scalp. In some cases
electrolysis has yielded good results.

_Traumatic aneurysm_ of the temporal artery was comparatively common
in the days when the practice of bleeding from this vessel was in
vogue, but it is seldom met with now.

_Arterio-venous aneurysm_ may also occur in the course of the temporal
artery, as a result of injury, and is best treated by complete
extirpation of the segments of the vessels implicated.

CHAPTER XII

THE CRANIUM AND ITS CONTENTS

Anatomy and physiology--Cerebral localisation--Lumbar puncture. HEAD
INJURIES--Concussion--Cerebral irritation--Compression--Contusion
and laceration of the brain, and traumatic intra-cranial
haemorrhage: _Middle meningeal haemorrhage_; _Haemorrhage from
internal carotid and venous sinuses_--Intra-cranial haemorrhage of
the newly born. Cerebral oedema--Wounds of brain--After-effects of
head injuries--Traumatic epilepsy and insanity--Infective
complications.

#Anatomy and Physiology.#--The _Cranium_ is irregularly ovoid in
shape, and its floor is broken up by various projections to form three
separate fossae--anterior, middle, and posterior--in which rest
respectively the frontal, the temporal, and the occipital lobes of the
brain; the cerebellum, pons, and medulla oblongata also occupy the
posterior fossa.

The _outer_ table is the most elastic layer of the calvarium, and it
varies greatly in thickness in different skulls and in different parts
of the same skull. It is nourished chiefly from the pericranium which
is firmly bound down along the lines of the sutures. The _inner_ or
vibreous table is thin and fragile, and its smooth internal surface is
grooved by the middle meningeal and other arteries of the dura mater,
and by the large venous sinuses. The intermediate layer--the
_diploe_--is highly vascular, branches of the meningeal vessels
anastomosing freely in its open porous substance with branches derived
from the pericranial vessels. Some of its veins open into the external
veins, and others into the intra-cranial sinuses, and they communicate
with the emissary veins as these pass through the bone, which explains
the spread of infective processes from the structures outside the
skull to those within. The possibility of withdrawing blood from the
interior of the skull by leeching, bleeding, or cupping depends on the
existence of the emissary veins.

_The Membranes of the Brain._--The _dura mater_ is a fibro-s