SPINAL NERVES
- Spinal nerves emerge intermittently from the spinal cord, exiting the vertebral canal.
- There are a total of 31 pairs of spinal nerves.
- These pairs are categorized based on their locations:
- Cervical nerves (C1–C8): These exit the neck region.
- Thoracic nerves (T1–T12): They exit the torso region.
- Lumbar nerves (L1–L5): These exit the lower back.
- Sacral nerves (S1–S5): They exit from the base of the spine.
- Coccygeal nerve pair: This exits from the tailbone (coccyx).
Spinal Ganglia :
- Structure: Ganglia are oval in shape and contain neuronal cell bodies (somata), satellite cells (a type of glial cell), and a protective connective tissue layer.
- Neuron Types:
- Sensory ganglia usually contain unipolar or pseudo-unipolar neurons.
- Autonomic ganglia contain multipolar neurons.
– Can be broadly categorized into 2 groups :
- 1. Sensory Ganglia:
- Dorsal Root Ganglia: These are associated with spinal nerves. Each dorsal root ganglion is located at the proximal end of each posterior root. They contain the cell bodies of sensory nerve fibers 1.
- Sensory Ganglia of Cranial Nerves: These are found in selected cranial nerves.
- 2. Autonomic ganglia :
- Sympathetic
- Parasympathetic