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.
Back (horse)
A horse has an average total of 18 thoracic vertebrae, with 5 located in the withers. Each thoracic vertebra is also associated with a rib. A horse also has, on average, six lumbar vertebrae. Some breeds, such as the Arabian, will sometimes, but not always, have five lumbar vertebrae and 17 thoracic vertebrae. There appears to be little correlation between back length and number of vertebrae, as many horses with short backs do have the typical number of vertebrae. The length of each vertebra in the lumbar region seems to have the greater influence on the strength of the horse's back.