MamasHealth.com Home Muscles and Muscle Injuries Achilles Tendonitis ACL Back pain relief Back surgery Back pain treatment Bursitis Carpal tunnel Cold therapy Fibromyalgia Flexible muscles Heat cramps Hemorrhoids Hernia Hypotonia Low back pain Muscles Muscle cramp Muscle strength Muscular dystrophy Myotonic dystrophy Repetitive strain R.I.C.E Shin splints Strains and sprains Tendonitis TMJ Trigger finger Varicose veins Whiplash Links Email Mama Ergonomic products Tummy tuck surgery	Muscles There are about 650 muscles in the human body. Muscles are made of fibers that enable them to shorten and lengthen, producing movements. Tendons connect muscles to bones. Your muscles make up about one half of your body's weight. Types of Muscles There are three main types of muscles: skeletal, smooth and cardiac. Skeletal (striated) muscles move your bones. These are the muscles that we can see and feel. Skeletal muscles attach to the bones through tendons. They come in pairs -- one muscle to move the bone in one direction and another to move it back the other way. Skeletal muscles are voluntary muscles. Meaning, that you think about contracting them and your nervous system tells them to do so. Skeletal muscles can perform two types of contractions: short single contractions (twitch) and long, sustained contraction (tetanus). Smooth muscles are found in the internal organs (digestive system, blood vessels, bladder, airways and, the uterus). Smooth muscle has the ability to stretch and maintain tension for long periods of time. Smooth muscles move involuntary. You do not have to think about movement for movement to occur. Cardiac muscle is found only in your heart. Cardiac muscle is also an involuntary muscle. It can stretch in a limited way, like smooth muscle, and contract with the force of a skeletal muscle. Cardiac muscle is a twitch muscle. Muscle injuries Most common muscle injuries are strains, sprains, cramps (charley horse), and repetitive stress injury.	Featured Book Advertise on MamasHealth.com Sponsor a contest on MamasHealth.com
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