Page 909 - My FlipBook

BLOOD -SUPPLY. 919

tooth, into rather a thick mass just over the rim of the alveolus, where
they are continuous with, or merge into, the periosteum, which covers
the outer surface of the alveolar process. This forms what has been
termed the dental ligament. I will describe the gingivae in connection
with the diseases which have their beginnings in them.
The blood-supply of the pulp of the tooth and its peridental mem-
brane is admitted to the api-
Fig. 484.
cal space, usually, by a single
arterial twig for each root.
A¥hen within this space, it
breaks up into a number of
branches, and one of these
enters the apical foramen,
while the others pass down
toward the crown of the
tooth within the structure
of the peridental membrane.
These are generally found
about midway between the
root of the tooth and the
alveolar wall, and in unin-
jected sections cut lengthwise
will often give the impression
that the membrane is com-
posed of two layers, as we
find it described in some of
the older works. As these
arteries proceed down the
sides of the root they send
out branches into the walls
of the alveolus that anasto-
mose freely with the arteries
that supply the gums. And
just at the rim of the alveo-
lus there is a pretty rich
plexus formed by union with Eoot and Membrane of Tooth: p,p, perid ental mem-
f» ! -J.
ii , • brane : ap, apical space : a, artery: al, al, a alveolar pro-
the arteries ot the periosteum cess; M.dentai ligament.
and of the gum—the gingival
plexus. This being the case, it is evident tliat the peridental mem-
brane may receive its blood-supply from either of these two opposite
sources. In alveolar abscess the blood-vessels of the apical space are
often completely destroyed, but, as the anastomosis with the vessels of
the gum over the alveolar rim and through the alveolar wall is so rich,
the membrane does not suffer from lack of blood.
The nerve-supply of the peridental membrane is also derived from
two sources. These correspond perfectly with the sources of the blood-
supply, and need no further description except to say that in this instance
the principal supply seems to be from the direction of the gum and
through the alveolar wall. This may not so plainly apj^ear from ana-
tomical examination, but experimental observation demonstrates that the