Before finishing the description of this group of muscles a very large, important ligament should be noted, which is found spread all over the abdomen of the horse. It is of a yellowish color and about one-eighth of an inch thick, attached in front to the back of the breast bone and to the pelvic bones behind. This is the first structure seen after removing the skin from the abdomen. This ligament gives great support to the organs contained in the abdominal cavity. The action, or uses, of the abdominal muscles are to support the organs contained in the abdominal cavity, to flex the back-bone and assist in passing of the feces. In the mare these muscles assist in parturition, or foaling. SHOULDER MUSCLES.--The shoulder muscles are very large and powerful. There are only three of great importance. Two situated on the outside of the scapula or shoulder blade are important, as they are muscles affected in the disease called shoulder sweeny. The other important one is that which passes down over the shoulder joint through the groove or pulley-like surface on the humerus, or shoulder bone. This is a long, powerful muscle, attached above to the lower end of the scapula, or shoulder blade, passing down through the groove mentioned, and is attached to the upper and front part of the radius or fore arm bone. Its chief point of importance rests in its action in raising the front leg, where it passes over the pulley-like surface mentioned, when it becomes injured or diseased; it is the seat of shoulder joint lameness. MUSCLES OF THE FRONT LEG.--Muscles of the front leg, from the shoulder down, are divided into two separate kinds, the extensor and flexor muscles. The extensor muscles are those which bring the leg forward. These muscles above are attached to the bones around the elbow joint, passing down in front of the arm bones. About three inches above the knee they become changed into the tendinous part of the muscles, or what is called the cords of the leg. Some of them are attached to the bones about the knee joint, while others pass over the front of the joint and are held down to their place by a band or ligament, forming a loop, as it were, for the tendinous portion of the muscle to glide into when the leg is in action. Each one of these loops through which the muscles pass are supplied with a synovial membrane to secrete the synovia, or oil, which lubricate it during action, the same as in the joint. This is a point of importance, as sometimes, on account of injury or strain of this part of the joint through which the muscles play there may be found a small, puffy enlargement containing oil secreted by the synovial membrane. This disease is called bursal enlargement.