Describe the basic anatomy and function of the spinal cord.

Question

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Answer 1

The spinal cord is the part of the CNS within the spinal column. The spinal cord communicates with all the sense organs and muscles except those of the head. It is a segmented structure, and each segment has on each side a sensory nerve and a motor nerve. One of the first discoveries about the functions of the nervous system was that the entering dorsal roots (axon bundles) carry sensory information, and the exiting ventral roots carry motor information. The cell bodies of the sensory neurons are in clusters of neurons outside the spinal cord, called the dorsal root ganglia. Cell bodies of the motor neurons are inside the spinal cord. In the cross-section through the spinal cord, the H-shaped gray matter in the center of the cord is densely packed with cell bodies and dendrites. Many neurons from the gray matter of the spinal cord send axons to the brain or to other parts of the spinal cord through the white matter, containing myelinated axons. Each segment of the spinal cord sends sensory information to the brain and receives motor commands from the brain. All that information passes through tracts of axons in the spinal cord. If the spinal cord is cut at a given segment, the brain loses sensation from that segment and below. The brain also loses motor control over all parts of the body served by that segment and the lower ones.