This is the first tutorial I'm going to do on the skull.
I'm just going to do a couple of tutorials because that's quite a lot to talk about.
The skull consists of 22 bones not including the ossicles of the ear.
These bones are connected by sutures.
So on this model, you can see these lines here on the skull.
These are sutures, which are immovable fibrous joints which connect these joints together.
The skull consists of the cranium and the mandible.
The mandible is this lower jaw bone and the cranium is the rest of the skull.
The cranium can be divided into an upper part and a lower part.
This tutorial will just be on the upper part of the skull.
The upper part contains the brain and it's referred to as the calvaria.
The lower part of the cranium is the facial skeleton, so all of these.
It's called the viscerocranium.
So that would be my next tutorial.
So you've got six bones which make up the calvaria -- the frontal, parietal, temporal,
occipital, sphenoid and ethmoid bones, so six bones.
The frontal bone, here.
You can just about see the greater wing of the sphenoid -- not just about, but you can
see the greater wing of the sphenoid here.
The rest of it, I'll show you in a bit.
The parietal bone is this large bone.
Well, it's two bones.
You've got two parietal bones on either side, which make up a lot of the side of the skull.
And you've got two temporal bones on either side.
And then the occipital bone.
You can see the ethmoid bone making up the medial wall of the orbit on both sides.
So those are the six bones that make up the calvaria.
First, I'm going to talk about the frontal bone.
You can see this big bone here is the frontal bone.
It's separated from the parietal bone by this suture.
This is the frontal bone, all of this.
It makes up the upper margins of the orbit laterally and medially.
So just some things to point out.
You can see these ridges here just above the orbit -- not so clearly, but you can make
them out.
These arches here are called the superciliary arches.
They're prominent in males than females.
And this angle here is quite deep because you can see this little depression where the
superciliary arches meet.
This is called the glabella.
So that's the frontal bone.
Next, I'm just going to talk about the parietal bone.
You've got two parietal bones.
You've got two parietal bones and two temporal bones, the rest are single bones.
So the occipital, frontal, sphenoid and ethmoid are single bones.
Parietal bones are paired and temporal bones are paired on either side.
So this big parietal bone makes up a lot of the lateral wall of the skull.
You can see at the front it articulates via the suture with the frontal bone and posteriorly,
it articulates via this suture with the occipital bone.
Inferiorly, it articulates with the temporal bone via this suture.
And it also articulates with the greater wing of the sphenoid via this suture.
So I'll just show you from the top what that looks like.
You can see this suture down the sagittal plane, so it's called the sagittal suture.
The two parietal bones articulate via that.
So those are the parietal bones, big bones on the side of the skull.
The next bone I'm going to talk about are the temporal bones, which as I've showed you
before and explained, they're on both sides.
So the temporal bones, this bone here.
There's quite a few things to point out on the temporal bones.
You've got a squamous part, which makes up part of the lateral wall of the skull and
you've got a petrous part, which you can see inferiorly.
I'll show you that in a second.
The squamous part is just this flat bit.
Squamous just means flat.
You've got squamous cells which are squashed, flat cells.
So the squamous part is the large flat bit, which forms the lateral wall of the cranium.
This articulates anteriorly with the greater wing of the sphenoid and posteriorly with
the parietal bone and the occipital bone down here.
So just here you can see this process, which is called the mastoid process.
This is quite important because a few muscles attach here, most notably the sternocleidomastoid
(it has an attachment there).
I'll just show you that.
So you can see this big sternocleidomastoid attaches there and you've got this muscle
here, the digastric muscle.
So that's the mastoid process.
And if you look from the back, you can see this little notch here, which is the mastoid
notch.
Also, you've got this process sticking out here, which is called the zygomatic process
of the temporal bone because this is the zygomatic bone and it sticks out towards that.
Then you've got this hole here, which is the external acoustic meatus (this little hole
there).
So you've got the squamous part, the mastoid process, the zygomatic process and this external
acoustic opening/meatus.
So I'll just rotate this around, so you can now see the petrous part of the skull.
If you just look at the temporal bone, you can see it runs all the way around her and
it's all of this bone here.
So that's the mastoid process.
We've also got this little pointy thing, which is the styloid process.
So from the inferior view, this is the petrous part of the temporal bone and
this houses the inner and middle ear.
We'll just have a look at that rotating around, you can see exactly how the temporal bone
works.
If we face the temporal bone on the inferior aspect, it's the petrous part.
The next bone I'm going to talk about is the sphenoid.
This bone confused me quite a bit when I was learning about it.
So from this lateral view of the skull, you can see the greater wing here and you can
see the greater wing on either side, but you've only got one sphenoid bone.
The sphenoid connects in the middle via body, which you can't see here.
I'll show you in a second.
The sphenoid, in the middle, it's got the body, it's got the greater wings, which you
can see laterally from outside the skull and it's got two lesser wings (which I'll show
you and you can see them from inside the skull) and then it's got two pterygoid processes
inferiorly, which point downwards.
So what you need to know about the sphenoid is that it consists of a body, two greater
wings, two lesser wings and two pterygoid processes.
The best way to show you it is, again, if you follow it as I rotate the skull inferiorly,
you can just keep an eye on the greater wing here.
And as I rotate it around, you still see the greater wing here.
So the greater wing, rotating it around and you can this pointing downwards.
These are the pterygoid processes.
You've got them on both sides.
See here the pterygoid processes sticking downwards.
The greater wing and then the pterygoid processes pointing downwards.
So what you've got here, you've got a lateral plate of the pterygoid process and a medial
plate of the pterygoid process.
This little hook thing that you can see is called the hamulus.
In between pterygoid processes, you've got the body of the sphenoid, which I'll show
you from an inside view.