How many thoracic vertebrae serve as posterior attachment points for ribs?

The correct answer is twelve because the thoracic region of the vertebral column consists of twelve vertebrae, specifically labeled T1 through T12. Each of these thoracic vertebrae provides a posterior attachment point for a pair of ribs, allowing for the structure and flexibility of the rib cage. This anatomical arrangement is crucial because the ribs articulate with the thoracic vertebrae at specialized facets, contributing to the overall structure necessary for respiration and protecting vital organs in the thoracic cavity. Additionally, since humans typically possess twelve pairs of ribs, it aligns with the twelve thoracic vertebrae, further confirming this answer's correctness.