BIO304H5 Study Guide - Final Guide: Myocyte, Motor Neuron, Motor Unit
Document Summary
Effective animal movement requires that the contraction of many fibers within a muscle- and of many muscles within the body be correctly timed with respect to one another. This coordination is generated within the nervous system, as most muscles contract only when aps arrive at the nmj. In addition to controlling the timing of contractions, the ns also regulates their strength by selecting among diff fiber types and by determining how many fibers will be active simultaneously. Several means for achieving fine control of muscle contraction have arisen during the course of evolution. The axon of a spinal motor neuron leaves the spinal cord thru a ventral root, continues to the muscle by the way of a peripheral nerve, and finally branches repeatedly to innervate skeletal muscle fibers. A single motor neuron may innervate only a few fibers or a thousand more. However, in vertebrates, each muscle fiber receives input from only 1 motor neuron.
