hello anatomy friends this is dr. Alsup and in this video we will be discussing how we can locate
and identify the muscles of mastication because you can't have a session of mastication without
talking about these muscles so we're gonna start out with one of the big ones the masseter muscle
sometimes pronounced masseeter muscle I go with the masseter and it is this large muscle right in this
region here so that is your masseter muscle it is a dominant muscle on the superficial side of
the ramus of the mandible sometimes referred to as the most superficial muscle of mastication in
fact we're looking right now in this particular view at the superficial part of the muscle it is
a very large muscle very thick muscle so there is all kinds of different fibers going in different
directions associated with the masseter this muscle is often described as quadrangular and will
have superior attachments or proximal attachments to the inferior margin of the zygomatic bone which
would be over here as well as the zygomatic arch which you can see a little bit of right here and
you even have some attachments all the way on to the maxillary bones if we continued on and if we
kind of pulled up some of these muscles in this region its distal or inferior attachments will of
course be on the mandible as will all the muscles of mastication and so it's going to spread out in
many different parts of the mandible in terms of its distal attachments so the lateral body the
entirety of the superficial ramus and into the angle of the mandible so I think the masseter
muscle is typically one of those easier to locate muscles associated with the head neck moving to
the temporalis region which will be up here we're looking kind of at an inferior lateral view in
order to see the temporalis muscle or at least see it well you have to remove the temporal fascia
which is what is occurring right here so we're pulling up the temporal fascia in order to see
the deep temporalis muscle you can see a little bit of the tendon here so this is the temporalis
muscle and this will be the temporal fascia this fascia is an investing fashion and is particularly
dense for an investing fashio the temporal fascia is not to be confused with the temporoparietal
fascia which is more superficial at the same level with the smash superficial in fact to
the temporal branches of the facial nerve so the temporal parietal fascia has been removed in this
dissection so I can see a little bit of the muscle fibers deep to the fashio so you know you're
looking at an investing fascia and specifically the investing fashion of the temporalis muscle
which is called the temporal fascia so you pull that up and then you would look at a dissection
with the temporal fascia being removed and that's what we're looking at here we're looking directly
at the muscle fibers and the tendons of the temporalis muscle it's a pretty wide expanse
specifically especially in comparison to a lot of the other muscles of mastication this muscle will
extend from the temporal fossa which is up in this region superiorly to the coronoid process
which you can see kind of right here and portions of the ramus as well as the temporal crest of the
mandible this muscle is always much thicker than I remember in a dissection so it's often
pretty difficult to do a clean reflection without affecting the deeper pterygoid muscles and in that
important or a vasculature so another pretty thick muscle of mastication so let's do move
to those deeper muscles of mastication starting with the lateral pterygoid muscle this muscle has
two heads and we have two different images here because I think they show different views kind
of of these two heads the superior head which I'm going to label here and here so that's going to
be the superior heads on both of these dissections the superior heads proximal attachment is way over
in the sphenoid bone region so at the greater wing of the sphenoid which you can't see very
well here but you can see the attachment towards the articular disc as well as the capsule of the
TMJ so that one of course is going to be more superior whereas the inferior head which I'm
going to label here in here the inferior head's proximal attachment is also on the sphenoid bone
so again not clearly visible in this image but it's going to be on the lateral aspect of the
lateral pterygoid plate of the sphenoid and it's distal attachment is going to be on that
pterygoid fovea and I think you can kind of see pretty nicely where that would be located there
the pterygoid fovea of the mandible which is in the neck region of the consular process it
is often closely associated with the second part of the maxillary artery which you can see pretty
clearly right here and occasionally that second part of the maxillary artery will pass deep to
the inferior head of the lateral pterygoid which is what is occurring in this particular donor
moving to the medial pterygoid muscle with the same images this muscle forms the deep portion
of the tear go masseteric sling so it's that sling that is going to be formed on either side of the
ramus of the mandible the masseter will be on the superficial part the medial pterygoid will
be on the deep part of the ramus of the mandible and so that's what's forming that sling I'm going
to label them right here it's a little difficult to see the medial pterygoid mainly because right
here because you have a lot of that neurovasculature and these types of dissections particularly
the inferior alveolar neurovasculature that's going to be kind of covering the medial pterygoid
in these dissections but just think if you had something on the other side of the ramus
of the mandible kind of mirroring the masseter muscle that's going to be the medial pterygoid
its proximal attachments are going to be all the way on the maxillary bone the Palatine
bone and it's gonna be on the other side or the medial surface of the lateral pterygoid plate of
the sphenoid so the lateral pterygoid was on the lateral surface of the lateral pterygoid
plate the medial pterygoid will be on the medial surface of the lateral pterygoid plate and then
of course it will have its distal attachment on the ramus of the mandible so if I were to
pick up these this neurovascular you would be looking directly at the medial pterygoid
same thing here but you can see a little bit of it kind of peeking out in certain spots
alright the less muscle I want to cover is not actually a muscle of mastication but considered
a muscle of facial expression but in very close proximity to the muscles of mastication and
this is the bucs inator muscle recall that the buccinator muscle is on a deeper plane than many
of the other muscles of facial expression and it is covered superficially by a buccal fat pad in
most people it's going to be variably shaped irregularly shaped and you can see it really
nestled here this buccal fat pad nestled here right in front of our anterior to the masseter
muscle but if you remove the fat pad then you are looking at the Buccinator muscle I'm gonna
label bits here and I love this particular image here I think it's a good image of the vaccinator
muscle this muscle covers the area superficial to the lateral teeth bearing regions of the maxilla
and the mandible and will be anterior to the ramus of the mandible so you can see that really
nicely right here so if you think about if you unreflecting or move the masseter muscle back
in place you would have the masseter muscle sitting right here and then the Buccinator
kind of right anterior to it you can even see a little bit of the remnants of the parotid duct
in these images because if you recall from that session the parotid duct is going to pierce the
bucs inator before emptying its contents into the oral cavity so there is that bucks inator these
are the muscles we wanted you to locate for this session so for muscles of mastication and when
the facial expression which is geographically closely related please make sure to review on
your own and reach out with any questions you may have thank you and have a wonderful day