The olfactory, optic, oculo-motor, pathetic, ophthalmic division of
the trigeminal, and the abducens nerves are all liable to be
implicated.

_Diagnosis._--It is scarcely necessary to state that bleeding from the
nose or mouth may occur after a blow on the face without the
occurrence of a fracture of the skull. It is only when it is long
continued and profuse that the bleeding suggests a fracture. Similarly
effusion of blood in the region of the orbit may be due to a simple
contusion of the soft parts ("black eye"), or to gravitation of blood
from the forehead or temple. Sub-conjunctival ecchymosis also may
occur independently of a fracture implicating the anterior fossa--for
example, in association with an ordinary black eye, or with fracture
of the orbital ridge or of the zygomatic (malar) bone.

Finally, paralysis of the cranial nerves may result from pressure of
blood-clot, or from the nerves being torn without the skull being
fractured.

#Fracture of the middle fossa# is usually the result of severe
violence applied to the vault, as, for example, when a man falls from
a height, or is thrown from a horse and lands on his head.

_Clinical features._--The most conclusive sign of fracture of the
middle fossa is the escape of dark-coloured blood in a steady stream
from the ear, followed by oozing of cerebro-spinal fluid. The bleeding
from the ear may go on for days, the blood gradually becoming lighter
in colour from admixture with cerebro-spinal fluid. Finally the blood
ceases, but the clear fluid continues to drain away, sometimes for
weeks, and in such quantity as to soak the dressings and the pillow.
In our experience, the escape of cerebro-spinal fluid is much less
common than is generally supposed. In most cases, on examining the ear
with a speculum, the tympanic membrane is found to be ruptured; when
it is intact, the blood and cerebro-spinal fluid may pass down the
Eustachian tube into the pharynx. The escape of brain matter from the
ear is exceedingly rare. Emphysema of the scalp sometimes results when
the fracture passes through the mastoid cells. The facial and acoustic
nerves and the maxillary and mandibular divisions of the trigeminal
are frequently implicated. Deafness is a serious and not uncommon
accompaniment of fracture of the middle fossa, as the fracture
involves the labyrinth and is attended with haemorrhage and the
formation of new bone.

_Diagnosis._--Care must be taken not to mistake bl