A&P Chapter 13 - Spinal Cord/Nerves

  1. spinal cord
    • extension of the brain stem from foramen magnum to L1/L2 vertebrae
    • 17" long, 3/4" diameter
    • 2 enlargements: cervical and lumbar
  2. cervical enlargement
    • between C4 and T1
    • nerves for arms and hands enter/exit the cord
  3. lumbar enlargement
    • between T9 and T12
    • nerves for legs and feet enter/exit the cord
  4. conus medullaris
    tapered, inferior end of the spinal cord
  5. denticulate ligaments
    filum terminale
    • help attach cord to coccyx
    • keep cord from moving around in vertebral cavity
  6. meninges
    • group of membranes that surround and protect the spinal cord
    • dura, arachnoid, pia
  7. dura mater
    • outer membrane
    • dense irregular tissue
  8. arachnoid
    • middle membrane
    • spider web-like
  9. pia mater
    • inner membrane
    • tightly fused to cord
  10. epidural space
    • between vertebrae and dura mater
    • composed of adipose
    • protects cord
  11. subdural space
    • between dura mater and arachnoid
    • filled with CSF
  12. subarachnoid space
    • between arachnoid and pia mater
    • filled with CSF
  13. spinal cord anatomy
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  14. posterior root (1)
    contains only sensory fibers that carry sensory info into the cord
  15. dorsal root ganglion (2)
    bulge containing cell bodies of sensory neurons
  16. anterior root (3)
    caries motor impulses out to effectors
  17. spinal nerve (4)
    • mixed nerve fibers
    • start at intervertebral foramen
  18. central canal (5)
    CSF filled space that runs the length of the cord
  19. lateral gray horns (6)
    unmyelinated neurons that run up and down the cord
  20. gray commisure (7)
    unmyelinated region that connects the lateral gray horns
  21. posterior white column (8)
    anterior white column (9)
    lateral white columns (10)
    groups of myelinated neurons that run up and down the cord
  22. posterior medial sulcus
    groove that divides cord into right and left posteriorly
  23. anterior median fissure
    groove that divides cord into right and left anteriorly
  24. spinal nerves
    • groups of nerves that connect the CNS to muscle and glands (and vice versa)
    • 31 pair - named for where the exit the cord
    • exit through intervertebral foramen
    • surrounded by connective tissue membranes
  25. pairs of spinal nerves
    • 8 cervical
    • 12 thoracic
    • 5 lumbar
    • 5 sacral
    • 1 coccygeal
  26. epineurium
    membrane that covers entire nerve
  27. perineurium
    membrane that covers nerve fascicles
  28. endoneurium
    membrane that covers individual nerve fibers
  29. fascicle
    bundle of nerve fibers
  30. rami
    first division of a spinal nerve immediately after it exits the intervertebral foramen
  31. plexus
    nerves braided together
  32. ventral ramus
    • all nerves that supply arms, hands, legs, feet, lateral and ventral trunk/head
    • except for T1/T2, they form plexuses to route to structures
  33. cervical plexus
    • from C1-C4/C5
    • supplies skin and muscles of the head, neck, shoulders
    • contains phrenic nerve (diaphragm)
  34. brachial plexus
    • from C5-C8 to T1
    • supplies hands and arms
    • contains ulnar nerve (upper arm)
  35. lumbar plexus
    • from L1 to L4
    • supplies anterior and lateral abdomen, external genitalia, upper legs
    • contains femoral nerve (upper leg)
  36. sacral plexus
    • from L4/L5 to S1/S4
    • supplies buttocks, lower legs, perineum
    • contains sciatic nerve (lower leg)
  37. dorsal ramus
    supplies back of head and dorsal trunk
  38. meningeal raums
    supplies meninges, vertebrae, and spinal cord
  39. rami communicantes
    supplies all autonomic structures
  40. dermatome
    • region/band of skin that sends info to the spinal cord
    • all spinal nerves except C1 supply dermatomes
    • used mostly during anesthesia
  41. reflex
    • an automatic response to a stimulus that is usually interpreted in the spinal cord
    • 2 classes: somatic and autonomic
  42. somatic reflex
    causes muscle contraction
  43. autonomic reflex
    • smooth and cardiac muscle contraction
    • gland secretion
  44. reflex arc
    • pathway that every reflex travels
    • receptor, sensory neuron, integration center, motor neuron, effector
  45. receptor (reflex)
    1. sensory dendrite that responds to a stimulus and generates an AP
  46. sensory neuron (reflex)
    2. ascending neuron that carries AP to spinal cord
  47. integration center (reflex)
    3. region in spinal cord where incoming sensations are converted to motor responses
  48. motor neuron (reflex)
    4. descending neuron that carries AP out to muscle/gland
  49. effector (reflex)
    5. muscle or gland that responds to original stimulus
  50. five classes of reflexes
    • monosynaptic
    • polysynaptic
    • ipsilateral
    • contralateral
    • intersegmental
  51. monosynaptic reflex
    two neurons, one synapse
  52. polysynaptic reflex
    multiple neurons, multiple synapses
  53. ipsilateral reflex
    impulse enters and exits on the same side of the body
  54. contralateral reflex
    impulse enters on one side of the body and exits on the other
  55. intersegmental reflex
    incoming sensory neuron splits and synapses in different segments of the cord
  56. stretch reflex
    • aka patellar/knee-jerk
    • monosynaptic and ipsilateral
    • receptors: muscle spindle cells
    • response: extension of the leg
  57. flexor reflex
    • polysynaptic, ipsilateral, intersegmental
    • receptors: pain receptors
    • response: withdrawal of structure receiving pain
  58. golgi tendon reflex
    • polysynaptic, ipsilateral
    • when a tendon is stimulated, the attached muscle relaxes
    • prevents muscle damage
  59. crossed extensor reflex
    • polysynaptic, contralateral
    • when an unexpected or painful stimulus is received, limb withdraws and opposite limb extends
Card Set
A&P Chapter 13 - Spinal Cord/Nerves
A&P Chapter 13 - Spinal Cord/Nerves