The brachialis (brachialis anticus), also known as the Teichmann muscle, is a
muscle in the upper
arm that
flexes the elbow. It lies deeper than the
biceps brachii, and makes up part of the floor of the region known as the
cubital fossa
The cubital fossa, chelidon, or elbow pit, is the triangular area on the anterior side of the upper limb between the arm and forearm of a human or other hominid animals. It lies anteriorly to the elbow (Latin ) when in standard anatomical position ...
(elbow pit). The brachialis is the
prime mover of elbow flexion generating about 50% more power than the biceps.
[Saladin, Kenneth S, Stephen J. Sullivan, and Christina A. Gan. Anatomy & Physiology: The Unity of Form and Function. 2015. Print.]
Structure
The brachialis originates from the anterior surface of the distal half of the
humerus,
near the insertion of the
deltoid 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. 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 of the ulna.
Blood supply
The brachialis is supplied by muscular branches of the brachial artery and by the recurrent radial artery.
Nerve supply
The brachialis muscle is innervated by the
musculocutaneous nerve, which runs on its superficial surface, between it and the
biceps brachii.
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.
["Brachialis Muscle." Kenhub. Kenhub, Aug. 2001]
Variation
The muscle is occasionally doubled; additional
muscle slips to the
supinator,
pronator teres,
biceps brachii,
lacertus fibrosus
The bicipital aponeurosis (also known as lacertus fibrosus) is a broad aponeurosis of the biceps brachii, which is located in the cubital fossa of the elbow. It separates superficial from deep structures in much of the fossa.
Structure
The bicip ...
, or
radius
In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...
are more rarely found.
Function
The brachialis flexes the arm at the elbow joint.
Unlike the biceps, the brachialis does not insert on the radius, and does not participate in
pronation and
supination of the forearm.
History
Etymology
The ''brachialis muscle''
[Di J.H. (Ed.) (1997).''Stedman’s concise me10b">Triepel, H. (1910). ''Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit eitte Auflage). Wiesbaden: Verlag J.F. Bergmann.] In
classical Latin
Classical Latin is the form of Literary Latin recognized as a literary standard by writers of the late Roman Republic and early Roman Empire. It was used from 75 BC to the 3rd century AD, when it developed into Late Latin. In some later period ...
''bracchialis'' means ''of or belonging to the arm'',
[Lewis, C.T. & Short, C. (1879). ''A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary.'' Oxford: Clarendon Press.] and is derived from classical Latin ''bracchium'',"arm".
The expression ''musculus brachialis'' is used in the current official anatomic nomenco
Terminologia Anatomica''.
[Federative Committee on Anatomical Terminology (FCAT) (1998). ''Terminologia Anatomica''. Stuttgart: Thieme]
Additional images
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)
See also
References
External links
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{{Authority control
Elbow flexors
Muscles of the upper limb