Patients with back pain due to lumbosacral nerve root irritation can have foot and ankle pain with weakness in dorsiflexion of the ankle. Usually, the strength of the dorsiflexor muscles are tested by pressing down on the front of the ankle and toes in order to press the foot in a downward position. The strength of the toes can be individually assessed by giving resistance to the extended toes.
Functionally, it is best to test the ankle dorsiflexor muscles by having the patient stand on one leg. The weight should be placed on the heel in order that the forefoot and toes can be raised up. The span or distance between the floor and the undersurface of the big toe can be measured and compared on both sides.
Ankle and foot dorsiflexor muscles are:
- tibialis anterior (L4, L5)
- extensor digitorum longus (L5, S1)
- extensor hallucis longus (L5, S1)
- extensor digitorum brevis (L5, S1)
All these muscles are supplied by the deep peroneal nerve. The dominant nerve root is L5 root.