the next two topics we'll cover are the axial skeleton and the appendicular skeleton and while there are some concepts we'll talk about in these videos mostly what I'll do is just name bones I'll tell you something extra about them like how you can palpate them on your own body where they got their name or why they're important but it'll just be a pretty formulaic here's this bone here's some stuff about it here's this bone here's some stuff about it and what these videos are really meant to do is support your lab study because in the lab when you're getting more hands-on with the bones you want to make sure you have some information that goes along with that to help you remember where these bones are and what their names are the first thing though we should do is make sure we know what the axial skeleton is the axial skeleton is just these bones shown down the midline of the body there's about 80 bones in the axial skeleton and it doesn't include the arms and legs because those are part of the appendicular skeleton but it also doesn't include any bones that support the arms and the legs what I'm talking about here is the clavicle and scapula and the entire pelvis those bones even though they're kind of down the midline of the body they're part of the appendicular skeleton so this is what you're looking at for the axial skeleton the skull the thoracic cage and the vertebral column so we'll start by looking at the skull but even that you can break down into different groups of bones like the bones of the face the bones of the cranium and then there's some associated bones as well we will be beginning with bones of the cranium those bones which enclose the brain so let's start with the frontal bone that's making up your forehead there are some different structures to know one is the squamous is the squamous part and from remember a squamous cell is kind of tapered at the end but the point is that it's a very flat kind of cell squamous means scale and I'm talking about like a scale off a snake or something a flat thin piece of tissue so this is the flat thin part of the frontal bone the zygomatic process is a big chunk of bone that you can probably palpate on your own face and the zygomatic process is a chunk of bone that's reaching out towards this bone the zygomatic bone so the name should make sense the zygomatic process wants to touch the zygomatic bone and it does the supraorbital margin is this entire Ridge here kind of above your eye and I don't know what your skull bones look like but you'll have either a hole or a notch in that bone so you'll have either a super orbital notch or a supraorbital foramen which means a small rounded hole one thing that we don't see that's part of the frontal bone here is the frontal sinus is a cavity in the frontal bone and we'll talk about sinuses later on all right parietal bones parietal means wall so these are the walls of your cranium so you have a right parietal bone in the left parietal bone and one of the structures you can find is the parietal eminence so these are the sharpest sticky-outy aspartyl bones right at the corners of your skull if you can find corners at all the other structure of the parietal bones you have to look on the inside of the skull to see and those are these grooves and these grooves contain in a living human the meningeal vessels these are blood vessels that run through your skull and they're found inside of these grooves okay let's keep going temporal bones have a lot going on the temporal bones are around your ears so whenever I think temporal bones I do this think about the area around my ear because I don't want to confuse it with my temples if you quote-unquote rub your temples you're probably not touching your temporal bones you're probably up here touching a different bone that we'll talk about later so go around the ear that's your temporal bone they have a squamous so a flat thin part they have an ear hole which we call the external auditory meatus a meatus is like a passageway through a thick part of bone then there are some processes remember these mean chunks of bone that stick out the mastoid process I think mass means maybe mountain so this means shaped like a mountain which I could kind of see and you can touch the mastoid process you can feel it behind your ear a big chunk of bone the styloid process is shaped like a stylus have you ever heard of a blackberry I'm sure some of you have but maybe not all of you blackberries were popular in the early cellphone days and they came with a stylus I guess tablets and stuff have these now so it's like a thin long writing implement and on the temporal bone you have a thin long little spike of bone called the styloid process there's also the zygomatic process we've already learned about one zygomatic process it's the part of the frontal bone that's reaching for your zygomatic bone well this saiga matic process is a chunk of bone back here near your ear that's reaching for beside the zygomatic bone and then finally here is the mandibular fossa a fossa is like a dish shape region it can be quite big or in this case pretty small this is where your mandible your lower jawbone inserts or attaches to the rest of your skull when you're chewing you can feel that joint that's where your mandible is going into the mandibular fossa now if we look on the other side of a temporal bone from the inside here we can see that there's also an internal auditory meatus remember this ear hole is the external but on the inside there's an internal auditory meatus and just like there is a flat thin squamous part of the temporal bone there is this rocky ridge on the inside the petrous region or petrus portion of the temporal bone you ever hear of petrified wood it's like wood that becomes rock or if you're petrified you're stiff and frozen like a stone so this is the rocky or the stone like region the manipular fossa we already talked about but here's another look at it and then you have a few other holes in the temporal bone the carotid canal which is also commonly referred to as the carotid foramen is just a hole for your carotid artery to go through and the stylo mastoid foramen is a very tiny hole it's in between the mastoid process that big chunk of bone and the styloid process that sharp spike of bone there's a little hole in between first of nerves the last thing about the temporal bone is that since it's part of your ear there are some bones in there that have to do with hearing these three tiny bones are called the auditory ossicles it includes the stay piece the smallest bone in your body the names are the malleus incus and stapes and we will be seeing them again when we study hearing ok the occipital bone is way at the base of your skull the most obvious feature here is the foramen magnum remember foramen is hole a round hole magnum is large so this is the large round hole and that's where the spinal cord attaches to the brain there are some other holes in the occipital bone called hypoglossal canals and they're kind of hidden you can see it from this view you can't quite make it out on this view there is a very small hole there's a nerve that goes through there it's called the hypoglossal nerve we're gonna study it when we study the nervous system what else the condylar fossa remember a fossa is a little dish shape area and then these last 1 2 3 4 structures I've drawn a little diagram here for those what we have here is a couple lines a crest and a protuberance so if you know where the foramen magnum is there is this ridge of bone traveling away from the Fremen magnum going up your skull I don't think I can quite make it out really Felix there's too much muscle covering it but that line of bone is called the external occipital crest so it's on that outside of your occipital bone and it's a Ridge or crest of bone now crossing transverse across that crest are the lines the inferior and superior nuchal lines and I can definitely feel the superior nuchal line at the back of my skull I don't think I can really make out the inferior nuchal because again that's quite deep in there beneath a bunch of muscle because many of these structures we're talking about are used for muscles to attach to you one last thing is the external occipital protuberance so that would be like if you go up your external occipital crest eventually you're going to come to kind of a spiky ish chunk of bone on the back of the head not sure you know I haven't felt many of my students heads like I think zero although I always threaten that I will so I don't know what yours feels like but I can for sure feel a pretty subtle spike a bone there again muscles are attaching to it so it's not gonna be super obvious but it does help if you can find this stuff on your own body the last thing I want to talk about is the fact that the occipital bone sits on the vertebral column so there's a bone in your spine that's like this it's called the atlas have you heard of that myth of atlas who was a god that has - it's cursed - I don't know to hold up the whole earth well atlas is your first vertebra it's called c1 it's the first cervical vertebra and you can see a picture of it here and it has these little cups and their job is to hold up the skull more specifically there are things called occipital condyles those are these lumps of bone hearing here those are occipital condyles so those articulate with the atlas and when you rock your head yes these condyles are rocking back and forth on the atlas a few more structures on the occipital bone there are some fossae which are you know dish shaped regions so you've got some for the cerebellum and some for the cerebrum just kind of these grooved out regions hypoglossal canal we already mentioned tiny little hole and last here is the jugular notch so the jugular notch or sometimes called yeah the jugular notch is a little notch out of the occipital bone so if you pick up an occipital bone you look near the back and you're looking for this little notch well why is it there well when the occipital bone becomes part of the skull meaning in this case when it articulates with the temporal bone that notch which looks like this is going to suddenly form a hole you know what I'm saying there was no hole before just a notch but when the skull is put together then you'll be able to see a hole has been made we call the hold of jugular foramen that's where your jugular vein brings blood out of your head and brain there's another passage called the inferior orbital fissure and another one called the foramen lacerum what these have in common with the jugular foramen is that they are all three passages that you can only see on a complete skull so keep in mind if you're looking for a certain hole it might not be there until you assemble a skull okay let's talk about the sphenoid bone in a previous video we did the shapes of Bones and we said you know a lot of the skull bones are flat like parietal bone we didn't even talk much about the parietal bone is fairly flat and not a lot of structures on it spino bone would be an example of an irregular bone because obviously there's a lot going on with the sphenoid bone this is the bone that I mentioned that when you rub your temples you're not rubbing the temporal bone you're actually rubbing the sphenoid bone because this bone stretches all the way across your skull and the ends of this bone make up the temples of your skull let's look at some of the structures we have some holes called the optic foramen ax which is plural or foramen also though they're called the optic canals and that's where the optic nerve comes in to carry visual information to your brain there's a fissure called the superior orbital fissure some nerves travel through that fissure and then the major structure really is there's almost like a seat shape here and if you have a 3-dimensional spheroid bone in your hand you would really be able to see it looks like a little seat or maybe a saddle because the name of this structure is sella turcica and literally that translates into Turkish saddle the person that named that the Turkish saddle had a very different life than you and I I don't know what a Turkish saddle looks like I barely know what a real any saddle looks like but sella turcica that's the name and the function of that is to protect the pituitary glands an endocrine gland will learn a lot about later on but it sits down right in that little saddle Pinoy bone has these big chunks of bone coming off here and here called the greater wings and it has some smaller chunks coming off in the same region called the lesser wings there are also a lot of holes through the sphenoid bone such as the foramen spinosum the spiny hole and this is very small and very round so my guess is that it was named the spiny hole because if you had a sharp spine like a cactus spine and made a very small circular hole you might want to call it the foramen spinosum perhaps a better name structure is prim foramen ovale this oval-shaped hole and then there's also foramen rotundum this rotund roundish shaped hole finally hanging off the bottom of the sphenoid bone are the pterygoid processes these are pretty unlike any other part of the sphenoid especially because at the bottom they have these little grabber looking structures they're called camel ich you lie or something they're their little hands coming down off the sphenoid bone which just looks like a super scary nightmare bat of course okay and the ethmoid bone is tucked right about here kind of been in between your eyes just just behind your nose there and because of its location you might not be surprised to know that when you smell something the smell travels up to the top of your nasal cavity and then to get to the brain it has to go through some holes through your skull so those are these little dots here these holes which are called the cribriform foramina are tiny little holes that your sense of your the nerves that pick up this so smell will pick up that scent and carry that information through here and up into the brain the the chunk of bone that these holes are drilled through is called the cribriform plate not to be confused with the perpendicular plate which is this long piece of bone hanging off the bottom of the ethmoid bone other notable structures would be the crista galli which means the roosters comb you know roosters have like that little flap of tissue in them I was gonna do it turkey noise and I realized we're talking about roosters so crista galli a roosters comb sticking up at the top of the ethmoid bone and at the bottom you'd have all these chunks of bone these are the nasal conchae there's a superior and a middle nasal conchae so those will help make the air that you breathe in through your nose become very turbulent so it gets more clean and more moist and more warmed up I've made a little note here that on lab models or any models of these bones typically you don't have a nice long perpendicular plate like this model is just a little boxy bone but I've kind of drawn in a longer perpendicular plate and ethmoid bone has a sinus but we said we talked about sinuses later on okay so those are all the bones that surround your brain and protect it and there's lots of holes because the brain needs a lot of blood so you need holes for blood to get in and out the brain has a lot of nerves because you need to carry information into the brain and you need to let motor commands get out of the brain the spinal cord is one place you can do that but there's also other little holes to do that as well so next we'll talk about the bones of the face