Final answer:
The humerus articulates directly with the radius and ulna bones of the forearm to form the elbow joint, which facilitates the arm's mobility and function.
Step-by-step explanation:
The humerus, the bone in the upper arm of a human, is directly connected to other bones in the arm by articulations, specifically with the radius and ulna bones of the forearm to form the elbow joint. The humerus is the single bone in the upper arm region and is the largest and longest bone of the upper limb. It articulates with the scapula at the shoulder and with the forearm at the elbow.
The forearm is composed of the ulna and the radius, with the ulna being located on the medial aspect (pinky-finger side) and the radius along the lateral (thumb) side of the forearm. These two bones of the forearm facilitate not only the bending and flexing at the elbow but also enable a variable degree of rotation of the hand, contributing to the limb's functionality.