The brachialis (brachialis anticus), also known as the Teichmann muscle, is a

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

in the upper

arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

that flexes the elbow. It lies deeper than the

biceps brachii The biceps or biceps brachii ( la, musculus biceps brachii, "two-headed muscle of the arm") is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. Both heads of the muscle arise on the scapula and join t ...

, 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 Prime mover may refer to: Philosophy *Unmoved mover, a concept in Aristotle's writings Engineering * Prime mover (engine), motor, a machine that converts various other forms of energy (chemical, electrical, fluid pressure/flow, etc) into energy ...

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 The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

, near the insertion of the

deltoid muscle The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle appears to be made up o ...

, 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 The coronoid process of the ulna is a triangular process projecting forward from the anterior proximal portion of the ulna. Structure Its ''base'' is continuous with the body of the bone, and of considerable strength. Anatomy Its ''apex'' is p ...

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 The musculocutaneous nerve arises from the lateral cord of the brachial plexus, opposite the lower border of the pectoralis major, its fibers being derived from C5, C6 and C7. Structure The musculocutaneous nerve arises from the lateral cord ...

, which runs on its superficial surface, between it and the

. 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 slip Anatomical terminology is used to uniquely describe aspects of skeletal muscle, cardiac muscle, and smooth muscle such as their actions, structure, size, and location. Types There are three types of muscle tissue in the body: skeletal, smooth, a ...

s to the supinator, pronator teres,

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 bic ...

, or

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

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 Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

and

supination Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

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 periods ...

''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 ''Terminologia Anatomica'' is the international standard for human anatomical terminology. It is developed by the Federative International Programme on Anatomical Terminology, a program of the International Federation of Associations of Anatomis ...

''.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 The transverse plane (also known as the horizontal plane, axial plane and transaxial plane) is an anatomical plane that divides the body into superior and inferior sections. It is perpendicular to the coronal and sagittal planes. List of cli ...

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)

References

External links

* {{Authority control Elbow flexors Muscles of the upper limb