Which of the following is a component of the thoracic cage?

• A. Clavicle
• B. Hyoid Bone
• C. Costal Cartilage
• D. Sternum

Answer: (D)

The thoracic cage is the protective bony framework around the chest organs, formed by the sternum in the front, the ribs with their costal cartilages around the sides, and the thoracic vertebrae in the back. The sternum, a flat bone along the midline, creates the anterior boundary and serves as the attachment point for the costal cartilages of the true ribs, effectively completing the front wall of the cage. The clavicle belongs to the shoulder girdle and connects to the sternum but is not itself a rib-cage bone; the hyoid bone sits in the neck and isn’t part of the rib cage. Costal cartilage is part of the rib cage by linking ribs to the sternum, but the central bone that best fits as a direct component of the thoracic cage is the sternum.