The brachialis muscle (brachialis) is one of the three muscles of the anterior compartment of the arm. It is only involved in flexion at the elbow and therefore the strongest flexor at the elbow, compared with the biceps brachii which is also involved in supination because of its insertion on the radius.
- origin: lower portion of the anterior surface of the humerus
- insertion: ulna tuberosity and coronoid process of the ulna
- innervation: musculocutaneous nerve and radial nerve (proprioceptive branch)
- action: flexion at the elbow
Although rare, supernumerary heads of brachialis have been reported and may cause entrapment of the median nerve and/or brachial artery3.