The Brachialis Muscle

Exploring the brachialis muscle

The brachialis is the second of three muscles that we’ll look at that move the forearm. Remember, we’ve already discussed biceps brachii. Although this muscle may not get as much attention as biceps brachii, it’s also important for understanding forearm movement.

What does brachialis mean?

The name brachialis comes from root “brachial” which refers to the arm.

Where does the brachialis muscle attach?

This muscle is located on the arm. Brachialis has a thick flat muscle belly that lies deep to the biceps brachii. Although, it can stick out from the sides of the biceps brachii. And, due to its location deep to the biceps brachii, if brachialis is well developed it makes biceps brachii look bigger! This is a simple muscle as it only crosses one joint.

Origin of brachialis

Brachialis originates on the distal half of the anterior portion of the humerus.

Insertion of brachialis

It inserts at the posterior end on the coranoid process of the ulna and the ulnar tuberosity.

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What actions does the brachialis do?

Brachialis crosses the elbow joint and acts as a synergist to biceps brachii. The primary action of brachialis is flexion of the elbow. It is active regardless of the position of the forearm. This is because it attaches to the ulna which is fixed.

What are the most common injuries to the brachialis?

Generally, injuries to the brachialis muscle are not especially common. However, rock climbers will sometimes overwork this muscle resulting in tendinitis, or even in a tear of this muscle. Symptoms of brachialis tendinitis or tearing include:

Pain or tenderness at the insertion end of brachialis at the front of the elbow

Consult your physician for assessment and treatment recommendations.

Postures where the brachialis muscle contracts

Anytime we are flexing the elbow, or attempting to flex the elbow against a resistance, brachialis will contract.

Brachialis is working together with the biceps brachii here in our shoulderstand.

If we do a posture such as uttitha hasta padangusthasana, the brachialis contracts when we flex the elbow.

Postures where the brachialis muscle is lengthened

We lengthen brachialis anytime we extend our elbow fully, such as in upward dog.

Postures such as purvottanasana, which require straight elbows, lengthen brachialis.