38 SKETCH OF THE ANATOMY OF THE HORSE. 



which is one of the bones of the hock. The part of the astragalus which 

 makes a joint with the tibia, is formed hke 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 vestigial bone, which is attached to the tibia, and 

 which corresponds to the ulna of the fore leg. 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 fore- 

 arm are the same in both, except that the ulna is complete in the 

 horse, only in very rare instances. The knee of the horse corres- 

 ponds to the wrist of man. The five bones between our wrist and the 

 first row of knuckles are represented in the horse by the cannon 

 and splint bones. His fetlock is analogous to the first row of 

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

 bone of our middle finger ; the short one, to the second bone ; the 

 pedal bone, to the third bone ; and the hoof, to its nail. The navicular 

 bone 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 complete and functional toe (or 

 finger) to each leg. Some early ancestors of the horse had, like our- 

 selves, five digits (fingers or toes) on all their limbs ; these digits 

 being respectively connected with the five bones that, in their present 

 equine descendants, are represented only by the cannon-bone and the 

 two splint bones. In the higher animals, the digits are numbered 

 from within outward^. Thus, the thumb of our hand is termed the 

 first digit ; and the little finger, the fifth digit. 



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

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

 of the bones which form them are, in both cases, held together by strong 

 inelastic ligaments, of which there are various kinds. Capsular liga- 

 ments, for instance, loosely encircle their joints in order to protect the 

 apparatus which lubricates the ends of the bones. Lateral ligaments 

 are placed on each side of the joint, and, being attached both above 

 and below it, keep the bones together, while often allowing con- 

 siderable play. Annular ligaments form protecting sheaths for the 



