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THE NERVOUS SYSTEM. 289 ;

nerve, and terminates at the jjosterior superior portion of the ophthalmic
(lentieular) ganglion, constituting its long- or sensory root.
Tlie Long Ciliary Nerves are two or three in number, and com-
mence from the nasal nerve as it extends across the optic nerve.
They pass along the inner margin of this nerve, and unite with
some of the short ciliary nerves from the ophthalmic ganglion.
They then pierce the sclerotic coat of the eye, pass forward between
it and the choroid coat, and are distributed to the ciliary muscles, the
cornea, and the iris.
The hipheno-eihmoidal (Luschka) or Posterior Ethmoidal (Krause)
Nerve passes from the nasal nerve to the posterior ethmoidal foramen
(posterior internal orbital canal), and is distributed to the mucous mem-
brane of the sphenoidal sinus and the posterior ethmoidal cells in front
of the body of the sphenoid bone.
The Internal Nasal or Ethmoid(d Nerve is in the line of continuation
of, and generally described as, the nasal nerve. It passes through the
anterior ethmoidal foramen, situated between the frontal and ethmoidal
bones, into the brain-case, just external to the cribriform plate. It then
extends in a shallow groove along the outer wall of this plate to the
cerebro-nasal slit near the crista galli, passes through this slit, enters the
nasal chamber, and divides into three branches—the internal or septal
branch, the lateral, and the anterior superficial branch.
The Internal or l^eptal BrancJi of the internal nasal nerve passes
downM'ard and forward, and supplies the anterior portion of the septum
of the nose.
The Lateral Branches of the hiterncd Nerve usually comprise two or
three filaments which are distributed to the anterior portions of the lat-
eral walls of the nasal chambers, including the extremities of the middle
and inferior turbinated bones.
The Anterior or tiuperjidal Branch passes dowuMard in a longitu-
dinal groove or canal on the internal surface of the nasal bone until
it reaches the lateral cartilage of the nose. Here it extends between
the bone and the cartilage, runs beneath the compressor naris, and
becomes superficial, terminating in the spine, the wing, and the tip of
the nose.
The Infratrochlear Nerve is one of the terminal branches of the nasal
nerve, it being given off* near the anterior ethmoidal foramen. It passes
forward along the inferior border of the superior oblique muscle and
parallel to the supratrochlear nerve, and receives a communicating branch
from it. As it approaches the trochlea it passes to the inner angle of
the eye and divides into t's\^o sets of branches. Those of the superior
set are distributed to the superficial structures of the superior evelid
while those of the inferior set are distributed to the superficial struc-
tures at the root and side of the nose, the superficial portion of the
inferior eyelid, the caruncle, conjunctiva, the lachrymal sac, and the
lachrymal duct.
Variations.—" The nasal nerve occasionally (frequently, Krause)
gives filaments to the superior and internal recti. A branch to the
levator palpebrse superioris has been met with (Fiisebeck) ; offsets
from the nasal nerve as it traverses the anterior internal orbital canal to
Vol. I.—19