The first, we have the pair of frontal sinuses,
these are pretty symmetrical and how
they're artistically illustrated,
but they may be asymmetrical,
the right one might be larger,
than the left one and vice versa.
Located just below the frontal sinuses,
are the ethmoidal air cells of the ethmoid bone.
And then, inferiorly located
are the large maxillary sinuses
and the last sinus is the sphenoid sinus
and that is shown in through here,
as we start to look at
communications of the sinuses,
with the nasal cavity.
The sphenoidal sinus, is also paired
and it is usually unequal in size,
because the septum does not evenly divide
the sphenodial sinuses into equal paths.
But here is the opening of the sphenoidal sinus,
into the nasal cavity,
this is a section through,
where the superior nasal concha,
is projecting towards us,
so, it's right above that particular area.
We have between the superior nasal
concha and the middle nasal concha,
in the superior meatus area,
we have the openings of the
posterior ethmoidal cells.
Just inferior to the middle nasal concha,
in the middle meatus area,
are the openings of the middle ethmoidal cells.
And then, this semilunar feature right
in through here in the middle meatus,
is the floor of the hiatus semilunaris
and the opening that is in here,
is the opening from the maxillary sinus.
And this is the anterior semilunar
extension of the hiatus in my lunaris,
from where we were, just a moment ago.
And then, also in this same
general area the middle meatus,
just inferior to the middle nasal concha,
we have another opening,
this is the infundibulum,
opening of the frontal nasal duct,
that drains the frontal sinus
and the anterior ethmoidal cells.
Located in the inferior meatus,
which is located right below
the inferior nasal concha,
is the opening of the nasal lacrimal duct.
So, lacrimal secretions begin in the
superior lateral aspect of the eye
and then, travel toward the
inferior medial aspect of the eye
and then, are collected by the nasal lacrimal duct
and then, tears enter the nasal cavity
in the region of the inferior meatus.