Triceps Brachii, also known as the triceps muscle, is a large muscle located on the back of the upper arm. This muscle is composed of three heads, namely the long head, the medial head, and the lateral head. While the term triceps brachii is commonly used to refer to this muscle, it also has several other synonyms. These include the three-headed arm muscle, the triceps surae, and the triceps extensor muscle. In addition, some people also refer to this muscle as the triceps muscle, the horseshoe muscle, or simply as the tri. Regardless of the term used, the triceps brachii plays a crucial role in arm extension, straightening of the elbow joint, and supporting various upper body movements.