The document summarizes the anatomy of the thorax. It contains: - The thorax is bounded superiorly by the root of the neck and inferiorly by the diaphragm. It contains the heart, lungs, and major blood vessels. - The mediastinum is the thick soft tissue partition that separates the two pleural cavities and contains the heart and other structures. - The lungs are enclosed in pleural cavities and separated from each other by the mediastinum.