Extrafusal muscle fiber Extrafusal muscle fiber Extrafusal muscle fibers are the skeletal standard muscle fibers that are innervated by alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement. They make up the large mass of skeletal muscle tissue and are attached to bone by fibrous tissue extensions (tendons). Each alpha motor neuron and the extrafusal muscle fibers innervated by it make up a motor unit. The connection between the alpha motor neuron and the extrafusal muscle fiber is a neuromuscular junction, where the neuron's signal, the action potential, is transduced to the muscle fiber by the neurotransmitter acetylcholine. Extrafusal
Trapezium (bone) tubercle found on the anterior surface of the bone. It is where sometimes abductor pollicis brevis muscle attaches. The carpal bones function as a unit to provide a bony superstructure for the hand. The trapezium is the most radial of the bones surrounding the carpal tunnel. It is important in thumb movement. The trapezium is susceptible to arthritis at the joint with the metacarpal bone of the thumb, due to overuse. The etymology derives from the Greek "trapezion" which means "a little table", from "trapeza" meaning "table", itself from "(te)tra-" "four" and "pod-" "foot". The bone was first documented in