Skeleton parts are the components of the human body's skeletal system, which is made up of BONES, cartilage, and ligaments. The ulnae (5 letters) are two long BONES in the forearm that connect to the elbow joint. The humeri (6 letters) are two long BONES in the upper arm that connect to the shoulder joint. The sterna (6 letters) are a series of flat BONES that form the front of the rib cage. Finally, BONES (5 letters) are the rigid organs that make up the skeleton.