Accessory muscles of the ankle are muscular anatomical variants that are usually asymptomatic but rarely cause symptoms or might be encountered on imaging studies.
The following accessory muscles around the ankle have been described 1-4:
- posteromedial/flexor compartment
- accessory flexor digitorum longus muscle (deep to the flexor retinaculum)
- accessory soleus muscle (superficial to the flexor retinaculum)
- peroneocalcaneus internus muscle (rare, deep to the flexor retinaculum)
- tibiocalcaneus internus muscle (unknown, deep to the flexor retinaculum)
- lateral/peroneal compartment
-
peroneus quartus muscles
- peroneocalcaneus externus muscle
- peroneus digiti minimi muscle
- peroneus accessorius muscle
-
peroneus quartus muscles
- anterior/extensor compartment
On this page:
Radiographic features
Accessory muscles look like normal muscles in an abnormal location on imaging studies.
Radiology report
The radiological report should include a description of the following features:
- accessory muscle with location
- signs of impingement
- nerve compression syndromes
Clinical importance
Accessory muscles might mimic pathological conditions such as tumors or mass lesions.
Related pathology
Accessory muscles of the ankle have been implicated in the following clinical conditions 3,4:
- ankle impingement syndromes
- tarsal tunnel syndrome
- chronic ankle pain
- hindfoot deformity
