38 SKETCH OF THE ANATOMY OF THE HORSE. 



The fore limb is drawn back, principally, by two muscles, one of which is 

 attached, at one end, to the abdominal tunic {see p. 34) and breast bone ; 

 and at the other, to the humerus and shoulder blade, close to the shoulder 

 joint. The other muscle (the latissinms dor si) has its origin on the vertebrae 

 of the loins and back, and is inserted on the humerus, which it consequently 

 draws backwards and upwards when it contracts. The first mentioned 

 muscle tends to draw it backwards and downwards. 



Muscles of the fore limb. — When the fore leg is advanced, the shoulder 

 joint is extended and the elbow joint flexed. When it is drawn back, the 

 opposite to this takes place. Agreeably to these actions, we find a powerful 

 muscle attached, by one end, to the front part of the shoulder blade, just 

 above the joint ; and by the other end to the front of the radius immediately 

 below the elbow joint, so that, when it contracts, it extends the shoulder and 

 flexes the elbow. Another muscle, being attached to the rearmost corner of 

 the shoulder blade and to the point of the elbow, flexes the shoulder and 

 extends the elbow. Besides these muscles, there are various others which 

 respectively aid in the flexion and extension of these joints. The chief 

 muscle that extends the k?iee, has its origin on the front part of the humerus, 

 just above the elbow joint, and running down the forearm, is joined to its 

 tendon, which passes over the knee, and which is inserted on the head of the 

 cannon-bone. The three muscles which bend the knee take their origin on 

 the back part of the humerus, just above the elbow joint, and are inserted on 

 the trapezium and splint bones. The two muscles which extetid the fetlock, 

 pastern, and coffin joints, run down the front of the forearm. One of them has 

 its origin at the head of the radius, and is inserted on the front part of the 

 lono- pastern bone. The other commences on the humerus, just above 

 the elbow joint, and ends on the front and upper part of the coffin bone. 

 The muscles which flex the fetlock, pastern, atid coffin joints {the flexor muscles of 

 the foot), and aid in bending the knee, take their origin on the back part of 

 the humerus, just above the elbow joint, and proceed down the back of the 

 forearm. A little above the knee they are joined to their tendons {the back 

 tendons), which pass through the sheath formed by the trapezium and the 

 annular ligament at the back of the knee. From thence they run down the 

 back of the cannon-bone. The front one, which lies next the suspensory 

 ligament, goes over the sesamoid bones, which form a pulley for it; 

 down the back of the pastern ; over the navicular bone, which also acts 

 as a pulley ; and is finally inserted on the base of the coffin-bone. The rear- 

 most tendon, which lies between the front one and the skin, forms a sheath 

 for its fellow at the back of the fetlock, and, dividing in two, is inserted on 



