Types of muscle

As in all vertebrates, horses have three types of muscle:

Build of skeletal muscle

Skeletal muscle is made up of several muscle bundles, which in turn are made up of muscle fibers. Muscle fibers have bundles of myofibrils, which are all parallel to one another, and are able to contract due to actin and myosin. Muscle is covered by a fibrous tissue called fascia, to which other muscles can attach, and muscles attach to bone via tendons.

Tendons of the lower leg

Tendons attach muscles and bone, and are classified as flexors (flex a joint) or extensors (extend a joint). However, some tendons will flex multiple joints and extend another (the flexor tendons of the hind limb, for example, will flex the fetlock, pastern, and coffin joint, but extend the hock joint). In this case, they are classified according to whether they flex or extend the joints of the digit. The following tendons are the main tendons found in the lower leg. When they pass over a joint, they are protected in a tendon sheath, which contains synovial fluid as a lubricant.

Main skeletal muscles of the horse

Muscles of the neck, shoulder, chest, and back

Muscles of the tail

The Coccygeus, Intertransversal caude, Sacralcoccygeus ventralis, Sacral coccygeus dorsalis, Sacral coccygeus lateralis, Sacro-coccygeus ventralis raise and move the tail.

Muscles of the forelimb

Muscles of the hindquarters and lower hindleg

Equine muscular disorders

Sources

Riegal, Ronald J. DVM, and Susan E. Hakola DVM. Illustrated Atlas of Clinical Equine Anatomy and Common Disorders of the Horse Vol. II. Equistar Publication, Limited. Marysville, OH. Copyright 2000.