MUSCULAR SYSTEM OF THE RED HOWLING MONKEY 147 



medially between the pectineus and adductor brevis, forming a broad 

 triangular partition which is inserted by fleshy fibers on the medial 

 lip of the linea aspera, from the beginning of the medial supracondylar 

 line to the proximity of the lesser trochanter (fig. 40). The muscle is 

 very thin near its femoral insertion. The adductor longus is separated 

 from the vastus medialis in front by the thin pectineus, and from the 

 ischiofemoral part of the adductor magnus behind by the previs. 

 The medial circumflex vessels cross the upper border of the long 

 adductor as they pass to the posterior muscular compartment of the 

 thigh and separate this border from the external obturator. Sirena 

 (1871) found on the right side of one of his specimens that the adductor 

 longus was one-third narrower than the muscle in the left. 



Nerve supply: The anterior ramus of the obturator nerve. 



Function: Adduction of the thigh. 



M. adductor brevis: This is actually larger than the adductor longus 

 between which muscle and the adductor magnus it hes. The brevis 

 arises from the lower ramus of the pubis on its femoral sm-face be- 

 tween the other two adductor muscles (fig. 36). This origin extended 

 up into the body of the pubis in the female. The muscle forms an 

 anteroposteriorly compressed septum similar in appearance to that 

 of the longus and passes distomedially to be inserted on the linea 

 aspera for a longer distance than that muscle (fig. 40). Its upper 

 border is in close relation to the lower one of the quadratus femoris. 



Nerve supply: The posterior branch of the obturator nerve pierces 

 the membrane and the external obturator to reach the adductor brevis 

 ventrally and near its upper border. It supplies the muscle and 

 continues its path through the belly to innervate the ischiofemoral 

 part of the adductor magnus. 



Function: Adductor of the thigh. 



M. adductor magnus: The larger of the adductor muscles is easily 

 differentiated into two parts, the ischiofemoralis and the ischio- 

 condyloideus. The origin of the magnus is by tendinous and fleshy 

 fibers from the femoral surface of the lower ramus of the ischium 

 between the semitendinosus dorsally and the adductor brevis ventrally 

 (fig. 36). The magnus covers the beginning of the semimembranosus, 

 with which it is closely associated, and also that of the quadratus 

 femoris. Immediately after the origin, the muscle is divided into its 

 two parts which may remain narrowly apposed to each other for a 

 long distance. 



Pars ischiofemoralis is found as a large anteroposteriorly com- 

 pressed triangular muscular body between the adductor brevis and 

 the ischiocondyloideus. Its fibers form muscular bundles that can be 

 easily separated. They run toward the femur and are inserted all 

 along the linea aspera from the medial supracondyloid line to ap- 



