Washington Master Esthetics Practice Exam

What structure is responsible for the movement of the upper arm?

1. Humerus

2. Radius

3. Ulna

4. Clavicle

The correct answer is: Humerus

The humerus is the long bone in the arm that extends from the shoulder to the elbow. It plays a crucial role in the movement of the upper arm due to its articulation with both the shoulder joint and the elbow. At the shoulder, the humerus connects with the scapula (shoulder blade) to form the glenohumeral joint, which allows for a wide range of motion in the arm. This joint enables activities such as lifting, throwing, and reaching. In contrast, the radius and the ulna are bones of the forearm, and while they are essential for forearm and wrist movement, they do not directly facilitate the movement of the upper arm. The clavicle, or collarbone, serves primarily to stabilize the shoulder but does not directly control the arm's movement. Thus, the humerus is the key structure that enables the mobility of the upper arm.