Temporomandibular joint air in fractures of the skull base

Basilar skull fractures involving the temporal bone extend through the tympanic part of the temporal bone in two-thirds of cases. The anatomical relationship of this part of the temporal bone and the temporomandibular joint enables air to pass from the auditory canal into the joint. Air in the temporomandibular joint is demonstrated on CT scans as an indirect sign of temporal bone fracture.