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96 ANATOMY.

The Inferior Border is more complicated than any of the others. It
is thicker at the termination of the lachrymal ci'cst than elsewhere,
which gives strength to the posterior wall of the lachrymal canal. It
is divided by the lower extremity of the lachrymal crest into two por-
tions, an anterior and a posterior.
The Anterior Portion, or that portion in front of the extremity of the
crest, extends downward, backward, and inward, and terminates in a
pointed process which articulates with the lachrymal process of the eth-
moid bone. As it extends downward it passes on the outer side of the
uncinate process of the ethmoid bone, and to the inner side of the orifice
to the maxillary sinus, and thus assists in closing the anterior portion
of the opening leading to the sinus. This portion also partly bounds
the lachrymal canal, and is supported by the uncinate process of the
ethmoid.
The Posterior Portion, or that situated behind the extremity of the
crest and below the orbital surface, articulates with the orbital plate
of the superior maxilla.
Development.—The lachrymal bone arises from one point of ossi-
fication, which is deposited about the eighth week of fcetal life.

The Nasal Bones.

The nasal bones, two in number, are situated at the upper portion of
the external nose, and form what is often termed the " bridge " of the
nose ; also the anterior boundary of the nasal chambers.
The nasal bone is oblong in shape, has the lower extremity wider
than the upper, and presents two surfaces, anterior and posterior ; Mith
four borders, superior, inferior, lateral, and median.
The Anterior or Outer iSurface (Fig. 44) varies in shape, but may be
said to be generally convex from side to side and concave from above
Fig. U.
Fm. 45.
vitA Frontnl B»
^l^^th
FrontaZ ^jniie-
until
'Orest
with
—Opposite boiiA, W\\ \Rrpcmlic-iuur
* '*
^lafcrfEtJimoid.
groove for luteal nerve

Outer Surface.. In«'»r Surface
Kigbt Kasal Boiiu. Left Xasal Bone.
downward. The upper portion is punctured by numerous nutrient
foramina ; the lower portion is smooth and rounded. Near the centre
of tliis surface will be seen a foramen which passes through to the
internal aspect of the bone, and transmits a small vein. This foramen