Triceps brachii muscle

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Triceps brachii
Triceps brachii
Muscles on the dorsum of the scapula, and the Triceps brachii.
Latin	musculus triceps brachii
Gray's	subject #124 444
Origin	long head: infraglenoid tubercle of scapula lateral head: posterior humerus medial head: posterior humerus
Insertion	olecranon process of ulna
Artery	deep brachial artery
Nerve	radial nerve
Actions	extends forearm, caput longum adducts shoulder
Antagonist	Biceps brachii muscle

The triceps brachii muscle (Latin for "three-headed" muscle of the arm, it is called a three headed muscle because there are three bundles of muscle, each of different origin, joining together at the elbow) is the large muscle on the back of the human upper limb. It is the muscle principally responsible for extension of the elbow joint (i.e. straightening of the arm). Though a similarly-named muscle, the triceps surae, is found on the lower leg, the triceps brachii is commonly called simply the "triceps".

Contents 1 Terminology 2 Origin and insertion 3 Actions 4 Training 5 Additional images 6 See also 7 References 8 External links

[edit] Terminology

Historically, in a now-extinct dialect of English, the plural form of the adjective triceps was tricipes, a form not in general use today, instead triceps is used in both singular and plural (i.e., when referring to both arms).

[edit] Origin and insertion

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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.)^[1]

Many mammals have a fourth head, the "Accessory head", which lies between the Lateral and Medial heads. In humans, the Anconeus is sometimes loosely called "the fourth head of the triceps brachii".

[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, e.g., when writing.

The triceps accounts for approximately 60 percent of the upper arm's muscle mass.

[edit] Training

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

Isolation movements include cable push-downs, "skull-crushers", French curls, and arm extensions behind the back. Examples of compound elbow extension include pressing movements like the push up, bench press (flat, incline or decline), military press and dips. A closer grip targets the triceps more than wider grip movements.

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

Elbow extension is important to many athletic activities. As the biceps is 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 and 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

• Triceps reflex

[edit] References

[edit] External links

• LUC tric
• UWASH tricepsbrachii
• 751829070 at GPnotebook
• SUNY Labs 06:11-0100
• Photo at Ithaca College
• Muscles/TricepsBrachii at exrx.net

v • d • e List of muscles of upper limbs Vertebral column trapezius · latissimus dorsi · rhomboid (major, minor) · levator scapulae Thoracic cavity pectoralis major · pectoralis minor · subclavius · serratus anterior Shoulder deltoid · rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) · teres major Arm Anterior coracobrachialis · biceps brachii · brachialis Posterior triceps brachii · anconeus Forearm Anterior superficial: pronator teres · palmaris longus · flexor carpi radialis · flexor carpi ulnaris · flexor digitorum superficialis deep: pronator quadratus · flexor digitorum profundus · flexor pollicis longus Posterior superficial: mobile wad (brachioradialis, extensor carpi radialis longus and brevis) · extensor digitorum · extensor digiti minimi · extensor carpi ulnaris deep: supinator · anatomical snuff box (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) · extensor indicis Hand Lateral volar thenar (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis) · adductor pollicis Medial volar hypothenar (opponens digiti minimi, flexor digiti minimi brevis, abductor minimi digiti) · palmaris brevis Intermediate lumbrical · interossei (dorsal, palmar)