152 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



are united by an aponeurosis. Origin, fascia of the sacrum and part of the ilium; 

 insertion, third trochanter, the small projection below the great trochanter; 

 action, abducts the thigh. 



d) Gluteus medius. The larger, thicker muscle anterior to the preceding and 

 partly covered by it. Origin, crest and anterior part of the ilium; insertion, 

 greater trochanter; action, like the preceding. When the two gluteus muscles 

 have been well separated, the origin of the tensor fasciae latae will be found on 

 the ventral edge of the gluteus medius dipping deep down to the ilium. 



e) Vastus lateralis. Cut through the fascia lata and its tensor by a longi- 

 tudinal slit extending to the knee. Under the fascia will now be seen the stout 

 vastus lateralis. Origin, greater trochanter dorsal to the insertion of the gluteus 

 medius. 



/) Vastus intermedins. This is the name given to what appears to be the 

 posterior part of the preceding muscle. It is partly separable from the vastus 

 lateralis and lies between this and the anterior head of the biceps femoris. Origin, 

 greater trochanter and surface of the femur. 



g) Rectus femoris. This is the thin muscle which is folded over the anterior 

 margin of the thigh; it extends on both lateral and medial surfaces of the thigh. 

 It originates on the ilium and the fascia lata and is fused with the fibers of 

 the tensor fasciae latae. The rectus femoris consists of two parts, the part just 

 described and a second part, which may be located as follows. Separate the 

 rectus femoris from the vastus lateralis to which it will be found slightly 

 fused, continuing this separation to the medial side of the thigh, spreading the 

 legs apart. The first part of the rectus femoris may be cut through at the 

 middle. On the medial side of the thigh internal to the first part of the rectus 

 femoris and ventral to the vastus lateralis is the second part of the rectus femoris, 

 a cylindrical muscle. Origin, ilium in front of the acetabulum. 



//) Vastus medialis. On the medial side of the thigh posterior to the first 

 part of the rectus femoris and not very well separable from it. Origin, 

 femur. 



The rectus femoris and the three vastus muscles together constitute the 

 great quadriceps femoris muscle. The origins of its several parts have already 

 been given. Insertion, on the tibia and the patella and the tendon which extends 

 over the patella; action, powerful extensor of the shank. 



i) Sartorius. The very long narrow muscle extending like a band along 

 the middle of the medial surface of the thigh. Origin, inguinal ligament; inser- 

 tion, tibia; action, adductor of the thigh, rotator of the thigh, extensor of the 

 shank. The sartorius lies between the vastus medialis and the next muscle to 

 be described, and covers some large blood vessels. 



j) Gracilis. A large thin muscle over the posterior half of the medial sur- 

 face of the thigh. Origin, pubic symphysis; insertion, fascia of the distal portion 

 of the thigh and proximal portion of the shank; action, adductor of the leg. 



