Final answer:
The thoracic cage, or rib cage, consists of 12 pairs of ribs along with the sternum, thoracic vertebrae, and costal cartilage, protecting the heart and lungs, and supporting upper body structures.
Step-by-step explanation:
The thoracic cage, commonly called the rib cage, is a critical structure in the human body that encloses and protects vital organs within the thoracic cavity, including the heart and lungs. This bony framework is composed of 12 pairs of ribs, the sternum, thoracic vertebrae, and costal cartilage. The ribs are anchored posteriorly to the thoracic vertebrae and are classified into true ribs (1-7), false ribs (8-12), and floating ribs (11-12). The sternum, known as the breastbone, is subdivided into the manubrium, body, and xiphoid processes. Together, these components provide protection and support for the shoulder girdles and upper limbs, facilitate breathing by enabling changes in the volume of the thorax, and serve as attachment points for muscles of the back, chest, neck, and shoulders.