The C7 nerve root controls which movement pattern?

The C7 nerve root controls which movement pattern?

• A. Elbow flexion, wrist extension
• B. Elbow extension, wrist flexion
• C. Shoulder abduction
• D. Finger flexion

Answer: (B)

Nerve root myotomes map specific muscle actions to each root level, so you can tell which movements are most affected when a root is irritated or compressed. For the C7 root, the main motor pattern involves elbow extension and wrist flexion. Elbow extension is carried by the triceps, which is innervated primarily by C7 (with some C6-8 contribution), so the ability to straighten the elbow against resistance points to C7. Wrist flexion relies on flexor muscles such as the flexors digitorum profundus and flexor carpi ulnaris, which are notably influenced by C7 as well. This combination—elbow straightening and wrist bending—best fits the C7 distribution. In contrast, elbow flexion is more typical of C5–C6, shoulder abduction is C5, and finger flexion aligns with C8–T1, so they don’t match the C7 pattern as closely.

Nerve root myotomes map specific muscle actions to each root level, so you can tell which movements are most affected when a root is irritated or compressed. For the C7 root, the main motor pattern involves elbow extension and wrist flexion. Elbow extension is carried by the triceps, which is innervated primarily by C7 (with some C6-8 contribution), so the ability to straighten the elbow against resistance points to C7. Wrist flexion relies on flexor muscles such as the flexors digitorum profundus and flexor carpi ulnaris, which are notably influenced by C7 as well. This combination—elbow straightening and wrist bending—best fits the C7 distribution. In contrast, elbow flexion is more typical of C5–C6, shoulder abduction is C5, and finger flexion aligns with C8–T1, so they don’t match the C7 pattern as closely.