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288 ANA TOMY.

which passes outward under the orbicularis palpebrarum, interlacing
with the facial nerve. The muscular branches are distributed to the
corrugator supercilii, frontalis!; and. orbicularis palpebrarum. The
cutaneous branches are two in number, median and lateral. These
extend posteriorly as far as the occiput. The deep or pericranial
branches are distributed to the frontal and parietal bones. This nerve
also sends a filament which supplies the mucous membrane of the frontal
sinus. Occasionally the division of the supraorbital nerve takes place
within the orbit, the larger branch passing through the supraorbital
foramen, while the smaller branch extends internally around the supra-
orl)ital arch or through the frontal notch, which is occasionally present.
The Lachri/mal Xnnr is the smallest of the three divisions of the
ophthalmic. It passes along the outer side of the frontal nerve into
the orbit through the anterior lacerated foramen, encased in an indi-
vidual sheath derived from the dura mater. It passes forward and
outward near the periosteum of the orbit above the external rectus
to the lachrymal fossa of the frontal bone, accompanied by the lachry-
mal artery. It then penetrates the external tendo palpebrarum of the
eye and terminates in the upper eyelid.
Branches of Distribution.—On approaching the lachrymal fossa the
lachrymal nerve sends a communicating cord to the orbital branch of
the second or superior maxillary division of the fifth. This branch is
sometimes called the inferior division of the lachrymal nerve, and occa-
sionally passes backward through a canal in the outer wall of the orbit,
its divisions foriiiing an arch from which branches are distributed to
the lachrymal gland and the conjunctiva. Within the lachrymal fossa
it sends branches to the lachrymal gland and the conjunctiva.
The Nasal or Oculo-xasal Nerve is intermediate in size between
the other two divisions of the ophthalmic nerve. It commences from the
under surface of the ophthalmic nerve, and passes through the widest
portion of the anterior lacerated foramen into the orbit between the two
heads of the external rectus muscle, accompanied by the fourth nerve.
On either side of it are the two divisions of the third nerve. From the
anterior lacerated foramen it passes obliquely inward and forward over
the optic nerv-e below the superior muscles of the orbit to the anterior
ethmoidal foramen on the inner wall of the orbital cavity. It here
divides into the internal nasal and infratrochlear nerves.
Branches of the Xa.sf(/ Xerve.—
Branch to the dura mater, I^ong ciliary,
Communicating branches to Spheno-ethmoidal,
sympathetic nerve. Internal nasal.
Ganglionic, Infratrochlear.
The Branch to the Dura Mater is a small filament which turns back-
ward and is distributed to tlie dura mater of the anterior cerebral fossa.
TJie Conimnnicating Branches to the St/nipathetie are a few distinct
filaments which communiciite with the sympathetic network about the
ophthalmic artery (Allen).
The Gang/ionic Branch is quite slender and about half an inch in
length. It usually commences from the nasal nerve as it extends
between the two heads. It passes along the outer side of the optic