Costodiaphragmatic recess

The costodiaphragmatic recess is a potential space in the pleural cavity inferior to the lungs, located at the junction of the costal and diaphragmatic parietal pleurae. On average, it measures approximately 5 cm vertically, and extends from the eighth to the tenth rib along the mid-axillary line.

The lungs expand into this recess during forced inspiration. However the recess never fills completely. During expiration, it contains no lung tissue, only pleural fluid.