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11 Cards in this Set
- Front
- Back
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How are spinal nerves named? |
Each of the spinal nerves is designated by a letter and a number. The letter indicates the region of the vertebral column from which the nerve emerges. (C, T, L, S and Co). The number indicates the location in each region where the nerve emerges from the vertebral column, with the smallest number always representing the most superior origin. There are 31 spinal nerves; 8 cervical nerves (C1-8) 12 thoracic nerves (T1-12) 5 lumbar nerves (L1-5) 5 sacral pairs (S1-5) 1 coccygeal pair (Co). |
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What is the functional classification of all the spinal nerves? |
The functional classification of spinal nerves are based on each specific regions of the body that they supply. C1-4: head & diaphragm movement C4-7: neck & shoulder movement C5-T2: upper limp movement T1-12: rib movement in breathing, vertebral column movement, and tone in postural back muscles. T11-L2: hip movement L2-sacral nerves: lower limb movement |
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Explain the anatomy of the spinal cord |
The spinal cord extends from the brain at the level of the foramen magnum down to the level of the second lumbar vertebrae. It is composed of cervical, thoracic, lumbar and sacral segments. The spinal cord gives rise to 31 pairs of spinal nerves which exit the vertebral column through intervertebral and sacral foramina. Each spinal nerve is a bundle of axons, schwann cells and connective tissue sheaths. The spinal cord is larger in diameter toward its inferior end. Two enlargements occur where nerves supplying the upper and lower limbs enter and leave the spinal cord. |
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Anatomy of the spinal cord cont: What are the two enlargements in the spinal cord? |
The cervical enlargement in the inferior cervical region corresponds to the location where nerve fibers that supply the upper limbs enter and leave the spinal cord. The lumbosacral enlargement in the inferior thoracic, lumbar and superior sacral regions is the site where the nerve fibers supplying the lower limbs enter and leave the spinal cord. |
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Anatomy of the spinal cord cont: What is the Conus Medullaris? |
Immediately inferior to the lumbosacral enlargement, the spinal cord tapers to form a cone like region called the conus medullaris. It's tip is the inferior end of the spinal cord and extends to the level of the second lumbar vertebra. |
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Anatomy of the spinal cord cont: What is the cauda equina? |
The numerous roots (origins) of spinal nerves extending inferiorly from the lumbosacral enlargement and conus medullaris resemble a horse's tail and are therefore called the cauda equina. |
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Anatomy of the spinal cord cont: Describe a cross section of the spinal cord |
A cross section of the spinal cord consists of a superficial white portion and a deep gray portion. The white matter consists of myelinated axons which form nerve tracts and the gray matter consists of neuron cell bodies, dendrites and axons. |
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Anatomy of the spinal cord cont: What is the anterior median fissure and posterior median sulcus, columns and tracts? |
An anterior median fissure and a posterior median sulcus are deep clefts partially separating the two halves of the spinal cord. The white matter in each half of the spinal cord is organized into 3 columns/funiculi called the ventral (anterior), dorsal (posterior) and lateral columns. Each column of the spinal cord is subdivided into tracts/fasicles also referred to as pathways. |
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Anatomy of the spinal cord cont: Explain tracts, and horns |
A collection of axons inside the CNS is called a tract, whereas outside of the CNS is called a nerve. The central gray matter is organized into horns. Each half of the central gray matter of the spinal cord consists of a relatively thin posterior (dorsal) horn and a larger anterior (ventral) horn. Small lateral horns exist in the levels of the cord associated with the ANS. |
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Anatomy of the spinal cord cont: Explain gray and white commisures |
The two halves of the spinal cord are connected by structures called the gray and white commisures, which contain axons that cross from one side of the spinal cord to the other. The central canal, located in the center of the the gray commisure, helps circulate CSF. |
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Anatomy of the spinal cord cont: Explain the ventral and dorsal roots |
Spinal nerves arise from numerous rootlets along the dorsal and ventral surfaces of the spinal cord. 6-8 of these rootlets combine to form a ventral root on the ventral (anterior) side of the spinal cord. Contain the axons of MOTOR neurons. Another 6-8 form a dorsal root on the dorsal (posterior) side of the cord at each segment. Contain axons of SENSORY neurons. Spinal nerves contain both sensory and motor axons. The two roots extend laterally from the spinal cord, passing through the subarachnoid space, piercing the arachnoid mater and dura mater, and join one another to form a spinal nerve. - sensory neuron cell bodies are contained within the dorsal root ganglion (a swelling or knot). |
