Case Study 1
A Case of Spinal Cord Injury
1. Describe the functional anatomy of the spinal cord using the following terms: white matter, gray matter, tracts, roots, and spinal nerves.
The spinal cord is a cylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull. (p. 481) The spinal cord, like the brain consists of two kinds of nervous tissue called gray and white matter. (p. 482) Gray matter is located deep to the white matter and forms an “H” pattern. White matter is on the periphery of the spinal cord. The gray matter is dull because it contains little myelin. It contains the somas, dendrites, and proximal parts of the axons and neurons. It is the site of synaptic contact between neurons, and therefore the site of all neural integration in the spinal cord. The white matter has an abundance of myelin which gives it it's pearly white appearance. It is composed of bundles of axons, called tracts, that carry signals and allow communication between different levels of the spinal cord.
5. Define the terms dermatome and myotome and explain how each relates to SCI.
Dermatomes show the relationship between a spinal nerve and the skin and myotomes show the relationship between a spinal nerve and muscle. Each spinal nerve (except C1) receives sensory input from a specific area of skin called a dermatome. A dermatome is an area of skin in which sensory nerves derive from a single spinal nerve root. There are 31 segments of the spinal cord, each with a pair (right and left) of ventral (anterior) and dorsal (posterior) nerve roots that innervate motor and sensory function, respectively. (http://emedicine.medscape.com/article/1878388-overview) A dermatome map is used to show how each zone of the skin is innervated by sensory branches of the spinal nerves. Viruses that lie dormant in nerve ganglia (for example the varicella zoster virus, which causes both chickenpox and herpes...
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