Bulky accessory brachialis muscle with abnormal aponeurosis: A case report

The brachialis muscle is one of the chief flexors of the upper arm, and its variation can affect the movements of the elbow joint. This case report presents a rare case of a large accessory brachialis muscle in the right arm that comes with an abnormal aponeurosis. The aponeurosis from the distal part of the aberrant muscle arches over the radial artery and is attached to the deep fascia of the right forearm. While rare, the presence of an accessory brachialis muscle coupled with the unusual aponeurosis can lead to compression of the radial artery, causing radial artery entrapment syndrome and creating potential difficulties in the catheterisation of the radial artery.