Peripheral Nervous System


Peripheral Nervous System, Peripheral Nerve

  • Anatomy
  1. Components
    1. Paired Cranial Nerves (12)
    2. Paired spinal nerves (31): Vertebrae imperfectly match the spinal nerve roots
      1. Cervical Nerve Roots (8)
        1. Cervical cord has 7 Vertebrae but has 8 nerve root pairs
        2. C1 exits above the C1 Vertebrae
        3. C8 exits below the C7 Vertebrae
      2. Thoracic Nerve Roots (12)
      3. Lumbosacral Nerve Roots (10)
        1. Spinal cord transitions to individual nerves below the L2 Vertebrae
        2. Analogous to the hairs of a horse (cauda equina)
      4. Coccyx (1)
  2. Spinal Levels
    1. Posterior Sensory Nerve root (dorsal root and spinal Ganglion)
    2. Anterior Motor Nerve root (ventral root)
  3. Dermatomes
    1. Sensory components are distributed along the skin in long swaths of nerve innervation