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 extensor hallucis longus muscle contributes to and can cause pain and/or numbness in the top of the foot, pain in the big toe, and foot cramps at night. It is a contributor to hammertoe and claw toes.
The extensor digitorum longus contributes to pain in the top of the foot. It contributes to hammertoe, claw toe, and foot drop.
The plantaris muscle is a very small muscle located behind the knee. It contributes to pain behind the knee and is occasionally involved in cramps in the calf.
The gastrocnemius muscle is a prime contributor to pain in the back of the knee. It can contribute to lower leg, ankle, and arch pain.
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.