Elbow extension involves which nerve roots and muscle?

• A. C5, C6 - biceps
• B. C6, C7, C8 - triceps
• C. C7, C8 - extensor digitorum
• D. C8, T1 - abductor digiti minimi

Answer: (B)

Elbow extension is carried out by the triceps brachii, which is innervated by the radial nerve. The motor roots that contribute to this muscle are mainly C7 and C8, with some contribution from C6. So, seeing triceps listed alongside C6–C8 aligns with the nerves that control elbow extension.

The other possibilities don’t fit because they pair the wrong muscle with elbow extension: the biceps flexes the elbow (innervated by the musculocutaneous nerve from C5–C6), extensor digitorum mainly extends the fingers (innervated by the radial nerve from C7–C8 but not responsible for elbow extension), and abductor digiti minimi is a hand muscle innervated by the ulnar nerve (C8–T1), not involved in elbow extension.