Handout5 - HANDOUT 5 SOMATIC MOTOR SYSTEM Compared to the...

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HANDOUT 5 SOMATIC MOTOR SYSTEM Compared to the autonomic system of efferent division, somatic motor system is simple in term of: 1/ number of neurons in the pathway: all somatic motor pathways require only one neuron that originates in the CNS (cell body is in the ventral horn of the spinal cord or in the brain) and project it long, myelinated axon to the target skeletal muscle. 2/ Somatic pathways are all excitatory when autonomous pathways can either be excitatory or inhibitory. A. Somatic motor pathway 1. Structure As the axon reaches the target skeletal muscle, it branches out so that each branch can innervate one muscle fiber. Each branch ends with a cluster of enlarged terminals lying on the surface of the fiber. Each terminal participate in a synapse, called neuromuscular junction (NMJ) NMJ contains -pre-synaptic axon terminal filled with synaptic vesicles and mitochondria -extensions of Schwann cells forming a thin layer covering the top of axon terminals to support
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This note was uploaded on 10/28/2010 for the course BIPN 100 taught by Professor French during the Winter '07 term at UCSD.

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