hi everyone this is Miss O'Brien in this presentation we are going to go over the first part of chapter 9 from your dental assisting textbook and this chapter is about the head and neck Anatomy um so for part one we're just going to be doing the bones and the TMJ and then we'll have a separate lecture for Part Two for the muscles and nerves because like chapter 8 chapter 9 has a lot of information and I just thought it would be better to split it up so let's go ahead and get started okay so um so when we're talking about Anatomy we have to use a lot of descriptive words so that everybody's kind of on the same page and you know the area to look when somebody's talking about a bone or a muscle or a nerve or whatever so you know being dental providers were particularly interested in the head and neck region and the oral cavity so most of what we'll be concentrating on is the the region of the head and neck especially the head so um so when we're talking about Anatomy the head is actually divided into 11 regions and a lot of these 11 regions are named for the bones in the area as well so the regions are the the frontal the parietal the occipital uh the temporal the orbital the nasal the infraorbital the zygomatic region the buccal the oral and the mental so as we go on we'll be talking about the bones and where they're located and just about every one of these regions are named after a bone which tells you the location okay and then just so we have a visual for these different regions we can see the frontal is up here on the top of the head and that's where the frontal bone is then the parietal region is sort of more the towards the back of the head where the parietal bones are the occipital region is in the area of the occipital bone then we have the orbital region whenever you hear orbit that's kind of should make you think about the eye you know that's the orbital socket of the eye so this is the orbital region and then the nasal region of course that's the nose then we have the oral region that's the mouth and around the mouth the buccal region is like the cheeks uh or the lower lower cheeks so when you hear buckle you kind of think uh cheek it's almost synonymous and then we have the zygomatic region so that's a little higher that kind of comprises part of the cheeks but it's more like the cheekbones a little bit higher on the face and then the mental region so whenever you hear mental that refers to the chin the chin area okay all right so bones of the skull so when we talk about the bones of the skull we divide them into two main categories or sections we've got the the cranium which is the you know the area around the bone and the face which you know is your face so so the cranium sometimes you'll hear this called the neurocranium and this is composed of eight bones that cover and protect the brain so that's their function is to cover and protect the brain so this is going to be your frontal bone your parietal bones plural there's a pair of them your occipital bone your temporal bones plural again those are a pair your sphenoid bone and your ethmoid bone and then when we're talking about the face sometimes you'll hear this referred to as the viscero cranium and this consists of 14 bones so there's a lot more paired bones with the face than with the um with the neurocranium so the zygomatic Bones the maxillary bones Palatine bones nasal bones lacrimal bones the vomer which is a single bone the inferior conche another pair of Bones and the mandible which is a single bone so most of the bones of the face are paired in a bilateral one on each side and most of the bones of the the neurocranium are single bones with two exceptions and then we've got six teeny tiny little Bones called auditory ossicles and they're inside they're deep inside the ear canal and you guys may have heard of these if you've taken you know biology classes or any sort of anatomy classes so these are all paired bones so we've got the malleus the incus and the stapes and again they're tiny tiny little bones that that function in hearing which is why they're located inside the um the auditory canal okay um so the neurocranium again this is the area that covers and protects the brain um so you know unfortunately we have to do some memorization in these classes you know you need to memorize the names of the bones um so you know I find that certain mnemonics can can help with that um and you know sometimes I'll look online and find them so I can't really take credit for these I just found them when I Googled so the neurocranium consists of eight bones so you got the occipital bone at the base of the back of the skull that's a single bone the parietal bones are paired the frontal bone is a single bone the temporal bones are paired they're on either side of the head the ethmoid bone is single and the sphenoid bone is single and we're going to see lots of pictures of all these so so don't worry so in order to remember these you could you know just remember the phrase old people from Texas eat spiders and the Owen old stands for occipital p and people parietal F and from frontal T in Texas temporal so you kind of get the picture so sometimes this can help you kind of have a better memory of these you know these bones it can help a little bit and then I always like to do visuals too so people from Texas eat spiders so and hopefully that will help you remember you know occipital parietal frontal temporal ethmoid sphenoids so hopefully that that will help and then the visceralocranium so this has a few more bones it's a little harder to remember so remember these are the facial Bones the visceralocranium so with the visceral Cranium we've got the vomer the inferior nasal conchae the nasal Bones the mandible the maxilla the Palatine Bones the zygomatic bones and the lacrimal bones and again we're going to see lots and lots of pictures of these and in class we will be like holding actual skulls I mean not real skulls obviously they're plastic so their models so so to remember these 14 bones another mnemonic device you can say Valerie cannot make my pet zebra laugh so Valerie is the V for vomer canned you know kanche for the inferior and nasal conche not nasal bones mandible Max lay P for Palatine Z for zygomatic and L for lacrimal so hopefully these little tricks will just help you a little bit in the you know the memorization portion of it so um so that's Valerie Bertinelli you guys may or may not know her she's an actress about my age so she was real popular when I was younger but she's I don't know maybe not doing so much anymore so um and then apparently she did make the zebra laugh I don't know how but but anyway so Valerie cannot make my pet zebra laugh so just remember that the you know the Romer or the kanche and the nasal Maxwell mandibular you know it can help a little bit okay um so when we talk about bones and Anatomy there's certain terminology that you're going to hear again and again um you know so so we need to know what these mean so again it's going to take a little bit of memorization but I have faith that you guys can do it um so foramen uh foramen is a natural opening in a bone through which blood vessels that's what BV stands for blood vessels nerves and ligaments pass so um so it's it's a little hole in the bone right or a big hole in the bone it can be bigger little depending on what needs to pass through it so so the foramen it's just you know it's a whole because how else would the blood vessels and the nerves and ligaments get through bone you know it's usually very very um dense so so you need a little hole to get through just like when you're running electrical wire for a house or something you need to drill a hole in the wall and then run it through the back of the wall and then drill another hole where it comes out the other side the human body is just kind of like that you know so so we need these for for Raymond or floramena plural on lots of bones in the body so and you'll see we've got the mental foramen all kinds of foramen in the head and neck that we'll talk about uh then a fossa a fossa is a hollow grooved or depressed area in the bone so um a fossa is like a concavity in the bone okay so it's like this grooved out area and usually something fits in there either another bone or maybe a salivary gland or something you know if it's in there so we'll see um Fosse as we go through meatus meatus is the external opening of a canal so think about your ear you know there's a hole where your ear opens so that's called um technically that's called the external auditory meatus so that's what a meatus is it's an external opening and then a process a process is a prominence or projection on a bone so a process is kind of the opposite of a fossa right a fossa is like a dip or a concavity in a bone whereas a process is a a projection or a convex area of the bone and all these exist for a reason you know usually these processes something adheres to them like a muscle or something like that or a ligament so you'll see you'll see as we go along okay and then a suture um so you guys have probably heard about sutures you know they talk about doing sutures after they operate on somebody you know they put in like little threads and sew them up stitches um well as suture is we're talking about it in terms of anatomy it's a jagged line where bones articulate and form a joint and it does not move so so there's a lot of sutures in the skull right the bones articulate but you know but they don't move so um so they form a joint that does not move so that's what a suture is and we'll see we'll see lots of those especially when we study the skull and then synthesis this is a site where Bones come together to form a cartilaginous joint so um so it's like a joint like your you know your jaw joint the TMJ there's a synthesis there and then tubercle this is a small rough projection on a bone so there's something called genial tubercles on the um you know on the back side of the mandible um and you know we'll talk about those again something connects to those usually some sort of muscle or ligament and then tuberosity tuberosity is a large rounded process on a bone so we have something called the maxillary tuberosity so behind your very last teeth on the upper Arch is a rounded portion of bone you can probably feel it with your finger that's your maxillary tuberosity so and there's other tuberosities in the body so so this is just your basic vocabulary when talking about Anatomy okay so let's not just have a quick learning check the cranium or you could say the neurocranium consists of how many bones and the face or viscerocranium consists of how many bones so think about you know old people from Texas eat spiders and the other Valerie cannot make my pet zebra laugh so count up the bones and hopefully you come up with eight for the cranium because remember there's some paired bones and then 14 for the face okay so hopefully that makes sense if not go back to the beginning and review all right so first bones that we'll start with I always wonder how they picked the first set of Bones to start with in the textbook they they don't say how so but anyway they're starting with the parietal bones so we're going to start with the bones of the cranium or the neurocranium the the you know the head and we're going to start with the parietal bones so there's actually two parietal bones one on each side and these form most of the roof and the upper sides of the cranium you know the skull they're joined by the sagittal suture at the midline of the stall so we talked about those sutures they're these jagged lines that hold bones you know where bones meet that don't move it's a joint that doesn't move so that's your suture so the parietal bones are joined by the sagittal suture at the midline of the skull and there's a line of articulation between the frontal and the parietal Bones called the coronal suture so there's a lot of sutures on the on the skull and we'll we'll see them all now in newborns um you know have you ever heard of a baby or an infant they have soft spots in their skull and this is where sutures haven't come together yet because you know you don't want a baby with a skull where everything's fused together because then there's no room for growth so babies are born with soft spots or fontanelles they're called and they have an anterior fontanelle where the coronal suture between the parietal bones and the frontal bone hasn't yet um formed or come together so so that basically you know there's a little bit of an opening and that leaves room for the skull to grow which is good because you know a baby brain is not as big as an adult brain you know you have to have that growth and development okay so here's your parietal bones in green okay so this is the parietal bones and then this is the sagittal suture can you see back here the sagittal suture it goes right up the middle and then here's the coronal suture so here's your frontal bone we'll get to that in a minute coronal suture sagittal suture parietal bone parietal bone so one on each side of the head so you can see it makes up a really really large portion of the head so remember between the frontal and parietal bones that's your coronal suture and the sagittal suture connects the two parietal bones so parietal bone so parietal bone sagittal suture we'll learn about this other suture here in a few slides and then coronal suture between the frontal bone and the parietal okay so that's your parietal bone okay and in class we are going to be looking at at skull models kind of like this one not with the body just the head and um and they're all numbered all the bones are numbered on there so in class I'll say okay let's look at bone number two that's your parietal bone so I've got those slides interspersed here so we won't be using those for the recorded lecture okay so the frontal bone I touched on this a little bit this forms the forehead it also forms part of the floor of the cranium and most of the roof of the orbits remember we said the orbits when you hear orbit you think ah but this is the Bony cavity that protects the eye so um so the the frontal bone forms part of that cavity and then it contains two frontal sinuses one located above each eye so sometimes when people get a sinus headache it really hits them over their eyebrows and that's because you know these frontal sinuses can be infected okay so here's your frontal bone so it's not just the forehead right see how it kind of comes down and around and it makes up the the top part of the orbit around the eye and then you've got sinuses in here so and sometimes Unfortunately they can get infected and really hurt so um okay so frontal and then right behind the frontal or just posterior is the parietal and then what did we call this suture we call that the coronal suture right and that's between the frontal bone and the parietal bone good okay and if we were looking at our skulls the frontal bone would be numbered one number one on the skull model okay so moving right along we're going to the occipital bone so this forms the back of the base of the cranium and it joins the parietal bones at the lambdoid suture so that's the name of the suture and then the occipital bone has this really incredible foramen in it it's a very unique feature and this is called the foramen magnum it's on the occipital bone and the spinal cord passes through the foramen so it's really kind of quite spectacular so here is your occipital bone here right it's as you can see it here it's the the base of the skull and the posterior or the back right and then we've got this lambdoid suture which you know joins that's the kind of dividing line between the occipital bone and the parietal bones then you have your sagittal suture which divides the parietal bones or joins them I should say and then lambdoid suture lambdoid suture is between the parietal and the occipital bone okay now if we were to take the top of the person's head off and look downwards this would be the view we have right and this is the the foramen magnum it's uh see for Raymond Magnum that's what this is and I kind of joke that's where they plug us into the Matrix but it's actually where the the spine passes through this large opening so it can connect to the brain if this large opening wasn't there how would the spine and the Brain connect they wouldn't you know you need this foramen you need this hole in the bone so you know so that the spine can pass through so most foramens you can see over here most foramens are kind of tiny quite tiny because only blood vessels and and nerves pass through them but the spine is very you know it's large kind of when you're talking about parts of the body it's substantial so in that case you need a very substantial foramen in order for it to pass through so that's your occipital bone okay an occipital bone would be number three on your skull model all right and the foramen magnum it gets its own number on the skull model because it's so big I'll see that in a second so each temporal bone encloses an ear and it contains the external auditory meatus remember I talked about the the hole in your ear that's your external auditory meatus you know you'd stick toothpaste or not toothpicks Q-tips in there to clean it out so when you put a Q-tip in your ear you're actually putting it in your external auditory meatus so this is the Bony passage of the outer ear remember we said meatus was a bony passage outside the to the outside of the body that's where this comes in and then there's something called the mastoid process of the temporal bone so this is a projection it's like a lump okay and it's on the temporal bone and it's located behind the ear and this is actually composed of airspaces that communicate with the middle ear cavity so it has a function in your ability to hear then also in the temporal bone there's something called the glenoid fossa and this is the lower portion of each temporal bone and this articulates with the mandible that's your lower jaw bone and the glenoid fossa is part of the temporomandibular joint the TMJ sometimes you hear people say oh I've got bad TMJ or I've got you know TMJ disorder that's what they're talking about that that joint and we'll see a lot more about that as we go on and then there's something called the styloid process and this extends from the under surface of the temporal bone so again these these processes and fossas and all that stuff they don't exist for no reason everything is there for a reason all the foramen are there for a reason the the processes are there for a reason something hooks to them the styloid process something hooks to it the glenoid fossa that's where the um you know the temporal and the mandible articulate so everything is there for a reason okay so your temporal bones like we said these are uh there's two of them so they're bilateral meaning one on each side and you can see it doesn't look too substantial from the lateral or side view but when you look underneath you're like wow that's a lot that's a lot of bone right so it's a lot more substantial depending on The View that you um you know the view that you have so here's a little styloid process it looks like a little earring right so the the styloid process and then the mastoid process oops I'm so sorry uh the mastoid process is posterior to it it's more towards the back of the head okay so the temporal bones these are going to be number four on your skull model when we look at that in class okay so the mastoid process is this lump and then the uh well it's actually a projection or a convexity and then the styloid process also on the temporal bone is right here and you can see it over here so the styloid process is anterior or more towards the front than the mastoid process and conversely you could say the mastoid process is posterior or more towards the back than the styloid process and the way I remember the styloid process is that it looks like to me like an earring and that's stylish so styloid process so I don't know if this helps you but it helps me remember things so styloid process looks like an earring and it's stylish okay and then the mastoid and the styloid processes are number five and number nine on the skull model so we'll we'll go over those in class okay so the glenoid fossa I like this drawing because they just called us the skull it just makes it so much easier than having to memorize all the various parts um so here's your temporal bone and remember we said that the glenoid fossa is on the temporal bone and the glenoid fossa is where the the mandible that's your lower jaw here the mandible articulates with the temporal bone at the glenoid fossa can you imagine that the glenoid fossa was not here it would be like you know it fits like a puzzle piece together here but if if the glenoid fossa wasn't there you'd have some real problems with your jaw so so again everything is there for a reason and sometimes the glenoid fossa you might hear it called the mandibular fossa um but but more often you'll hear it called the glenoid fossa okay and that would be number eight on your skull model okay so this phenoid bone this is like a crazy bone that I kind of love I have a love-hate relationship with it because it's like super complex but it's so cool it looks like Batman or something uh it's like the superhero of the bones so so this phenoid bone it's made up of a body and paired greater and lesser Wings right it's got it looks like it has wings it doesn't really but it looks like it and this forms the anterior part of the base of the skull so you can't really see a lot of it when you when you're looking at the anterior view of the skull or even the lateral view of the skull you can't see a lot of it but um but it's really it's it's big and it's like right in the middle in the middle of everything so it's a cool bone so each greater Wing articulates with the temporal bone on either side okay so um so the sphenoid is one bone but it spreads across the skull inside um so it you know so it's articulating with the temporal bone the right and the left temporal bone so you know it spans a great distance there and then anteriorly uh it articulates with the frontal and zygomatic bones to form part of that eye orbit okay so there's a lot of Bones involved in forming that eye orbit you know so far we have the frontal and the sphenoid and there's even more okay and then each lesser Wing articulates with the ethmoid and the frontal bones and uh and these form part of the orbit so so two parts of the sphenoid bone help form the orbit of the eye and then there are sinuses located in the sphenoid bone posterior to the eye and so these are just kind of Open Spaces the sinuses and there's something called the pterygoid process and extends downward from the sphenoid bone and it consists of two plates so there's a lateral pterygoid plate and this is the the point of origin for the internal and external pterygoid muscles which we'll learn about in our next lecture next week and then there's a medial pterygoid plate that ends in the hook-shaped hamulus so so again everything has a purpose like for instance these plates the lateral plates you know muscles attached to them so um so everything's there for a reason okay so here's your sphenoid bone it doesn't look as impressive as it actually is in this picture but we have more pictures so so if you were to slice the skull in half this is an internal View so you can see here and then you can see if you were to slice the top of the skull off and you're looking downwards that's the view here and you can see it's got some you know a lot of foramen there all right and then if you looked uh you can't really see this from the anterior but when they make the anterior translucent then you can really see the full the full effect I mean look at that that's that's pretty big goes all the way across and articulates with those temporal bones so it's a substantial bone and here's uh an actual bone so so here's the greater Wings right and then here's the Lesser Wings although they're pretty significant got the sinuses you've got various foramen or foramina as the plural and then you've got the the lateral plates and the medial plates okay so that's your sphenoid bone and just another a little look at it so you've got your sphenoid sinuses the left and the right it's got sinuses in there and then here I like this picture because you can see the the greater Wing you know here in the maroon color then the Lesser wing and the green color and you can see the optic Canal optic nerves pass through there to get to the eye uh foramen rotundum foramen o Valley foramens but no some you don't have to worry about memorizing those and then you've got the pterygoid process so you've got the lateral pterygoid plate and the medial pterygoid plate so remember the lateral is more towards the outside and the medial is more towards the middle okay and then you can see um the the sphenoid bone here in yellow so here's the greater wing so you can see the greater Wing when you look at the lateral view of the skull when it's intact but you wouldn't be able to see the lateral plates I mean we can see it here because other Bones have been dissected and then here you can see the hamulus which is just so cute you can see it on radiographs when you take certain radiographs and we talk about that in DNA 134 but when you see the hammerless I always say by a lottery ticket because that's your lucky day to see something so cool okay and then this monoid bone again when we take the skulls apart it's going to be really fun and everything the spinoid bone is number 18 then you've got your greater Wing which is labeled 10 and 62. there's a part of it called the Stella turkica which sticks up in the middle and that's number 63 so again we'll be looking at these in class as well okay now we have the ethmoid bone um always feels like a little bit of a letdown when I'm done with the sphenoid bone but we're going to move along the ethmoid is a nice bone too so the ethmoid it forms part of the floor of the cranium uh part of the orbit so another bone that's involved in the orbit there's a lot of them and the nasal cavity so so this is a complex bone and it has these like honeycomb like spaces like little circles with borders on them like you know like uh I don't know like honeycomb you know so and um and these are called your ethmoid sinuses so you have sinuses in several different bones and then the medial conscience Superior Concha these extend from behind the ethmoid bone so let's take a look at all that okay so here's your ethmoid bone when you look from the you know the back view of the skull and when it's you know dissected you get a pretty good look at it and then you can see it's kind of in here tucked kind of behind the nasal cavity behind the orbits and if you dissect the skull and look at the inside lateral view it looks like that so it's actually it's got a pretty neat shape to it and this is what it looks like so that's and these are the honeycomb the sinuses they were talking about so um so this is the Krista golly um I think that's something uh something to do with a rooster I believe in uh in Latin I want to say it's supposed to be like the the head of a rooster I think um and then you've got the um let's see the superior nasal Concha and the middle nasal Concha there's also an inferior nasal Concha but it's not part of the ethmoid bone and then a particular perpendicular plate okay so that that's your your ethmoid bone so it's got a pretty interesting shape to it and a very Prominent Point at the top which is your Krista galley okay and then the ethmoid bone is going to be number 15 and the Crystal golly is number 58 on the skull model okay so let's just uh jog our memories a little bit and do a quick learning check the foramen magnum is found on the blank bone so think about what the foramen magnum is for and what bone that might be on what position of the head it would be and the blank passes through this opening so again what passes through that foramen magnum okay let's uh take a look so the foramen magnum is found on the occipital bone you know at the base of the head and it makes sense that it's there because the spinal cord passes through that opening so it's a very very very large foramen very substantial okay now the auditory ossicles there's six auditory ossicles so these are the bones of the middle ear so there's there's three for each year three for the right ear three for the left ear so each ear contains uh malleus and incus and a stapes and the malleus is supposedly shaped like a hammer I don't see it uh the incus is supposedly shaped like an anvil I don't see that either the stapes is supposed to be shaped like a startup and I do see that you guys will see that but the malleus and incus I feel like they're kind of stretching you know stretching that because I don't see the hammer or the Anvil but whatever so okay so the auditory articles the malleus the incus and the stapes so so these are located in the inner ear or the middle ear uh so so here's your external auditory meatus the opening your external auditory canal your tympanic membrane or your eardrum right and then you've got the auditory ossicles the malleus the ankles and the stapes they're here okay and this is left ear same thing as on the right ear so these function in hearing and they move sort of they vibrate so they don't move move but they do vibrate so so there is like some movement to them um and then here's uh just drawing of that model so you've got the external auditory canal the external auditory meatus is the opening the tympanic membrane or the eardrum then you have the malleus the incus and the stapes all working in conjunction together helping you hear okay and then here's some dissected um ones so um so so here's the um the uh wait a second this would be the stapes and then the uh okay here's the stapes and then the malleus and then the incus so again the malleus is this one that's supposed to look like a hammer all right and then the stapes is the Stirrup supposed to look like the Stirrup and then the incus is supposed to look like the Anvil so again to me it's a little bit of stretch for that but the stapes definitely I see a star up there and they even call this a foot plate you know even though it's in your ear okay so the external auditory meatus on our skull is going to be number 42 very easy to locate because it's where your ear would be and it's just a hole so okay oh let's think back a little uh the styloid process is located on the or I'm sorry the styloid process is located blank to the mastoid process so do you think do you remember that styloid process it looks like an earring is that located anterior or posterior to the mastoid process and then both of these structures are located on the blank bone so think about that I know it's a little bit of a stretch it was a few slides ago so let's look at it so the styloid process is located anterior to the mastoid process and both of these structures are located on the temporal bone okay so you can go back and take a look at the slide but trust me the styloid process is anterior to the mastoid process it's more towards the front of the head okay great so um so this is from your textbook this is a lateral view of the skull so um so we haven't gone over all of this yet um but but we've you know we've done the um neurocranium bones so you know things like number 26 the parietal bone and uh and the occipital bone back here and then the temporal bone the external auditory meatus the um the styloid process right the mastoid process back here uh let's see we did the um the lambdoid suture um we can't really see the sagittal suture but we did do the coronal suture number five the frontal bone so we touched on a lot of this the mandible kind of made a little bit of a appearance not so much because it's not one of the neurocranium bones it's a visceral Cranium bone and then that glenoid fossa remember we talked a little bit about the glenoid fossa where the mandible and the temporal bone articulate so um yeah so we have learned a lot so far but there's still a lot more to learn a lot more to learn so all right if you guys are ready I'm gonna keep going okay and then the frontal view of the skull so you know so the frontal bone here number three um again this is in your book it's a little bit hard to read on some of these but um we haven't gotten to a lot of these facial bones yet um but you know we are going to get there um so you guys can just go through here and see you know what we've touched on so far we've got the middle nasal Concha here um the uh let's see the inferior nasal Concha we haven't done that one yet um and I'm just trying to see what else we we went over um yeah so that's about it so by the time we get through the entire presentation you'll you'll have heard of all of these structures okay so another quick learning check uh what part of the sphenoid bone may be seen on the lateral view of the skull I should say the intact skull because if it's dissected you can see more but if you were just looking at the lateral view of the skull the only part of the sphenoid bone that you would see is the greater Wing okay so you guys can go back and look through the uh the diagrams and pictures and check that out okay so the posterior view of the skull so so remember occipital bone parietal bones sagittal suture lambdoid suture you know you can see a lot um what else did we uh study I think that's what all you need to know for that one so all right great let's keep going um so sutures on your skulls they're going to be uh 23 24 25 will be the coronal sagittal lambdoid again we will go over those in class okay another learning check I'm really putting a lot in there so which suture joins the occipital and parietal bones do you guys remember if you said the lambdoid suture you would be correct because once again here is the lambdoid suture all right number five lambdoid suture occipital bone number six number seven is the parietal bones plural two of them they're paired okay and then view of the external base of the skull so you can see the foramen magnum is what really strikes you right so and that's on the occipital bone and then you guys can just kind of go through here you know maybe going through uh the picture in your textbook would be a little more meaningful um as you could see it better so um so again it's we haven't gone over a lot of these bones because many of them are the visceralocranium and we've just done the neurocranium so far so but let's keep going okay so now we are going to talk about the bones of the face or the viscerocranium we also call it okay so from an anterior view of the skull from the front view you know if you're just looking at the front of a skull or the front of somebody's face the visible facial bones are going to be the lacrimal bone the nasal bone the vomer the nasal conchae the zygomatic bone the maxilla and the mandible and the maxilla and the mandible are particularly interesting to us as future dental health care providers because the maxilla holds the upper teeth and the mandible hold the lower teeth so so we have a lot of interest in those bones okay so let's just take an anterior look at the skull and see what bones we see so here you've got your nasal bone right down the center of the nose your vomer it's inside the nose you can't see it usually but here it is the inferior nasal Concha okay that's a separate bone from the middle nasal Concha or Superior we've got the the maxilla and that's the two that's the bone that holds the upper teeth or maxillary teeth we've got the mandible which is like kind of u-shaped comes up on each side and the mandible holds the lower teeth or the mandibular teeth okay we've got the zygomatic bone that's those uh kind of cheekbones you know and then the lacrimal bone so lacrimal bone again there's two lacrimal bones one on each side and it makes up a part of the orbit the eye orbit so that's yet another bone that makes up part of the eye orbit okay so zygomatic bones let's go back for a second here's your zygomatic bone here so the the top part of your cheek right under your eye okay so zygomatic bones there's two bones there's one on each side so bilateral or paired and these are also sometimes called malar Bones although you don't really hear that very often but you know once upon a time maybe they use that uh but you guys remember zygomatic bones so these form the prominence of the cheek and lateral wall and floor of the orbit so some people have very prominent zygomatic bones and they say oh wow they have great cheekbones like you know models and stuff so that's your your zygomatic bones they're you know very high on the cheek the frontal process of the zygomatic bone extends upwards and articulates with the frontal bone so we'll see a picture of that so the processes are named for the bone they connect to okay so the frontal process of the zygomatic bone articulates with the frontal bone the zygomatic process of the of the frontal bone articulates with the zygomatic bone okay so these process took me a while to get that but these processes they're named for the bone that they articulate with or touch okay so you have a you know like on the zygomatic and temporal Bones on the temporal bone you have a zygomatic process that hooks the zygomatic bone and on the zygomatic bone you have a temporal process that hooks to the temporal bone so you'll see it can kind of be a little bit confusing so these zygomatic bones they rest on the maxillary bones which articulate with the zygomatic process okay and the temporal process articulates with the zygomatic process of the temporal bone so the temporal bone has a zygomatic process that articulates with the zygomatic bones and the zygomatic Bones have a temporal process that articulate with the temporal bone okay and these two processes together they form the zygomatic Arch and that's what creates that that prominence of the cheek okay so here's your uh here's your zygoma or zygomatic bones okay they're right here they actually form that prominence of the cheek but then they form portion of the orbit okay right here and you can see a lateral view here so the maxillary process of the zygomatic bone articulates with the maxilla or the maxillary bone okay and then the temporal process of the zygomatic bone actually articulates with the temporal bone and then the frontal process of the zygomatic bone actually articulates with the frontal bone okay I know that can be kind of confusing and here's the zygomatic Arch so the zygomatic Arch is actually partially the zygomatic bone and partially the temporal bone so the temporal bone has a zygomatic process right and that hooks to the zygomatic bone and the zygomatic bone has a temporal process that hooks to the temporal bone okay so that's kind of the naming convention so so that gives you a pretty good idea of the you know all of that stuff so remember that zygomatic Arch is part temporal bone and part zygomatic bone okay and the zygomatic bones will be number 11 on your um on your skulls that we study and the zygomatic Arch again is the temporal process of the zygomatic bone and the zygomatic process of the temporal bone and this will be number six on your skulls that we look at okay and then the maxillary bones so this is your upper jaw right or your top teeth are part of the maxillary bone bones so the maxillary bones is two bones it's paired bone sometimes you hear it called maxillae that's plural or the single is maxilla so this forms the upper jaw and part of the hard palate now the hard palate that's the roof of your mouth okay and that's the maxillary bones that form the roof of your mouth or the heart palate so the maxillary bones are joined together at the midline by the maxillary suture so here we have another suture but it's it's inside you know it's not external it's internal so the maxillary bones don't move they're held together by that suture and then the zygomatic process of the maxillary bones extends upward to articulate with the zygomatic bone so let's just look at that real quick here you go here is the the maxillary process of the zygomatic bone that articulates with the maxilla okay and then the maxilla has a zygomatic process or I'm sorry the the maxilla has a zygomatic process that articulates with the zygomatic bone it's reciprocal so the maxillary bones contain maxillary sinuses and yes those can get infected and when they do you might feel like your teeth are going to fall out because of the inflammation it can be very painful very uncomfortable and then the alveolar process of the maxillary bones these form the support for the maxillary teeth so remember before we were talking about the alveolar bone surrounding the tooth or the alveolar process that's part of the maxillary bone for the upper teeth and we have an alveolar process on the mandibular bone that surrounds the lower teeth then we've got the maxillary tuberosity so remember we said the tuberosity is kind of in the back of your upper teeth behind the molars you can feel a big kind of lump of bone that's your maxillary tuberosity and it's a rounded area on the outer surface of the maxillary bones posterior to the teeth and again this is something you're going to see on dental X-rays when you take them that's one of our landmarks okay so here's the maxilla you can see it's like that's a lot of bone right it's kind of big bigger than you might think because we always think of the maxilla as just like the the teeth you know we think about that alveolar process and just think that's the Maxima but but it's actually pretty substantial and then it articulates with the zygomatic bones here um and let's see so here's the frontal process so that's here and that's called The frontal process because it articulates or joins the frontal bone right so here's your frontal processes okay then we have the infraorbital margin and for orbital foramen you know blood vessels nerves pass through here to iterate the eyes then we have the zygomatic process so the zygomatic process is what connects with the zygomatic bones the zygomatic Bones have a maxilla maxillary process that hooks with the maxilla okay now we've got the nasal cross nasal Notch we've got the maxillary sinuses you know they're kind of positioned above the teeth so if they get infected and inflamed that pushes down on the nerves of those teeth and it makes it feel like your teeth are going to fall out I remember the first time I got a really bad sinus infection I was so so sick and I was like oh my gosh I've got this horrible sinus infection and I'm going to have to go to the dentist because I feel like my teeth are ready to fall out I didn't realize that they were connected which they were um so uh oops I'm so sorry uh and then the alveolar process so that's the bone around the teeth basically so all right um and then we'll get into other structures later as we see them okay so the maxillary bones are going to be number 13 on your skull all right so quick learning check uh the zygomatic Arch is composed of processes from which two bones okay so yes the zygomatic bone that's kind of a given what is the other bounce well how do you think if you said temporal bone that would be correct so the zygomatic Arch is composed of the temporal process on the zygomatic bone and the zygomatic process on the temporal bone okay think about it okay and then Palatine bones so when I see Palatine I think palette hard palate roof of your mouth right so the Palatine bones it's two bones and these are not strictly considered facial bones but they are so for our purposes they are facial bones okay I don't know why the text says that um each bone consists of two plates so there's a horizontal plate you know going from one side to the other and a vertical plate going up and down and the horizontal plates form the posterior part of the hard palate and the floor of the nose so the very very very back of the roof of your mouth the hard palate and the floor of the nose and then the vertical plates these form part of the lateral walls of the nasal cavity you know think about their vertical they're going up and down so they form those walls and they articulate with the maxillary bone anteriorly so let's look at pictures of all that okay so here's your Palatine bones they don't look super substantial this is the horizontal plate and this is the maxilla right and this is the hard palate so the hard palate is made up of the maxilla and the Palatine bones okay and then here's the lateral view of the Palatine bones all right and the Palatine bones will be number 17 on your skull model and then the median Palatine suture let me just go back this is the medium Palatine suture it runs through the the entire hard palate okay and here's a little foramen this is called your incisive foramen and the incisive nerve runs through here can I all right um so another look at the hard palate um this is made up of the Palatine and the maxilla bone so if you had a question on a test that say what bones make up the hard palate you would answer hopefully the Palatine and the maxilla bones or maxillae um so so we've got the horizontal plate of the Palatine bones and then this is called the Palatine process but as the maxilla bone okay so this is the maxilla this is the Palatine bone then we've got your incisive foramen and we've got the Palatine process of the maxilla that's all this then we have we've got some greater Palatine forama this is where the greater Palatine nerve exits then we've got these are the horizontal plates of the Palatine bone and this is called your transverse Palatine suture okay and that joins the the maxilla and the Palatine bones and then we've got our medial Palatine suture which joins the right and left sides of the maxilla and the right and left sides of the Palatine bones so all right and that's the roof of your mouth essentially all right nasal bones we have two nasal bones and these form the bridge of the nose and they articulate superiorly or from above with the frontal bone so your forehead or your frontal bone kind of hooks into these nasal bones and these do make up a small portion of the nasal septum but not the complete nasal septum so here is your nasal bone looks like the right nasal bone look here here's a styloid process here's the external auditory meatus mandible all kinds of fun stuff here are the nasal bones seems like it would be one bone but it's actually two okay so you can see uh you know here's the frontal bone so the frontal bone and the nasal bones articulate so frontal bone nasal bone they hook to each other then we have the perpendicular plate of the ethmoid bone okay these are the bones forming the walls of the nasal cavity then we've got the vomer as well back here we've got the sphenoid the Palantine process of the maxilla and then here's the Palatine bone so these are all articulating or you know contacting each other hooking together okay and the nasal Bones on the skull would be number 12. when we get to that okay so learning check the hard palate is made up of which two bones okay what did we say so hard palate okay when you see palette hopefully you'll see Palatine bone and say oh yeah I'm on to something so so that's pretty much a gimme it's a hard palate Palatine bone what's the other bone that makes up the hard palate well if you said maxillary then you are correct all right so the hard palate or the roof of the mouth is made up of the Palatine and maxillary bones okay now we have the lacrimal bones these are two itty bitty tiny tiny bones so it's two bones they're paired and they make up part of the orbit at the inner angle of the eye very small thin bones and they lie directly behind the frontal processes of the maxillary bones which we'll see okay so here's the lacrimal bones there's one on each side they're in purple here lacrimal and then here's lacrimal so they're making that part of the eye orbit right it's a lacrimal bone so they're very very small and those will be number 14 on your skulls okay then we have the vomer which is a single bone it has a flat shape and it forms the base of the nasal septum so it's part of that nasal septum the lower part okay so here's the vomer it's actually pretty substantial when you look from a lateral View but here's the vomer okay and that forms the majority of the nasal septum okay so vember bones number 16 on your skull model okay then we have the nasal Concha each lateral wall of the nasal cavity has three projecting sutures that extend inward from the maxilla and these are called your nasal conchae each Concha extends scroll like into the navel cap cavity which we'll see in a second or nasal cavity and there's a superior middle and inferior nasal Concha these are formed from the ethmoid bone so let's take a look so you can see the inferior nasal Concha here right and then the middle nasal Concha here and then the superior nasal contrast so usually when you're looking at an anterior view of the skull when it's not dissected like this you'll probably just see the inferior nasal Concha maybe the middle but not the superior okay so you can see the ethmoid bone is in red here the metal nasal conscious coming off the ethmoid bone um and then the maxilla you see okay and so you can see in here a little bit more clearly when it's uh dissected is the superior Concha the middle Concha and the inferior nasal Concha looks a little bit different from a lateral view than it does from an anterior View okay so learning check this is a really hard one the orbit of the eye is made up of which Bones so maybe pause here and think about it like what seven bones is it made up of you know I can think of a lot of them I'm not sure if I could hit them all right now so all right so either pause or whatever because I'm about to tell you the answer okay so here's the orbit of the eye here so um which Bones is this made up of so it's got a portion of it's the maxilla bone okay the frontal bone here in purple uh the zygomatic bone and blue see that area there the ethmoid bone makes up a portion of it that's here in a different color purple okay the lacrimal bone is this green it's in green on this drawing the sphenoid bone also sphenoid bone here you go it's like this khaki color and then the the Palatine bone too which you wouldn't really expect but you can see just a tiny tiny little bit the Palatine bone so um so those are actually the seven bones one two three four five six seven seven bones that make up the orbit of the eye and there's another mnemonic that I found online many friendly zebras enjoy lazy summer picnic so if you have to memorize that which I'm not going to make you memorize that that would be your mnemonic so there you go okay now let's talk about the mandible mandible is very interesting and it's Unique because guess what it's the only movable bone of the skull okay now I know what you're saying those inner ear bones the incus the malleus and the stapes those vibrate so they technically move I guess but but the mandible is the only only bone that moves moves right so this forms the lower jaw it's the only movable bone of the skull if it didn't move how would you eat you know so um the alveolar process of the mandible supports the teeth of the mandibular Arch that's your lower teeth the mandible is u-shaped and it's the strongest and longest bone of the face very interesting it actually develops prenatally in two parts and then it ossifies or hardens into a single bone in early childhood so you know when a child born they actually have two mandibles and then it becomes one there's something called a symphysis is located at the midline and this forms the mental protuberance or the chin okay so let's take a look at all of that okay well not quite yet we're not going to look at a picture yet we're just going to go over some structures of the mandible and there are many um mental foramen so we know mental means chin frame and means whole it's a whole linear chin actually it holds plural there's one on each side so this is bilateral meaning one on each side and the mental foramen it's located on the facial surface between the mandibular premolars so we'll see a lot more about this when we're studying the teeth and again the mental nerve runs through the mental foramen so it's you know it's one of the nerves that innervates the teeth then we have the genial tubercles remember we said tubercles are rounded raised areas so genial tubercles these are small rounded raised areas on the medial or back surface of the mandible right underneath your incisor teeth the middle teeth then we had the myelohyoid ridge this is on the lingual surface of the body of the mandible we have the angle of the mandible this is where the mandible meets the ramus so it's kind of where it turns Direction we have the mandibular Notch this is on the border of the mandible and it's anterior to the angle again we'll see all this in pictures we've got the ramus which is the vertical portion so we said the the mandible is kind of u-shaped the ramus is the part that goes vertical or upwards versus across um and then we've got a coronoid process this is the anterior portion of each ramus we've got the condyloid process or condyles sometimes they're called This is a posterior process of each ramus and this articulates with the temporal bone you know at the glenoid fossa right and this forms the TMJ so it's also called the mandibular condyle or sometimes condyle you've got a sigmoid Notch and this separates the coronoid and condyloid processes or condylar processes then we've got a mandibular foramen another hole on the lingual surface of each ramus this is where the inferior alveolar nerve passes through we've got the oblique Ridge and this is on the facial surface of the mandible near the border of the ramus sometimes you'll hear that called the external oblique Ridge then we've got the retromolar area so this is a portion of the mandible directly posterior to the last molar on each side so retro kind of means behind so this is the area behind the last molar on each side so let's take a look at the mandible remember longest biggest bone of the uh the cranium and it's uh movable so that makes it very unique so here's here it is from the interior here it is looking from the posterior here's the lateral view okay and then here's the lingual View so um so we've got the um let's just go over here's the alveolar process right here that's that's the bone around the teeth the alveolar process okay the angle this is where it changes Direction okay number two is the angle so this is where the mandible changes Direction it goes from vertical direction to horizontal then we have um the the ramus is this area number 22 is the ramus so number three is the anterior or front border of the ramus okay number four would be considered the base of the mandible number five would be considered the body of the mandible so that's really this whole area is the body of the mandible body of the mandible okay um number six is the coronoid process okay that's that front front part more anterior you can see it here uh here and here not your coronoid process um number seven is called the digastric fossa that's on the lingual side number eight is the the head okay we call that the head and that's actually um that's actually the condyle they also call it uh let's see number nine is the inferior border of the ramus so this this whole part this vertical part is the ramus and this is the inferior border of the ramus okay the number nine number ten is the lingula that's here that's right over the number 11 the mandibular foramen the lingula is like some bone that kind of hangs over that that mandibular foramen the the hole in the bone number 12 we've got the mandibular Notch okay number 12 is the mandibular Notch they call it that's that you know you can see it here you can see it here not sure mandibular notch so so that's between the coronide coronoid process and the condyle or condylar process which weirdly I don't think they have the condyle labeled on here they're just calling it The Head and the neck but that's the condyle there yeah that's kind of weird um yeah the conduct condylate process this is the posterior process of each ramus articulates with the temporal bone to form the TMJ also called the mandibular condyle that's what this is number eight that they're calling it the head that's the condylar process okay okay uh let's see we said mandibular Notch foramen mental foramen so remember foramen as a whole mental means chin this is your mental foramen number 13. you can see it here number 13 and then you can see it on the other side on the left side there too and uh nerves pass through there and blood vessels then you have 14 the mental protuberance that's your chin okay then you've got the myelohyoid groove and the myelo hyoid line okay that's number 17 here and number 16 is the groove 18 is the neck of the condyle 19. that's your oblique line or external oblique Ridge sometimes you'll hear it called and then 20 is the posterior border of the ramus again the ramus is this whole vertical part A Stereo border of the ramus um don't worry about 21 22 is the ramus so this whole thing is the ramus right and then number nine is the border of the ramus then we've got the sub lingual fossa that's number 23 sublingual fossa so fossa is like a Groove then we've got the sub mandibular fossa number 24 you can kind of see a Groove a little bit better here and that's where salivary glands kind of fit in there um and then the superior and inferior mental spines also called genial tubercles so genial tubercles are right here in the same area as the digastric fossa okay which is where the where a muscle attaches so that's your mandible it's got a lot of parts important parts okay so again mandibular Notch right coronoid process condylar process ramus body of the mandible base of the mandible angle where it changes directions mandibular foramen your oblique line uh let's see what else is important um yeah that's about it for this one so all right mental foramen I think we said alveolar process around the teeth the bone around the teeth and that's the mandible oh my gosh another view okay so the head or the condylar process this is the condylar process this is a little coronoid process with a notch in between the lingula that's a little bit of bone overhanging the mandibular foramen those are both bilateral you've got the submandibular fossa here you've got the inferior mental spine you've got the digastric fossa the superior mental spine the the sublingual fossa here the angle of the mandible okay so that's your posterior View and when we look at the mandible bone on the skull it's number 20 coronoid process 21 condylar process which is more posterior is number 22. and we'll be able to see the mental foramen number 52. okay then we have the hyoid bone so this is actually a bone of the neck you know it's not part of the cranium so um so the hyoid bone is kind of interesting because it doesn't articulate with any other bone every other bone like hooks into another bone but not the hyoid bone is considered a quote-unquote floating bone because it's not articulating with any other bone so it's actually suspended between the mandible and the larynx so it's kind of in your throat and it functions as primary support for the tongue and other muscles it's kind of shaped like a U-shaped like a horseshoe and it's got a like a central body and then some lateral projections some pointy Parts on it and then externally the position is in the neck between the mandible and the larynx like we said and it's suspended from the styloid process remember the one I said look like an earring and I said it had a function well guess what here's its function one of its functions so it's suspended from the styloid process of the temporal bone by two stylohyoid ligaments so it's held in place by ligaments which are soft tissue okay that's how it stays in place it doesn't articulate with other bones but it does you know it stays in place with these ligaments so it's a little bit unique in that respect and you can see this is where the hyoid bone is it's kind of shaped like a horseshoe and then it's got they call them horns lesser horns and greater horns projections so it's just it's kind of underneath the chin like kind of high on the throat area but again it's the stylus the ligaments from The Stylist are what keeps it in place which is kind of cool okay learning check again we haven't had one in a while what is the only bone of the neuro or visceral Cranium that is not movable not including the ossicles that is movable I'm sorry I'm sorry that is movable not including the ossicles the oscicles don't really move they vibrate so that would be the mandible right the mandible is the only bone of the neuro and visceralocranium that moves okay um so let's talk real quick about postnatal development um you know this is a very long chapter I fully admit that uh so at Birth the cranial vault is very large um and the cranial base and the face are small you know babies are built a little bit differently uh the face lacks vertical vertical Dimension because the teeth have not yet erupted and we see this not just with babies but with people that lose their teeth you know they lose bone in their you know in their mouth their maximum mandible mandibular alveolar processes diminish because there's no teeth there so their faces kind of collapse a little it's kind of an interesting look so anyway uh you know these babies don't have teeth so they don't have a lot of vertical dimension in their lower face um so uh so postnatally you know the fusion of Bones will take place in postnatal development not prenatal so after birth um so several bones of the skull have not fused a single bones at Birth so that's where these soft spots in the infant skulls come in or we call them fontanels you know there's there needs to be room for the baby's head to grow so if these bones were all fused there wouldn't be it just wouldn't happen you know so so by having little openings or soft spots the infant's bone or their brain can grow and then later on the um the bones of the cranium can fuse together and Harden so here's um so look at this when you look at a baby's head you know babies have like really large you know kind of upper heads the upper part of their head is very large and prominent but um they lack vertical Dimension so this this is like a you know exactly what this is see how it's kind of flat below the nose the majority of the the head is like really the upper part of the skull and then because they don't have teeth and they're um mandible you know hasn't grown yet they they lack vertical Dimension here so um so this is that synthesis menti which you know when a child's born it's not fused yet but at some point it fuses and then the mandible is just one bone then you have this interfrontal suture and then you have an anterior fontanelle so you can see the sutures aren't all closed so so there's some space and that allows for the baby's brain to grow and then the the um the bones will fuse together later and then you can see they've got the lambdoid suture and then they've got a fontanelle here so it's just an opening between the bones okay and it just allows for growth and look at how the vertical Dimension you know from the eyes to the bottom of the chin is very small area versus the eyes to the top of the to the top of the skull and then again we've got the the sagittal suture the lambdoid suture and the ossifying posterior font now so things are starting to harden up at this point ossifying okay and then development of facial bones so so the mandible like we saw there's that um see it's in two halves at Birth the symphysis meant I divides it and um so the mandible is present in two halves of birth separated by the synthesis meanti and this fuses during the first year so before the baby's one year old it's going to be fused normally um so also the condylar process lengthens and the chin or the mental protuberance doesn't reach full development till after puberty so the child's head grows for you know more than a decade and then males usually have more pronounced development of the chin than females then with the maxilla you know the maxilla is entirely filled with developing tooth buds at Birth so everything's there it just has to grow and then vertical growth of the upper face um largely due to dental alveolar development and formation of the maxillary sinuses so as the teeth erupt and the alveolar bone develops and the maxillary sinuses form that's when the the baby or the child starts to get more vertical dimension in their face that's when the the top of the skull doesn't look disproportionately large and the you know from the eyes to the chin looks disproportionately small okay so the difference between male and female skulls there are some differences female skulls tend to be smaller and lighter and have thinner walls and the female forehead retains a rounded anterior frontal Contour the teeth are usually smaller and they have rounded incisal edges on the anterior teeth male skulls tend to be larger heavier and have more rugged muscle markings and prominences and male teeth tend to be larger than female teeth and they're more of a square shape incisely you know on those biting edges of the anterior teeth they're more of a square shape versus rounded and the forehead's flatter as a result of larger developing frontal sinuses so there are some differences between male and female skulls okay and then uh we're going to talk about the temporomandibular joints too there's one on each side so TMJ temporomandibular joint so the join is on each side of the head and this allows movement of the mandible for speech and mastication now when you see mastication that means chewing like chewing food so there's two bones involved in the the temporomandibular joints there's the the temporal bone or it should say bones really because there's one on each side and the mandible and the mandibles attached to the cranium by ligaments of the TMJ and it's held in position by the muscles of mastication so the TMJ this joint involves bones and ligaments and muscles is very complex so it's made up of three bony parts so remember we talked about the glenoid fossa and that's that oval depression on the temporal bone and it's just anterior to external auditory meatus and that's where the condyloid process fits in um and then there's articulate Eminence now that's a raised portion of the temporal bone and it's just anterior just in front of that glenoid fossa then we've got the candiloid process or the condylar process sometimes you'll hear it called and that's part of the mandible we saw that and that that articulates with or lies in the glenoid fossa so so we'll see how it all comes together so here's your um here's the opening to your ear your external auditory meatus um and then uh here's your your styloid process and again see the styloid mandibular ligament also attaches to that this is called a joint capsule and then this is a temporomandibular ligament so it attaches the um the mandible to the temporal bone so if we look at this closer up we can start to talk about some of these different structures so so the condyle is here that it's really covered with ligaments but here's the condyle right and the condyles here so um so the condyle articulates with this glenoid fossa this is the glenoid fossa up here and that's part of the temporal bone and then the glenoid fossa as it comes forward it becomes the articular the articular Eminence right so it's got a concavity where the condyle articulates and then it turns into the articular Eminence which is a convexity there okay and that's where the the mandible kind of articulates with the temporal bone okay so this is a little bit more I think this kind of shows it a little bit better so here's the you know the condyle here's the con condyle or condylide process so that fits into the glenoid fossa on the temporal bone and this is the mandible you can see it up here okay that's when the mouth is closed and then you have the articular Eminence is here so they articulate so here's glenoid fossa the concavity and then it turns into the articular Eminence which is a convexity okay so when the mouth opens you have this Glide and hinge action or hinge action first and then when you open the jaw wider it becomes a gliding tinge action so you've got the um the mandible when you start to open the mouth the mandible it was sitting in the glenoid fossa when the mouth was closed and when you open the glenoid fossa as the jaw tilts open the glenoid fossa kind of moves forward I'm sorry the the condylar process moves forward in the glenoid Pro and the glenoid fossa so you can see when the mouth's open the the the mandible kind of tilts forward and the the condyleoid process see how it fits in here when the mouth is open it's just pointed a little bit more interiorly okay now if you open the mouth and that's your hinge action now if you open your mouth really wide which can be a problem for people with TMJ the um the mandible the condoiloid process of the mandible it goes from the glenoid fossa where it was sitting originally with the mouth closed and then it became the hinge action when you opened a little when you open really wide it comes all the way out of the glenoid fossa and follows that Contour of the articular Eminence right so and then you have your mouth open really wide and it kind of tilts forward a little bit so that's basically the the TMJ movement in a nutshell so there's something called a capsular ligament that encloses the TMJ and it's a fibrous joint capsule so it completely encloses that TMJ then this wraps around the margin of the articular Eminence and the articular fossa superiorly and wraps around the mandibular condyle inferiorly so that's your capsular ligament so it just kind of encloses the the entire thing so here's the The Joint capsule or capsular ligament okay and then the articular space so the area between the capsule or ligament and the surfaces of the glenoid fossa and the condyle that's your articular space so in the space there's an articular disc also called a meniscus and this is basically a cushion it's connective tissue it's very dense it's very specialized but it's a cushion and it divides the articular space into upper and lower compartments so the articular disc kind of sits between the the mandibular the mandible bone and the temporal bone and then the compartments are filled with synovial fluid and this lubricates the joint and fills the synovial cavity because if you just had you know if it was bone on bone it could be very detrimental to those bones over time but luckily you have like a meniscus in here you can see the meniscus in here and it kind of softens things you know and it keeps them keeps everything like from from grinding against each other basically and causing harm over time or arthritis so the meniscus is very very important for comfort all right so here's um here's the head of the mandible and here's the articular desk in the glenoid fossa okay so it's like a little pillow between the mandible and the temporal bone okay and if it wears down for some reason it's going to be there's going to be pain so the tmgj performs two types of movement the hinge action and the gliding movement so the hinge action this is the first phase of the mouth opening when you only open your mouth a little bit then you have the hinge action like I showed you in the other picture so only the lower compartment of the joint is used the condylar head rotates around a point on the under surface of the articular disc and then the body of the mandible drops down and backwards it kind of tilts a little bit so um so the the joint or the jaw is opened by the external pterygoid the digastric the myelohyoid and the geniohyoid muscles so we'll learn more about muscles in the next half of the chapter and then the mouth is closed by the temporal the masseter and the internal pterygoid muscle so let's just look back at that hinge action so when the when the jaw starts to open slightly you have this hinge action where the condyle just kind of moves a little bit forward and the the jaw drops open so it kind of pivots okay so um now we've got the gliding movement so again the TMJ performs two types of movement the hinge action which we talked about and the gliding movement so the gliding movement this allows the lower jaw to move forward and backwards involves both upper and lower compartments of the joint the condyle and the articular disc Glide forward and downward along the articular eminence and this occurs during a protrusion and lateral movements so either forward movements or side to side movements of the jaw why they wider opening of the mouth involves both the hinge and gliding movement and protrusion this is achieved by the internal and external pterygoid muscles which contract bilaterally again we will talk more about this when we get to the muscles next next week and the lateral movement is the internal and external pterygoid muscles they contract on only one side of the face to to perform the lateral movement and then side to side grinding movements these alternate contraction of the internal and external pterygoid muscles so it's really the internal and external pterygoid muscles are very very um prominent in these types of movements so just to remind you I'm going back real quick so here's the Glide and hinge action so so the condyle it actually comes out of that glenoid fossa okay when you open your mouth really really wide it it slides along the glenoid fossa and then it slides right out along the articular Eminence okay so that's your Glide and hinge action that's when you open your mouth really really wide okay oh and I have the picture here so so condylar process or condyloid process of the mandible this is the glenoid fossa the temporal bone articular Eminence of the temporal bone and you can see as the mouth opens wider the condylar condylode process kind of moves forward through the glenoid fossa and then along the articular Eminence here and then the internal and external pterygoid muscles we talked a lot about these as far as um the with the various parts of the gliding movement the internal and external pterygoid muscles they're very prominent with that and you can see here is the lateroid pterygoid muscle and the uh the medial pterygoid muscle okay I'm sorry medial pterygoid muscle and lateral pterygoid muscle so again we'll learn a lot more about that when we get to the muscles of the head and neck okay and then a lot of people have terrible problems with their TMJ their temporomandibular joint so much so that we call it temporomandibular disorders because people you know a lot of times it can affect one or both of the tmjs it can be one side or the other or both a lot of times stress people will grind their teeth or clench their teeth grinding is called bruxism and that is very hard on the TMJ you know that kind of trauma can cause issues so so TMD temporomandibular disorder this can be caused by trauma or systemic disease like arthritis or wearing or aging um and you know it's really really hard to to cure these disorders you know or treat these disorders so diagnosis can be difficult and a lot of times it requires multi-disciplinary approach you know it might require the help of you know general dentist and oral surgeon all kinds of things so it's really you know these these disorders can be quite quite uncomfortable for people okay and then TMD symptoms they vary but they can include headache pain muscle tension um wide range of pain types there can be pain around the eyes pain on chewing pain in the face head necks muscle spasms of the muscles of mastication and these muscle spasms can cause tissue damage over time which can lead to increased pain and muscle tension so it's really this like circular kind of of disorder where everything just kind of gets worse joint sounds you know we always check the TMJ when we do our intraoral and extra oral exams on patients so um so you might hear clicking or popping or crepitus which sounds like a grinding sound you can hear that when the mouth is opened or closed and the patient might hear crackling cracking or grinding sounds you know that could be the bone against the bone kind of thing um there could be limitations in movement this can lead to difficulty and pain on chewing um yawning or opening the the mouth widely can be very painful charismus or muscle spasms this is the most common cause of restricted movement of the mandible you know opening the mouth or removing the jaw so so it is a very complex disorder and very very hard to treat okay so the causes it's often considered related to stress or clenching of the jaw or bruxism you know grinding of the teeth these can contribute other causes can be like injuries to the jaw or the head or the neck diseases of the joint including different types of arthritis and malocclusion this is when the teeth come together in a manner that places abnormal strain on the joint and the tissue so over time that can lead to disorders of the joint okay and this is how we perform our extraoral exam and whenever you do an extra oral exam you stand behind the patient you put your fingers lightly on the TMJ on each side and then you have the patient open and close and there's a lot of different things that we look for you know did you hear a pop did you feel croppinous did um you know does the mouth move to one side when it opens or closes um so you know there's a lot of things to look for and that's it that's it this is a really long chapter and to think that was only half of it is just crazy so so anyway hopefully uh you guys hung in there until the end you know you can always like watch these things in small pieces which is probably better so um so just remember when we go over the actual skull you guys will get you know it's nice to have a Hands-On thing so I think that'll help you like visualize the bones better but hopefully you know having the recording will help a little bit too so um so I will see you guys in class thank you so much for listening and hanging in there with me and we will see each other very soon thanks so much see you in class