_mastoid_, _condyloid_, and _occipital_, passing to the transverse
(lateral) sinus; the _parietal_, which enters the superior sagittal
(longitudinal) sinus; and a branch from the nose which traverses the
foramen caecum and enters the anterior end of the superior sagittal
sinus.

The supra-trochlear, supra-orbital and auriculo-temporal branches of
the trigeminal nerve, together with the greater and lesser occipital
nerves, supply the scalp with sensation, while the muscles are
supplied from the facial nerve.

The _lymph vessels_ pass to the parotid, occipital, mastoid, and
submaxillary groups of glands, the different areas of drainage being
ill-defined.

INJURIES OF THE SCALP

#Subcutaneous Injuries.#--_In simple contusion_ of the superficial
layers, owing to the density of the tissues, the blood effused is
small in quantity and remains confined to the area directly injured,
which is firm and tender to the touch, swollen and discoloured. The
disappearance of the swelling may be hastened by elastic pressure and
massage.

_Haematoma of the scalp_ results when lacerated vessels bleed into the
sub-aponeurotic space. Owing to the laxity of the connective tissue in
this area, the effused blood tends to diffuse itself widely, and,
according to the position assumed by the patient, gravitates to the
region of the eyebrow, the occiput, or the zygoma. When a large artery
is torn the swelling may pulsate. A haematoma of the scalp may readily
be mistaken for a depressed fracture of the skull, owing to the fact
that the margins of the effusion are often raised and of a firm
resistant character. A differential diagnosis can usually be made by
observing that the swelling is on a higher level than the rest of the
skull; that the raised margin can to a large extent be dispersed by
making firm, steady pressure over it with the finger; and that, on
doing so, the smooth and intact surface of the skull can be
recognised. When a fracture exists, the finger sinks into the
depression and the irregular edge of the bone can be felt. In doubtful
cases, if cerebral symptoms are present, an exploratory incision
should be made.

Even a large haematoma is usually completely absorbed, but the
dispersion of the clot may be hastened by massage and elastic
pressure. Any excoriation or wound of the skin must be disinfected.

Sometimes a blood-cyst, consisting of a connective-tissue capsule
filled with a yellowish-red fluid, remains, and may req