What is the insertion of the triceps brachii?

• A. Deltoid tuberosity of the humerus.
• B. Radial tuberosity.
• C. Olecranon of the ulna.
• D. Coracoid process.

Answer: (C)

The main idea is where the triceps brachii attaches to bone to produce elbow extension. The triceps brachii converges into a tendon that inserts on the olecranon process of the ulna, placing the triceps as the prime mover for extending the elbow. This insertion on the ulna allows the muscle to pull the forearm straight by levering against the elbow joint. The deltoid tuberosity is where the deltoid inserts, supporting shoulder abduction; the radial tuberosity is the insertion for the biceps brachii, which aids in forearm flexion and supination; and the coracoid process serves as an origin for some muscles like coracobrachialis and the short head of the biceps, not the distal insertion for the triceps.