Diseases, Conditions & Concerns / Question
Published: June 11, 2002
Dear TeenHealthFX,
How does muscle really work?
Signed: Wants Info on Muscles
Dear Wants Info on Muscles,
There are more than 600 muscles in the human body. Each muscle is made up of bundles of closely interlocking muscle fibers. The contraction of skeletal muscles causes the movement of bones at joints. The two ends of a skeletal muscle are usually attached via tendons to the bones, which meet at the joint. The force that a muscle generates via its attachment depends on the number and thickness of its fibers
A contracting muscle exerts a force on bones through its connecting tendons. When the force is great enough, the bone moves as the muscle shortens. A contracting muscle exerts only a pulling force; as the muscle shortens, the bones attached to it are pulled toward each other. Flexion of a limb is its bending or movement toward the body and extension is straightening or movement away from the body. These motions require at least two separate muscles, one to cause flexion and the other extension.
Signed: TeenHealthFX
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