MUSCLES OF THE POSTERIOR LIMBS. 



345 



B. The posterior portion ' (anterior portion of the lon(/ vastus of veterinary 

 anatomists), the largest of the two, is applied to the aponeuroses of the pre- 

 ceding, and extends from the sacral spine to the inferior extremity of the thigh. 

 It is prismatic, very broad at its upper end, and singularly contracted at the 

 opposite extremity. A wide and strong fibrous band, which becomes aponeurotic 

 towards the superior extremity of the muscle, covers the inner face in its inferior 

 portion. The muscular fibres appear to become longer as they are more pos- 

 terior ; all pass from the upper end to collect on the tendinous layer. 



The muscle arises, by the superior extremity of its fasciculi, on the gluteal 



fascia, sacral spine, sacro-sciatic ligament, the enveloping aponeurosis of the 



coccygeal fascia, and the ischiatic tuberosity. It terminates : 1. On the circular 



* imprint situated behind the trochanter minor, by a branch detached from the 



Fijr. 193. 



SUPERFICIAL MUSCLES OF THE CROUP AND THIGH OF THE HORSE. 



1, Middle gluteus; 2, anterior portion of the superficial gluteus; 3, tensor fascia latas ; 4, posterior 

 portion of the superficial gluteal; 5, biceps femoris; 5', semitendinosus ; 6, semimembranosus. 



deep tendon. 2. On the anterior face of the patella, along with the external 

 patellar ligament, by the inferior extremity of that tendon. 



Relations. — Externally, with the gluteal fascia, which, in being prolonged on 

 the posterior portion, increases in thickness, and becomes more or less elastic. 

 Inwardly, with the middle gluteus {ghiteus maximus), the trochanter major, and 

 deep layer of the fascia lata, which isolates it from the vastus externus ; with 

 the anterior face of the patella, on which it glides by means of a synovial bursa 

 before being inserted ; with the sciatic nerves and great adductor of the thigh. 

 By its anterior border it is closely united to the muscle of the fascia lata ; by 

 ' Lesbre proposes to name it the accessory of the superficial gluteus. 



