What movement is primarily produced by the triceps brachii?

The triceps brachii is primarily responsible for extension at the elbow joint. This muscle is located on the posterior aspect of the upper arm and consists of three heads: the long head, lateral head, and medial head. When the triceps brachii contracts, it pulls on the olecranon process of the ulna, which leads to the straightening of the elbow. This movement is essential for various activities such as pushing, throwing, and any action that requires the arm to be extended.

The other options each involve different muscle groups and movements that the triceps brachii does not primarily undertake. For instance, flexion at the elbow typically involves the biceps brachii and brachialis muscles, while abduction of the arm is mainly the function of the deltoid muscle, and medial rotation of the shoulder involves muscles such as the subscapularis and pectoralis major. Thus, understanding the primary movements associated with specific muscles is crucial for both anatomy and functional analysis of upper extremity movements.