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
Bertram A. Bone Atoll, Wake Island, Johnston Atoll and Palmyra Atoll. Bone was meanwhile promoted to the rank of lieutenant colonel in May 1939. In November 1939, the 1st Defense Battalion was activated in San Diego with Bone as its commanding officer. As experienced artillery officer, Bone supervised the formation and initial training. His battalion consisted of the batteries with 5"/51 caliber guns, searchlight and aircraft sound locator and antiaircraft groups with M2 Browning and M1917 Browning machine guns and were ideal for the defense of the islands from the attack from the sea and air. At the beginning of March 1940, 2nd