hi all this is dr. O and in this video we're going to talk
about the temporal mandibular joint and specifically what type of joint
is the temporal mandibular joint and what actions occur about this joint
so let's start with talking about what makes up the TMJ or the temporal mandibular joint the bony
portions we discussed in the last video we can see are the mandibular fossa of the temporal bone and
the condylar process that sits nicely within it from the mandible and then that articular tubercle
found anterior to both the other important part of this joint is going to be that particular
disc so this is a disc of fibrocartilage and it acts to actually separate the joint cavity
into two specific compartments now this is why I've gotten very italicized large word
here modified so a hinge joint you can typically think of an elbow where you can extend and flex
at the elbow in the TMJ what we see actually are four movements and this is enabled by that
articular disc could have modifying the joint and allowing from our movements to take place
so before we watch this let's take a look and do some palpation so go ahead and put your
hands on your temporal mandibular joint and actually open your mouth to a certain point
and then open a little wider
and then back so what you feel is that mandibular condyle at first you can feel kind of the movement
of it just kind of rocking within that fossa and then you see it come forward so let's see
how this looks in this really wonderful animation we can see here so we've got the disc lit up in
orange shown right here so from a lateral view you can see how that condyle actually moves
and glides along so we see some movement like a hinge and then the gliding as well
all right so let's break down those different movements so if we start from a closed position
we start to open the mouth we need to do depression so depression is kind of moving
in an inferior direction so you depress your shoulders when you push them down your back
so depression of the TMJ is opening of the mouth so we see depression and that mandibular condyle
stays in the place of the mandibular fossa along the way then what we see is called protraction
so protraction also known as retreat protrusion is movement in an anterior posterior plane so
we see now how that is moving away from where it originally was more anteriorly the clothes then
we need to undo the motions that we had done which will start with retraction bringing it
back into the mandibular fossa and then elevation closing the mouth and so what happens is actually
these hinge movements are happening within the inferior compartment the depression and
elevation are within the inferior compartment and then the superior compartment is where we
see that gliding taking place that protraction and retraction enabled by that particular disc
you when we're considering the neurovascular of a joint we can think about it being opportunistic
so what we see is that specific structures that pass around the area or supply muscles
in the area will also supply that joint so the major sources we're seeing here are a
regular temporal nerve which takes a parent innervation from the area and blood supply
through the maxillary and the superficial temporal arteries so let's take a look at
this in 3d so we have represented here a lot of the vasculature and the nerves to the area
now that is the superficial temporal artery and the maxillary artery and
the nerve lid up there is the auricular temporal nerve and you'll see how close
in proximity these are to the temporomandibular joint
you all right so our question is a dislocation of the TMJ is typically through the gliding
movements or the translational movements so which compartment of the synovial cavity is involved in
these movements so take a moment to choose your answer and when you're ready let's talk about it
so when we're talking about the gliding motions that is our superior compartment so the answer
here is a the superior compartment and you can see how this has moved forward so that is protraction
that will then retract back into the mandibular fossa with closing of the mouth the inferior
compartment is where we see the hinge joint movements happening so elevation and depression
great that's everything for this video thank you so much
and let me know if you have any questions at all