The Muscular system
The muscular system is an organ system consisting of skeletal, smooth and cardiac muscles. It permits movement of the body, maintains posture, and circulates blood throughout the body.
A skeletal muscle contains many long fibres arranged in bundles called fascicles. Each fibre consists of smaller strands, called myofibrils. These contain yet smaller parts called myofilaments. A muscle contracts when sets of these myofilaments slide past each other in response to nerve signals
By Britne pollins