A protrusion of the intervertebral disc between C5 and C6 would affect which spinal nerve?

• A. C5
• B. C7
• C. C6
• D. C4

Answer: (C)

Discs in the cervical spine are named by the nerve that exits at that level, and a herniation tends to compress the nerve root that passes through the corresponding foramen. A protrusion between the C5 and C6 vertebrae sits right where the C6 nerve root travels, so it compresses the C6 nerve root as it exits the spinal canal. That’s why the correct nerve is the one labeled C6.

For context, a protrusion between C4 and C5 would affect the C5 nerve root, between C6 and C7 would affect the C7 nerve, and between C3 and C4 would affect the C4 nerve. Clinically, C6 involvement can present with weakness of elbow flexion and wrist extension, sensory changes on the lateral forearm, and a diminished brachioradialis reflex.