Brachialis muscle

The brachialis muscle is the primary flexor of the elbow joint, positioned in the anterior compartment of the arm, deep to the biceps brachii. It covers the lower half of the humerus and the front of the elbow joint.

Origin

The brachialis muscle generally originates from the lower half of the anterior surface of the humerus. Anatomical studies further reveal that it is composed of two functional components: a larger superficial head and a smaller deep head.

Insertion

The muscle fibers converge to form a thick tendon, which inserts broadly onto the tuberosity of the ulna and the rough depression on the anterior surface of the coronoid process. Specifically, the superficial head tends to insert more distally onto the ulnar tuberosity, while the deep head inserts more proximally onto the coronoid process..

Innervation

The brachialis muscle is primarily innervated by the musculocutaneous nerve. However, a significant proportion of cases also show additional innervation from the radial nerve, particularly to the inferolateral fibers of the deep head.