Accessory muscles of the ankle

Changed by Joachim Feger, 28 Dec 2021

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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
anterior/extensor compartment
- peroneus tertius muscle (very common)
- extensor hallucis capsularis tendon
- anterior fibulocalcaneus muscle (rare)
- accessory extensor digiti secundus muscle (rare)
- tibioastragalus anticus of Gruber muscle (rare)

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 tumours or mass lesions.

Related pathology

Accessory muscles of the ankle have been implicated in the following clinical conditions ^3,4:

-</ul><h4>Clinical importance</h4><p>Accessory muscles might mimic pathological conditions such as tumours or mass lesions. </p><h4>Related pathology</h4><p>Accessory muscles of the ankle have been implicated in the following clinical conditions <sup>3,4</sup>:</p><ul>
+</ul><h4>Clinical importance</h4><p>Accessory muscles might mimic pathological conditions such as <a title="Tumours" href="/articles/neoplasm-2">tumours</a> or mass lesions. </p><h4>Related pathology</h4><p>Accessory muscles of the ankle have been implicated in the following clinical conditions <sup>3,4</sup>:</p><ul>

References changed:

1. Aparisi Gómez M, Aparisi F, Bartoloni A et al. Anatomical Variation in the Ankle and Foot: From Incidental Finding to Inductor of Pathology. Part I: Ankle and Hindfoot. Insights Imaging. 2019;10(1):74. <a href="https://doi.org/10.1186/s13244-019-0746-2">doi:10.1186/s13244-019-0746-2</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/31363861">Pubmed</a>
2. Sookur P, Naraghi A, Bleakney R, Jalan R, Chan O, White L. Accessory Muscles: Anatomy, Symptoms, and Radiologic Evaluation. Radiographics. 2008;28(2):481-99. <a href="https://doi.org/10.1148/rg.282075064">doi:10.1148/rg.282075064</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/18349452">Pubmed</a>
3. Cheung Y. Normal Variants. Magn Reson Imaging Clin N Am. 2017;25(1):11-26. <a href="https://doi.org/10.1016/j.mric.2016.08.002">doi:10.1016/j.mric.2016.08.002</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/27888843">Pubmed</a>
4. Carroll JF. Accessory Muscles of the Ankle. Radsource – November 2008. <a href="https://radsource.us/accessory-muscles-of-the-ankle/">MRI Web Clinic</a>
1. Aparisi Gómez M, Aparisi F, Bartoloni A et al. Anatomical Variation in the Ankle and Foot: From Incidental Finding to Inductor of Pathology. Part I: Ankle and Hindfoot. Insights Imaging. 2019;10(1):74. <a href="https://doi.org/10.1186/s13244-019-0746-2">doi:10.1186/s13244-019-0746-2</a>
2. Sookur P, Naraghi A, Bleakney R, Jalan R, Chan O, White L. Accessory Muscles: Anatomy, Symptoms, and Radiologic Evaluation. Radiographics. 2008;28(2):481-99. <a href="https://doi.org/10.1148/rg.282075064">doi:10.1148/rg.282075064</a>
3. Cheung Y. Normal Variants: Accessory Muscles About the Ankle. Magn Reson Imaging Clin N Am. 2017;25(1):11-26. <a href="https://doi.org/10.1016/j.mric.2016.08.002">doi:10.1016/j.mric.2016.08.002</a>
4. Carroll JF. Accessory Muscles of the Ankle. Radsource - MRI Web Clinic (2008). <a href="https://radsource.us/accessory-muscles-of-the-ankle/">MRI Web Clinic - November 2008</a>

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