The skull has flat bones (occipital parietal frontal, lacrimal and nasal) and the thoracic cavity (sternum and spine) and the pelvis, (ilium and the ischium). Flat bones protect internal organs including the brain and heart. Flat bones are a little smooth and may be utilized as an armor. In addition, http://arthritis60257.suomiblog.com/how-does-arthritis-affect-bones-22486243