Abstract
Accessory muscles and variations are not uncommon at the upper and lower extremity.
They are often overlooked because they are asymptomatic and present as incidental
findings on imaging. However, they may present as a soft tissue swelling, thereby
mimicking soft tissue tumors. Other symptoms are attributed to impingement on neurovascular
structures and to exercise-related pain. Thorough knowledge of the anatomy, systematic
imaging analysis, and the awareness of it are the clues to correct identification.
On ultrasound, accessory muscles have a similar echotexture as other muscles, whereas
the signal intensity on magnetic resonance imaging (MRI) is similar to muscle. Because
of the intrinsic contrast with the adjacent intermuscular fat, accessory muscles are
best depicted on MRI without fat suppression. This article provides a short overview
of the anatomy of most prevalent accessory muscles of the upper and lower limb and
its potential pathogenic nature.
Keywords
accessory muscle - variants - ultrasonography - magnetic resonance imaging
