Ankle: Accessory Soleus Muscle

fig. 1

What is ASM?

The accessory soleus muscle is an extra muscle belly in the calf, typically located near the soleus muscle and inserted near the Achilles tendon. An accessory soleus muscle (ASM), can sometimes be a source of pain and swelling in the ankle, potentially mimicking or contributing to Achilles tendinopathy. Diagnosis typically involves an MRI, and treatment may range from conservative management to surgical excision, especially in athletes or when conservative measures fail.

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Click the image in fig. 1 to watch a video about ASM.

Symptoms

• pain

• swelling

• numbness

• tenderness in the posteromedial ankle

Treatment

• Rest, ice, compression, elevation (RICE), pain relievers, physical therapy

• Surgical excision of the ASM, which may be necessary if conservative treatment fails or in cases of severe symptoms