Intervertebral disc herniation refers to the displacement of the nucleus pulposus (the gel-like inner core of the disc) through a tear or weakened area in the annulus fibrosus (the outer fibrous ring). The displaced disc material extends beyond the normal boundaries of the disc space and may compress or irritate nearby spinal nerve roots or, less commonly, the spinal cord.Etiology and Risk FactorsHerniation commonly results from degeneration, in which aging reduces disc hydration and...

Pneumothorax means the presence of air in the pleural space — the thin potential gap between the visceral and parietal pleura. This condition disrupts the normal pressure balance that keeps the lungs inflated, leading to partial or complete collapse of the affected lung.Normal physiologyUnder normal conditions, the pleural space maintains a slightly negative intrapleural pressure, which keeps the lungs expanded against the chest wall. This negative pressure creates a delicate balance between...

A hiatal hernia is the abnormal protrusion of the stomach or other abdominal organs through the esophageal hiatus of the diaphragm into the thoracic cavity.Normally, the gastroesophageal junction (GEJ) lies below the diaphragm and is supported by the phrenoesophageal membrane, the diaphragmatic crura, and connective tissues. Weakening of these structures—due to aging, congenital defects like a short esophagus, or increased intra-abdominal pressure from coughing, obesity, pregnancy, or heavy...