Video - Skeletal muscle histology

Skeletal muscles are composed of large, elongated, and cylindrical cells that are also called muscle fibers. Each fiber has multiple nuclei in the periphery, and the capillaries that supply the skeletal muscle are typically found at the corners of the muscle fibers. Within each muscle fiber, there are myofibrils, which are long, thin structures made up of repeating units called sarcomeres.

Sarcomeres are the basic functional units of muscle contraction and are made up of thick and thin filaments that slide past each other during muscle contraction. With high-power magnification and electron microscopy, we can identify some of the different parts of the sarcomere that form the striations, such as the A band, I band, and the Z discs that run down the middle of the I bands.

Skeletal muscle fibers are surrounded by a layer of connective tissue called the endomysium and are grouped into bundles called fascicles, also surrounded by another layer of connective tissue called the perimysium. The entire muscle is surrounded by a layer of connective tissue called the epimysium.