COMPARATIVE ANATOMY OF THE MUSCULAR SYSTEM 151 



Origin, distal end of humerus; insertion, lateral surface of the ulna; action, 

 strengthens the elbow joint, which it covers, and possibly rotates the ulna. 



9. The muscles of the thigh. (Fig. 43.) 

 Rabbit: 



a) Tensor fasciae latae. The anterior half of the lateral surface of the 

 thigh is covered by a tough fascia or aponeurosis called the fascia lata. In the 

 dorsal part of this will be found a short muscle, the tensor fasciae latae, which 

 is more or less continuous with adjacent muscles. Origin, ilium; insertion, in 

 the fascia; action, tightens the fascia. 



fascia lata 



sartorius 



rectus 

 femoris 



vastus 

 lateralis 

 tensor fascia 

 latae 

 vastus 

 intermedi 

 vastus 

 medialis 

 femur 

 sartorius 

 adductor 

 longus 

 biceps 

 femoris 



semitendinosus 

 adductor 

 magnus 

 semimembranosus 



gracilis 



POSTERIOR 



membranosus 

 semitendinosus 



FIG. 43. Cross-sections through the thigh of A, rabbit, and B, cat to show the location of the 

 muscles. Black spots are nerves, small circles, blood vessels, a, greater saphencus nerve, artery, 

 and vein; b, peroneal nerve; c, tibial nerve; d, sciatic vein; e, femoral nerve, artery, and vein; /, sciatic 

 nerve. (A from Bensley's Practical Anatomy of the Rabbit, University of Toronto Press.) 



b) Biceps femoris. Slit open the fascia lata. Posterior to the fascia occupy- 

 ing the middle portion of the lateral surface of the thigh is the large biceps 

 femoris. Separate it from the muscle posterior to it which forms the posterior 

 margin of the thigh (semimembranosus). On removing the surface fascia from 

 the biceps it will be found divisible into two heads. Follow these heads dorsally 

 to their origins, clearing away the tough surface fascia. Origin of the smaller 

 anterior head, neural spines of adjacent vertebrae, of the larger posterior head, 

 ischial tuberosity; insertion, by a tendon on the kneecap and on the fascia of 

 the shank; action, abductor of the thigh and flexor of the shank. 



c) Glutens maximus. Remove the fascia over the sacral region. The 

 gluteus maximus is under the fascia, a thin muscle whose posterior part is partly 

 covered by the biceps femoris. The muscle also has an anterior part which is 

 continuous with the tensor fasciae latae. The two parts of the gluteus maximus 



