as consisting of three 

 parts as usual. 



M. triceps longus (figs. 7, 10, 16, 17, 20, 21, 22, 23) in the Zalophus 

 Avas divisible into tAvo portions. The more caudal part arose from 

 the dorsal third of the slight ridge that bisects (roughly) the in- 

 fraspinous space of the scapula, and by an aponeurosis covering the 

 teres major. It passed to the olecranon, twisted in a peculiar man- 

 ner, and was attached rather lightly at this point. It was then ap* 



