informal leader. An individual within an organization that is viewed as someone worth listening to due to their perceived experience and reputation among peers. The informal leader does not hold any position of formal authority or power over the peers choosing to follow their lead but can influence the decisions of others.
The mediastinum (from Medieval Latin mediastinus, midway) is the central compartment of the thoracic cavity surrounded by loose connective tissue, as an undelineated region that contains a group of structures within the thorax.he mediastinum lies within the thorax and is enclosed on the right and left by pleurae. It is surrounded by the chest wall in front, the lungs to the sides and the spine at the back. It extends from the sternum in front to the vertebral column behind, and contains all the organs of the thorax except the lungs.
mediastinal shift a shifting or moving of the tissues and organs that comprise the mediastinum (heart, great vessels, trachea, and esophagus) to one side of the chest cavity.The condition occurs when a severe injury to the chest causes the entrapment of air in the pleural space (tension pneumothorax).f or pertaining to the mediastinum. mediastinal flutter movement of the tissues and organs of the mediastinum back and forth with each movement of air into and out of an open sucking wound in the thoracic cavity.