<unk>  occurs when gas or air is present in the<unk>  layer of the skin.<unk>  refers to the tissue beneath the cutis of the skin, and<unk>  refers to trapped air.  Since the air generally comes from the chest cavity,<unk>  usually occurs on the chest, neck and face, where it is able to travel from the chest cavity along the fascia.
Subcutaneous emphysema
Tracheal deviation
Barrel chest
Trapped lung
Pleural friction rub
Skin crepitation
Round atelectasis
Pulmonary consolidation