Brachialis Muscle

Origin

The brachialis muscle originates from the:

- distal half of the anterior aspect of the humerus;

- adjacent parts of the intermuscular septum.

The proximal end of its origin site on the humerus is V-shaped and surrounds the distal end of the insertion site of the deltoid muscle.

Insertion

The fibers of the brachialis muscle travel inferiorly and insert onto the:

- anterior aspect of the coronoid process of the ulna;

- tuberosity of the ulna.

Key Features & Anatomical Relations

The brachialis muscle is found in the anterior compartment of the arm. It is a flat, fusiform type of skeletal muscle. It is located:

- anterior (superficial) to humerus;

- posterior (deep) to the biceps brachii muscle and the musculocutaneous nerve;

- medial to the brachioradialis muscle, radial nerve, and radial collateral, and radial recurrent arteries;

- lateral to the pronator teres muscle.

The brachialis muscle contributes to the formation of the floor of the cubital fossa.

Actions & Testing

The brachialis muscle flexes the forearm at the elbow joint. This action is not affected by pronation or supination of the forearm. It can be tested by flexing the forearm at the elbow joint against resistance, during which it can be palpated (Standring, 2016).

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.