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Hi, my name is Danielle Mueller and I am here to talk to you today about the human skull.
We have this [skull] would be more if you looked at an actual human skull you would
see it looking like this. No paintings, no markings, you can see the suture lines where
the bones meet together there. But, you know, it is very plain. You can see the different
holes, features on here. This skull that I am primarily work with here has numbering
on it because it came with a key and also the sutures have been highlighted with this
yellow paint here. This really helps you see clearly and defines were the bones are actually
coming together and meeting. And you can tell were one bone starts and stops. So we will
focus on this skull here for this demonstration. I’m going to start here with the frontal
bone which is in the very front of the skull here. As you move more posterior and laterally
you can see the two parietal bones here. As you move further back on the most posterior
part of the skull you see the occipital bone back here. As you turn the skull we are going
to talk about these sutures that are in between the frontal bone and parietal bone. You see
the coronal suture running here. Between your two parietal bones you see the sagittal suture
running down the middle of the skull. And then as you turn towards the back between
the two parietal and occipital bone is the lambdoid suture. When we turn to the lateral
side of the skull you can see this suture right here. It’s going to be the squamosal
suture and that separates the parietal bone from the temporal bone. The bones that we
discussed previously don’t have a lot of features or markings so we didn’t really
talk about them in depth. Now we are moving to some bones that have different features.
On your temporal bone you can see the external auditory meatus, that’s the opening of the
ear. The mastoid process is this large process right here and the styloid process is this
small little piece of bone here. Coming off of your temporal bone you have the zygomatic
process of the temporal bone. So it is named for the bone it is going towards not the bone
that it is coming off of. So then right here is your zygomatic bone and the part right
here is the temporal process of the zygomatic bone. If you talk about the whole arch right
here that is considered the zygomatic arch. As we turn back to the anterior view of the
skull you can see the lacrimal bone which is right here and it is only about the size
of the tip of your finger. And you can usually tell right where it is because you are going
to see this hole right here that is the lacrimal canal. So that is the hole that is going through
the lacrimal bone and it connects the eye and the nasal cavity there. Coming medially,
what you can see right here is the nasal bone. It is made of two bones that come together
right there at the bride of the nose. That’s right here where your glasses would sit. If
you go inferior to that you are going to see the maxilla or maxillary bone right here.
It has the infraorbital foramen, the little hole, right here and you can see where all
of the teeth are, well this guy is missing a lot of teeth but, where all the teeth come
together [with the skull] each one of these little bumps right here is going to be an
alveolar process. Now just let me switch over to this one because he has all of this teeth.
You know each one of these bumps is going to be an alveolar process where the teeth
are attached there. Let’s see, looking back kind of at the orbit here, right above the
orbit you have the supraorbital notch or foramen. In some people it is an actual foramen so
there’s a little piece of bone coming across right here but for a lot of people that little
bony strut is broken so it appears as just a notch. In the orbit itself where the eyeball
would sit here, there are a couple of different features. You have the optic foramen, which
is the hole running right through here where the pipe cleaner is going in that’s where
the optic nerve runs through into the inside of the skull. So if we open the skull up you
can see it travels into the interior of the skull. You also have the boomerang shaped
or C shaped structure there. The top part is considered the superior orbital fissure
and the bottom part is the inferior orbital fissure. When you look inside the nasal cavity
here you have the nasal septum that is actually made up of two different bones. The bottom
part is made of the vomer and the top part is the perpendicular plate of the ethmoid.
The ethmoid you can see mainly on the inside of the skull and we will get to that in a
minute. And another feature that you can see is that you have these little, like, bony
scrolls or almost like little shelves of bone inside here. You have the middle nasal concha
here and the inferior nasal concha here. If we go back looking at that maxillary bone
here or the maxilla, if we tip and look at the base of the skull here the maxilla, this
is all still part of the maxilla here the hard palate. So, this is the palatine process
of the maxilla. The hole that you can see right here at the very front of that hard
palate would be the incisive foramen. And then you have right here the median palatine
suture in between the two pieces of that palatine process there. The back part of the hard palate,
that bony palate on the roof of the mouth, you have a suture here. This right here is
the palatine bone itself. To either side you have the greater palatine foramen. You can
see to each side there. The palatine is its own bone, but it is only a small portion of
the actual hard palate there. When you look at the rest of the base of the skull, you
can see a lot of foramen and holes, canals. There are a lot of different canals where
you have blood vessels and nerves coming through in the base of the skull here. So when you
look here on each side here you have the foramen ovale. Right next to that is the foramen spinosum,
that’s the little, small hole underneath the foramen ovale. Towards the midline you
have the foramen lacerum, here on either side and then if you move further down you’ll
see the carotid canal here. And that’s where the carotid artery would travel through. And
then below that this jellybean shaped structure right here is going to be the jugular foramen
and that is where the jugular vein enters into the skull. The large hole that you see
right here is foramen magnum. That where the spinal cord exits. And to either side of that
right here you have the hypoglossal canal. That enters into the skull as well. To either
side of the foramen magnum you have these flat articular surfaces and that is the occipital
condyles, right here. When we turn and go to the inside of the skull we can see some
of the extent of the bones we talked about previously. The ethmoid bone is right here.
We talked about that previously. The perpendicular plate right here of the nasal septum is part
of the ethmoid bone. This is another extent of that here. All of this is considered the
ethmoid. Running right down the middle here is the crista galli. To either side of the
crista galli you have the cribriform plate. The cribriform plate actually has many little,
tiny holes in it. Right here it kind of looks grey because many people have touched it with
their pencil, but if you had an actual human skull you would see actual tiny, little holes
that are about the size of a straight pin fitting through it. And that’s where the
olfactory nerves come up from the nasal cavity into the brain. If we move further down here
we can see the sphenoid bone. So we saw the sphenoid right here. So coming inside this
is the major extent of the sphenoid here. A lot of times people think it looks like
a bat or a butterfly with the wing shaped structure right here. So these parts that
jut out right here are the lesser wings and the major portion right here are considered
the greater wings of the sphenoid. A bunch of the foramen that we have looked at previously
you can see from a different view here. This was that optic foramen that came out through
and into the orbital cavity. That is where the optic nerve travels into the brain. You
can see the foramen ovale right here. The foramen spinosum again right below it, smaller.
More towards the midline is the foramen lacerum. And then up here, you couldn’t see this
one from the base of the skull, is the foramen rotundum and each of them have a corresponding
pair on the other side of the skull. Another feature of the sphenoid would be the sella
turcica right here. This indented portion right here is where the pituitary gland sits.
It stands for, another name for it is the Turkish saddle. That’s what sella turcica
means in Latin and it almost looks like a saddle you can imagine someone sitting in
here and putting their feet here to either side. So that is the sella turcica right here.
As we move more posterior, we move from the sphenoidal bone to the temporal bone. So the
temporal bone was out here on the outside right here. This is the inside of our temporal
bone right here. You can see this large bony shelf right here. That is the petrous portion
of the temporal bone. On that the hole that you see right here is the internal auditory
meatus. Inferior to that we once again see that jellybean or kidney bean shaped opening
or hole. That right there is the jugular foramen. And then as we move further down we move down
into the occipital bone again. We see the foramen magnum with the hypoglossal canals
to either side of it. So that is the major components that you can see inside of the
skull. One of the last bones that we look at that belong to the skull is the mandible.
The mandible is the lower jaw. It will articulate with the mandibular fossa. So are mandibular
fossa right here, those depressions that’s where the mandible articulates and you see
that movement of the mandible with the opening and closing of the mouth. So the mandible
is divided into three regions. You have the main portion right here, the body. As you
kind of turn you can see that bend right here, that is going to be the angle of the mandible.
And then this top portion here after you have made that turn is the ramus of the mandible.
You have two sets of foramen on the mandible. You have the mental foramen that you see on
the front of the mandible and as you turn to the posterior side you have two more foramen
and those are the mandibular foramen. The last two feature on the mandible would be
the coronoid process here that sticks up and then the mandibular condyle on the very most
posterior part. Once again that is what is articulating with the mandibular fossa. You
can also see, just like on the maxilla, you have the alveolar process. You can see the
alveolar process on the mandible as well. I hope that this tutorial has helped you get
a better understanding of the different features of the skull, the bones, all the canals, openings,
processes you see on the skull. So I hope this helps and makes your study of A and P
a little bit easier. Thank you.