Hi everyone, this is Dr. Kingston,
and in this video we'll be talking about the contents and
relationships of the sublingual space.
And our objective here is to
identify exactly what those are.
The sublingual space is inferior to
the tongue and deep to the mucosa of the oral floor.
It's part of the oral cavity,
so it shares that inferior border of
the mylohyoid muscle that you see here and here.
Laterally it's surrounded by the mandibular body.
And medially, it is bounded by the genioglossus muscle,
which you can see right there.
We haven't encountered genioglossus yet,
but you can see it up here in this image on the right.
There are two of them,
even though they look like there's just one,
there's one right and one left.
And these are going to extend from
the genial spines on the mandible,
which sit right there,
and they extend up into the body of the tongue and
function to protrude it anteriorly or stick it out.
Because of its central location here,
it divides the right sublingual space
from the left sublingual space.
The sublingual space is a fascial space
and just like the other fascial spaces
that we've covered in this course
they're going to communicate
with surrounding fascial spaces.
So you learned this pathway up here from
the infraorbital down to
the submasseteric space into
the pterygomandibular, lateral pharyngeal,
retropharyngeal quite a while ago now.
So now we're going to add to it.
The sublingual space communicates directly with
the submandibular space and
the lateral pharyngeal spaces around
the posterior border of the mylohyoid. So that
mylohyoid muscle doesn't entirely
close off the oral cavity from the neck.
And we see a number of structures
like the lingual artery and
the hypoglossal nerve pass deep to
the mylohyoid to get from the neck into the oral cavity.
Well, where you have structures passing through,
you also have fascia that surrounds them.
So that's what creates this communication.
Again, these communications provide
a pathway for the spread of infection and metastasis.
And the lateral pharyngeal space
provides a direct pathway
into the retropharyngeal, or
the danger space, that leads into the thorax.
So you'll need to be very cognizant
of infections that might occur here.
And that's going to include
infections of the mandibular teeth.
In addition to having a direct route to the thorax,
infections in the sublingual space can be
life-threatening without ever even spreading.
So infection can cause what's
referred to as Ludwig's angina,
which is cellulitis, or edema,
fluid retention and swelling in
the sublingual or submandibular spaces.
So here you can see all of
this dark fluid here causing the swelling.
And this can cause the tissues of
the pharynx to pinch together and close off.
So in this picture you can see
that all of the swelling is literally
pushing this poor individual's tongue up and back and
closing off the space here in the oropharynx.
This is an emergency and it needs immediate treatment.
So luckily, this person in the x-ray here did not
end up having full closure of the pharynx.
And according to Radiopedia,
he was able to get treatment before
breathing issues became really severe.
For being such a small fascial space,
the sublingual space is actually home to
a surprisingly large number of structures.
These are going to fall into two categories.
We have things that are
supplying the tongue, neurovasculature for the tongue.
This is going to include the lingual nerve,
the lingual vein, the lingual artery,
and the hypoglossal nerve.
And then we also have some salivary glands and
ducts from salivary glands traveling through here.
So we've mentioned the submandibular gland
before sits mostly in the submandibular triangle.
It's duct is going to be running through
the space. And, sitting just inferior to it,
here is the sublingual gland,
which sits entirely within the sublingual space.
That sublingual gland is actually the largest gland
to exist entirely within the sublingual space.
Kind of unsurprisingly then it's also the smallest of
the three big salivary glands
because it has to fit in such a narrow space.
You can find its location in
the oral cavity by identifying
the sublingual fold of mucosa that
covers its surface. So see right there.
The actual glands
sit deep to that mucosa and sends up
many small little ducts here that are
going to open directly onto the oral floor.
The duct of the submandibular gland,
which sits for the most part
down here in the submandibular triangle,
also travels through the sublingual space.
So the deep portion of the submandibular gland is
going to sneak up over the edge of the mylohyoid muscle
and it will send its duct
anteriorly, where it's going to
exit through the sublingual caruncles.
Unlike the sublingual glands,
the submandibular glands only have the one duct.
All of its products will
enter the oral cavity right here.
These two salivary glands are
close enough neighbors that they
share an innervation pathway.
Salivary glands get parasympathetic innervation
to make them secrete.
And in this case that
parasympathetic pathway originates up
with the facial nerve.
However, instead of traveling with the facial nerve
out through the stylomastoid foramen and onto the face,
those fibers are going to branch off in
the middle ear and join the chorda tympani,
which is going to travel out into
the infratemporal fossa where it
joins up with the lingual nerve.
The lingual nerve is a branch of
V3, the mandibular nerve.
It's going to travel into the oral cavity.
It's carrying some somatic sensory fibers
for the tongue and
for the mucosa of the inferior oral cavity.
Those parasympathetic fibers will ride along
with the lingual nerve into the sublingual space,
where they're going to synapse in
the submandibular ganglion before
making a short jump to their target gland.
Now the lingual nerve has
a very distinct relationship with the submandibular duct.
This will allow you to
identify them and more importantly,
it'll help you tell them apart.
So the lingual nerve we can see here in
the BlueLink image travels into the oral cavity.
It is going to travel anteriorly and inferiorly.
It is going to loop down
underneath that submandibular duct.
Then it's going to come
up the other side of it to
approach the tongue from underneath here,
sending its fibers now anterior and superior.
The end result here is that it ends
up cradling the submandibular duct,
just like you might cradle a baby.
So you can see this relationship
right here in the image on the right.
It comes inferior to the duct again,
and then back superior to get to the tongue,
That was a pretty good transition into
the neurovascular structures that
we're going to see in the sublingual space.
So in addition to the lingual nerve,
we're going to find one other large nerve
here and that is the hypoglossal.
See him right here?
The hypoglossal nerve is carrying
somatic motor innervation to
the intrinsic and extrinsic tongue muscles.
And in order to reach them,
it's also going to pass deep to
mylohyoid to enter into the sublingual space.
And then just like we saw with that lingual nerve,
it's going to approach
these muscles from an inferior position.
A branch of the lingual drainage system
is also going to be traveling along with it.
So it has no matching artery here.
Therefore, we call it the
vena commitans of the hypoglossal nerve.
Arteries found in the sublingual space are
going to be branches of the lingual artery.
So as it enters the sublingual space,
just like everything else here,
by passing deep to the mylohyoid,
it's going to give off the dorsal lingual artery,
which will head superiorly
to supply the posterior tongue,
the palatine tonsil, and part of the soft palate.
The bulk of the lingual artery then is going to pass
deep to the hyoglossus muscle.
And as it approaches this anterior part
of the sublingual space,
it's going to split into two branches.
The deep lingual artery,
which is kind of confusing because it's
the more superior of the two
is going to pass more
superiorly along the deep surface of the tongue.
And the sublingual artery will stay
deeper within sublingual space
and supply the sublingual gland
and other tissues that make up the oral floor.
The lingual vein is ultimately responsible
for draining the submandibular space and
the tributary pattern that forms it
follows pretty close to
the branches of the lingual artery,
but it isn't an exact match.
So anteriorly we have
deep lingual and sublingual veins
spreading along with their partner arteries.
But you'll notice posteriorly here that these
drain back to the vena commitans
for the hypoglossal nerve,
which eventually joins a few other branches
back here to form the lingual vein.
It's good to remember here that
veins tend to be quite variable
and there's often a network of
them rather than one big thing.
The hyoglossus muscle, which
is another extrinsic tongue muscle like
the geniohyoid, provides somewhat of
an obstacle for nerves and
vessels entering the sublingual space.
Most of these, as you can see
by all of the blue structures on here,
are going to travel lateral
to the muscle to get where they're going.
The major exception is the lingual artery,
which is labeled in green to show that it is different.
This decides to take a deeper route
and heads medial to hyoglossus.
This gives it an extra layer of protection,
which is a good thing for an artery.
The hyoglossus muscle also
separates the sublingual space into
a posterior and anterior compartment with
the hyoglossus muscle sitting
entirely within that posterior space.
Anteriorly,
we have a pretty clear view
of the genioglossus muscle here.
And that is what, remember, divides
the sublingual space into right and left.
We can see the neurovasculature in this area
sorting itself out by where it's going to go.
So for instance, we can see that relationship
of the lingual nerve and the submandibular duct.
We can see the deep lingual vessels
running together up along the deep surface of the tongue.
And we can see the sublingual vessels and
hypoglossal nerve heading into the deep sublingual space.
One thing that I want to add here too,
if you look at these lingual vessels,
the way that they're drawn, the way that they're shown
in most anatomical images.
They look like they're pretty big and they
kinda just come to an abrupt end here.
And that's not entirely the case.
They obviously don't extend any further.
But instead of just ending,
they have really extensive anastomoses
with their partner from the right or the left.
So they're not ending so much as they are forming a loop.
All right, That is
the end of the material for this video.
Here is your review question.
The indicated structure here
enters the sublingual space by
travelling be medial to the hyoglossus muscle.
We can see in the image here.
Here is that hyoglossus muscle.
And we can clearly see the structure coming
out from its medial side.
This is our lingual artery.
And it is, remember the only structure
that is going to course
deep to the hyoglossus muscle
within the sublingual space.
That brings us to the end. Thank you for watching.