<P> Skeletal muscle is one of three major muscle types, the others being cardiac muscle and smooth muscle . It is a form of striated muscle tissue, which is under the voluntary control of the somatic nervous system . Most skeletal muscles are attached to bones by bundles of collagen fibers known as tendons . </P> <P> A skeletal muscle refers to multiple bundles (fascicles) of cells joined together called muscle fibers . The fibres and muscles are surrounded by connective tissue layers called fasciae . Muscle fibres, or muscle cells, are formed from the fusion of developmental myoblasts in a process known as myogenesis . Muscle fibres are cylindrical, and have more than one nucleus . They also have multiple mitochondria to meet energy needs . </P> <P> Muscle fibers are in turn composed of myofibrils . The myofibrils are composed of actin and myosin filaments, repeated in units called sarcomeres, which are the basic functional units of the muscle fiber . The sarcomere is responsible for the striated appearance of skeletal muscle, and forms the basic machinery necessary for muscle contraction . </P> <P> Connective tissue is present in all muscles as fascia . Enclosing each muscle is a layer of connective tissue known as the epimysium; enclosing each fascicle is a layer called the perimysium, and enclosing each muscle fiber is a layer of connective tissue called the endomysium . </P>

The basic structural and functional unit of skeletal muscle is the