ribcage

The rib cage, or thoracic cage, is the bony and cartilaginous enclosure that protects the heart and lungs and supports respiration. It consists of 12 pairs of ribs, costal cartilages, the sternum, and the thoracic portion of the vertebral column.

Ribs are curved bones with a head that articulates with the bodies of thoracic vertebrae, a neck, a tubercle that articulates with the transverse process, and an anterior connection via costal cartilage. Ribs 1–7 are true ribs with direct cartilage attachments to the sternum. Ribs 8–10 are false ribs that join the cartilage of the rib above, and ribs 11–12 are floating ribs with no anterior attachment.

The sternum comprises the manubrium, body, and xiphoid process, to which the upper seven pairs attach their costal cartilages. The costal cartilages contribute to the elasticity of the cage and help transmit force during respiration.

Functionally, the rib cage protects thoracic organs, supports the shoulder girdles, and serves as an attachment site for muscles of respiration, the upper limb, and the back. It participates in breathing by allowing expansion and contraction of the thoracic cavity, coordinated with the diaphragm and intercostal muscles.

Developmentally, ribs arise from somites and ossify from cartilage regions during fetal development, with growth continuing into adolescence. Variations and deformities can occur, such as pectus excavatum or pectus carinatum, and rib fractures or deformities may arise from trauma or disease. Imaging of the rib cage is common in assessing chest injuries and thoracic disorders.