C6 myotome is associated with which movements?

C6 myotome is associated with which movements?

• A. Knee extension
• B. Elbow flexion and wrist extension
• C. Great toe extension and hip abduction
• D. Finger abduction and adduction (interossei)

Answer: (B)

In myotome testing, each nerve root is linked to certain muscle movements. The C6 level is most clearly associated with elbow flexion and wrist extension. The biceps brachii mainly uses the C5–C6 roots to bend the elbow, while the wrist extensors (extensor carpi radialis longus and brevis) are strongly powered by C6. So asking a patient to resist elbow flexion and to resist wrist extension directly assesses the integrity of the C6 myotome. The other movements map to different roots: knee extension is controlled by L3–L4 via the femoral nerve, great toe extension by L5, hip abduction by L4–S1 via the gluteal nerves, and finger abduction/adduction by the interossei is primarily T1. Because those don’t align with C6, they’re not the best indicators of this myotome.

In myotome testing, each nerve root is linked to certain muscle movements. The C6 level is most clearly associated with elbow flexion and wrist extension. The biceps brachii mainly uses the C5–C6 roots to bend the elbow, while the wrist extensors (extensor carpi radialis longus and brevis) are strongly powered by C6. So asking a patient to resist elbow flexion and to resist wrist extension directly assesses the integrity of the C6 myotome.

The other movements map to different roots: knee extension is controlled by L3–L4 via the femoral nerve, great toe extension by L5, hip abduction by L4–S1 via the gluteal nerves, and finger abduction/adduction by the interossei is primarily T1. Because those don’t align with C6, they’re not the best indicators of this myotome.