hello all this is dr. Alsup and now that we have a better understanding of where that parotid gland
is located and what are its functions let's start dissecting this area and finding structures that
can be located within the parenchyma of the parotid gland or in less fancy terms what is
deep within the parotid gland and if you think about it that product land is covering a lot of
territory and because it's so big it necessarily is going to be associated with other structures
that aren't functionally but geographically related to the parotid gland okay there will
be three main structures which were embedded embedded within or deep to the parotid gland
and we'll start from superficial in our work our way deep so the most superficial within will be
the facial nerve the facial nerve trunk and its branches that will kind of expand all over this
region the next so kind of intermediate will be the retro mandibular vein and then deepest and
it is quite deep is the external carotid artery I'm going to introduce the facial nerve and its
two main motor divisions but we will dive deeper into those specific branches with dr. Fox in the
face session so the main trunk of the motor root will exit the skull via the stylo mastoid foramen
which is going to be quite deep in this region you can actually even see a little bit of the
styloid process right here from here the trunk will split into two main divisions this will
be the temporofacial and the cervicofacial and from there that's where you'll get that five
main set of branches that will serve the muscles of facial expression there are other branches of
the facial nerve as well or other motor branches in this this kind of region but are going to be
more heading this posteriorly or inferiorly and these include the posterior auricular nerve which
is usually the first branch of the motor root after exiting the stylo mastoid foramen but it's
gonna head posterior this nerve will innervate the auricularis posterior and the occipital belly
of the occipital frontal and there will also be a digastric branch of the facial nerve which will
affarin li serve or innervate the posterior belly of the digastric as well as its close neighbor
the style of hyoid muscle if you look deep to the facial nerve trunk you will have a vein of
variable size typically it's a relatively short vein before it splits into different divisions
and this is the retro mandibular vein this vein is formed by the union of the superficial temporal
vein and the deeper maxillary vein they will come together and you will have the formation
of the retro mandibular actually the formation or the coalescence of these two veins occurs
within the parotid gland so you'll actually have portions of the superficial temporal and maxillary
veins within the product land as well but it is within that product layer that you'll have
the formation of the retro mandibular and then fairly quickly and around the inferior end of the
parotid gland the retro mandibular vein divides into two branches or divisions the anterior so
here's that retro mandibular vein recall that it's typically a very short trunk the anterior
division of the retro mandibular vein will join with the facial vein before these eventually
drain into the internal jugular the posterior division will join with the posterior auricular
vein which is going to be posterior to the year to form the external jugular vein and hopefully
we remember the external jugular vein it's one of those superficial veins at the neck you can see it
running superficial to the sternocleidomastoid muscle right here very deep and always a lot
deeper than I am expecting is the external carotid artery or your ECA the external carotid artery is
a terminal branch of the common carotid artery and it is the that has the branches in the neck
as well as branches to the superficial and deep face regions and there will be eight main branches
some of these we've already discussed and some will be new to us but we're going to go through
each one in these next few slides we will start with the branches that come off anteriorly from
the external carotid and these three branches are typically the easiest to locate because they are
interior but also because they tend to be larger in size typically the first branch of the external
carotid will be the superior thyroid artery this one is typically easier for me to locate
just because it's the one that's going to descend rather than a send or move transversely like most
other branches of the external carotid so you can see it descending here it will supply the superior
portions of the thyroid gland as well as portions of the larynx through the superior laryngeal
artery next you will have the lingual artery which may share a common origin with the facial artery
but if it doesn't share a common origin it's typically the more inferior of the arteries this
artery will supply the tongue as well as some of the suprahyoid muscles and the facial artery
supplies just what you think it should supply which is the face mostly the superficial face
but there are some portions of the deeper face but mostly we'll focus on that superficial face region
there is one medial branch of the external carotid and this is the a sending pharyngeal
artery this is often the second branch of the external carotid but it is much harder to see
based on this branching point than the anterior branches it will a send on the pharynx deep to
the internal carotid artery and will send many important branches to the pharynx so that's the
main supply but it losses some branches to the pre vertebral muscles even some small branches to the
mill middle ear and some small contributions even to the cranial meninges there - posterior branches
of the external carotid artery and these are often easiest to locate as they head towards their hard
targets you will have the occipital artery which is heading towards that post stare lateral neck
and scalp whereas the posterior auricular artery supplies portions of the scalp and around right to
the posterior portions of the ear so they're going to similar places the posterior auricular artery
will stay a little bit closer to the posterior ear last but not least are the terminal branches
of the external carotid artery and the largest of these two will be the maxillary artery which
is not very visible in this particular dissection but as we begin to explore the deep face and the
infra temporal fossa we're going to spend quite a bit more time here so this is going to be the
dominant supply of the deep face the superficial temporal artery will continue to a send in fact
it's usually easiest to see superior to the parotid gland and this artery will supply the
lateral scalp and the face so there is a lot going on within or deep to the parotid gland all kinds
of good stuff now let's take a moment to review so question damage to one of the terminal branches of
the external carotid artery would most greatly affect the deep face region - so damaged - which
one I should really ask damage to which one of the terminal branches of the external carotid artery
would most greatly affect the deep face region so take a moment there's a few key things I would
look at in this stem so we are looking at one of the branches of or one of the terminal branches
of your eca and it would most greatly affect the deep region so hopefully you have landed on that
see the maxillary artery is the correct answer it is both a terminal branch of the external carotid
artery as well as the major supplier the deep face the superficial temporal artery is the other
terminal branch of the external carotid artery but does not supply the deep face so at least
doesn't dominantly supply it the facial artery also supplies the face but as we mentioned it
is mostly the superficial face and it's also not a terminal branch the lingual artery is
going to supply the tongue and the superior thyroid artery will do what a good superior
thyroid artery should and supply the superior portions of the thyroid gland all right so that
is our review of the contents that are going to be found within or deep to the parotid gland as
you review this please do feel free to reach out and thank you for your time and attention