59. Spinal nerves - number, groups, formation. Functional or analysis of the spinal nerves. The spinal ganglion. Dorsal branches of the spinal nerves.

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