Rib
Ribs are classed as flat bones which usually have a protective role in the body. Humans have 24 ribs, in 12 pairs. All are attached at the back to the thoracic vertebrae, and are numbered from 1–12 according to the vertebrae they attach to. The first rib is attached to thoracic vertebra 1 (T1). At the front of the body most of the ribs are joined by costal cartilages to the sternum. The ribs connect to the vertebrae with two joints, the costovertebral joints.
Sex differences in human physiology
The following further generalizations have been made regarding male-female skeletal differences:Studies have measured male and female canine and other teeth, yielding different results as to which sex has the larger, where observed differences in size are small. Finally, contrary to popular belief, males and females do not differ in the number of ribs; both normally have twelve pairs.