The plane through the anterior margin of the trachea and the main bronchi, and its continuation through the bronchopericardial membrane and dorsal wall of the pericardium, divides the mediastinum into an anterior and posterior compartment. The knowledge of the contained structures and the relations of the mediastinal organs, satisfies the requirements for assessment of horizontal sections. On this basis, demonstrations were made of typical cross-section views of the inferior, middle, and superior mediastinum.