00:02
We also have a closely related
special sense called taste,
when there are typically
considered five primary tastes
sour, sweet, bitter, salty,
and savory or umami.
00:18
And there's been
a lot of debate back and forth
about different portions
of the oral cavity
sensing these different tastes
more than others.
00:27
Although it really does seem
that taste buds
can really sample all of these
pretty much everywhere in the mouth.
00:35
So what are the taste receptors?
Well, the taste receptors
are the taste buds.
00:40
And as you can see here in a very
zoomed in portion of the tongue,
they tend to live in these
little furrows or grooves
that can be located
mostly in the tongue,
although there are some elsewhere
in the oral cavity.
00:54
And so they're special
little areas on the epithelium
that line the tongue
in between these little bumps.
01:02
And these little bumps sometimes get
special names as papillae.
01:07
So we have these large ones here
called the Circumvallate papillae.
01:11
And then many, many smaller ones,
such as the Foliate papillae,
and Fungiform papillae.
01:17
As well as other papillae
that don't actually have taste buds,
which are the Filiform papillae.
01:25
When it comes to taste,
the pathways are actually
a little bit more complicated
than you might expect.
01:31
And the key landmark is
the anterior two thirds
versus the posterior third
of the tongue.
01:38
Due to some very complicated
embryological development,
the facial nerve or
cranial nerve VII,
is actually what will provide
taste sensation
to the anterior two-thirds
of the tongue.
01:54
The posterior third of the tongue
will actually be carried out
by the glossopharyngeal nerve
or cranial nerve IX.
02:02
And there is a little bit of taste
beyond the tongue
further back into
the pharyngeal area
that will be carried out
by cranial nerve X,
which is the vagus nerve.
02:16
And they'll all go back to what's
called the gustatory nucleus.
02:20
Gustatory is our
fancy word for taste,
just like olfaction is
our fancy word for smell.
02:26
And eventually work its way back up
to the thalamus
for the primary gustatory area
for processing of taste.