Final answer:
The human rib cage consists of 12 pairs of ribs, classified as true, false, and floating ribs, each playing a specific role in protecting the thoracic cavity and supporting the upper body.
Step-by-step explanation:
The anatomy of the ribs involves a complex articulation with the thoracic vertebrae, which is crucial for the stability and protection of the thoracic cage. Ribs are flattened, curved bones that are numbered 1 through 12. Each rib has several components including the head of the rib, which primarily articulates with the costal facet on the body of the corresponding thoracic vertebra, and to a lesser degree, with the vertebra above it.
The tubercle of the rib articulates with the facet on the transverse process of the same vertebra. The angle of the rib reflects its greatest curvature and signifies the most posterior part of the thoracic cage, aligning with the medial border of the scapula in the anatomical position. The costal groove carries essential blood vessels and a nerve.
Ribs are classified into three types: true ribs (1-7), which attach directly to the sternum, false ribs (8-12), which either attach indirectly to the sternum or not at all, and floating ribs (11-12), which do not attach to the sternum or to the costal cartilage of another rib.