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240 ANATOMT.

The Posterior Ethmoid Artery arises from the inner side of the oph-
thabuic nearly opposite the posterior ethmoidal foramen. It passes
through this foramen, and is distributed, by a small meningeal branch,
to the portion of the dura mater situated in the anterior fossa of the
brain-case, as well as to the mucous membrane lining the posterior
ethmoidal cells and to the superior portion of the internal nose.
The Anterior Ethmoidal Artery is larger than the posterior. It arises
from the inner side of the ophthalmic close to the anterior ethmoidal
foramen. It passes through this foramen into the brain-case immedi-
ately above the cribriform plate of the ethmoid bone, and is accompanied
by the nasal nerve. The artery and nerve pass together through the
cerebro-nasal slit (anterior nasal foramen) of the ethmoid bone into
the nasal chamber, where the vessel receives the name of the anterior
nasal arterv. The anterior ethmoidal artery is distributed through its
branches to the antero-ethmoidal cells, the dura mater of the ante-
rior fossa of the brain-case, the mucous membrane of the olfactory
portion of the nasal chamber, including the superior and inferior tur-
binated ])ones, and to the roof and septum of the nose, the branch
supplying the septum anastomosing with the naso-palatine artery. It is
also distributed to the frontal sinus, a branch passing between the nasal
bones and lateral cartilage in company with the nasal nerve, and anas-
tomoses on the face with branches from the facial artery.
The Muscular Arteries, branches of the ophthalmic, consist of two
principal ones, superior and inferior, and several smaller twigs.
The Superior Muscular Artery is the smaller of the two larger
branches of the ophthalmic, and is distributed to the levator palpebrre
superioris, superior rectus, and superior oblique muscles. The existence
of this artery is not constant.
The Inferior 3Iuscular Artery passes anteriorly from the ophthalmic,
and is distributed to the external and inferior recti and inferior oblique
muscles. Its existence is more constant than the superior branch, and
it furnishes the principal number of the anterior ciliary arteries.
The Sinaller Muscular Arteries arise from the ophthalmic at various
points along its course, as well as from its lachrymal and supraorbital
branches. They are distributed to the different muscles of the eye.
The Supraorbital Artery is the largest branch of the ophthalmic. It
arises in the posterior portion of the cavity of the orbit as the artery
crosses the optic nerve. It passes above the muscles of the eye,
accompanied by the frontal nerve, and extends anteriorly between tlie
periosteum covering the roof of the orbital cavity and the levator pal-
pebral superioris muscle to the supraorbital foramen in the frontal bone.
It passes through this foramen and divides into two branches, sujierfif-ial
and deep. These branches anastomose with the temporal and angular
arteries, and with their fellows of the opposite side.
The Superficial Branch is distributed to the frontal muscle and to the
integument over this region.
The Deep Branch is distributed to the periosteum of the frontal bone.
. The superficial and deep branches of the supraorbital artery also send
branches to the muscles within tlie orbit, and, as the supraorbital passes
out of the orbit, it supplies the diploe of the frontal bone by a branch