costodiaphragmatic recess
Last reviewed 01/2018
The costodiaphragmatic recess describes the sharp gutter at the junction of costal and diaphragmatic pleurae in each pleural cavity. The recesses act as potential spaces.
During inspiration, the negative pressure of the cavity is reduced so as to induce inferior expansion of the lungs into the recesses. During expiration, the lungs contract and the parietal pleural margins are drawn into apposition by the surface tension of the film of fluid between them.
The recess, seen as the costodiaphragmatic angle in erect PA chest radiograms, is often filled with a rim of transudate fluid in patients with heart failure. This is radio-opaque and appears as 'blunting' of the angle - a supportive but not pathognomic sign.