Which movement is primarily associated with the L5 nerve root?

Which movement is primarily associated with the L5 nerve root?

• A. Great toe extension
• B. Dorsiflexion
• C. Plantor flexion
• D. Ankle inversion

Answer: (A)

Movement of extending the big toe is the best match for the L5 nerve root because the L5 myotome predominantly includes the extensor hallucis longus, the muscle that extends the great toe. In clinical exams, weakness or inability to extend the big toe strongly points to L5 involvement, making this movement the most characteristic sign of an L5 radiculopathy. Dorsiflexion involves multiple roots (primarily L4–L5) and is not as specific to L5 as great toe extension. Plantar flexion is mainly mediated by S1, and ankle inversion involves several roots with less direct, exclusive association to L5.

Movement of extending the big toe is the best match for the L5 nerve root because the L5 myotome predominantly includes the extensor hallucis longus, the muscle that extends the great toe. In clinical exams, weakness or inability to extend the big toe strongly points to L5 involvement, making this movement the most characteristic sign of an L5 radiculopathy.

Dorsiflexion involves multiple roots (primarily L4–L5) and is not as specific to L5 as great toe extension. Plantar flexion is mainly mediated by S1, and ankle inversion involves several roots with less direct, exclusive association to L5.