Which bone forms the upper arm?

Which bone forms the upper arm?

• A. Humerus
• B. Cranium
• C. Femur
• D. Pectoralis major

Answer: (A)

The upper arm is built around a single long bone called the humerus. It runs from the shoulder to the elbow, making it the main bone that forms the arm. Its rounded head fits into the shoulder socket to create the shoulder joint, and its distal end connects with the forearm bones at the elbow. The other options aren’t bones of the upper arm: the cranium is part of the skull, the femur is the thigh bone in the leg, and pectoralis major is a chest muscle that moves the arm rather than forming the arm itself. So the humerus is the bone that forms the upper arm.

The upper arm is built around a single long bone called the humerus. It runs from the shoulder to the elbow, making it the main bone that forms the arm. Its rounded head fits into the shoulder socket to create the shoulder joint, and its distal end connects with the forearm bones at the elbow. The other options aren’t bones of the upper arm: the cranium is part of the skull, the femur is the thigh bone in the leg, and pectoralis major is a chest muscle that moves the arm rather than forming the arm itself. So the humerus is the bone that forms the upper arm.