32 SKETCH OF THE ANATOMY OF THE HORSE. 



upon which they rest. They form the highest point of the bony framework 

 of the croup. In the absence of a recognised popular term, we may call the 

 rearmost points of the pelvis \X-\q points of the buttock. 



The head of the thigh bone makes a ball and socket joint with the pelvis ; 

 while its lower end articulates with the tibia to form the stifle joint, in front 

 of which \hQ patella (knee cap) is placed. The patella serves for the attach- 

 ment of muscles which extend the stifle joint. It is kept in position by 

 strong ligaments. A portion of the thigh bone projects, from the outside, 

 above the hip joint. The tibia articulates, at one end, with the thigh bone ; 

 and at the other, with the astragalus, which is one of the bones of the hock. 

 The part of the astragalus which makes a joint with the tibia, is formed 

 like a pulley, the grooves of which have an outward and forward direction. 

 The OS calcis is placed behind the astragalus, and projects above it; its 

 summit being called the point of the hock. The small bones of the hock are 

 interposed between the astragalus and os calcis, and the cannon-bone and the 

 two splint bones. The fibula is a rudimentary bone, which is attached to the 

 tibia, and which corresponds to the ulna. According to Chauveau, the 

 patella has no analogue in the fore extremity. The bones below the hock 

 are similar to those below the knee. 



Analogies between the bones of man and the horse. — The horse possesses no 

 collar bone, consequently there is no bony connection between his fore 

 extremity and trunk. The humerus, elbow and forearm are the same in 

 both, except that the ulna is, comparatively, far more developed in man 

 than in the horse. The knee of the latter corresponds to the wrist of the 

 former. The five bones between the wrist and the first row of knuckles are 

 represented by the cannon and splint bones ; two of these bones having dis- 

 appeared in the evolution of the horse {see Chap. XXX.). The fetlock is 

 analogous to the first row of knuckles of our hand. The long pastern bone 

 corresponds to the first row of bones of the fingers ; the short one, to the 

 second row ; the coffin bone, to the third row ; and the hoof, to our nails. 

 The navicular bone is a detached bone which has no counterpart in our 

 frame. In the hind limb, the stifle represents our knee ; the tibia, the 

 shin ; the hock, the ankle ; the point of the hock, the heel ; and so on. In 

 man, the fibula is a fully developed bone. We may thus see that the 

 horse is an animal which moves on the tips of his fingers and toes (unguli- 

 grade) ; and that he has only one toe (or finger) to each leg. 



Joints and Ligaments. — Joints may be divided into those which 

 admit of more or less motion, and those which are immovable. The ends 



