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Spinal Chords/Nerves
| Question | Answer |
|---|---|
| anatomical segmentation of the spinal cord | C7, T12, L5, S5, starts at foramen magnum, has spinal cord segments with posterior and anterior spinal nerves, and ends at conus medullaris/L2 |
| relationship between the spinal cord segments and the vertebral bodies. | pairs of spinal nerves help determine spinal segments, nerves enter through vertebral bodies and protects |
| functional significance of the cervical and lumbar cord enlargements | higher number of neurons present |
| anatomically speaking, why are the enlargements present | associated with the limbs |
| "reflex" | stereotyped response to a given sensory input |
| spinal reflex | reflex with circuitry contained within the spinal cord |
| spinal nerve - sensory | posterior horn, posterior funiculus, posterior root, PRG is primary afferent |
| spinal nerve - motor | anterior horn |
| spinal cord reflex arc | receptor, afferent neuron (sensory input) with PRG, interneuron, efferent neuron (autonomic and motor), and target organ (largely skeletal muscle - could also be glads or smooth muscle) |
| fiber types for motor axons | anterior |
| fiber types for sensory axons | posterior |
| What is the functional significance of increasing diameter and myelination? | makes processing faster |
| sensory | primary afferent - sensory info into cord, ascending tracts - info to the brain |
| efferents | lower motor neurons and autonomics - axons go to the periphery, depending tracks - instructions go to efferents |
| integrative | reflexes and program pattern generators |
| spinal cord segment | 1 pair of spinal nerves |
| spinal nerves | posterior dorsal root, anterior ventral root |
| end of cord | conus medullaris |
| 2 enlargements | cervical (brachial) plexus and lumbar (lumbosacral) plexus |
| cervical | upper back and arms |
| thoracic | middle torso |
| lumbar | butt and legs |
| rexed laminae | posterior horn is laminae I-VI (2nd layer is substantial gelatinosa) |