The supraclavicular fossa

The presence of a supraclavicular fossa and the visibility of its floor on chest radiographs have been ignored in the radiologic literature. In a study of 500 randomly selected chest radiographs, we could identify the floor of the fossa in 29% of patients. There is extreme normal variation in the visibility, depth, and symmetry of the two sides. However, the fossa floor is a frequent normal finding with which all radiologists should be familiar and which can occasionally stimulate a parenchymal lung abnormality such as a fluid level or an emphysematous bleb in the upper outer lung fields.