Trunk nerves (intercostal, sympathetic, vagus nerve)
Posterior (dorsal) spinal roots
Radices posteriores (dorsales) nervorum spinalium
- Origin
- Arise from pseudo-unipolar sensory neurons located in the dorsal root ganglion (DRG) within the intervertebral foramen
- Insertion
- Enter the posterolateral sulcus of the spinal cord to synapse in the posterior gray horn or ascend in the dorsal columns
- Function
- Exclusively sensory: conveys light touch, vibration, proprioception, pain (nociception), and temperature from the body to the CNS
- Innervation
- Somatosensory and viscerosensory afferent
- Movement & chain
- Centripetal afferent impulse propagation
- Palpation
- Assessed via dermatomal pinprick, light touch, temperature, and vibration testing
- Clinical
- Sensory radiculopathy (sciatica caused by lumbar disc herniation producing sharp radiating dermatomal pain and numbness; positive Straight Leg Raise / Lasègue sign), post-herpetic neuralgia, tabes dorsalis.
- Segmental innervation
- Spinal dermatomes C2-S5
- In clinical practice
- Performing Lasègue straight leg raise test, mapping dermatomal sensory loss, titrating neuropathic medications (gabapentinoids, SNRIs)
- Region in the model
- Trunk nerves (intercostal, sympathetic, vagus nerve)