Definition
By: Gregory R. Waryasz, MD
The brachialis muscle of the musculoskeletal system is characterized by being the main flexor of the elbow.
It is part of the arm. It consists of skeletal muscle fibers.
Its unique structural features include its flattened fusiform shape. It lies deep to the biceps brachii muscle with its distal attachment covering the anterior elbow.
The origin is the distal half of the anterior surface of the humerus.
The insertion is the coronoid process and the tuberosity of the ulna.
The blood supply is from the radial recurrent artery and venous drainage is from the accompanying veins.
The innervation is from the musculocutaneous nerve.
The brachialis muscle as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in the embryo.
The function of the brachialis muscle is to flex the forearm in all positions at the elbow joint. The function of the brachialis does not change whether the forearm is in pronation or supination. It is responsible for keeping the elbow flexed. The synergists are the brachioradialis and the biceps brachii.
Diseases are not commonly described.
Commonly used diagnostic procedures include clinical history, physical exam, and MRI.
References
Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.
Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Wheeless? Textbook of Orthopaedics: Brachialis (http://www.wheelessonline.com/ortho/brachialis_muscle)