2oS THE ARTISTIC ANATOMY OF ANIMALS 



It is only by reason of the homology of situation with 

 the corresponding muscle in man that we give the name 

 under which we are studying it ; indeed, its structure is 

 different, for it does not present the long, broad, aponeurotic 

 tendon which, in its superior part, characterizes this muscle 

 in the human species. 



It arises above from the inferior surface of the ischium, 

 and from the tuberosity of the same bone. In the pig, 

 and especially in the horse, it passes further upwards, to 

 arise from the aponeurosis of the coccygeal muscles. So 

 that if we compare it with that of the ox, which does not 

 extend beyond the ischium, we find that it is associated 

 with the semi-tendinosus in determining the difference of 

 aspect to which we have already called attention in connec- 

 tion with the region of the pelvis situated below the root of 

 the tail. 



The semi-membranosus is then directed downwards and 

 forwards, to take its place on the internal surface of the 

 thigh, where it is partly covered by the gracilis muscle. 

 It is inserted in the following manner : 



In the dog and the cat it is divided into two parts, 

 anterior and posterior. The first, the more developed, is 

 attached to the internal surface of the inferior extremity 

 of the femur ; the second to the internal tuberosity of the 

 tibia. 



The same arrangement occurs in the ox. 



In the horse it is inserted into the internal surface of the 

 internal condyle of the femur. 



The semi-membranosus is an extensor of the thigh when 

 it takes its fixed point at the pelvis ; it is also an adductor 

 of the lower limb. If it takes its fixed point below it assists 

 in the action of rearing. 



It is now necessary for us, especially as regards the horse, 

 to add some indications relative to the exterior forms of 

 the region constituted by the semi-membranosus and semi- 

 tendinosus. These two muscles form, by their union, a 

 surface contour, slightly projecting and of elongated form, 

 which occupies the posterior border of the thigh, the 

 contour corresponding to the region known as the hutiock, in 



