Flexor Digitorum Longus: Pain Pattern and Treatment
The flexor digitorum longus is a deep calf muscle whose tendon runs behind the inner ankle and under the sole to the four smaller toes. It curls those toes and grips the ground at push-off. Its documented pattern is pain across the ball of the foot and into the four smaller toes, from a trigger point deep in the calf. The foot is examined and the calf is not, which is why it is missed.
Attachments and action
Origin: The back of the tibia below the soleal line.
Insertion: The bases of the distal phalanges of the second through fifth toes.
Action: Flexion of the four lesser toes at all joints; assists plantar flexion and inversion of the foot.
Where the pain is felt: Across the middle of the sole at the ball of the foot. Into the four smaller toes. Sometimes the inner ankle and the inner calf.
Common causes: Running on soft sand or uneven ground; shoes with a thin, flexible sole; gripping the ground with the toes for balance; a long period on tiptoe; a leg-length difference.
Patients say: "The ball of my foot and my toes ache after I walk." "It feels like I am walking on a stone." Toe pain that the foot X-ray did not explain.
When to get evaluated: Forefoot pain with numbness between the toes or a lump that clicks needs a Morton's neuroma assessed. Pain in the ball of the foot with swelling after a sudden increase in activity needs a stress fracture ruled out. Foot pain with numbness in someone with diabetes needs medical evaluation first.
How this muscle is examined and treated
Examination tests toe flexion against resistance, checks the sole for the referred tenderness, and presses deep through the inner calf for the point that reproduces the forefoot pain. Needling here addresses the muscle deep in the calf from the inner side. Assessment and treatment happen in the same visit.
Related conditions
Ankle & Foot PainSports & Performance InjuriesChronic Pain Patterns
This page is educational. It describes muscle referral patterns commonly associated with pain; it does not diagnose your condition. Individual patterns vary. For evaluation of your specific pain, see a licensed clinician. Seek immediate medical care for emergencies. Eugene Baek, L.Ac. · New Jersey License 25MZ00080600