What is the name of the only bone present in the brachium?

The only bone present in the brachium, commonly referred to as the upper arm, is the humerus. This long bone extends from the shoulder to the elbow and plays a crucial role in the structure and movement of the arm. The humerus is involved in various critical functions, including providing attachment points for muscles that control movement at the shoulder and elbow joints.

The other options represent bones associated with the forearm and shoulder but do not belong to the brachium itself. The radius and ulna are forearm bones that connect to the humerus at the elbow but are not found in the upper arm. The scapula, or shoulder blade, is part of the shoulder girdle and contributes to the overall shoulder structure but is not located within the arm. Thus, the humerus is correctly identified as the only bone of the brachium.