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. 



rectus 

 femoris 



vastus 

 lateralis 

 tensor fasciae 

 latae 

 vastus 

 tntermedius 

 vastus 

 medial is 

 femur 

 sartorius 

 adductor 

 lougus 

 biceps 

 femoris 



serai tendinosus 



adductor 



magnus 



semimembranosus 



gracilis 



fascia lata 





sartorius 





/^^^><^\- tensor fasciae 







rectus 



— femoris 







vastus 



lateralis 





•^^-rm 



vastus 

 Y" medialis 







-I vastus 



I intermedius 



/|| 





TT femur 

 "trV- — adductor 

 U \ longus 



{ IB \ 1 



J I 





4f "w_ ^~—~ j 



~ir+— adductor 

 fi \ femoris 

 \T\ tenuissimus 



mLI biceps 

 H / femoris 







~ffj — gracilis 







se m i memb ranosus 









\bemitendinosus 



A 



B 



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 saphenous 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) Gluteus 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 



