costa - any of the 12 pairs of curved arches of bone extending from the spine to or toward the sternum in humans (and similar bones in most vertebrates)craniate, vertebrate - animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium craniate, vertebrate - animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium bone, os - rigid connective tissue that makes up the skeleton of vertebrates true rib - one of the first seven ribs in a human being which attach to the sternum costal cartilage - the cartilages that connect the sternum and the ends of the ribs; its elasticity allows the chest to move in respiration |