MYOLOGY 69 



bone, with insertion apparently onto the proximal phalanx 

 of the thumb. 



The innervation of the smaller muscles of the hand was 

 not sought. 



MUSCLES OF THE POSTERIOR LIMB 



As the muscles of the posterior limb are the most im- 

 portant to the present paper, and serious doubt was enter- 

 tained regarding the homology of one of them, it was 

 found advisable thoroughly to investigate the innervation 

 of the hind leg. For the same reasons and because the 

 lumbar plexus was found to differ to an important degree 

 from that of the cat and man, it is here figured and will be 

 discussed. 



The nerves of the lumbar plexus pass caudad deep within 

 the psoas major, as usual. The N. femorahs arises chiefly 

 from the third lumbar nerve, but smaller branches come 

 also from the second and fourth. It is normal in extending 

 into the femoral or Scarpa's triangle and thence distad 

 upon the medial surface of the thigh, sending a small 

 branch to the pectineus. The N. obturatorius arises from 

 the second and third nerves by means of a part of the 

 femoralis, and also from the fourth, by a portion of the 

 ischiaticus. It passes to the lateral side of the pelvis 

 through the obturator foramen at its extreme cranial 

 border. The N. ischiaticus arises from the fourth and 

 fifth lumbar nerves only. It passes over the sciatic notch 

 caudad to the level of the acetabulum as usual, but sends 

 off a small branch, the N. gluteus superior, over the gluteal 

 notch of the ilium just caudad of its postero-inferior spine. 

 This penetrates the iliacus and deeper gluteal muscles. 

 The N. pudendus arises from the sixth lumbar nerve and 

 passes just mediad to the obturator intemus to the vicinity 

 of the superior tuberosity of the ischium. 



