What are skeletal muscles composed of?

Skeletal muscles are composed of bundles of elongated, cylindrical muscle fibers. Each muscle fiber is a multinucleated cell that contains many myofibrils, which are the contractile elements of the muscle. Myofibrils are composed of actin and myosin filaments, which slide past each other during muscle contraction. The sliding of the filaments is powered by the hydrolysis of adenosine triphosphate (ATP) by myosin.

Each myofibril is surrounded by a membrane called the sarcoplasmic reticulum. The sarcoplasmic reticulum stores calcium ions, which are released into the myofilaments during muscle contraction. The release of calcium ions causes the actin and myosin filaments to slide past each other, resulting in muscle contraction.

The entire muscle fiber is surrounded by a membrane called the sarcolemma. The sarcolemma is responsible for maintaining the proper ionic environment for muscle contraction. It also contains receptors for hormones and neurotransmitters, which regulate muscle contraction.

Skeletal muscles are attached to bones by tendons. Tendons are composed of dense connective tissue that transmits the force of muscle contraction to the bones.