Three of those connect to non-costal cartilage, and two are deemed to be ‘floating,’ which means they only connect to the spine. Of all 24 ribs, the first seven pairs are often labeled as ‘true.’ These bones are connected to the costal cartilage, while the five other ‘false’ sets are not. The human rib cage is made up of 12 paired rib bones each are symmetrically paired on a right and left side. Although fixed into place, these ribs do allow for some outward movement, and this helps stabilize the chest during inhalation and exhalation. At the chest, many rib bones connect to the sternum via costal cartilage, segments of hyaline cartilage that allow the rib cage to expand during respiration. The rib cage is collectively made up of long, curved individual bones with joint-connections to the spinal vertebrae. The xiphoid process which hangs down at the inferior end of the process (“xiphoid” is from the Greek for sword), starts out as cartilage, and does not typically ossify into bone until an individual is about 40 years old.The ribs partially enclose and protect the chest cavity, where many vital organs (including the heart and the lungs) are located. The central, thin body provides articulation points for costal cartilage from ribs 2 through 7. The manubrium, at the superior end of the sternum and wider than the rest of the bone, provides articulation points for the clavicles and for the costal cartilage extending from rib 1. The sternum has three parts: the manubrium, the body, and the xiphoid process. (C) Lateral view of the left side of the sternum. (A) The sternum with costal cartilage shown in blue, anterior view. The anterior aspects of the ribs (located medially) attach to costal cartilages which allow for elasticity of the thorax while linking the ribs to the costal notches on the sternum.Ībove: The sternum. The articular facets on the head and costal tubercles of the rib articulate posteromedially with costal facets on the thoracic vertebrae. This is the end that connects to costal cartilage (unless it is a floating rib).Ībove: The structure and markings of a rib. This is the end that articulates with the vertebra. On an individual rib, one end has various processes, facets, and bumps. The white extensions of the ribs are costal cartilage connecting the ribs to the sternum. The sternum is the neck-tie shaped bone at the center of the chest shown in white. The true ribs are shown in red, the false ribs are shown in green and blue, and the floating ribs are blue. Lastly, rib pairs 11-12 are considered floating ribs because they do not have any costal cartilages attaching them in any way to the sternum.Ībove: The right side of the rib cage and the with the sternum. Rib pairs 8-12 are considered false ribs because they only attach to the sternum by attaching their combined costal cartilages with the costal cartilage of the 7th rib. Rib pairs 1-7 are considered true ribs because they attach to the sternum via their own separate costal cartilages. The cartilage strips are called costal cartilage (“costal” is the anatomical adjective that refers to the rib) and connect on their other end to the sternum. Ten of the twelve ribs connect to strips of hyaline cartilage on the anterior side of the body.

The rib below that is rib 2, and it connects to the T2 thoracic vertebra, and so on. The most superior rib is designated rib 1 and it articulates with the T1 thoracic vertebrae. Each pair articulates with a different thoracic vertebra on the posterior side of the body. The number is the same in both males and females. It consists of the ribs, the sternum, and the thoracic vertebrae, to which the ribs articulate. The thoracic cage, also called the rib cage, surrounds and protects the heart and lungs in the thoracic cavity.

Rib cage diagrams