AKT.13 BRACHIAL FLEXORS IN PRIMATES HOWELL AND STRAUS 7 



M. biceps hrachii longum. — The single head of this biceps was 

 quite robust. It arose by a sharply defined tendon from the glenoid 

 border at the coracoid base, passed through a well-defined bicipital 

 groove, and inserted upon the radius only. There was no lacertus 

 fibrosus. 



M. coracohrachicdis, partes iiiedia et profunda. — Common origin 

 was shortly tendinous from a coracoid process that was unusually 

 long. Pars profunda was short and inserted upon the surgical 

 neck on a level with the teres major insertion, which was very 

 broad and which extended above the latissimus tendon at this point. 

 Pars media was entirely superficial to the musculocutaneous nerve 

 and was exceedingly long, inserting from the teres major practically 

 to the epicondyle. Just above the latter point the muscle divided 

 into two slips between which passed the median nerve, which then 

 continued to the entepicondylar foramen. The manner in which 

 this muscle passed upon either side of the median nerve was en- 

 countered in no other simian or prosimian dissected. 



M. hrachialis., partes lateralis et medialis. — This muscle was al- 

 most completely divisible. No part of the medial division originated 

 above the deltoid insertion and it was much smaller than the lateral 

 division, which took origin not only from the humerus but also from 

 the aponeurotic investment of the deltoid along the oblique line of 

 its insertion. Insertion of the brachialis was upon the ulna, as usual. 



No trace of an epitrochleo-anconeus was encountered. 



Tarsius (philippinensis?).— U.S.N.M. No. 218238, male, with 

 humeral length of 29 mm. ; right side. 



M. hiceps hrachii^ capita longv/m et hreve. — These heads had the 

 usual origins from the glenoid border and the coracoid, respectively, 

 and both inserted upon the bicipital process of the radius; but they 

 were entirely separable throughout their length. The same condi- 

 tion was encountered in Tarsius saltator (Johns Hopkins Anat. No. 

 169, female). Distally the long head was situated fairly anterior to 

 the short one (there was no twisting), and the insertion of the latter 

 was slenderly tendinous, but the former was chiefly fleshy and was 

 the broader throughout its length. There was no sign of a lacertus 

 fibrosus. 



M. coracobrachialis., partes profumda et media. — The pars pro- 

 funda may be said to have had no connection with the common 

 coracoid tendon but arose independently and fleshily from the 

 coracoid, thence extending directly to the surgical neck of the 

 humerus and inserting as far as the distal border of the teres major 

 tendon (in this animal quite separate from the latissimus tendon) 

 and entirely deep to the tendon. The pars media split cleanly from 

 the biceps breve some 6 mm. from the origin. The musculocutaneous 



