where does the head of the rib articulate with
Articulation of head of rib The articulations of the heads of the ribs (or costocentral articulations) constitute a series of gliding or arthrodial joints, and are formed by the articulation of the heads of the typical ribs with the facets on the contiguous margins of the bodies of the thoracic vertebrae and with the intervertebral fibrocartilages between them; the first, eleventh and twelfth ribs each articulate with a single vertebra.
Sternum The sternum or breastbone is a long flat bone located in the center of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Shaped roughly like a necktie, it is one of the largest and longest flat bones of the body. Its three regions are the manubrium, the body, and the xiphoid process.[1] The word "sternum" originates from the Greek στέρνον, meaning "chest".