Spinal Cord

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Spinal Cord
2013-06-01 11:38:27

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  1. where does the spinal cord travel
    vertebral canal
  2. where does spinal cord extend in babies and adults
    • babies: extend to sacrum
    • adults: first lumbar vertebra
  3. cone shaped termination of spinal cord
    conus medularis
  4. cervical enlargement and lumbar enlargement innervate:
    uppler limb and lower limb region
  5. intervertebral foramina
    where spinal nerves exit the vertebral column
  6. bundle of spinal nerves beyond conus medularis
    cuada equina and within the nerve lies the filum terminal (extension of the pia mater)
  7. neurons that supply instruction to/from body travels within:
    spinal nerves
  8. how are spinal nerves numbered?
    according to vertebral level of which they exit. this results from difference in overall length of spinal cord and vertebral column
  9. dura mater is surround by space filled with fat
    epidural space (common site for injection of anesthetic during labor)
  10. when the dura mater extends outward around spinal nerves it becomes:
    epineurium which is the outermost layer of a nerve
  11. what are the 2 specializations of the pia
    • denticulate ligaments: anchor the spinal cord to dura mater and limit movement of spinal cord
    • filum terminale
  12. Consists of myelinated axons that are oriented vertically to communicate with higher or lower regions of CNS
    white matter is grouped into 3 columns
  13. contains unmyelinate neurons of CNS, interneurons
    gray matter. portions of sensory neurons and motor neurons reside here
  14. gray matter is organized into 3 columns
    dorsal, ventral, lateral horns
  15. at the center of the spinal cord
    the central canal is a cavity in continuity with ventricles of brain
  16. the system of neurons that bring info up to brain
    ascending pathway. here signals travel along 1st, 2nd, and 3rd order neurons
  17. spinothalamic tract ascending signal pathway
    • 1st order neuron: sensory neuron that extends from source of stimulus to dorsal horn to synapse w/ interneurons
    • 2nd: extends from dorsal horn, decuassates to contralateral side where its axons enter white matter. the axons run up to thalamus where it synapses
    • 3rd order: extends from thalamus to appropriate somatosensory cortex
  18. system of neurons that bring motor info from brain to down to appropriate spinal level
    descending pathways. signals travel along 2 pathways
  19. corticospinal tract descending pathway
    • voluntary motor commands orignate at primary motor cortex
    • upper motor neuron (pyramidal neuron) is where interneuron travels down white matter of corticospinal tract
    • decussation occurs in medulla and tract continues down spinal cord
    • at the appropriate tract the axon leaves and enters ventral horn where is synapses with lower motor neuron
    • lower motor neuron is the motor neuron of the PNS and it leaves spinal cord to innervate skeletal muscles
  20. spinal nerve forms from joining of
    dorsal and ventral root
  21. where does dorsal root carry sensory info
    dorsal horn
  22. dorsal root has large collection of cell bodies
    dorsal root ganglion.
  23. sensory neuron that have cell body in middle of course of axon
    unipolar or pseudounipolar
  24. where do neurons of ventral root have their cell bodies
    ventral and lateral horns.
  25. the axons of the ventral root are entirely
  26. carries somatic motor and somatic sensory to posterior body wall
  27. carries somatic motor and sensory to lateral and anterior body wall
    ventral ramus. also innervates the limbs
  28. carry visceral motor (sympathetic) and visceral sensory neurons to and from viscera
  29. to distribute neurons, this runs parallel to spinal cord and sends branches towards thoracic and abdominal cavities
    sympathetic trunk (chain)
  30. ventral rami travel along inferior surface of ribs
    intercostals nerves. send small branches to nearby muscle, bones, and skin
  31. ventral rami join network called
    plexus which are important for innervation of the limbs. brachial plexus: upper, lumbosacral plexus: lower
  32. involuntary circuits that doesn't involve brain
    spinal reflexes
  33. simples reflexes that involve sensory neuron and synapse with motor neuron
    monosynaptic reflex. stimulus travels along sensory neuron and has axon terminal in ventral horn where motor neurons are stimulated. stretch reflex
  34. stretch reflex causes
    contraction of same muscle leading to greater stability of joints. patellar reflex (knee-jerk)
  35. reflexes involve one or several interneurons
    polysynaptic reflex. withdrawal reflex
  36. withdrawal reflex pathway
    stimulus travels along sensory neuron that synapses with several interneurons. several sets of motor neurons are stimulated to withdraw from painful stimulus. inhibitory signals sent to muscles can oppose withdrawal.