L5 radiculopathy would typically present with weakness in which movement?

L5 radiculopathy would typically present with weakness in which movement?

• A. Weakness of dorsiflexion of the foot and great toe extension
• B. Weakness of plantarflexion of the foot
• C. Weakness of knee extension
• D. Loss of sensation on the plantar surface of the foot

Answer: (A)

L5 radiculopathy disrupts the muscles that lift the foot and extend the big toe. The L5 nerve root supplies muscles like the tibialis anterior and extensor hallucis longus (and extensor digitorum longus), which produce dorsiflexion of the foot and extension of the great toe. When this root is affected, you typically see weakness in these movements, often described as foot drop and difficulty extending the big toe. In contrast, plantarflexion is mainly controlled by S1 via the gastrocnemius/soleus, knee extension by L3–L4 via the quadriceps, and plantar surface sensation by S1–S2, so those do not align with L5 radiculopathy. Thus, weakness in dorsiflexion and great toe extension best fits an L5 radiculopathy.

L5 radiculopathy disrupts the muscles that lift the foot and extend the big toe. The L5 nerve root supplies muscles like the tibialis anterior and extensor hallucis longus (and extensor digitorum longus), which produce dorsiflexion of the foot and extension of the great toe. When this root is affected, you typically see weakness in these movements, often described as foot drop and difficulty extending the big toe. In contrast, plantarflexion is mainly controlled by S1 via the gastrocnemius/soleus, knee extension by L3–L4 via the quadriceps, and plantar surface sensation by S1–S2, so those do not align with L5 radiculopathy. Thus, weakness in dorsiflexion and great toe extension best fits an L5 radiculopathy.