A disk herniation compressing the L5 nerve root may present with weakness of which muscle?

A disk herniation compressing the L5 nerve root may present with weakness of which muscle?

• A. Anterior tibialis
• B. Gastrocnemius-soleus
• C. Extensor hallucis longus
• D. Iliopsoas

Answer: (C)

L5 radiculopathy from a disk herniation typically shows weakness in muscles that extend the toes and assist with dorsiflexion. The extensor hallucis longus is the muscle most representative of this pattern because it is primarily innervated by the L5 nerve root and is responsible for extending the big toe (great toe) and aiding dorsiflexion. When the L5 nerve is compressed, weakness of the extensor hallucis longus is expected, whereas ankle plantarflexion (gastrocnemius-soleus) is mainly S1, hip flexion (iliopsoas) is mainly L2-L3, and anterior tibialis weakness can occur with L4-L5 involvement but is less specific to L5. Thus, weakness of the extensor hallucis longus best fits L5 nerve root compression.

L5 radiculopathy from a disk herniation typically shows weakness in muscles that extend the toes and assist with dorsiflexion. The extensor hallucis longus is the muscle most representative of this pattern because it is primarily innervated by the L5 nerve root and is responsible for extending the big toe (great toe) and aiding dorsiflexion. When the L5 nerve is compressed, weakness of the extensor hallucis longus is expected, whereas ankle plantarflexion (gastrocnemius-soleus) is mainly S1, hip flexion (iliopsoas) is mainly L2-L3, and anterior tibialis weakness can occur with L4-L5 involvement but is less specific to L5. Thus, weakness of the extensor hallucis longus best fits L5 nerve root compression.