Mellüreg

Mellüreg, in Hungarian anatomy, denotes the thoracic cavity, the space within the chest bounded anteriorly by the sternum, laterally by the ribs and costal cartilages, posteriorly by the thoracic vertebrae, and inferiorly by the diaphragm. It houses the heart, lungs, and major vessels, as well as portions of the trachea and esophagus, and contains the membranes that enclose these organs—the pleurae and the pericardial sac.

The mellüreg is divided into a central mediastinum and two lateral pleural cavities that enclose the lungs. The pericardial cavity lies within the mediastinum around the heart. The mediastinum extends from the superior thoracic aperture to the diaphragm and is traditionally subdivided into superior and inferior parts; the inferior mediastinum is further divided into anterior, middle, and posterior compartments, with the middle containing the heart and pericardium, and the great vessels and portions of the trachea and esophagus occupying other compartments.

The pleural cavities are lined by a pair of pleurae: the visceral pleura adheres to the lungs, while the parietal pleura lines the thoracic wall and mediastinum; the pleural space between them contains a small amount of pleural fluid to reduce friction. The diaphragm forms the floor of the mellüreg and separates it from the abdominal cavity; the chest wall and intercostal muscles enable respiration.

Clinical relevance: The mellüreg is subject to conditions such as pneumothorax (air in the pleural space), pleural effusion (fluid accumulation), hemothorax, and mediastinal pathology including tumors or lymph node enlargement. An understanding of its compartments aids in diagnosing and managing thoracic diseases.