Triceps muscle, any muscle with three heads, or points of origin, particularly the large extensor along the back of the upper arm in humans. It originates just below the socket of the scapula (shoulder blade) and at two distinct areas of the humerus, the bone of the upper arm. The upper arm is located between the shoulder joint and elbow joint. It contains four muscles - three in the anterior compartment (biceps brachii, brachialis, coracobrachialis), and one in the posterior compartment ( triceps brachii). 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. The triceps, also known as the triceps brachii , is a big muscle found on the back of many vertebrates' upper limbs. It is the muscle that is primarily responsible for elbow joint extension (straightening of the arm).
