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CNS & PNS

CNS & PNS. Nerves, pathways. CNS Brain, spinal cord Processing center Nuclei PNS Spinal and cranial nerves Information relay system ganglia. Meninges (spinal cord). Dura mater: outer layer Subdural space; Serous fluid (lubricant) Arachnoid mater:

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CNS & PNS

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  1. CNS & PNS Nerves, pathways

  2. CNS • Brain, spinal cord • Processing center • Nuclei • PNS • Spinal and cranial nerves • Information relay system • ganglia

  3. Meninges (spinal cord) • Dura mater: outer layer • Subdural space; Serous fluid (lubricant) • Arachnoid mater: • Subarachnoid space (between arachnoid and pia) filled with CSF & blood vessels • Pia Mater: inner layer • Shrink wrapped to spinal cord & brain

  4. Spinal cord anatomy • Gray matter: cell bodies & unmyelinated axons • White matter: Myelinated axons

  5. Organization • Dorsal = Sensory • Ventral = Motor

  6. Ascending sensory tracts

  7. Ascending somatosensory pathway • Crossover in MO, to opposite side of body • Synapse in thalamus • Projection to cerebral cortex

  8. Sensory tracts

  9. Descending motor tracts

  10. Descending Motor pathway • Project from motor cortex • Crossover @ lower MO • Synapse in spinal cord • Project to effector

  11. Motor tracts

  12. Neural pathways From brain To brain

  13. Spinal reflexes • Sensory & motor nerves - where are they? • Somatic - skeletal • Visceral - smooth, cardiac, glands

  14. Reflex Arc

  15. Withdrawl reflex

  16. Disorders • Paralysis - Some amount of loss of sensation or motor ability (long- or short-term); associated with spinal injury or infection • Neuritis - Inflammation of a nerve, due to trauma or infection • Prolonged swellings leads to loss of sensory or motor function

  17. Disorders • Sciatica - Intense pain (neuralgia) along sciatic nerve • Often caused by herniated lumbar disc (fibrocartilage) putting pressure on lumbosacral spinal nerves • Herpes virus - resides in ganglia of sensory nerves; produces lesions at nerve endings • Herpes zoster - chicken pox/shingles virus • Genital herpes

  18. Nerves of PNS • Cranial nerves: 12 • Spinal nerves: 31 • Collected in plexuses • Convergence & divergence of nerve tracts

  19. Divisions of PNS • Somatic • Voluntary • Autonomic • Visceral (involuntary)

  20. Autonomic division differences

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