Muscular System
When a muscle contracts, it pulls a tendon, which acts on the horse's bones to move them. Muscles are commonly arranged in pairs so that they oppose each other (they are "antagonists"), with one flexing the joint (a flexor muscle) and the other extending it (extensor muscle). Therefore, one muscle of the pair must be relaxed in order for the other muscle in the pair to contract and bend the joint properly. A muscle is made up of several muscle bundles, which in turn are made up of muscle fibers. Muscle fibers have myofibrils, which are able to contract due to actin and myosin. A muscle together with its tendon and bony attachments form an extensor or flexor unit.
Read more about this topic: Horse Anatomy
Famous quotes containing the words muscular and/or system:
“Intellectual tasting of life will not supersede muscular activity. If a man should consider the nicety of the passage of a piece of bread down his throat, he would starve.”
—Ralph Waldo Emerson (1803–1882)
“Intimately concerned as we are with the system of Europe, it does not follow that we are therefore called upon to mix ourselves on every occasion, with a restless and meddling activity, in the concerns of the nations which surround us.”
—George Canning (1770–1827)