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
Artificial bone which is one of the most stable forms of calcium phosphate, makes up about 60 to 65 percent of the bone. The rest of the bone is composed of materials including chondroitin sulfate, keratan sulfate and lipid. Increased research and knowledge regarding the organization, structure of properties of collagen and hydroxyapatite have led to many developments in collagen-based scaffolds in bone tissue engineering. The structure of hydroxyapatite is very similar to that of the original bone, and collagen can act as molecular cables and further improve the biocompatibility of the implant. In the United States, more than 6.5 million bone