The flexor digitorum longus muscle can cause and contribute to pain in the foot that radiates into the back of the leg. It can contribute to the development of hammertoe and claw toe.
The abductor hallucis muscle is located on the bottom of the foot. It can cause pain in the ankle and heel. There is a deep aching pain in the heel and ankle when trying to rest.
The flexor digitorum brevis muscle is located on the bottom of the foot. It can cause a sharp stabbing pain in the ball of the foot that becomes a deep ache when resting.
The flexor hallucis brevis muscle contributes to pain on the bottom of the foot, just under the big toe. It can also be a factor in plantar fasciitis, hammer toe, turf toe and gout.
The adductor hallucis muscle contributes to pain in the ball of the foot just under the toes. It can be a primary contributor to plantar fasciitis.
The tibialis posterior muscle can cause and contribute to pain in the lower leg just above the heel. This pain will often extend into the heel and the bottom of the foot. The pain will sometimes extend up into the lower calf. If you have fallen arches, you should check the tibialis posterior for trigger points and tightness because dysfunction of this muscle will allow your ankles to collapse inward.
The quadratus plantae is a primary contributor to plantar fasciitis and calcaneal compartment syndrome. Pain is felt in the heel.