ART. 13 BRACHIAL FLEXORS IN PRIMATES HOWELL AND STRAUS 23 



The muscular slip described by Fick (1925) in his chimpanzee 

 " Tschego " is very probably homologous to the muscle in our ani- 

 mal. [In Fick's animal it had a tendinous origin from the upper 

 part of the coracobrachialis (medius) and passed over the brachial 

 vessels and nerves to insert on the anterior border of the dorso- 

 epitrochlearis (sive latissimo-tricipitalis).] 



For the reason that the term " coracobrachialis longus " has been 

 so loosely and ambiguously applied, we prefer to discard this name 

 completely and to call this slip, clearly worthy of a distinctive 

 appellation, a coracobrachialis superficialis, to designate a muscle 

 from the coracoid to the medial epicondyle that bridges over and 

 passes superficial to all the brachial nerves and other muscles, except 

 tlie dorsoepitrochlearis. We can, for the present, be certain that 

 it has been found only in those mammals for which adequate illus- 

 trations have been presented, or else in those rare instances when 

 an author has stated specifically that the muscle is entirely superficial 

 to the median nerve. 



Parsons (1898) gave a considerable number of genera in which 

 he found that " the longus is best developed," but on the same page 

 mentioned that the only instance in which he had found the muscle 

 superficial to the median nerve was in the tree porcupine SphingwruSy 

 for which he gave a good illustration. Likewise Wood (1867) had 

 a figure of Ornithorhynchus^ which seems to have had a similar 

 arrangement. But the same author presented another figure in 

 which this muscle is indubitably assigned to man, in which he stated 

 that this " slip is not uncommonly found." There would seem to 

 be some serious question here. Le Double (1897) lists but one cer- 

 tain instance of its occurrence in man, and it is almost certain that 

 had it been found in any instance by a student of the department 

 of anatomy of the Johns Hopkins University Medical School dur- 

 ing the past 15 years the fact would have been called to the attention 

 of one of the staff. During this time several hundred cadavers have 

 been dissected, and no gross anatomist now on the faculty has ever 

 seen it in man. 



M. hrachialis. — Whether the ideally primitive brachialis actually 

 consisted of a single muscle going to both radius and ulna or of two 

 slips, the evidence seems to point to the probability that the condi- 

 tion of two distinct slips is more primitive than that of complete 

 fusion, as now often found in man and other mammals. The inser- 

 tion in mammals is usually upon the ulna, occasionally upon the 

 radius, and rarely on both antibrachial bones (Leche). In such a 

 basically primitive primate as Tardus there was in one specimen 

 {T. philipfinensisf) a lateral head from the surgical neck of the 

 humerus entirely distinct from a medial head, arising just distal to 



