Sarcomeres in Muscle Cells: Structure, Function & Number

Each skeletal muscle fiber (cell) contains many myofibrils. Each myofibril is made up of thousands of repeating units called sarcomeres. These repeating units are responsible for the contraction and relaxation of the muscle fiber. The number of sarcomeres in a muscle fiber varies depending on the size and type of the fiber. For example, a small fiber may contain only a few hundred sarcomeres, while a large fiber may contain several thousand sarcomeres.