Description[edit | edit source]

The Brachialis Muscle[1]

The brachialis muscle is the primary flexor of the elbow. This muscle is located in the anterior compartment of the arm along with the biceps brachii and coracobrachialis.

Origin[edit | edit source]

Distal anterior aspect of the humerus, deep to the biceps brachii.[2]

Insertion[edit | edit source]

Coronoid process and the ulnar tuberosity.[2][3]

Nerve[edit | edit source]

The brachialis often has a dual innervation - medially innervated by the musculocutaneous nerve and laterally by the radial nerve[4]. The majority of the motor supply is supplied by the musculocutaneous nerve[4]. The radial nerve descends in the groove between the brachialis and brachioradialis muscles, above the elbow[4].


Blood supply[edit | edit source]

Tributaries of the brachial artery and the recurrent radial artery[2][4]. Occasionally it is supplied by other arteries, such as branches from the ulnar collateral arteries[4].

Function[edit | edit source]

The brachialis is the major flexor of the elbow[3]. It has a large cross-sectional area, providing it with more strength than the biceps brachii and the coracobrachialis.[5] In order to isolate the brachialis muscle the forearm needs to be in pronation, due to the biceps brachii's function as a supinator and flexor.[5] By pronating the forearm the biceps is put into a mechanical disadvantage.

Cross Sectional View of the Upper Arm[6]

Clinical relevance[edit | edit source]

The brachialis muscle can be commonly injured by repetitive forceful contractions or muscular contractions with the arm in hyperextension. This is commonly seen in climbers, due to the pronation of the hand and the extended started position.[7] Physical activity that involves a lot of pull-ups, curls, and rope climbing can also initiate brachialis muscle pain.[8] A strain to the brachialis tendon can also cause a patient to present with a lacking elbow extension due to painful end-range stretching of the tendon. Due to the location of the pain, medial epicondylitis and lateral epicondylitis should also be evaluated.

The brachialis acts as the floor of the cubital fossa[6], and is part of the radial tunnel. It may be implicated in Erb's palsy if the brachial plexus becomes injured, leading to elbow flexion weakness.

Video[edit | edit source]

Assessment[edit | edit source]

To assess the strength of the brachialis, place the elbow at 90 degrees of flexion with the forearm fully pronated. Then have the patient resist an inferior force placed on the distal forearm.[9]

Resources[edit | edit source]

  1. Anatomography. English: Brachialis muscle. [Internet]. 2013 [cited 2018 Mar 21]. Available from:
  2. 2.0 2.1 2.2 Brachialis [Internet]. [cited 2018 Mar 21]. Available from:
  3. 3.0 3.1 Kamineni S, Bachoura A, Behrens W, Kamineni E, Deane A. Distal insertional footprint of the brachialis muscle: 3D morphometric study. Anatomy Research International. 2015;2015.
  4. 4.0 4.1 4.2 4.3 4.4 Plantz MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Brachialis Muscle. [Updated 2022 Feb 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
  5. 5.0 5.1 Marieb EN, Hoehn K. Human anatomy & physiology. 10th ed. Boston, Ma: Pearson; 2016.
  6. 6.0 6.1 Gray, Henry. 1918. Anatomy of the Human Body [Internet]. [cited 2018 Mar 21]. Available from: 
  7. Bond T. Tom’s Physiotherapy Blog: “Climber’s elbow” - Brachialis Tendonitis [Internet]. Tom’s Physiotherapy Blog. 2013 [cited 2018 Mar 21]. Available from:
  8. Brachialis muscle pain & trigger points [Internet]. [cited 2018 Mar 21]. Available from:
  9. Muscolino JE. Kinesiology: the skeletal system and muscle function. 2nd ed. St. Louis, MO: Mosby/Elsevier; 2011.