Brachialis muscle

Brachialis

Deep muscles of the chest and front of the arm, with the boundaries of the axilla. (Brachialis visible at bottom right.)

Position of brachialis (shown in red).
Details
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 (C5, C6)
Actions flexion at elbow joint
Identifiers
Latin musculus brachialis
Dorlands
/Elsevier		 m_22/12548498
TA A04.6.02.018
FMA 37667

Anatomical terms of muscle

The brachialis (brachialis anticus) is a muscle in the upper arm that flexes the elbow joint. It lies deeper than the biceps brachii, and is a synergist that assists the biceps brachii in flexing at the elbow. It makes up part of the floor of the region known as the cubital fossa.

Structure

The brachialis originates from the lower half of the front 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. It also arises from the intermuscular septa of the arm, but more extensively from the medial than the lateral; it is separated from the lateral below by the brachioradialis and extensor carpi radialis longus muscles.

Its fibers converge to a thick tendon, which is inserted into the tuberosity of the ulna[1] and the rough depression on the anterior surface of the coronoid process of the ulna.

Variation

The muscle is occasionally doubled; additional nip to the supinator, pronator teres, biceps brachii, lacertus fibrosus, or radius are more rarely found.

Innervation

The brachialis muscle is innervated by the musculocutaneous nerve, which runs on its superficial surface, between it and the biceps brachii.[1] Part of it is also innervated by the radial nerve (proprioceptive branch) which allows it to be split during certain approaches to the arm. The divide between the two innervations is at the insertion of the deltoid.

Function

The brachialis flexes the arm at the elbow joint.[1] Unlike the biceps, the brachialis does not insert on the radius, and does not participate in pronation and supination of the forearm.[1]

History

Etymology

The brachialis muscle [2] and brachial muscle [3] can be considered as the anglicized variant of the Latin expression musculus bracchialis.[4] In classical Latin bracchialis means of or belonging to the arm,[5] and is derived from classical Latin bracchium,"arm".[5] The expression musculus brachialis is used in the current official anatomic nomenclature Terminologia Anatomica.[6]

Additional images

See also

This article uses anatomical terminology; for an overview, see Anatomical terminology.

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

  1. 1 2 3 4 Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. p. 662,672. ISBN 978-0-8089-2306-0.
  2. ↑ Dirckx, J.H. (Ed.) (1997).Stedman’s concise medical dictionary for the health professions. (3rd edition). Baltimore: Williams & Wilkins.
  3. ↑ Anderson, D.M. (2000). Dorland’s illustrated medical dictionary (29th edition). Philadelphia/London/Toronto/Montreal/Sydney/Tokyo: W.B. Saunders Company.
  4. ↑ Triepel, H. (1910). Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit einem Anhang: Biographische Notizen.(Dritte Auflage). Wiesbaden: Verlag J.F. Bergmann.
  5. 1 2 Lewis, C.T. & Short, C. (1879). A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. Oxford: Clarendon Press.
  6. ↑ Federative Committee on Anatomical Terminology (FCAT) (1998). Terminologia Anatomica. Stuttgart: Thieme

External links

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