Skeletal muscle is a type of striated muscle which is under the control of the voluntary nervous system (SNS). These muscles (skeletal muscles) are attached to the bones by tendons so it is possible to use them in order to move the body. The movement generated by a muscle is known as its action. Skeletal muscles usually act in groups that together produce the coordinated motion of a joint. A muscle belly is a type of muscle that has a large mass of tissue in the middle of the muscle between the origin and insertion. Muscle contraction occurs when nerve impulses travel along the nerves to the muscles. An innervation can be defined as a measurable impulse from a nerve. A muscle is composed of motor units which are each constituted by only one neuron and muscle fibers that it innervates (a single neuron can innervate many different muscle fibers).
