The pleural cavity is a thin, fluid-filled space located between the two layers of the pleura, which are membranes surrounding the lungs. This cavity plays a crucial role in respiratory mechanics, allowing the lungs to expand and contract smoothly during breathing. The fluid within the pleural cavity reduces friction between the lung surfaces and the chest wall. The pleura consists of two layers: the visceral pleura, which covers the lungs, and the parietal pleura, which lines the chest wall. Any abnormalities in the pleural cavity, such as fluid accumulation or infection, can lead to conditions like pleuritis or pleural effusion, affecting lung function and overall health.