The musculature system Phantom Riders 4-H club Kenai Peninsula, Alaska

Muscles  There are a lot of facts about how muscles work that can be hard to understand  Read all of the facts but some of the points have been re-written with more basic language. The easier language is in red.  Have fun!

Muscles make up half of the body weight. Muscles work with the skeleton (and tendons and ligaments) to move the body. (Advanced Fact) When muscles are stimulated to contract or change shape by nerve impulses from the brain, then sends nerve impulses back to brain indicating the degree of contraction so movement is smooth.

The superficial (closest to the skin) muscles

Three Basic Muscle Types 1. Smooth muscles (involuntary)  Visceral muscle  Location – Digestion system & Uterus (stomach, intestines, etc)  Prolonged activity w/o fatigue (that just means they can work for a long time without getting tired)

2. Cardiac Muscle (Involuntary Striated) - Contractions require no nerve stimulus - Rhythmic contractions with no conscious control All that means is that the cardiac muscle is found in the heart. It doesn’t require nerves with messages from the brain to work, it works all the time. Just like our hearts, horse’s hearts beat all the time.

3. Striated, Skeletal Muscles – attached to bones of skeletal system either directly or by tendons and act voluntarily. A. Bones serve as levers and muscles move the body voluntary. B. Arranged in opposite sets – one set of muscles bend the limb (flexor muscle), one set straightens the limb (extensor muscle) C. Voluntary muscles become fatigued & need short rest periods. The muscles that move the skeleton are the ones that help us move our bodies. They work with the bones and either pull or push the skeleton into action.