Rib cage
The rib cage is the arrangement of ribs attached to the vertebral column and sternum in the thorax of most vertebrates, that encloses and protects the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdle to form the core part of the human skeleton. A typical human rib cage consists of 24 ribs in 12 pairs, the sternum and xiphoid process, the costal cartilages, and the 12 thoracic vertebrae.
Mammal tooth
Rabbits and other lagomorphs usually shed their deciduous teeth before (or very shortly after) their birth, and are usually born with their permanent teeth. The teeth of rabbits complement their diet, which consist of a wide range of vegetation. Since many of the foods are abrasive enough to cause attrition, rabbit teeth grow continuously throughout life. Rabbits have a total of 6 incisors (two upper an one lower on either side), three upper premolars on each side of the maxillary bone (total of six), three upper molars on each side, two lower premolars on each side of the jaw, and two lower molars on each side of the jaw. There are no canines. Three to four millimeters of tooth is worn away by incisors every week, whereas the posterior teeth require a month to wear away the same amount.