The-Spinal-Cord - In addition to relaying information to...

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1 •In addition to relaying information to and from the brain, the spinal cord integrates an processes information on its own. i.e.- A reflex controlled in the spinal cord, not in the brain, makes you drop a scalding-hot frying pan after you have accidentally grabbed it. Gross Anatomy of The Spinal Cord (SC) the spinal cord’s major contributions are: 1. it conducts PNS sensory data to the brain & motor response info to the PNS 2. It is capable of making decisions which are collectively known as spinal reflexes The SC is structurally & functionally integrated w/ the brain Anatomy •SC is 45 cm (18 in) long; max width of 1.4 cm (½ in) •There is a groove along the dorsal and anterior surfaces •The amount of gray matter is largest in the sections of the SC that deal w/ sensory and motor control in the limbs. These areas of the spine are enlarged. Cervical Enlargement innervates shoulder girdle & upper limbs and the Lumbar Enlargement innervates the pelvic girdle & lower limbs. •The entire spine can be divided into 31 segments based on origin of spinal nerves (similar to vertebral labels) C 3 is 3rd cervical segment, etc. •Each segment is associated w/ a dorsal root, dorsal root ganglion, and ventral root. Contents Dorsal root ganglion : neuron cell bodies Dorsal root : sensory axon/dendrites Ventral root : motor axons Dorsal & ventral root ganglia join distally to form spinal nerves. Spinal nerves are classified as mixed nerves , because they contain both afferent (sensory) and efferent (motor) fibers
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2 •Cervical series spinal nerves take their names from the vertebra that follows them, except SNC 8 (there are only 7 cervical vertebrae) •Thoracic, lumbar & sacral spinal nerves take their name from the vertebra that immediately proceeds them them. •The SC elongates until age 4, when the spine keeps growing, but the SC does not! *This is why they can do a spinal tap…… •The actual solid spine ends at L 1 , the rest of the spinal nerves are filaments that hang down and resemble a horse’s tail, so they were given the name cauda equina .
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