A skeletal structure is composed of bones and joints that provide support and movement for the body. The PELVIS, which is a 6-letter word, is a large bone at the base of the spine that supports the trunk and connects the legs. The TARSUS, also a 6-letter word, is a group of seven bones in the foot that form the ankle joint. The ribcage, a 7-letter word, is a set of bones that protect the heart and lungs and form the chest cavity. Together, these three components make up the skeletal structure of the human body.