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sacro-sciatic ligament ; from the tuberosity of the ischium, 

 and from the fascia lata. 



Insertion. — Into the outer border of the patella, and to its 

 external ligament. 



Use. — The heads of the biceps, from having different 

 insertions, will perform different uses. The anterior, or upper 

 one, will assist the rectus and vasti in extending the thigh ; 

 but the posterior will aid in its flexion ; they will both have 

 some effect in abducting the limb, and in rotating it inwards 

 — the hock at the time turning outwards. 



SEMI-TENDINOUS AND SEMI-MEMBRANOUS. 



These are placed behind the biceps, and originate from 

 the bones of the coccyx, fascia lata, and tuberosity of the 

 ischium. 



Use. — To flex the leg and turn the stifle inwards. 



MUSCLES OF THE THIGH. 



These muscles are included between the stifle and hock ; 

 they are all fixed to the os calcis. 



GASTROCNEMIUS EXTERNUS. 



Origin. — By two heads, the outer one from a rough hol- 

 low just above the external condyle of the os femoris. 



GASTROCNEMIUS INTERNUS. 



Origin. — From a little above the external condyle of the 

 os femoris. In passing over the hock it expands, and is im- 

 planted around the summit of the os calcis ; thence it is 

 continued down the back part of the leg, and here takes the 

 name of tendo perforatus. 



Use. — To extend the hock, and to flex the fetlock and 

 pastern. 



PLANTARIS. 



A slender muscle passing along the outer and back part of 

 the thigh. 



