MYOLOGY 79 



caudo-lateral fibers of the proximal portion show a tendency 

 to be integral with the vastus lateralis. Insertion is onto 

 the proximo-cranial portion of the capsule of the knee. 



M. vastus medialis (figs. 7, 33) is located medio-caudad 

 of the rectus femoris and has origin over a small area on the 

 medial femur distad of the head. The fibers of the proximo- 

 lateral portion are with some difficulty separable from the 

 vastus femoris. Insertion is onto the capsule of the knee. 



The innervation of the four extensors of the thigh is by 

 the N. femoraHs. 



The adductors of the thigh are five, as follows: 



Mm. pectineus adductor brevis 



gracilis adductor magnus 



adductor longus 



M. pectineus (figs. 7, 32, 33) lies partly superficial upon 

 the medial aspect of the leg between the adductor longus 

 and the iliopectineal fossa or Scarpa's triangle. It has 

 origin from the pectineal process ventrad of the acetabulum. 

 Insertion is mostly fleshy upon the caudal border of the 

 femur extending from the base of the lesser trochanter for 

 almost half the length of the shaft. 



The pectineus is the only muscle of the flexor group 

 served by a branch of the N. femorahs. 



M. gracilis (figs. 7, 32, 33) arises by two heads. The 

 posterior one has fleshy origin from the caudal border of 

 the ischium, while the anterior arises from the border of 

 the pubis deep to the origin of the adductor longus. The 

 contiguous borders of the two heads fuse and the insertion 

 of the single muscle sheet thus formed is fascial upon the 

 proximo-cranial border of the tibia. 



In Teonoma both heads are broader and the origin of 

 the cranial one is to all intents entirely hidden by the 

 adductor longus. In these respects Neotoma is fairly in- 

 termediate between the other two subgenera. 



