What movement does contraction of the triceps brachii primarily cause?

The triceps brachii is a key muscle located on the back of the upper arm, and its primary function is to extend the elbow joint. When the triceps brachii contracts, it pulls on the ulna through the olecranon process, straightening the arm at the elbow. This action is vital for various movements, such as pushing an object away from the body and performing actions like throwing or pushing.

The muscle’s anatomical position and its role in leveraging the skeleton make it specifically suited for extension rather than any other movement listed. Other muscles are responsible for flexing the elbow or for shoulder movements and forearm rotation, so these options do not align with the function of the triceps brachii. Thus, the contraction of this muscle results in the extension of the elbow joint, confirming that the correct answer is indeed associated with this specific action.