lung and airway disorders
Overview of Pleural and Mediastinal Disorders
Introduction
Thepleurais a thin, transparent, two-layered membrane that covers the lungs and also lines the inside of the chest wall. The layer that covers the lungs lies in close contact with the layer that lines the chest wall. Between the two thin flexible layers is a small amount of fluid (pleural fluid) that lubricates them as they slide smoothly over one another with each breath. The area containing the fluid is called the pleural space. In abnormal circumstances, air or excess fluid can get between the pleural surfaces, enlarging the pleural space. If excess fluid accumulates (called Pleural Effusion ) or if air accumulates (called Themediastinum(chest cavity) refers to an area that is bordered by the breastbone (sternum) in front, the spinal column in back, the neck on top, and the diaphragm below. It contains the heart, the thymus gland, some lymph nodes, and parts of the windpipe (trachea), esophagus, aorta, thyroid gland, and parathyroid glands. It does not include the lungs. The mediastinum is divided into three parts: Front (anterior) Middle Back (posterior) Mediastinal Masses , abnormal masses such as cysts and tumors, can form in the mediastinum. 