The entrapment neuropathy of the ulnar nerve at the elbow is a frequent pathology with a variety ofetiologies. One of them is the presence of an accessory muscle, such as the anconeus epitrochlearis. Although thismuscle is frequently found in the general population, it is a rare cause of nerve compression. Despite its similarityto the idiopathic form, there are certain features that may suggest that the compression is due to this accessorymuscle. This work reports a representative case in which the anconeus epitrochlearis was discovered during thesurgical intervention.

The entrapment neuropathy of the ulnar nerve at the elbow is a frequent pathology with a variety ofetiologies. One of them is the presence of an accessory muscle, such as the anconeus epitrochlearis. Although thismuscle is frequently found in the general population, it is a rare cause of nerve compression. Despite its similarityto the idiopathic form, there are certain features that may suggest that the compression is due to this accessorymuscle. This work reports a representative case in which the anconeus epitrochlearis was discovered during thesurgical intervention.