Identify the structure represented by the letter (D):

The structure represented by the letter is the thoracic vertebra. The thoracic vertebrae are a series of twelve bones in the upper and mid-back region of the spine, situated between the cervical region (neck) and lumbar region (lower back). They are characterized by their attachment to the ribs, which helps form the rib cage and provides structural support and protection for the thoracic cavity, including vital organs like the heart and lungs.

Understanding the thoracic vertebra's unique features, such as the presence of costal facets for rib articulation and the overall shape of the vertebrae, is critical for radiologic evaluations. These vertebrae also play a key role in supporting the upper body and maintaining proper posture. Familiarity with these anatomical structures is essential for imaging interpretations, such as X-rays or MRIs, where distinguishing between different vertebral segments is necessary for accurate diagnoses and treatment plans.