A. CT scan and interpretive diagram. Transverse cross-sectional views of the thoracic cavity demonstrate its kidney-like shape, resulting from the protruding vertebral bodies, and division into three compartments. B and C. Dimensional and coronal cross-sectional diagrams demonstrating linings of pleural cavities and lungs (pleurae). Each lung is invested by the inner layer of a closed sac that has been invaginated by the lung. Inset: A fist invaginating an underinflated balloon demonstrates the relationship of the lung (represented by the fist) to walls of the pleural sac (parietal and visceral layers of pleura).

A Dean D, Herbener TE. Cross-Sectional Anatomy. Baltimore, MD: Lippincott Williams & Wilkins, 2000.1