324 



FASCIA AND MUSCLES OF THE HORSE 



Relations. —Later ally, the skin and fascia, the biceps, and the medial head 

 of the gastrocnemius; medially, the coccygeal fascia, the sacro-sciatic ligament, 

 the semimembranosus; anteriorly, the biceps femoris, branches of the femoral 

 artery, and the great sciatic nerve. 



Blood-supply.— FosterioT gluteal, obturator, and posterior femoral arteries. 



Nerve-supply. — Posterior gluteal and great sciatic nerves. 



Origin of ohliquus ab- 

 dominis intern us 

 Inguinal ligament {part 

 removed) 



Iliacus 



Tensor facia laics 



Rectus femoris 



Vastus medialls 

 Sartorius 



Gracili 



Patella 



Medial patellar li(i<iinetif ^^ 

 Tendon of smiorius 



Tendon of gracilis 



Fascia cruris 



Fig. 2S7. — Muscles of Pklvis and Thigh of Young Horse, Right Side; Medial View. 

 1, Psoas minor, and 1', its insertion; 2, psoas major; 3, 3', heads of obturator internus; 4, sacro-coccygeus ven- 

 tralis; 5, coccygeus; 6, retractor ani (cut); 7, sacro-sciatic ligament; 8, lesser sciatic foramen; 9, semimembranosus; 

 10, lumbo-sacral plexus; 11, obturator nerve and vessels (cut); 12, femoral vessels (origin) ; 13, pubis; 14, prepubic 

 tendon; 1.5, deep inguinal lymph glands; 16, opening for external pudic vein. Vertebree are numbered by regions. 



7. Semimembranosus^ (Figs. 276, 287, 288, 576).— This very large, three- 

 sided muscle lies on the medial surface of the preceding muscle and the gastroc- 

 nemius, and has two heads of origin. 



Origin. — (1) The posterior border of the sacro-sciatic ligament; (2) the ventral 

 surface of the tuber ischii. 



' This muscle was incorrectly designated the adductor magnus by Percivall and Strange- 

 ways. Its name, however, is not at all descriptive of its structure in the domesticated animals. 



