DEFINE MEDIASTINUM. DESCRIBE THE SUPERIOR MEDIASTINUM UNDER THE FOLLOWING HEADINGS: (A) BOUNDARIES (B) CONTENTS (C) APPLIED ASPECT. (LE) DIVISION OF MEDIASTINUM AND NAME THE CONTENTS OF SUPERIOR MEDIASTINUM? (SE) SUPERIOR MEDIASTINUM- BOUNDARIES AND CONTENTS. (SA) Mediastinum is the space in the thoracic cavity in between the two pleural cavities Divisions of the mediastinum Mediastinum is divided into superior and inferior mediastinum by an imaginary plane passing through sternal angle ( anteriorly) and the lower border of 4 TH thoracic vertebra ( posteriorly). The inferior mediastinum is further divided into anterior, middle and posterior mediastinum. It is divided by the pericardium which occupies the middle mediastinum. The part of mediastinum in front of the pericardium is anterior mediastinum, and that behind the pericardium is the posterior mediastinum. Superior mediastinum Boundaries: - Anteriorly- manubrium sterni Posteriorly- upper four thoracic vertebra Inferiorl...