This simple sentence comprised Section 1 of the Equal Rights Amendment (ERA), which was first proposed in Congress by the National Women's Party in 1923.
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.
Muscle Fiber Types. Skeletal muscle fibers have metabolic and mechanical differences that allow them to be classified into different types. A motor unit, which consists of a somatic efferent neuron and all the muscle fibers it innervates, is comprised of muscle fibers that are all of the same type.hus the classification for muscle fibers also applies for motor units. Some of the different characteristics of muscle fiber (and motor unit) types are listed in the table. These are grouped in colors according to four basic features about muscle fibers.