hi let's talk about the nasal and the oral cavities so the nasal cavity is supported
externally by the nose and it is an exclusive route for respiration I'm not saying that food
and drink can't leave via the nose but let's just say that it's not meant to the external structure
of the nose is very simple there is a bridge of the nose and the bridge of the nose is continuous
inferiorly down to the lip via the nasal columella then there are the ala of the nose ala
is winged and these ala surround the nares or the nostrils this is a sagittal section of a
cadaveric specimen we can see there is the Naris or the nostril there the nasal vestibule
would be the portion of the nose outside of the the nasal cavity and the nasal cavity then runs
from the vestibule back to the choana which is the internal Naris the nasal cavity is divided
into right and left nasal cavities via the nasal septum and that nasal septum is tripartite we have
the perpendicular plate of the ethmoid bone the vomer and some septal cartilage anteriorly if
we look at the lateral wall of the nasal cavity we'll see three ridges these ridges are called
conchae or turbinates there's an inferior Concha a middle concha and a superior concha and what these
conchae do is as air is brought into the nasal cavity it encounters this and the turbulence
brings as much of that air into contact with the nasal epithelium as possible this warms the air
it moistens the air it brings odorants to the olfactory nerves and it traps any impurities in
the nasal mucus secreted by the mucosa so that it may be eliminated from the respiratory tract now
between and among these nasal conchae are various recesses so for instance superior to the superior
nasal Concha is the sphenoethmoidal recess which is between the superior concha and the sphenoid
bone then there's the superior nasal meatus the superior nasal meatus is between the superior
and middle nasal cochae the middle nasal meatus between the middle and the inferior Concha and
then the inferior meatus that's the inferior nasal Concha with respect to the sphenoethmoidal recess
there's a very important communication between that area and the sphenoidal sinus we can see that
the opening here is traversed by this red wire and what happens is materials can move between
that sphenoethmoidal recess of the nasal cavity and the sphenoidal sinus there in this recess in
this superior nasal meatus we have openings for the posterior ethmoidal cells as you may
recall from osteology the ethmoid bone contains a number of air cells these air cells in total form
the ethmoidal sinus the posterior ethmoidal cells communicate with the nasal cavity via
the superior nasal meatus the middle nasal meatus has very many communications with different parts
of the skull if we look at the the middle nasal meatus we'll see that there is a semilunar hiatus
or there is this moon-shaped opening and along that semilunar hiatus are openings and entrances
to a few different structures so represented by the blue wire here we can see the opening
between the frontal sinus and the nasal cavity so this is the frontonasal duct the drains into the
ethmoidal infundibulum which is the funnel shaped aspect of the anterior portion of the semilunar
hiatus right there we also have the anterior ethmoid 'el cells draining into the semilunar
hiatus and we have the maxillary sinus opening into the semilunar hiatus as well so we have
quite a few things here within this semilunar hiatus the frontal sinus the maxillary sinus
and those anterior ethmoid 'el cells are all communicating via this hiatus into the nasal
cavity the inferior nasal meatus is a little more simple that includes the opening for the
nasolacrimal duct the nasolacrimal duct is a tube that connects the medial aspect of the eye with
the inferior nasal meatus and it's a pathway by which tears can move from the surface of the eye
to the inside of the nose to help keep the nasal mucosa moistened when an individual cries more
tears traverse this nasolacrimal duct mixing with the nasal mucosa and the duct can be overwhelmed
and those tears may spill down an individual's face the mouth and the oral cavity is a space by
which both the respiratory and digestive systems share in common and thus it's the proximal part of
what people refer to as the aerodigestive pathway the oral cavity begins at the mouth so there's an
oral fissure between the superior and inferior lips and then the oral cavity may be divided
into the oral vestibule which would be the space between the lips and the teeth and the oral cavity
proper the oral cavity proper would be everything beyond the occlusal surface of the teeth and that
oral cavity proper is going to contain the tongue and be continuous with the pharynx in
particular than nasopharynx so we've discussed the pathways by which air may enter and leave
the respiratory system both the nose and nasal cavity and the mouth and oral cavity thank you