Topic 23 (Spinal Cord)(1)

Topic 23 (Spinal Cord)(1) - BIOL 255 Topic 23 Spinal Cord...

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10/7/12 1 BIOL 255 Topic 23 Spinal Cord and Nerves Topic 23 Gross Anatomy of the Spinal Cord Spinal Cord Meninges Sectional Anatomy of the Spinal Cord Spinal Nerves • Reflexes Spinal Cord—Introduction The spinal cord provides a vital link between the brain and the rest of the body. The spinal cord and its attached spinal nerves serve two important functions: 1. a pathway for sensory and motor impulses 2. responsible for reflexes, which are the quickest reactions to a stimulus Gross Anatomy of the Spinal Cord Length: 16–18 inches Roughly cylindrical, slightly flattened posteriorly and anteriorly Two longitudinal depressions on external surface: Posterior median sulcus on posterior surface Anterior median fissure on anterior surface Gross Anatomy of the Spinal Cord Parts of the spinal cord: 1. Cervical 2. Thoracic 3. Lumbar 4. Sacral 5. Coccygeal Gross Anatomy of the Spinal Cord
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10/7/12 2 Gross Anatomy of the Spinal Cord The diameter of the spinal cord changes along its length because the amount of gray matter and white matter and the function of the cord vary in different regions. The cervical enlargement is located in the inferior cervical part of the spinal cord and innervates the upper limbs. The lumbosacral enlargement extends through the lumbar and sacral parts of the spinal cord and innervates the lower limbs. Gross Anatomy of the Spinal Cord The spinal cord is shorter than the vertebral canal that houses it. The tapering inferior end of the spinal cord is called the conus medullaris and is the official end of the spinal cord proper (usually at the level of the first lumbar vertebra). Gross Anatomy of the Spinal Cord Inferior to the conus medullaris, groups of axons called the cauda equina project from the spinal cord. Within the cauda equina is the filum terminale, which is a thin strand of pia mater that helps anchor the conus medullaris to the coccyx. Gross Anatomy of the Spinal Cord The spinal cord is associated with 31 pairs of spinal nerves that connect the CNS to muscles, receptors and glands. Each side contains: 8 cervical nerves (C1–C8). 12 thoracic nerves (T1–T12). 5 lumbar nerves (L1–L5). 5 sacral nerves (S1–S5) 1 coccygeal nerve (Co1) Spinal Cord Meninges The spinal cord is protected and encapsulated by spinal cord meninges, which are continuous with the cranial meninges. Some of the spaces between some of the meninges have clinical significance.
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