A unique origin of the brachioradialis muscle from the triceps brachii.

Presently, a few brachioradialis muscle (BR) variants have been reported, mainly concerning their inserting tendons or the accessory forms (accessory BR muscles). During a routine dissection of a 74-year-old female donated cadaver, a unique muscle variant was observed unilaterally. An aberrant origin of the BR from the lateral head of the triceps brachii was identified on the left arm. The radial nerve (RN) superficial branch coursed posteriorly to the BR before obtaining its superficial position. On the right arm, the BR was typical. So far, some of the BR variants in its origins have been reported, such as arising from the muscular belly of the brachialis or the insertion of the deltoid muscle. Thus, the present variant could be a worth noting rare case. Furthermore, the posterior position of the RN superficial branch could have potential clinical significance and may cause entrapment neuropathy.