The muscle situated at the posterior of the upper arm is known as the triceps. At its upper extremity, the triceps features three distinct “heads.” One of these is connected to the outer border of the scapula (shoulder blade), while the other two attach to either side of the humerus (upper-arm bone). The lower section of the triceps is linked to the olecranon process of the ulna (the bony prominence on the elbow). When the muscle contracts, it results in the straightening of the arm.