A 45-year-old patient with cervical spondylosis at C5-C6 level presents with pain radiating down the lateral forearm and thumb, weakness of elbow flexion and wrist extension, and a diminished biceps jerk. Which nerve root is compressed?

• A C4 nerve root
• B C6 nerve root ✓
• C C5 nerve root
• D C7 nerve root

Explanation

C6 nerve root compression produces a distinct clinical pattern: pain/paresthesia in the lateral forearm, thumb, and index finger (C6 dermatome); weakness of biceps brachii (elbow flexion, also C5) and brachioradialis; diminished biceps and brachioradialis reflexes (biceps reflex is C5-C6, brachioradialis reflex is C6). C7 root compression would affect triceps (elbow extension), wrist flexors, and produce the triceps jerk deficit with symptoms in the middle finger. C5 compression causes deltoid weakness and absent biceps jerk with proximal arm symptoms.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.