Extensor muscles of the thigh of crab-eating monkeys (Macaca fascicularis)

On the basis of 44 hindlimbs of 11 male and 11 female crab-eating monkeys (Macaca fascicularis), the morphology of the extensor group of thigh muscles is described and some functional indices (Stern, 1971) are calculated. For the attachment and measurements of muscles, the results obtained in this study generally agreed with those of otherMacaca species and New World monkeys reported by various authors. The functional indices did not show any significant differences between the right and left hindlimbs or between male and female series, and the following facts were confirmed: the origin of m. sartorius has a more anterior attachment than is found in man and anthropoid apes; the insertion of m. sartorius has a more distal attachment than is found in man and a more proximal than is found in anthropoid apes; the m. rectus femoris has only one tendon of origin in all cases; and, the origin of m. vastus lateralis is intermediate between good leaper and slow climber types.