The Danger space is a potential space located behind the true retropharyngeal space, which connects the deep cervical spaces to the mediastinum. In healthy patients, it is indistinguishable from the retropharyngeal space. It is only visible when distended by fluid or pus, below the level of T1-T6, since the retropharyngeal space variably ends at this level.
It is a potential path for spread of infections (e.g. retropharyngeal abscess) from the pharynx to the mediastinum.