The brachialis (also brachialis anticus or Casserio muscle) is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa (elbow pit). It originates from the anterior aspect of the distal humerus; and commonly also receives additional innervation from the radial nerve. The brachialis is the prime mover of elbow flexion generating about 50% more power than the biceps.
Structure
Origin
The brachialis originates from the anterior surface of the distal half of the humerus,
Innervation
The brachialis muscle is innervated by the musculocutaneous nerve (also Casserio nerve), which runs on its superficial surface, between it and the biceps brachii.
Variation
The muscle is occasionally doubled; additional muscle slips to the supinator, pronator teres, biceps brachii, lacertus fibrosus, or radius are more rarely found.
Function
The brachialis flexes the arm at the elbow joint. and brachial muscle can be considered as the anglicized variant of the Latin expression musculus bracchialis. In classical Latin bracchialis means of or belonging to the arm, and is derived from classical Latin bracchium,"arm".
Additional images
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File:Brachialis muscle - animation03.gif|Position of brachialis (shown in red). Animation.
File:Brachialis muscle01.png|Still image.
File:Gray413 color.png|Horizontal section through the middle of upper arm. (Brachialis labeled at center left.)
File:Muscles of upper limb.(cross section - human cadaver).jpg|Muscles of forearm, including insertion of brachialis tendon. Cross section. (Brachialis labeled at bottom left.)
File:Gray207.png|Left humerus. Anterior view.
File:Gray213.png|Bones of left forearm. Anterior aspect.
File:Nerves_of_the_left_upper_extremity.gif|Nerves of the left upper extremity.
File:Slide10zzz.JPG|Brachialis muscle (labeled in green text)
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