hi all this is dr. O and in this video we're going to talk about the
mandibular nerve or v3 we're going to start here with somatic pathways and
follow up with some autonomic pathways that run through v3 in the next video
specifically we're going to answer what are the main branches of v3 when considering mastication
and what do they innervate and which branches are affected by an inferior alveolar nerve block
now you'll remember that be three exits the skull through foramen ovale and it
exits then into the infra temporal fossa there you see a short trunk
as well as an anterior and a posterior division in this donor we can see that
the anterior division has been reflected upwards but its branches are along here and
we can see the posterior division below now the trunk would be further superior in this
space and a little bit difficult to see in this image and we're going to start off here
with branches that come directly from the trunk and in terms of muscles of mastication there is
one branch that we need to be concerned about here which is the nerve to the medial pterygoid
and this comes off very close to the foramen ovale so it's a little harder to conceptualize
or visualize in a donor image but we do have a little part of it that is peeking
out right here now I'll move that so you can actually see the structure but keep in mind
this is the posterior division and here is that anterior division so off of the trunk
would be much more superior you can imagine the nerve to the medial pterygoid kind of
coursing posterior to the posterior division to then reach the medial pterygoid muscle
and the medial pterygoid muscle is that which you can see outlined here
you
next let's talk about that anterior division this is really important in
terms of these muscles of mastication most of the ranges of the anterior division are
going to be motor branches going to these muscles so the first ones we see our deep
temporal and what those look like in a donor is always going to be deep to the temporalis
muscle so we'll usually see an anterior and posterior branch and like we do here
next is a masseteric nerve and both in this image on the right as well as in the donor you can see
it's been cut because we've removed the masseter muscle to see as deep as we are in this space
you
next we see the nerve to lateral pterygoid and this is coming off in the area of lateral
pterygoid where this anterior divisional course between the superior and the inferior heads of
the lateral pterygoid so that's what we're seeing right here so near to that space we
see the nerve to lateral pterygoid again since it's been removed in this image we just see this
bit right there now after the lateral pterygoid is given off and after it passes through the lateral
pterygoid muscle then it changes its name to the buccal or the long buccal nerve now this is the
only sensory branch of the anterior division and you might also see the nerve two lateral
pterygoid coming off of buccal so when the name change happens can vary depending on the source
now let's move to the posterior division we see one of the first branches off of
the posterior division is the auricular temporal nerve on this image of the donor
here you kind of see two distinct roots that wrap around the middle meningeal artery and
then join together to travel up and around so this nerve irregular temporal nerve will
travel with the superficial temporal artery now's a good time to pause and think about
when you've heard about irregular temporal nerves before which gland are we talking
about we were talking about the parotid gland and the postganglionic fibers from the cranial
nerve nine glossopharyngeal will follow in this space so we'll talk about that more
in the future but I just wanted to make note of that while we're here next we see the two major
branches of posterior division one a little bit more medially and a little more anteriorly we
see the lingual now the lingual nerve here we'll see passes medial to the mandible and then enters
into the oral cavity verses them the inferior alveolar nerve which is a little more lateral
a little more posterior will enter into the mandible through the mandibular foramen so
you can see that represented here as well and so all of this space would be within the mandible
let's talk a little bit more about inferior alveolar nerve very important nerve we see
as it passes down into the infra temporal fossa into the mandible through the mandibular foramen
then it gives off a bunch of little branches and these little branches make up the inferior dental
plexus which would be found inside a mandible the last branch it gives off before exiting the
mandible will be the incisive branch over here we can't necessarily see it but you can imagine it
heading deep in the mandible to get to you the incisors and then finally it forms the
mental nerve so the mental nervous nerve is the termination of inferior alveolar nerve it exits
the mental foramen out onto the area of the chin and is a sensory branch to the skin of the chin
in terms of an inferior alveolar nerve block this will affect the branches to the mandibular teeth
on that same side so the incisive branch and the inferior dental plexus as well as that mental
nerve which will lead to some numbness around the area of the chip so I'm going to start this
video just to see these branches where we are in a little bit more 3d to one another
we'll see right away that branch coming up and around is the auricular temporal nerve the one
highlighted coming out toward us toward where the masseter sits as the masseteric nerve and
then medial to the mandible but still remaining kind of outside of the oral cavity we see the
buccal nerve that was the termination of the anterior division now from posterior Lee we
see those two major branches from the posterior division first is the inferior alveolar nerve
that exiting through the mental foramen anteriorly
and then more medially with in the oral cavity we find the lingual nerve which
will be sensory to the tongue and more that we'll talk about in future videos
now lastly I just wanted to show you where v3 is coming out of the skull
you see that that's coming out of foramen ovale and there are a lot of branches off
of that main trunk two muscles in the area including the medial pterygoid muscle you
so let's take a question now so the question is which of the following is
a parently innervated by a branch of the anterior division of v3
just highlight anterior division so is that the anterior 2/3 of the tongue the buccal
mucosa and posterior gingiva mandibular teeth or the skin on the anterior oracle and external
acoustic meatus so take a second to make your choice and then check in when you're ready
all right so the correct answer here is B b4 buckle
so the buckle nerve is that termination of the anterior division of v3 all of the other
branches are branches of the posterior division so think about which nerve will innervate the
anterior two-thirds of the tongue sensory so that will be lingual right here then what
about the mandibular teeth that's going to come from inferior alveolar nerve and
then finally the skin of the anterior oracle oracle and external acoustic meatus that we're
talking over here about our auricular temporal nerve okay I hope that that makes some sense
to you and always feel free to ask questions that's everything for this video thank you you