Muscular contraction

Muscular contraction is when tension is generated by a muscle. This is generally in response to stimulation by the nervous system.

The contraction causes the muscle fibers to shorten in length, which generally shortens the length of the muscle. Depending on its configuration, contraction can also cause a muscle to thicken the way a biceps bulges when flexed. The diaphragm, being bound to both sides of the rib cage, pulls itself downward in response to its shortening length.