ear, however, remains intact, the deafness being of middle ear type. In
transverse fractures the line crosses the petrous bone at right angles to its
long axis, i.e. it traverses the floor of the skull anteroposteriorly. It may
cross the internal acoustic meatus or, if situated more laterally, will involve
the internal ear, in which case the medial wall of the middle ear may be
fractured. The tympanic membrane remains intact, so that there is no
Fig. 199. Injury to left ear due to explosion of rifle grenade. Horizontal section. 1, Rupture of drum-
head, with blood clot on anterior margin; 2, Scala tympani just internal to round-window membrane,
with thin layer of haemorrhage on the walls; 3, Fundus of internal meatus with haemorrhage.
Fig. 200. Radiograph demonstrating a longitudinal fracture of the right temporal bone.
haemorrhage from the external meatus, but there is loss of internal ear
function. Thus in the typical longitudinal fracture the middle ear is opened,
while in a transverse fracture the inner ear is involved.
A peripheral paralysis of the facial nerve has been recorded in about 46
per cent of fractures of the skull and almost all the cases which survive are
associated with middle ear deafness. Therefore the prognosis of cases in
which the labyrinth capsule is involved may be extremely grave.