The costodiaphragmatic recess, also called the costophrenic recess or phrenicocostal sinus, is the posterolateral fringe of the pleural space, a potential space around the lung inside the pleural cavity. It is located at the acutely angled junction ("reflection") between the costal and diaphragmatic parietal pleurae, and is interpreted two-dimensionally on plain X-rays as the costophrenic angle. It measures approximately 5 cm (2.0 in) vertically and extends from the eighth to the tenth rib along the mid-axillary line.