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Nervous System

Spinal Cord

Spinal Cord Neuron and Nerve The spinal cord (Figure 04a) lies along the middorsal line of the body. It has two main functions: (1) it is the center for many reflex actions, and (2) it provides a means of commu-nication between the brain and the spinal nerves that leave the cord (Figure 04b). The white matter of the cord is white because it contains myelinated long fibers of interneurons that run to-gether in bundles call tracts. These tracts connect the cord to the brain. The dorsal ones are primarily ascending to the brain, while the ventral tracts bring information down from the brain. The inner portion of the

Figure 04a Spinal Cord
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Figure 04b CNS and PNS
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cord is filled with a mass of nerve cell bodies called gray matter. Each spinal nerve emerges from the spinal cord as two short branches, the dorsal and the ventral roots. These roots join just before the nerve leaves the vertebral column.

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