MUSCULAR SYSTEM OF THE RED HOWLING MONKEY 3 



The collaboration of Drs. G. Bergold and L. Carbonell of the Institute 

 Venezolano de Investigaciones Cient'ficas, Dr. E. Mondolfi, Prof. A. 

 Bodini, Prof. M. de Montbrun, Prof. R. Bodini, and Mr. C. Sanchez 

 of the Universidad Central de Venezuela, and Mr. W. Pantin is here 

 acknowledged. Mrs. Ranice Birch Crosby, Director of the Department 

 of Arts as Applied to Medicine, Johns Hopkins University School of 

 Medicine, gave most valuable help with figures 23 and 35. Mrs. R. 

 Kimmerer, Mrs. P. Spencer, and Mrs. O. Schon helped in typing the 

 manuscript. 



Muscles of the Head 



Trigeminal Group 



M. temporalis: It is an extensive but not very thick triangular 

 muscle whose base corresponds to the linea temporalis and lambdoid 

 crest, the apex to the insertion on the mandible (fig. 1). The linea is 

 more marked in older individuals of both sexes where it is seen as a 

 long, sharp ridge extending from about the middle of the lambdoid 

 crest to the superciliary arch. Origin of the muscle is by fleshy fibers 

 from (1) the back of the orbit on the facies temporalis of the alisphenoid 

 and frontaUs. A crest which follows the sphenomalar articulation is 

 occasionally seen at the point of attachment of these fibers; (2) the 

 entire medial waU of the temporal fossa where its fibers ascend to the 

 temporal line; (3) the lambdoid crest; and (4) the cranial side of the 

 transverse root of the zygoma. Finally, (5) many bundles come from 

 the caudal half of the inner surface of the temporal aponeurosis and 

 also invade the jugal arch on its deep aspect. Anterior fibers are almost 

 vertical w^hile those of more dorsal location are increasingly obHque 

 until they become almost horizontal and forw^ardly directed when the 

 origin is from the lower part of the lambdoid crest and transverse root 

 of the zygoma. A central tendon is formed within the sagittal plane 

 of the muscle and divides it into a superficially thicker and a deep 

 thinner part. Starck (1933) says that the tendon is covered by two- 

 thirds of the fleshy mass. Insertion of the muscular fibers takes place 

 on both aspects of the coronoid process (fig. 2) and the tendon. This 

 last ends on the margins of the bony eminence. Some of the tendinous 

 fascicles continue distally as a lateral and a medial bundle attached 

 to the margins of the retromolar fossa. Starck (1933) found in three 

 specimens of A. (Mycetes) auratus {=Alouatta seniculus) that the 

 temporalis was almost twice as large in the adult male (21.0 g.) as 

 in the adult female (13.5 g.) and ten times that of the juvenile (2.1 g.). 

 Sirena (1871) remarks on the large size of the muscle in Alouattafusca. 



