 Today, we're going to talk about the bones of the cranium. The cranial bones make up the superior portion of the skull, those bones that actually touch the brain and are part of that brain casing. We will show you the bones as well as the bone markings for each bone that we want you to go over in lab. So as we look at the skull, we see the frontal bone here, and this particular skull is unique because normally this suture that you see, this line down the middle, is fused as a bony suture. But this one has not completely fused, and this is called a metopic suture. This one is not necessarily abnormal, but it is unusual to have that through to adulthood. But this is considered one bone, the frontal bone. Now on the superior portion of the skull, we see two bones. These are the parietal bones, and separating the parietal bones is a suture. And this suture is called the sagittal suture on the parietal bone. Next, we want to look at the bones on the lateral portion of the skull. And here, you see the temporal bone. And you see the suture that separates the temporal bone from the parietal bone here and the other bone in the front here called the sphenoid bone. This suture is called the squamous suture. This bone, again, is the temporal bone. And there's several markings on this bone that we would need you to be familiar with. One of them is this large process here called the mastoid process. And you can feel that right behind your ear. That's that bony protuberance right behind your ear. Also, you see just anterior to the mastoid process. You see this opening here that leads to the canal in your ear. This is called the external auditory meatus. Meatus means a canal, external auditory meatus. That will lead into the skull. And you can see right here on the back of this ridge what we would then consider to be the internal auditory meatus. That's where the nerve will exit the ear and be able to access the brain through that opening. Now on the temporal bone, we have another process here that is actually named for the bone that it points to, which is this upper facial bone. So this process, it's on the temporal bone, but it is called the zygomatic process. This as well as this process here will make up the zygomatic arch. So the posterior side of the arch is the zygomatic process of the temporal bone. But this anterior process of the arch is called the temporal process. And it is on the zygomatic bone, this facial bone. So these two processes together, notice there's a suture here, will make up the entire zygomatic arch. There's another feature. You see this is a facial bone here called the mandible. And you see that the mandible articulates with the temporal bone in a shallow depression right here called the mandibular fossa. So you see where the mandible will fit right into that nice shallow depression, the mandibular fossa. Another bone of the cranium on the posterior side is called the occipital bone. And you see that the occipital bone has a suture separating it from the parietal bones. This suture here is called the lambdoid suture. This is called the lambdoid suture. The features on the occipital bone that we would like for you to know is this large opening for the spinal cord. Some of your pictures you might study might look like this. So I want to show you in this orientation. So again, this is the occipital bone. This opening is the foramen magnum, the opening for the spinal cord. Now the first vertebral bone is called the atlas. And it will sit right here on these two smooth surfaces that you see on either side of the foramen magnum called the occipital condyles. You see you have two occipital condyles. A smooth surface for a bone articulation is a condyle. So that's the occipital bone. And you see where the spinal cord will come right up through that foramen magnum on the occipital bone. Now interestingly, this lambdoid suture that I showed you will often make a side, an extra bone here. And so we call this extra bone a sutural bone. And everybody will have the sutural bones, but they will be shaped differently and be in different locations along that lambdoid suture. But this is called a sutural bone. Now there's two more bones to the cranium. And they're easiest to see on the interior portion of the cranium. So this bone here, as I'm outlining for you, is housed against the temporal bone. So it comes across here and down here. So you see how it'll articulate with the temporal bone here and the frontal bone up here. This one is called the sphenoid bone. The sphenoid bone. These side pieces here, these flattened pieces where the cranium sits in, are called the greater wings. So you see how it almost looks like a butterfly, especially when you're looking at it in lab. You might notice that. So the greater wings of the sphenoid bone. Now in the middle of the sphenoid bone, you'll see what seems to be an indentation. This indentation is where the pituitary gland sits, which is our master gland to our endocrine system or our hormone system. So it's very well protected here in the middle of the skull. This indentation in the sphenoid bone is called the celatursica. So make sure you try to notice that on the skulls, the celatursica. And then with the same sphenoid bone, I want you to notice that the sphenoid bone does make up the back of the orbital. Because I want you to notice that there's two openings here, and you see that? Two openings that are for the optic nerve to come from the eye to the brain. And so these openings, this one and this one, are called the optic canals, or optic ferramina. Ferramina is plural for ferramin. One optic ferramin, two optic ferramina. So those are the parts of the sphenoid bone that we would like for you to know. The last bone of the cranium is this bone here. You can see where the suture separated from the frontal bone. This small bone here is called the ethmoid bone. The ethmoid bone is made up of several different bone markings. This marking here in the middle of the ethmoid bone is called the crista galley. It's called the crista galley. On either side of the crista galley, you'll see flat areas here with some holes or openings in them. This flattened area here and here are called the crib reform plates. They were named after the game cribbage, because they have these small openings in them just like a cribbage board did back in, I guess the 60s when they were playing cribbage a little more often. So these openings here are called the olfactory ferramina. So again, one opening is a ferramin. So you see there's several here. And these are for the olfactory nerves that would sit here underneath the brain for the receptors to go down into the nasal cavity here. So those again are olfactory ferramina. Several openings for the olfactory nerve to go down into the nasal cavity. So let me show you the last part of the ethmoid bone, which can actually be seen in the nasal cavity itself. This part here, this wall here in the middle that comes down, this is called the perpendicular plate of the ethmoid bone. And that is part of your nasal septum, that wall that comes down the middle of the nose is part of the nasal septum. But that is part of the ethmoid bone and it is a cranial bone and not a facial bone. One other thing to notice while we're here is this upper piece here that's coming off of the ethmoid bone as well. Off of the ethmoid bone as well. These upper pieces here are called conchi. This one is called the middle nasal conchi and you'll see another one on the opposite side when you're looking at the skulls. Those are also part of the ethmoid bone, again part of the cranium and not a facial bone. So try to find those when you are in lab in the nasal area as well. Those are the cranial bones. The next video will show you the facial bones.