The two upper arm bones are called humeri, which is a Latin word meaning 'SHOULDER'. The humerus is the bone that connects the SHOULDER to the elbow and is the longest bone in the upper arm. It is also the only bone in the upper arm that connects to the SHOULDER joint. The humerus is a long bone with a rounded head at one end and a narrow neck at the other. It is the main bone of the upper arm and is responsible for movement of the arm.