Brachialis Muscle Anatomy

Overview
Origin Distal anterior surface of the humerus
Insertion Ulnar tuberosity
Action Flexes the elbow
Nerve Musculocutaneous nerve (C5-C7)
Radial nerve (C5, C6)
Artery Radial recurrent artery
Brachial artery

Location & Overview

The brachialis muscle is a muscle of the upper arm. It is located on the anterior side of the arm alongside the coracobrachialis and the biceps brachii. It is located underneath the biceps brachii muscle. Traditionally the brachialis muscle is described as having just one head. However, a 2007 study suggested that the brachialis may actually have two heads. A superficial head and a smaller deep head [1] [2].

anterior view of the brachialis muscle

Here we can see an anterior view of the brachialis muscle.

Origin & Insertion

The brachialis muscle originates at the distal anterior surface of the humerus (which is close to the deltoid muscle’s insertion). The brachialis then inserts at the ulnar tuberosity [3].

brachialis muscle origin

The brachialis muscle originates at the distal anterior surface of the humerus (highlighted in red).

brachialis muscle insertion

The brachialis muscle inserts at the ulnar tuberosity (highlighted in blue).

Actions

The brachialis muscle’s primary function is flexion of the elbow joint. It generates more power than the biceps brachii during flexion. It is estimated that this extra flexion power is approximately 50% more than the biceps. Because the brachialis does not insert on the radius like the biceps brachii, it does not assist in supination and pronation of the forearms [4] [5].

Innervation

The brachialis muscle is innervated by the musculocutaneous nerve (C5-C7) and radial nerve (C5, C6) [6] [7].

Blood Supply

Blood is supplied by the radial recurrent artery and brachial artery [8].

Want some flashcards to help you remember this information? Then click the link below:
Brachialis Muscle flashcards

References

References
1, 4, 8 Plantz MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Brachialis Muscle. [Updated 2020 Sep 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551630/
2 Leonello DT, Galley IJ, Bain GI, Carter CD. Brachialis muscle anatomy. A study in cadavers. J Bone Joint Surg Am. 2007 Jun;89(6):1293-7. doi: 10.2106/JBJS.F.00343. PMID: 17545433.
3, 5, 7 Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincot Williams & Wilkins; 2017.
6 Frazer EA, Hobson M, McDonald SW. The distribution of the radial and musculocutaneous nerves in the brachialis muscle. Clin Anat. 2007 Oct;20(7):785-9. doi: 10.1002/ca.20521. PMID: 17854055.