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The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of three parts: the medial, lateral, and long head. [1] It is the muscle principally responsible for extension of the elbow joint (straightening of the arm).
The elbow is the region between the upper arm and the forearm that surrounds the elbow joint. [1] The elbow includes prominent landmarks such as the olecranon , the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the medial epicondyles of the humerus .
These three muscles act as flexors at the elbow joint. [5] The extensor carpi radialis brevis and longus are both weak flexors at the elbow joint. Brevis moves the arm from ulnar abduction to its mid-position and flexes dorsally. Longus is a weak pronator in the flexed arm and a supinator in the outstretched arm.
The olecranon (/ oʊ ˈ l ɛ k r ə n ɒ n /, from Greek olene 'elbow' and kranon 'head'), is a large, thick, curved bony process on the proximal, posterior end of the ulna.It forms the protruding part of the elbow and is opposite to the cubital fossa or elbow pit (trochlear notch).
The antagonistic pair of biceps and triceps working to flex the elbow. Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes. An example of an antagonistic pair is the biceps and triceps; to contract, the triceps relaxes while the biceps contracts to lift the arm.
It perforates the lateral head of the triceps brachii muscle at the triceps' attachment to the humerus.. The upper and smaller branch of the nerve passes to the front of the elbow, lying close to the cephalic vein, and supplies the skin of the lower half of the arm.
The radial nerve and profunda brachii pass through the triangular interval and are hence vulnerable. The triangular interval has a potential for compromise secondary alterations in thickness of the teres major and triceps. [7] It is described based on cadaveric studies that fibrous bands were commonly present between the teres major and triceps.
The muscle is used to stabilize the elbow during rapid flexion and extension while in a midposition, such as in hammering. The brachioradialis is synergistic with the brachialis and biceps brachii; the triceps brachii and anconeus are antagonistic.