yOINTS AND LIGAMENTS. 27 



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

 both, except that the ulna is, compai-atively, 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 (Chap. XXIX.). 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 cofiin 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 

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

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

 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 admitting often of considerable play. Annular 

 ligaments form protecting sheaths for the passage of tendons; and interassmm 

 ligaments bind bones closely together. Besides these, we have susj>ensmy 

 and check ligaments, which, as far as we are at present concerned, are 

 respectively represented by the structures, bearing these names, which are 

 found in the legs, below the knees and hocks. 



The ligaments to which I have referred are, like tendons, composed of 

 white fibrous tissue (a variety of connective tissue, see p. 12), which is 

 hard, strong, and inelastic. YeJow ligaments are, without going into minute 

 differences, to be distinguished by the fact of their yellow colour, and by the 

 possession of considerable elasticity, which enables them to passively bear 

 weights which would otherwise fall on the muscles. A familiar instance of 

 the manner in which elastic ligaments mechanically save the expenditure of 

 muscular force, is afforded by the arrangement which keeps the claws of a 

 cat retracted without entailing exertion on the animal ; for each claw is kept 

 back by a small elastic ligament, which becomes stretched when the digits 

 of the paw are extended by their muscles. As soon as these muscles 

 cease to act, the ligaments, by their power of contraction, regain their 

 natural length and retract the claws. An enormously powerful elastic hga- 

 ment is attached to the withers, and goes straight from them, in the form 

 of a cord, to the top of the head (the bony prominence between the ears), to 

 which it is inserted. At about a third of the distance from the head to the 

 withers, a broad sheet of elastic tissue is given off from the corded portion, 



