| Brachialis | |
|---|---|
 Deep muscles of the chest and front of the arm, with the boundaries of theaxilla. (Brachialis visible at bottom right.) | |
 Position of brachialis (shown in red). | |
| Details | |
| Origin | Anterior surface of thehumerus, particularly the distal half of this bone |
| Insertion | Coronoid process and thetuberosity of the ulna |
| Artery | Radial recurrent artery,brachial artery |
| Nerve | Musculocutaneous nerve (C5-C7) andradial nerve (C5, C6) |
| Actions | Flexion atelbow joint |
| Identifiers | |
| Latin | musculus brachialis |
| TA98 | A04.6.02.018 |
| TA2 | 2469 |
| FMA | 37667 |
| Anatomical terms of muscle | |
Thebrachialis (brachialis anticus) is amuscle in the upperarm thatflexes the elbow. It lies beneath thebiceps brachii, and makes up part of the floor of the region known as thecubital fossa (elbow pit). It originates from the anterior aspect of the distal humerus;[1] it inserts onto thetuberosity of the ulna. It is innervated by themusculocutaneous nerve,[2] and commonly also receives additional innervation from theradial nerve.[3] The brachialis is theprime mover of elbow flexion generating about 50% more power than the biceps.[dubious –discuss][1]
The brachialis originates from the anterior surface of the distal half of thehumerus,[1] near the insertion of thedeltoid muscle, which it embraces by two angular processes. Its origin extends below to within 2.5 cm of the margin of the articular surface of the humerus at the elbow joint.[2]
Its fibers converge to a thick tendon which is inserted into thetuberosity of the ulna,[2] and the rough depression on the anterior surface of thecoronoid process of the ulna.[4]
The brachialis muscle is innervated by themusculocutaneous nerve, which runs on its superficial surface, between it and thebiceps brachii.[2] However, in 70-80% of people, the muscle has double innervation with the radial nerve (C5-T1). The divide between the two innervations is at the insertion of the deltoid.[3]
The brachialis is supplied by muscular branches of thebrachial artery and by the recurrentradial artery.[5]
The muscle is occasionally doubled; additionalmuscle slips to thesupinator,pronator teres,biceps brachii,lacertus fibrosus, orradius are more rarely found.[citation needed]
The brachialis flexes the arm at the elbow joint.[2] Unlike the biceps, the brachialis does not insert on the radius, and does not participate inpronation andsupination of the forearm.[2]
Thebrachialis muscle[6] Inclassical Latinbracchialis meansof or belonging to the arm,[7] and is derived from classical Latinbracchium, "arm".[7] The expressionmusculus brachialis is used in the current official anatomic nomencoTerminologia Anatomica.[8]
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This article incorporates text in thepublic domain frompage 444 of the 20th edition ofGray's Anatomy(1918)
