Overview

The brachialis is a broad muscle beneath the biceps at the front of the upper arm. It is less visible than the biceps, but it is one of the elbow’s most dependable flexors.

Because the brachialis attaches to the ulna rather than the radius, it bends the elbow whether the palm faces up, down or inward. That makes it active in curls, pulling movements and everyday lifting in almost any hand position.

Location

Begins on the lower half of the front of the humerus
Runs deep to the biceps brachii
Crosses the front of the elbow and attaches to the ulna

Origin, Insertion, Nerve Supply, and Action

Origin: Distal half of the anterior humerus and nearby intermuscular septa
Insertion: Coronoid process and tuberosity of the ulna
Nerve supply: Musculocutaneous nerve, mainly C5–C6; the lateral portion may also receive a radial-nerve branch
Action: Flexes the elbow in every forearm position

Function

Produces elbow flexion with the palm up, down or neutral
Works with the biceps and brachioradialis during lifting
Controls the elbow while lowering an object

Common Problems

The brachialis can become sore or strained after a sudden increase in pulling, climbing or curl volume. Symptoms are often felt deeper than typical biceps soreness and may sit lower in the upper arm near the elbow.

Pain in this area can also come from the biceps tendon, elbow joint or a nearby nerve, so location alone cannot confirm which structure is involved.

When to Get It Assessed

Seek an assessment after a sudden injury if there is marked bruising, swelling, weakness or loss of elbow motion. Persistent pain that is not responding to reduced loading also deserves review.

References

OpenStax. “Muscles of the Pectoral Girdle and Upper Limbs.” https://openstax.org/books/anatomy-and-physiology-2e/pages/11-5-muscles-of-the-pectoral-girdle-and-upper-limbs
StatPearls. “Anatomy, Shoulder and Upper Limb, Brachialis Muscle.” https://www.ncbi.nlm.nih.gov/books/NBK551630/
Moore KL et al. Clinically Oriented Anatomy. Wolters Kluwer.

Brachialis