A muscle is a bundle of contractile cells, or muscle fibers, that allows movement in
humans and other animals. In the body, there are three types of muscle:
Muscular tissue structural varies according to its function. Smooth muscle (A), made up of individual strands (1), has an inner layer of circular muscles (2) effecting contraction and an outer layer providing a wave-like motion (3). Cardiac muscle (B) in the wall of the heart (4) has branching fibers (5). Skeletal muscle (C) is arranged in fiber bundles (6) for versatile function. Each fiber has myofibrils distributed within it (7).
• muscle contraction
• muscular system