Brachialis - Musculus brachialis
Origin: Anterior surface of the humerus, particularly the distal half of this bone
Insertion: Coronoid process and the tuberosity of the ulna
Artery: Radial recurrent artery
Nerve: Musculocutaneous nerve
Action: Flexion at elbow joint
The Brachialis (Brachialis anticus) covers the front of the elbow-joint and the lower half of the humerus. It arises from the lower half of the front of the humerus, commencing above at the insertion of the Deltoideus, which it embraces by two angular processes. Its origin extends below to within 2.5 cm. of the margin of the articular surface. It also arises from the intermuscular septa, but more extensively from the medial than the lateral; it is separated from the lateral below by the Brachioradialis and Extensor carpi radialis longus. Its fibers converge to a thick tendon, which is inserted into the tuberosity of the ulna and the rough depression on the anterior surface of the coronoid process.
Variations.—Occasionally doubled; additional slips to the Supinator, Pronator teres, Biceps, lacertus fibrosus, or radius are more rarely found.
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).