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THE NERVOUS SYSTEM. 297

scribed as passing to the depressor anguli oris and platysma myoides
muscles (Henle), to the integument below the chin (Krause and
Schwalbe), and to the submaxillary gland (Meckel, Henle, Curnow).
The Inferior Dental Branches are numerous, and form loops or plex-
uses beneath the roots of the teeth similar to those found above the
superior teeth. From these loops fine filaments pass through the apical
foramina in the roots of the teeth of the lower jaw to supply the pulp
and tooth with sensation. There are also filaments which pass upward
and supply the alveolo-dental membranes and gum tissue.
The Incisor Branch is the continuation of the main trunk of the
inferior dental nerve. It jiasses forward under the inferior canine and
incisor teeth, and forms loops or plexuses similar to those formed by the
main branch, from which filaments are distributed to the teeth and sur-
rounding tissues in like manner.
The Mental or Labial Nerve is the larger of the two terminal divis-
ions of the inferior dental nerve. It passes outward from the canal
through the anterior dental (mental) foramen, and immediately breaks
up into three branches beneath the depressor anguli oris muscle. The
inferior branch descends, and is distributed to the chin. The two supe-
rior branches ascend to su])])ly the lip, its mucous membrane, and the
labial glands. These three bi-anches freely interlace with the supra-
maxillary branch of the facial nerve.
The inferior dental nerve occasionally receives one or two communi-
cating filaments from other branches of the inferior maxillary nerve.
The Lenmr Inferior Dental Nerve (Sapolini) is frequently present.
It arises from the Gasserian ganglion, and laiitcs M'itli the inferior
dental nerve after entering the inferior dental canal.
SYMPATHETIC GANGLIA CONNECTED AYITH THE
FIFTH NERVE.
The sympathetic ganglia (ganglia of the fifth nerve) found in con-
nection with the trifacial nerve belong to the general sympathetic sys-
tem found throughout the body. This sym])athetic system is composed
of a large number of ganglia, cords, and plexuses.
The Ganglia are separate centres for the conveyance and distribution
of various cords and filaments, consisting of motor, sensory, and sym-
pathetic fibres. They contain ncrvc-cclls very similar to those found in
the encephalon and sjiinal cord. These ganglia are arranged in two
chains situated on each side of the l)ody near the central line. They
commence with the ophthalmic ganglion in the orbit, and extend
downward along each side of the vertebral column, and terminate below
in the ganglion impar in the coccygeal region.
The ganglionic or sympathetic system is independent and separate
from the general nervous system, but is intimately connected with it by
communicating l)ranches which pass from the motor and sensory roots
of the cerebro-spinal nerves, as well as by direct filaments which extend
between it and the cerebro-spinal centres. The sympathetic nervous
system is distributed to the mucous membranes, the viscera, the coats of
blood-vessels, and to the non-striated or involuntary muscular fibres.