PHS 3341 Lecture 13: Muscle Structure and Function Part 2
7 Dec 2016
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Document Summary
Skeletal muscles are innervated by motor neurons of the somatic nervous system. Axons of these neurons travel in nerves and then branch profusely as they enter muscles. A neuromuscular junction (nmj) is the point of contact between a motor neuron and the muscle fiver it innervates. It occupies ~0. 01% of the muscle fiber"s surface area. As a rule each muscle fiber is innervated by a single axon and has only one. Nmj, located approximately midway along the fibers length. The muscle fiber will grow out from here during development. The axon terminal with synaptic vesicles that contain acetylcholine (ach. ) The axonal endings lie in a shallow trough on the muscle fiber surface. Have active zones where the synaptic vesicles are contained. The motor end plate - a specialized part of the sarcolemma (highly folded) that contains ach receptors. Though exceedingly close, axonal ends and muscle fivers are always separated by a space called the synaptic cleft.
