Which movement is primarily associated with the L4 nerve root?

Which movement is primarily associated with the L4 nerve root?

• A. Dorsiflexion
• B. Plantar flexion
• C. Great toe extension
• D. Knee flexion

Answer: (A)

Dorsiflexion of the ankle is the movement most closely tied to the L4 nerve root. The tibialis anterior, the primary muscle lifting the foot upward, is mainly innervated by L4 (with some L5 contribution). This makes dorsiflexion a classic sign of L4 involvement; weakness in dorsiflexion points toward an L4-related issue, while plantar flexion involves S1–S2, great toe extension is mainly L5, and knee flexion involves different nerve roots. So among the options, dorsiflexion best reflects the L4 distribution.

Dorsiflexion of the ankle is the movement most closely tied to the L4 nerve root. The tibialis anterior, the primary muscle lifting the foot upward, is mainly innervated by L4 (with some L5 contribution). This makes dorsiflexion a classic sign of L4 involvement; weakness in dorsiflexion points toward an L4-related issue, while plantar flexion involves S1–S2, great toe extension is mainly L5, and knee flexion involves different nerve roots. So among the options, dorsiflexion best reflects the L4 distribution.