Triceps brachii muscle

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. It is commonly referred to as the "tricep".

## 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.

## Origin and insertion

The three heads have the following names and origins:

* The "Long head": infraglenoid tubercle of the scapula
* The "Lateral head": posterior shaft of the humerus, lateral and superior to the radial (spiral) groove.
* The "Medial head": posterior shaft of the humerus, medial and inferior to the radial (spiral) groove.

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.)

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

## 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.

## 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.

## Additional images

Gray208.pngLeft humerus. Posterior view.Gray214.pngBones of left forearm. Posterior aspect.Gray413 color.pngCross-section through the middle of upper arm.Gray418.pngPosterior surface of the forearm. Superficial muscles.Gray521.pngThe scapular and circumflex arteries.Gray523.pngThe axillary artery and its branches.Gray525.pngThe brachial artery.Gray809.pngThe right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.Gray810.pngSuprascapular and axillary nerves of right side, seen from behind.Gray818.pngThe suprascapular, axillary, and radial nerves.

## External links

* LUC *tric*
* UWASH *tricepsbrachii*
* *751829070* at GPnotebook
* SUNY Labs *06:11-0100*
* Photo at Ithaca College
* Triceps exercise at zoomblog.com
* *Muscles/TricepsBrachii at exrx.net*
* Triceps workouts at tricepworkout.net

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