Which spinal level corresponds to ankle dorsiflexion?

Which spinal level corresponds to ankle dorsiflexion?

• A. L3
• B. L4
• C. L5
• D. S1

Answer: (B)

Ankle dorsiflexion is produced mainly by the tibialis anterior, which is innervated by the deep peroneal nerve arising from the L4 nerve root (with some contribution from L5). In neurological testing, the L4 myotome is assessed by ankle dorsiflexion strength, so this movement most directly reflects L4 integrity. If L4 is affected, dorsiflexion weakness or foot drop is likely. By contrast, plantarflexion is predominantly S1, and great toe dorsiflexion aligns more with L5, while knee extension involves L3-L4. Thus, the spinal level most closely associated with ankle dorsiflexion is L4.

Ankle dorsiflexion is produced mainly by the tibialis anterior, which is innervated by the deep peroneal nerve arising from the L4 nerve root (with some contribution from L5). In neurological testing, the L4 myotome is assessed by ankle dorsiflexion strength, so this movement most directly reflects L4 integrity. If L4 is affected, dorsiflexion weakness or foot drop is likely. By contrast, plantarflexion is predominantly S1, and great toe dorsiflexion aligns more with L5, while knee extension involves L3-L4. Thus, the spinal level most closely associated with ankle dorsiflexion is L4.