Anatomy study note · Back
Spinal nerves
31 pairs of mixed nerves attached to the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.
Key points
- 31 pairs: C8, T12, L5, S5, Co1.
- Posterior root = sensory (with ganglion); anterior root = motor; spinal nerve and rami = mixed.
- Spinal nerve → small posterior ramus (back) + large anterior ramus.
- Cervical nerves exit above their vertebra; T/L/S exit below.
- Greater occipital nerve = posterior ramus of C2.
- Ventral root: basal-lamina neurons. Dorsal root: neural-crest ganglion cells.
- Schwann cells: neural crest.
- Dorsal root ganglion: pseudounipolar neurons, no synapses.
- Nerve: epineurium → perineurium (blood–nerve barrier) → endoneurium.
The full note in the atlas also covers
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Written from
- Snell’s Clinical Anatomy by Regions, 10th ed., ch. 2, PDF pp. 166–171, 178
- Inderbir Singh’s Human Embryology, ch. 17, PDF pp. 318, 321, 323–325
- BRS Cell Biology & Histology, 7th ed., ch. 9, PDF pp. 163–166, 166, 171–172
More from the back
- Suboccipital muscles
- Thoracic vertebrae
- Thoracolumbar fascia
- Vertebral column
- Atlas (C1)
- Axis (C2)
- Cervical vertebrae
- Deep muscles of the back
- Intervertebral discs
- Ligaments of the vertebral column
- Lumbar vertebrae
- Spinal cord
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