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84 ANATOMY.

of the nose. Usually there is left but one small 0}3ening. Along the
superior border of this surface are a number of cellular openings, which
are closed in by articulation with the lachrymal and ethmoid bones.
The anterior two-thirds of the thin plate of bone below the aperture is
smooth and concave, forming most of the external wall of the inferior
meatus of the nose. The posterior third is slightly roughened for artic-
ulation with the vertical plate of the palate bone.
The Lachnpnal Groove is at the anterior superior angle of the nasal
surface, behind the nasal process : it is converted into a canal by articu-
lation with the lachrymal bone, the uncinate process of the ethmoid,
and the lachrymal process of the inferior turbinated bone. The canal
extends downward and backward, terminating in the inferior meatus
of the nose. In the recent state it is lined by a mucous membrane,
the lachrymal duet.
The Lachri/mal Tubercle is a small prominence of bone at the junc-
tion of the infraorbital ridge with the external border of the nasal
process. This tubercle serves as a guide to the lachrymal sac, which is
the expanded portion of the lachrymal duct, situated posterior to the
tubercle.
The Posterior Palatine {Palato-maxiUary) Canal, for the passage of
the posterior palatine vessels and anterior palatine nerves, commences
about the middle of the posterior border of the bone and runs downward
and forward as a groove, which in the articulated bone is closed by the
vertical plate of the palate bone to form a canal.
The Anterior Border of the nasal surface is thin and deeply indented
in its central portion, forming the lateral boundary of the anterior naris.
The portion of this border above the indentation is roughened and
articulates with the nasal bone ; that below articulates with its fellow
of the opposite side, and forms half of the nasal spine.
The Lateral or Facial Surface is concave, and extends from the anterior
border to the root of the malar process. The outer portion of its supe-
rior bord(!r is roughened for articulation with the lower border of the
orbital process of the malar bone. Internally, this border is smooth,
and curves upward from the imier portion of the infraorbital ridge.
The Infraorbital Foramen.—Just below this ridge, about midway of
the border, is an oval aperture for the passage of the infraorbital nerve
and vessels. Between this foramen and the infraorbital ridge arises the
proper elevator nuiscle of the upper lip (levator labii superioris proprius).
71ie Canine Fminence is a vertical ridge that divides the lower portion
of this surface, and corresponds in position to the root of the canine tooth.
It gives origin to the depressor muscle of the wing of the nose and also to
the depressor of the upper lip. Tlie Incisive or 3Iyrtiform Fossa is a slight
depression between the canine eminence and the median border of the
bone. It gives origin to the depressor muscle of the wing of the nose
and to the dej>ressor of the upper lip. Above, and a little external to
the incisive fos>^a, arises the compressor of the nose (compressor nasi).
The Canine Fosm is a larger depression on the outer side of the
canine eminence. The floor is very thin, and an opening into the
antrum may be readily made through it. This fossa gives origin to
the elevator muscle of the angle of the mouth (levator anguli oris).