68 



is diminished. The gluttsuM medius is also relatively longer than in 

 inan, and is four times as thick as the preceding musele. The glu- 

 iceus minor is narrow, long, and thin. The pyriformit is narrovver 

 than in man. The tendon of the obturator internus passes as usu^l 

 between tha gemini, of which the inferior is much the largest. The 

 obturator exteraus is considerably larger than the inlernal. The 

 quadratus Jėmoris has vcry littie of the square in its shape, beiog 

 much longer than it is broad, and becoming nan'ow and rounded at 

 its insertion. 



The biceps cniris consists of two portions, each maintaining a 

 distinct cou'se and having a distinct insertion : one of these raay 

 be termed ischiojihularis, and is inserted into the head of the^- 

 bula s the other may be termed Jemoro-Jibularis ; its insertion is 

 into the outer edge of\\\eJibula from the head to the middle of the 

 bone, and into ihe fascia in front of the leg. The semitendinosuS 

 and semimemliranosus have the šame origins as in the human sub- 

 ject, and the latter musele a similar insertion ; but the semitendino- 

 sus separates from it at the lovver part of the thigh, and continues 

 fleshy for some distance below the knee-joint; after which the ten- 

 don expands into a broad strong aponeurosis, which is attached along 

 the anterior and inner aspect of the tibia to \vithin a short distance 

 of its lower extremity. In its insertion, the semitendinosvs o( the 

 Chimpanzee approaches more nearly to the human type, being im- 

 planted by a narrower tendon in front of the tibin immediately be- 

 neath the insertion of the gracilis ; but both these museles are 

 inserted lower dovvn than in man. 



Mr. Ovven remarked, that the names of these last-mentioncd 

 museles by no means agree with the proportion of tendon found in 

 them either in the Orang or the Chimpatizee, the fleshy portion 

 being in these animals of much greater extent ; — a fact vvhich is in 

 aeeordance with a law that receives many illustrations from the 

 myology of the Orang Utan, viz. that the extent of the fleshy part 

 of a musele is in proportion to the quantity of motion it has to 

 produce : and this is generally indicated by the degree of motion 

 allowed by the structure of the joint which is the centre of the mo- 

 tion in question. Thus in the human subject it is very rare that ati 

 individual can, by the contraction of the flexors of the leg, bring 

 the heel in contact with the back of the thigh; but in the Orang 

 Utan this action is readily performed, and vvithout the slightest op- 

 position at the knee-joint. 



The tensor vagincejemoris exists distinctly in the Chimpatizee, but 

 3^0 trace of it was found in the Orang. A more povverful rotator of 

 the thigh inwards exists in both animals in a peculiar musele, which- 

 may be termed invertor Jemoris. It \vas first discovered by Dr. 

 Traill in the Chimpanzee ; and its origin, form, and insertion in that 

 animal agree with those which are met with in the Orang Utan. 

 Mr. Owen considers that from its insertion into the under and outer 

 part of the trochanter major, and consequently very near to the 

 centre of motion, it can have littie eflėct in dravving the thigh up 

 towards the body as compared with the power of the proper flexors 



I 



