Peroneus Tertius: Pain Pattern and Treatment
The peroneus tertius is a small muscle on the outer front of the shin, beside the long toe extensors, whose tendon runs in front of the outer ankle to the outer edge of the foot. It lifts the foot and turns it outward. Its documented pattern has two spots: the front and outside of the ankle, and the outer heel. It is a muscle behind an ankle sprain that never fully healed, and behind an ankle that keeps turning. Not everyone has it. This is a sub-page of the peroneal group page.
Attachments and action
Origin: The lower third of the front of the fibula and the adjacent interosseous membrane.
Insertion: The top of the base of the fifth metatarsal.
Action: Dorsiflexion of the ankle and eversion of the foot; it is a variant muscle, absent in some people.
Where the pain is felt: At the front of the ankle and just in front of the outer ankle bone. At the outer heel, behind and below the outer ankle bone. An ankle that feels weak and turns easily.
Common causes: An ankle sprain, above all; walking or running on a slope; high heels; a foot that rolls out; a long period in a boot or cast; hiking on rough ground; a habit of sitting on the feet.
Patients say: "My ankle sprain never healed." "Front of the ankle and the outside of my heel, both." An ankle that gives out on uneven ground. "The X-ray and the MRI of the ankle were fine."
When to get evaluated: Ankle pain after a twist with an inability to take four steps, or with tenderness on the ankle bones themselves, needs an X-ray first. An ankle that stays swollen and unstable after a sprain needs assessment for a ligament tear. A hot, red, swollen ankle with fever needs medical evaluation.
How this muscle is examined and treated
Examination tests lifting the foot and turning it outward against resistance, then presses the small muscle on the outer front of the lower shin for the point that reproduces the front-ankle and outer-heel pain, and checks the ankle ligaments. Needling here addresses the muscle on the outer front of the lower shin. Assessment and treatment happen in the same visit.
Related conditions
Ankle & Foot PainSports & Performance InjuriesTendinitis
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