Variation in the Insertion of Brachialis Muscle- A Case Report

While dissecting the right upper limb of an adult male cadaver an additional slip of brachialis muscle was found. Normal Anatomy: The muscle has two heads. Superficial inserting into ulnar tuberosity innervated by musculocutaneous nerve, the deep head inserts into coronoid process of ulna and supplied by radial nerve. Embryology: Failure of muscle primordia to disappear may account for additional heads. Case report: An additional slip originated from lateral aspect of superficial head, descended lateral to biceps tendon as a content of cubital fossa. Present unilaterally supplied by radial nerve. The additional slip split to enclose tendon of biceps brachii. Superficial slip passed in front and deep slip behind biceps tendon. The tendon so formed inserted into shaft of radius below the tuberosity. The superficial slip sent communicating slips to flexor digitorum superficialis muscle beneath which passed ulnar artery. Clinical significance of additional head: Radial component is incorporated into the action of brachialis. Communicating fibres to neighbouring muscles may compress the ulnar artery causing vascular symptoms. The presence in cubital fossa is a source of pain in compression syndrome. Vascular pedicle can be utilized in surgeries like distal biceps tendon transfer and reconstruction of ligaments of elbow joint.