Striated muscle fiber, also known as skeletal muscle fiber or voluntary muscle fiber, is a specialized type of muscle cell found in the skeletal muscles of animals, including humans. It is responsible for the movement of the body and the maintenance of posture.
The term "striated" refers to the appearance of alternating light and dark bands, or stripes, that are visible under a microscope. This distinct pattern is due to the arrangement of contractile proteins within the cell, specifically myosin and actin, which are responsible for muscle contraction. These proteins form overlapping filaments that create the striated appearance.
Each striated muscle fiber is a long cylindrical cell with multiple nuclei. It is composed of smaller units called myofibrils, which are the functional units of muscle contraction. Myofibrils consist of repeating units called sarcomeres, which are linked end-to-end to form the length of the muscle fiber.
Striated muscle fibers are considered voluntary muscles because their contraction is under conscious control. When stimulated by nerve impulses from the central nervous system, the muscle fiber undergoes a process called the sliding filament theory, in which actin filaments slide over myosin filaments, causing the sarcomeres to contract and generate force. This mechanism enables the muscle fiber to pull on its attachments, such as bones, and create movement.
Overall, the striated muscle fiber plays a crucial role in the body's ability to move, maintain posture, and perform various physical activities.
