Triceps brachii muscle

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Triceps brachii
Triceps brachii
Latin musculus triceps brachii
Gray's subject #124 444
Origin long head: scapula
lateral head: posterior humerus
medial head: posterior humerus
Insertion    olecranon process of ulna
Artery: deep brachial artery
Nerve: radial nerve
Action: extends forearm, caput longum adducts shoulder
Antagonist: Biceps brachii muscle
Dorlands
/Elsevier		 m_22/12551300

The triceps brachii muscle is a muscle of the posterior compartment of the upper limb. It is the muscle principally responsible for extension of the elbow joint.

Contents

[edit] Etymology

Triceps is Latin for 'three-headed', reflecting the three parts of this muscle. Brachii means 'of the arm'. Triceps brachii is often called the triceps (both singular and plural). However, some authors describe the triceps surae muscle, and so this term is somewhat ambiguous.

[edit] Origin and insertion

The three heads have the following names and origins:

The fibers converge to a single tendon to insert onto the olecranon process of the ulna (though some research indicates that there may be more than one tendon.)[1]

Many mammals have a fourth head, the "Accessory head", which is between the Lateral and Medial heads.

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[edit] Actions

The triceps is an extensor muscle of the elbow joint, and is an antagonist of the biceps and brachialis muscles. It can also fixate the elbow joint when the forearm and hand are used for fine movements, eg when writing.

The triceps accounts for approximately 70 percent of the upper arm's muscle mass.

[edit] Training

The triceps can be worked through either isolation elbow extension movements, contract statically to keep the arm straightened against resistance, or compound pressing movements.

Isolation movements include cable push-downs, "skull-crushers", and arm extensions behind the back.

Static contraction movements are pullovers, straight-arm pulldowns, and bent-over lateral raises, which are also used to build the butt deltoids and latissimus dorsi.

Examples of pressing movements are press ups, bench presses (level, incline or decline), military presses and dips. Using a closer grip stabilizes the arm allowing more weight to be used, so the triceps can be worked harder without being limited by the strength of the pectorals or shoulders.

Elbow extension is important to many athletic activities. As biceps are often worked more for aesthetic purposes, this is usually a mistake for fitness training. While it is important to maintain a balance between the biceps and triceps for postural & effective movement purposes, what the balance should be and how to measure it is a conflicted area. Pushing and pulling movements on the same plane are often used to measure this ratio.

[edit] Additional images

Left humerus. Posterior view.

Bones of left forearm. Posterior aspect.

Cross-section through the middle of upper arm.

Posterior surface of the forearm. Superficial muscles.

The scapular and circumflex arteries.

The axillary artery and its branches.

The brachial artery.

The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.

Suprascapular and axillary nerves of right side, seen from behind.

The suprascapular, axillary, and radial nerves.

[edit] See also

[edit] References

  1. ^ Madsen M, Marx R, Millett P, Rodeo S, Sperling J, Warren R (2006). "Surgical anatomy of the triceps brachii tendon: anatomical study and clinical correlation.". Am J Sports Med 34 (11): 1839-43. doi:10.1177/0363546506288752. PMID 16735585. 

[edit] External links

v • d • e
List of muscles of upper limbs
VERTEBRAL COLUMN
THORACIC WALLS
SHOULDER
ARM
FOREARM
HAND