good day future doctors this is the continuation of the discussion about histology of the oral cavity and its associated structures before we'll discuss the other structures associated with the oral cavity let's have a short review of the skin there's an importance why we need to review ourselves of the structures of the skin and i will explain the reasons later the skin has two important layers the epidermis and the dermis and as you can see in the picture the epidermis corresponds to the lining epithelium of the skin which is stratified squamous keratinized epithelium okay and the underlying connective tissue corresponds to the dermis of the skin we will now discuss the five layers of the epidermis let's start with the lowermost layer and that's stratum basale take note it is spelled as b-a-s-a-l-e okay it's named stratum basale because it is found nearest to the basement membrane and what you notice it is primarily composed of one layer of cuboidal or columnar cells on top of the stratum basale you have the stratum spinosum or stratum spinosum okay and as you can see there are multiple layers of cells in there and i will explain later on why this layer is particularly called called i mean stratum spinozu okay on top of the stratum spinosum you have their group of cells with granules in their cytoplasm thus this layer is named stratum granulosum okay and the granules could contain keratohyalin granules which will eventually give rise to the keratin that's why the skin has a keratinized layer okay and then it can also contain the lamellar granules which are responsible for regulating the movement of water across the skin okay and then on top of the stratum granulosum you have stratum lucidum and what do you notice the cells there are somehow translucent in appearance translucent light staining translucent translucent lucidum okay so that's the reason why that layer is particularly called stratum lucidum and the highly keratinized layer and the most superficial one the one that is constantly discommitted okay every time we rub our skin and apply friction on our skin the layer of cells that will be slapped off is will actually come from the stratum corneal we'll try to label an actual skin specimen so this red rectangle is showing us the what stratum basale remember it is only composed of one layer of columnar two cuboidal cells on top of the stratum basale you have the stratum spinosum and let's have a closer look at the cells that you can find in our stratum spinosum okay the cells of the stratum spinosum actually have what we call tonofilaments and these tonal filaments make the cells appear as if they have thorns okay the tonofilaments will make the cells appear as if they have spines spines okay so that's why this layer is particularly called stratum spinosum because the cells appear to have spines and these spines are referring to the tonofilaments so appreciate the presence of the tonofilaments on the surfaces of the cells of the stratum spinosum so this is the stratum basales composed of one layer of cuboidal two columnar cells on top of it is the stratum spinal also now you know why these layers particularly called stratum spinosum or spinosum on top of the stratum spinosum you have here a dark staining group of cells okay because these cells have what granules in their cytoplasm so the third yellow arrow is actually pointing at the stratum granulosum so looking at this picture you know very well that the red arrow is pointing to the stratum granulosum because that particular layer appears darker than the rest of the layers of the epidermis because the cells of the stratum granulosum contain what granules okay keratohyalin granules and lamellar granules i want you to appreciate the layer immediately on top of the stratum granulosum can you appreciate that that layer is somehow light staining uh it's somehow translucent in appearance that is now the stratum lucidum okay and you can see that on top of the stratum lucidum you have that the dark staining thick layer of stratum corneal do you know that skin can also be classified as thin skin and thick skin okay so i want you to take a look at the thin skin the picture on the left side of the screen the yellow arrow is pointing to the stratum granulosum and what do you notice on top of the stratum granulosum you don't have there a layer that is light stain so a thin skin okay doesn't have stratum lucido okay so a thin skin only has what four layers of that four layers in the epidermis you have the stratum basale stratum spinosum stratum granulosum then you have the outermost layer which is stratum corneal okay i want you to take a look at the picture on the right side of the screen okay you can clearly see there that the yellow arrow is pointing at the stratum granulosum and there's a light staining layer on top of the stratum granulosum and that is your stratum lucidum so what makes a thick skin thick it's not actually because of the thickness of the entire epidermis it's because of the presence of the stratum lucidum and take note there are only two areas in the bodies in the bodies in the body that have uh stratum lucidum and that is the palm and the soul palm and the soul okay so the rest of the the portions of the skin in the body has what type of skin thin skin so if somebody will call you angkapalam you have to correct them the thick skin in my body is only present in my palm and soul we will now discuss the oral cavities primarily composed of the mouth and all the associated structures you have the tongue the teeth and the salivary glands which are connected to the oral cavity via their ducts okay and tonsils are also included the oral cavity is further divided into the oral cavity proper and the vestibule so i want you to close your mouth and make sure that you will clench your teeth the space that is found within the clenched teeth that's the oral cavity proper and the space between the teeth and the cheek or the buccal mucosa is called the vestibule so i want you to imagine our oral cavity proper you know very well that you can find on its superior part the heart palate and the soft palate okay and its floor is actually the one formed by the tongue okay and its posterior border is actually formed by the oral pharynx and the second portion of the other cavity is the vestibule it's actually the space between the teeth and the cheek or the buccal mucosa vestibule on the right side of the face and vestibule on the left side of the face oral cavity is lined by stratified squamous epithelium that is the epithelium that is best suited to provide protection against friction and abrasion because every time we try to chew food grind food and masticate food there would always be friction okay the stratified squamous epithelium or also known as oral mucosa is further classified into three you have the masticatory you have the lining mucosa and you have the specialized type of mucosa let me first start with a specialized type of mucosa this is basically stratified squamous epithelium that is incorporated with taste buds and the only area in the oral cavity that has taste buds is the dorsal or superior surface of the tongue so whenever you try to stick your tongue out the surface of the tongue that you can directly see is the dorsal tecnota or superior surface of the tongue and what makes them special or specialized is because of the presence of the taste buds let's now go to the second type of oral mucosa or stratified squamous epithelium in the oral cavity and that is masticatory mikosa take note these are structures that are always exposed to shearing force or friction okay so i want you to imagine that you're you're masticating or chewing food food will grind against our gums okay and we also what uh grind our food against our hard palate so both the gums and the heart palate should be covered with a masticatory mucosa and what's masticatory mikosa it is lined by stratified squamous keratinized epithelium it has to be keratinized why because the gums and the heart palate should be protected against shearing force and friction so areas other than the dorsal or superior surface of the tongue and the gums and the heart palate okay will all be covered by lining mucosa and take note lining mucosa is lined by what stratified squamous non keratinized so we'll try to identify what type of oral mucosa is present in the following structures in the oral cavity number one we have the heart palette masticatory stratified squamous keratinized very good gums or jin jiva you have to take note of the other term gums or gingiva again masticatory or stratified squamous keratinized epithelium is corresponding to the cheek portion okay one of the borders of the vestibule okay you try to to to feel the surface of your buckle mucosa is it rough or smooth okay it's smooth right because it is covered by a lining mucosa and that the dorsal or superior surface of the tongue okay is what covered by what specialized type of mucosa very good because of the presence of the taste buds the oral side of the lip okay try to palpate it is it is it rough or smooth smooth right so therefore it's lined by what lining mucosa inferior surface of the tongue okay inferior surface of the tongue if you fold your tongue backwards okay that's the inferior surface of the tongue so do you have taste buds there no okay does it feel rough or smooth smooth okay so therefore the inferior surface of the tongue is not covered by specialized type of mucosa instead it is covered by lining mucosa which is what stratifies queen most non-keratinized so again the masticatory mucosa is present in both the gums or gingiva and the hard palate take note it is lined by stratified squamous keratinized epithelium but sometimes okay the stratified squamous epithelium could also be para keratinize and most people wonder huh when i when i studied epithelium i only learned about the terms keratinized and non-keratinized so what do we mean by para keratinize when you say keratinized epithelium the superficial layer of cells have already lost their nuclei and they are already replaced with keratin that's why as you can see in the picture the uppermost layer of the epithelium doesn't have any more cells with nuclei instead everything is replaced with keratin a non-keratinized stratified squamous however okay have live or viable cells under superficial layer that's why you can see cells with nuclei on the surface of the lining epithelium so why what do you think now is the appearance of a para keratinized epithelium let's explain that one on the next slide so i want you to take a look at the picture on the right side of the picture you have the akiratini stratified epithelium okay because the superficial layer have already lost the cells and the cells already replaced with keratin i want you to focus on the left side of the picture okay can you appreciate that there are areas that are already replaced by keratin but there are still areas with cells with nuclei okay so when you say para keratinize it's a stratified squamous epithelium that shares the characteristic of both keratinized and non-keratinized epithelium okay so in a para keratinized epithelium there are areas already replaced by keratin but in some areas you can still see new cells with nuclei okay but the nuclei of these cells have compacted chromatin so therefore their nuclei would appear darker than the other cells in the other layers of the uh lining epithelium okay and take note according to our ppt the para keratinized epithelium has an incomplete keratinization okay so take note masticatory mucosa okay is lined by either stratified squamous keratinized or para epithelium so for masticatory micosa you have all the layers of the epidermis except for what layer remember there's one layer in the epidermis that is only present in the palm and the soul and that is what stratum okay you have to take note of that huh so if i will ask you in the exam masticatory mucosa okay is uh equivalent to stratified squamous keratinized and para keratinize epithelium however it doesn't have what layer of the epidermis so the answer is what satisfied i satisfied stratum lucidum okay and just like what you've learned from your anatomy the underlying there misses two layers you have the papillary and the reticular the papillary layer is what composed of areolar connective tissue and then the reticular layer is composed of dense irregular connective tissue another important characteristic of the masticatory mucosa is that it has connective tissue papillae okay i want you to focus on the two red arrows can you appreciate that at the area where the red arrows are pointing you have their invagination of the connective tissue or the dermis into the epidermis okay and those invaginations now by the dermis into the epidermis or by the connective tissue to the epithelium you call that as connective tissue papillae okay and you know the purpose of having connective tissue popular in masticator mikosa this connective tissue papillae will provide relative immobility so that even if you will grind or masticate the food against the gum and the hard palate these two structures will not move to allow you to complete the process of mastication and grinding of the food that you're about to swallow so therefore masticatory micosa is immobile because of the presence of the connective tissue papillae so you can compare the presence of connective tissue populate to two people who are holding hands together and nothing can break them apart so therefore connective tissue populate can really provide what a mobility so i will try to prove to you guys that the heart palette is really lined by stratified squamous keratinized or para keratinize epithelium or you also known it as masticatory mucosa and it should have what abundant connective tissue papillae for immobility okay so take a look at the picture the red arrow is pointing to the masticatory mucosa of the heart palate yellow arrow is pointing to the bone okay and then the blue arrow is pointing to the roof of the heart palette okay and that's basically the floor of the nasal cavity remember that the lining epithelium for the nasal cavity and the rest of the respiratory tract except for the alveoli is what sudo stratified ciliated columnar okay epithelium so if you're going to make a cut section of the heart palate you will see what pseudostratified selected column epithelium on its superior portion there's there's supposed to be a bone in the middle and then you have at the inferior portion the masticatory mucosa okay blue sudo certified sedated columnar yellow arrow bone okay and red arrow masticatory mucosa this is how the hard palate looks like under the microscope so the blue arrow is pointing to the pseudo-stratified created columnar epithelium which is basically the the roof of the heart palette or the floor of the nasal cavity yellow arrow is pointing to the bone and red arrow is pointing to the masticatory mucosa of the heart palette what do you notice it's a stratified squamous keratinized epithelium and you have there the abundance of what connective tissue papillae another structure that is covered by masticatory mikosa is the gingiva or the gum okay and then take a look at the picture of the gingiva or the gum under the microscope letter a is basically the tooth okay and letters bed are parts of the gum or the gingiva okay i want you to focus on the lining epithelium can you appreciate the abundance of connective tissue populate there so therefore that will only tell us that the gingiva or the gum is covered with masticatory mucosa the second type of oral mucosa is the lining mucosa it is lined by stratified squamous non-keratinizing epithelium and these are the structures covered by the lining mucosa you have the oral side of the lip you have the buccal mucosa or the cheek the inferior surface of the tongue which is not provided with taste buds by the way so therefore it's not considered as a specialized type of oral mucosa you have the floor of the mouth okay it's also almost basically the same as the inferior surface of the tongue and the soft palate are the oral side of the lips the inferior surface of the tongue and the soft palate mobile structures the answer is yes so therefore expect that the lining mucosa or the stratified squamous non-keratinizing epithelium should have less connective tissue populate or lesser connective tissue play compared to masticatory mucosa to allow mobility take note in the lining mucosa even if you have the stratified squamous non-keratinizing epithelium you only have three layers of cells if you can remember we have discussed that the epidermis basically has what five layers of of cells right you have the stratum basale stratum spinosum stratum granulosum saturn lucidum and stratum corneal okay but take note in the lining mucosa you only have three and i will try to explain this one in the next succeeding slides but the three layers are stratum basale stratum spinosum and stratum superficially so you don't have stratum granulosum saturn lucidum and stratum corneal in the lining mucosa let's have a review in masticatory all the the layers of the epidermis are present except for stratum lucidum which is only present in the palm and soul in the lining mucosa you only have three basale spinosum and superficiale so again the lining because only has three layers you have stratum basale stratum spinosum and the uppermost layer which is stratum superficiale so i will try my best to make you understand why there are only three layers in the lining mucous of the oral cavity the picture on the left side of the screen is an example of a thin skin okay you have that a single layer of what stratum basale okay the the one closest to the basic membrane then on top of it you have the stratum spinosum then you can clearly see the presence of that dark staining layer which is stratum granulosum okay and on top of the stratum granulosum the keratinized layer that is the stratum corneal okay i want you to compare the picture on the left side of the screen to the picture on the right side of the skin the picture on the right side of the screen is a lining mucosa of the oral cavity can you appreciate that you cannot find the stratum granulosum in the lining mucosa of the oral cavity okay so that's why in the oral cavity you only have three layers the single layer stratum basale on top of it is the stratum spinosum and since there is no stratum granulosum everything on top the layer on top of stratum spinosum will now be referred to as stratum superficially so take a look at this picture number one is the single layer we call the stratum basale number two is the stratum spinosum and number three since you cannot see stratum granulosum in there that is now called as the stratum super fish okay so review masticatory micosa has four layers stratum basales atom spinosum stratum granulosum stratum and it doesn't have the stratum lucido and in the lining mucosa you only have what three stratum basales stratum spinosum and stratum superficially the third type of oral mucosa is the specialized type and what makes it specialized because of the presence of taste buds and the only area in the oral cavity that has taste buds is the dorsal or superficial surface of the tongue so that leads us to the discussion of the tongue the tongue is a freely movable organ that we can find on the floor of the mouth and it is basically attached to the higher bone okay and take note that the tongue has skeletal muscles because we can voluntarily control the movement of our tongue so do not answer in the quiz that the tongue has smooth muscles because your mud your tongue does not move on its own okay so take note that the skeletal muscles of the tongue are further classified into intrinsic and extrinsic when you say intrinsic these are muscles of the tongue that are attached to other muscles that you can find within the flesh of the tongue okay but if the muscle of the tongue is attached to a bone you will now call it as an what extrinsic type of muscle before we go to the histology of the tongue we might as well have its gross anatomy so i want you to take a look at the portion labeled as sulcus terminalis can you appreciate that the sulcus terminalis is like an inverted v okay and at the tip of the inverted v or the sulcus terminalis you have there a depression we call the foramen siku and you know the importance of sulcus terminal is it will actually divide the tongue into posterior one third and anterior one third i want you to take a look at the posterior one third the posterior one third of the tongue is actually composed of tonsils okay so meaning if you directly place the food on the posterior portion of the tongue you will not be able to appreciate the taste of the food because what you have in the posterior one third of the tongue are only tonsils okay the taste buds or the structures that contain taste buds are located in the bigger portion of the tongue and that's the anterior two-thirds again the sulcus terminalis divides the tongue into the bigger anterior portion and the smaller posterior portion and the posterior portion contains lingual tone cells as discussed a while ago the tongue is divided into anterior two thirds and posterior one third because of that inverted v groove or line and that is called the sulcus terminalis and at the tip or apex of that inverted v v-shaped circle's terminal is you have there the foramen siku what do you think is the importance of the foramen circuma i will explain that in the succeeding ppts we will now discuss the embryology of the thyroid gland because this is somehow related to the foramen cecum do you know that the thyroid gland is derived embryologically from the base or the posterior portion of the tongue that's why you can see in number two you have there the development of the duct okay and the duct uh came from the base of the posterior uh portion of the tongue and that duct will continuously migrate downwards and number three you can see that the distal end of the the duct will eventually form the thyroid gland as the thyroid gland will completely develop okay i want you to refer to number four that duct will undergo atrophy but the area where the duct arise from will remain as a depression okay and that depression now will now be referred to as the foramen siku so therefore the foramen siku is a shallow depression on the midline of the tongue at the apex of the sulcus terminals and it is a remnant of the more cranial part of the duct that gave rise to the thyroid gland the sulcus terminal is divides catan into anterior two-thirds and posterior one-third the posterior one-third as you have learned is composed of lingual tonsils and these lingual tonsils are there to provide immunologic protection let us focus ourselves on the anterior two-thirds of the tongue because this is the portion of the tongue that is that will help us perceive taste because there are structures there that contain taste buds and these structures are called papillae okay so again take note taste buds are contained in papillae and papillae are only found in the anterior two-thirds of the tongue and there are four types of papillae okay let us focus on the different types of the lingual papillae okay the first one is the filiform populate and i want you to bear in mind remember this from from now on that the filiform papillae is found uh on the dorsal surface of the tongue okay or the superior surface of the tongue and mixed along with the filiform papillae you have there the fungi form papillae okay they are named fungi form papillae because they have a shape like that of a mushroom and mushrooms belong to the family of fungi okay fungi form papillae the biggest of this papillae are the ones that are arranged along the surface terminal list okay yeah they are named up in the ppt as valet populate but the complete name is circumvaled papillae i will show you the spelling later on these are the biggest among the types of papillae and they are found along the sulcus terminalistic note of that so dorsal or superior surface of the tongue you have the filiform and the fujiform found along the surface terminal so meaning it's located near the posterior one third of the tongue you have the circumvallate populate the biggest among the types of papillae and found on the lateral portion of the tongue lateral reach of the tongue okay you have there the fourth type of papillae and that is the foliate papillae so what we will try to do is to identify the appearance or morphologic characteristics of this populate under the microscope again the anterior two-thirds of the tongue contains the lingual papillae and there are four types you have the filiform the fungi form the circumvallate the biggest among them and the foliate the one that you can find on the lateral surface of the tongue let's just have a review on the dorsal or superior surface of the tongue you have the filiform papillae and the fungi form papillae and then in the lateral portion of the tongue you have the foliate papillae okay and then along the sulcus terminals you have the biggest among the the types of lingual papillae and that is the circumvale papillae so i want you to use your imagination what if i will make a cut section from that portion of the tongue okay so that portion is actually near the surface terminally so most likely the cut section will demonstrate circumvaled papillae okay and since it's almost found near the dorsal or surface surface of the tongue i also i should also get to see what fungi form papillae and filiform papillae but the cut section should never demonstrate the presence of foliate populate because folate papillae are only found in the lateral portion of the tongue okay and we only took the sample from the anta dorsal surface of the tongue or superior surface of the tongue that is almost near the location of the circumvalled papillae or the the sulcus terminalis okay so that's why you can see on the second photo on the right side of the screen you have there are only three types of papillae okay you don't see the foliage populate because they are only found on the lateral side of the tongue so let's try to view the second picture on a bigger scale okay so let's try to examine this picture let's try to take a look at the papillae that is labeled as valid papillae that is the circumvaled papillae okay and it's very obvious in the picture that the circumvaled papillae is the biggest among all the types of uh papillae okay and i want you to take a look at the red arrows the red arrows are pointing to the taste buds so that will only tell us that the circumvaled papillae are provided with taste buds okay and then since the cut section was also made along the dorsal surface or superior surface of the tongue therefore we can also see fungi form papillae and filiform papillae i appreciate the fact that fungi form populate are shaped like mushrooms and they also have taste buds okay sandwiched between the two types of papillae you have there the filly form papillae and by looking at the rest of the papillae you can clearly say that the most abundant lingual papillae is the feely form papillae and whoever made this picture or drawing okay intentionally made the filiform papillae appear as if they are horny or what you call this they have spines or or spikes okay because this type of lingual papillae is highly keratinized there's one unique characteristic i want you to take talk about filiform papillae yes they are present in the tongue but they do not contain taste buds so the question now is why make the filiform populate the most abundant type of lingual papillae if they don't have taste buds so what's the purpose of the the filiform papillae okay just imagine they make the surf the dorsal surface or superior surface of the tongue rough so that whenever you place food the food will not easily slip off of your mouth okay so the filiform papillae may not make us perceive how delicious the food we are trying to eat but they will try to keep the food inside our mouth so once the food is already locked in the tongue because of the presence of the keratinized filiform papillae then the other three types of papillae the circumvale the foliate and the fungi form will be able to what perform their function which is to what to perceive that taste okay so filiform papillae are highly keratinized they do not have taste buds but they are there for a purpose and that is to provide what mechanical role so the first type of papillae that we will discuss are the filiform papillae i want you to appreciate in the picture that this type of papillae are highly keratinized so if you are presented with a picture of a lingual papillae and you can see that it is highly keratinized there's no other best answer except for what filiform papillae can you appreciate that this filiform papillae are somehow curved okay and then they look like inverted ice cream cones okay so remember they do not have taste buds okay and they are only there to provide what mechanical rules so let's have a closer look at the filiform populate in the next slide again they are highly keratinized they are somehow curved but not all photos will will show the the that property of the filiform populate and there is no presence of taste buds let's have another picture of filiform population so that you will be able to familiarize yourselves with how they appear under the microscope so these are filiform papillae okay i appreciate the appreciate the shape they look like inverted ice cream cone they are highly caratinized and they are somehow curved okay so the the shape the the curvature of the filiform papillae will enable them to get hold of the food take note filliform papillae are found on the dorsal and superior surface of the tongue and they are the most abundant please always remember that we have two types of papillae on the dorsal or superior surface of the tongue we have the filiform papillae okay and the fungi form papillae and it's very obvious in the picture that the blue arrow is pointing to a filiform papillae because that papillae is highly keratinized you don't see any taste buds okay and it's somehow curved okay this second blue arrow is pointing to another filiform papillae but i want you all to focus on that type of papillae pointed by the black arrow can you appreciate that that type of papillae is mushroomed in a is mushroom like in appearance so ladies and gentlemen this is the fungiform papillae okay so fungi form papillae are actually located in the dorsal or surface superior surface of the tongue and it is mixed along the filiform papillae okay and i want you to take a look at the red arrows the red arrows are what uh pointing to the areas in the in the fungi form populate where you can find the taste buds okay so it's very obvious in the picture that the taste buds of fungi form populate are found on its surface dorsal surface why call it dorsal surface because that is also pertaining to the dorsal surface of the tongue okay so if you will be asking the exam where can you find the taste buds in a fungi form papillae you can write down in your paper dorsal portion or superior portion okay so let's have another example of a picture of a fungi form papillae so that you will be able to you know learn the skill on how to identify this lingual populace blue arrow is pointing to a highly keratinized filiform papillae the second blue arrow is also pointing at another filiform populate can you appreciate that somewhere in between these two filiform populate you have another fungi form populate and look at the location where you can find the taste buds dorsal or superior surface this slide will just remind us that the fungi form papillae and the filiform papillae are both located in the dorsal or superior surface of the tongue okay and fungi form popular is best described as located singly okay among filiform papillae on the dorsal or superior surface of the tongue because again the philippine papillae are the most abundant type of lingual papillae so let's discuss the fungi form papillae okay it has a narrow base and it has a mushroom shape okay and take note it is visible to the naked eye so we'll try to show you i'll try to show you a picture later on now so that i can prove to you that the fujifilm papillae are visible to the naked eye okay and they have taste buds on their dorsal surface and i think i have already mentioned this a while ago and compared to filiform populate this type of papillae is lightly keratinized okay there are less numerous than filiform papillae and they are scattered singly okay among the filiform populate on the dorsal or superior surface of the tongue so i want you to go to the mirror and stick your tongue out and and check for the presence of fungi form papillae which are directly visible to the naked eye i hope by showing you this picture you can already identify that we have here filiform papillae and you have one fungi form papillae in the middle and i hope you can appreciate the location of the taste buds in the fungi form papillae filiform papillae do not have taste buds the next type of papillae that we will discuss is the one that you can find on the lateral side of the tongue okay and take note this type of papillae is poorly developed in adults and they are best demonstrated in the tongue of children so do not expect that if your tongue will be sampled for histology slide do not expect that you can see well developed foliate papillae okay take note this type of papillae will form regest okay on the side of the tongue okay can you appreciate the the the area in the tongue that is labeled as foliate papillae can you see regis in there okay so those three just are actually the foliate papillae so take a look at this picture can you appreciate reach number one reach number two reach number three reach number four okay so those are the foliate papillae so this is how the folate papillae will look like under the microscope move to the next slide please so this is your reach number one reach number two reach number three and reach number four ladies and gentlemen these are the foliate papillae which are found on the lateral side of the tongue and they are only well developed in children okay i know some of you will say no no doctor i think i might confuse the folate populate as fungi form populate because they look like the same okay so i always want you to bear in mind that the fujifilm papillae is located singly among filiform papillae on the dorsal or superior surface of the tongue in the picture you don't even see one filiform papillae in there okay so therefore these are not fungiform papillae and i also want you to appreciate that the taste buds of this type of papillae is located on the lateral side while the taste buds of the fungi form papillae are found on their superior or dorsal surface okay so i hope you can appreciate in the picture that the taste buds of folate papillae are found on their lateral sides so this is another picture of the foliate papillae okay you don't see any fillet form popular in the picture right so even if they look like mushrooms to you guys you cannot identify them as fungi form populate and then aside from the fact that the taste buds of this type of papillae are found on the lateral side arranged along the sulcus terminals okay are the largest among the types of lingual papillae and you can actually have eight to twelve of them along the sulcus terminals and these are the circumvale papillae okay so this is how the circumvale papillae will look like under the microscope the taste buds of this type of papillae are also found on their lateral sides the clue okay for you to easily identify that the papillae you're looking at okay it's a circumvaled papillae is the presence of that invagination or moth like invagination on its lateral side so if you see spaces or invaginations on the lateral side of the papillae then that type of papillae is a circumvaled populate so again the largest among the types of lingual papillae next it has moth like invagination which i have already emphasized on the previous slide and we could have eight to 12 of them okay in front of the sulcus terminalist okay and then the taste buds are found on its lateral side so these are our sulcus terminals you take a look at their arrangement so they are following the arrangement or the shape of the sulcus terminals this is also another good picture of our circumvaled papillae and you can clearly see the invaginations on their lateral side so this is a circumvaled papillae you can see the invaginations on its lateral side and the taste buds are also located on its lateral portion this is another picture of a circumvaled papillae i hope you can still remember that minor salivary glands are unencapsulated and they are only found in the connective tissue of the different areas in the oral cavity these areas could include the lip and then the the palate and then you have the tongue okay so there's one special type of minor salivary gland that we can find in the tongue and we call it as von abner gland okay take note it's very important to take note that this one abner gland is associated with two types of lingual papillae you have the foliate and the circumvallate papillae so whenever you see a circumvaled papillae please appreciate that on the area lower to the papillae you must see minor salivary glands and those glands are the bone abner gland and what do they do this glands are specialized in producing amylase so which can help in digesting carbohydrates and they can also produce lingualite paste okay take note um when you are asked in biochem where is the first site of carbohydrate digestion you will answer oral cavity because you have the salivary amylase or the thyroid that's correct but if you are asked where is the first site for lipid digestion the answer is not the oral cavity even if you have one abner glands producing lingual lipase because lingual lipase will only become active if it is exposed to an acidic environment so while if it is in the mouth it is inactive it will not start digesting fats but once the food is swallowed and the food is already large into the stomach the acidity of the stomach will activate lingual lipase and lingual lipase that will start breaking down lipids so the first site for lipid digestion is actually the stomach and it's because of the lingual lipase this is a circumvaled population and please appreciate the presence of those von abner gland on the area below the circumvaled papillae okay because avon abner glands are associated with two types of popular you have the circumvallate and you have the foliate so this one is also another example of a circumvaled papillae you have invaginations on its lateral side and you can see the presence of taste buds on its lateral portion appreciate the glands that you can find below the circumvallate papillae so those are the von abner glands okay and these are minor salivary glands so these are your foliate papillae can you appreciate that at the area lower than that of the foliate papillae you have that structure labeled as lsg that's lingual salivary gland so that is okay so let's play a game identify that popular i'll give you five seconds to identify the type of lingual papillae five seconds again these are what filiform populate five seconds so if you answered circumvaled populate you are correct because it's very obvious that this type of papillae has invaginations on its lateral side and there's also the presence of the von abner's gland on its underlying connective tissue five seconds yeah filiform papillae very good five seconds identify the one pointed by the black arrow if you answered funji form populate you're correct because that type of papillae is mixed along with the filiform populate so the surrounding populations are actually filiform type okay so deba the fujifilm papillae are found singly among filiform populate and the taste buds are found on its superior or dorsal surface we will now go to the taste buds these are ovoid bodies that you can find within the lingual papillae okay and this is the reason why the the dorsal or the superior surface of the tongue is said to have what specialized type of oral mucosa do you know that each taste bud could contain up to 100 cells and there are three types of cells that we can find in a taste buds so we'll try to identify them one by one taste buds are all void like structures that you can find in our lingual population i want you to take a look at the foliate properly in the picture and highlight that on the lower picture is the ovoid shape taste bud okay take note that in each taste bud you have around 50 to 100 cells and there are three types of cells in there and we will name them one by one so these are the taste buds in one of our lingual population so they are really ovoid in shape there are three types of cells in our taste buds the first type is the most important one the one that will help us perceive the taste and we call it gastatori cell okay some books will call them taste cell because they are there to perceive taste okay and they are also called neurosecretory cells okay but if you'll have an exam and if the exam is identification i would recommend that you use the term gastatori okay take note in each avoid shape taste but there could be around 100 cells right 50 to 100 half of these cells okay are gastatory cells so the most abundant type of cell in a taste bud is the gastatori cell okay i want you to take a look at the gastatori cells okay you look at the apical portion can you appreciate that they have microvilli okay and then yeah and then look at their basal portion can you appreciate that this types of cells are innervated so they have direct connection or signups with nerves so therefore these are the cells in the taste buds that can really help us perceive the taste again on the apical portion of the gastrotori cells you have their microvilli which will help them sample the fluid that comes in contact with them so that we can perceive the taste of the food okay and then on the basal portion you have their what nerves that will form synapse with these cells and these nerves are branches of cranial nerve cranial nerve number seven facial nerve cranial nerve number nine glossopharyngeal nerve and cranial nerve number 10 vagus nerve so these are the nerves that will actually function to help us perceive taste the next type of cell that we can find in our taste buds is the supporting cell okay take a look at the cells pointed by the blue arrow so those are our supporting cells look at them they have the same shape and same size as that of our gastatori cells what makes them different from the from the gastatory cell is that even if they have microvilli these cells do not form synapse with the nerve so they are not there to perceive taste so what do you think is the function of these cells they are there to occupy space okay so that they can provide support to the gastatori cells which are the active cells of the taste buds the third type of cell are the ones that you can find on the basal portion of the taste buds okay and since they are found on that area we will name them as the basal cells take note these basal cells are active stem cells so meaning this cells can divide and give rise to the other two types of cells remember please remember that the gustatory and the supporting cells can only last for 10 days so after 10 days they will die and what will replace them are the basal cells so let's try to identify the cells of the taste buds these blue arrows are pointing to basal cells okay because of what their location you can easily identify them because of their location okay and then this second set of blue arrows are pointing to the gastatori cell and what's the clue you're looking at the gastatory cell they always have a lighter staining nucleus compared to the inactive supporting cells okay so meaning that the nuclei of supporting cells are dark stained because they are they are inactive so they are not using their dna so they have higher amount of heterochromatin so therefore the next group of blue arrows are pointing to what supporting cells very good and as you have learned that the posterior part of the tongue only contains what lingual tonsils so this one is a good picture of how the posterior one third of the tongue will look like so that is actually an example of a lingual tone cell so this is how the lingual tone cell will look like can you appreciate the presence of multiple lymphatic nodules in there and these lymphatic nodules are actually covered by stratified squamous epithelium so we are now down to our last topic which is all about the teeth hey okay so take note that uh we have two sets of teeth when we were younger we actually had the residuals or the milk teeth we have actually 20 of them and then when they were removed they were they were replaced by the permanent teeth we actually have a total of 32 permanent teeth so take a look at the picture the blue arrow is pointing to a deceitus or milk teeth okay you know very well that this one will be replaced eventually by the permanent teeth the permanent heat will arise from the maxilla or the mandible bone we have a total of 20 primary deciduous or milk teeth and we have 32 permanent teeth so we will now discuss the anatomy of the tooth the portion that you see when a person will smile that is called the crown the portion of the tooth that is covered by the gingiva or the gum you call that as the neck the portion of the tooth that is attached to the bone to the maxilla or the mandible you call that as the root again the parts of the tooth exposed above the gums the one that you can see if a person will open his mouth that is the crown and the portion covered by the gingiva that's the neck and the portion that is attached to the bone okay you call that as the root we will now discuss the soft parts of the tooth okay the yellow arrow is pointing to the pulp cavity what do you notice it is in the pulp cavity where we can find the blood supply and the nerve supply of the tooth so that's why it's very important for the harder parts of the tooth to cover or to protect this pulp cavity the green arrow is pointing to the root canal it's actually a continuity of the the the pulp cavity and what do you notice as the pulp cavity will go down to the root it will actually form a canal it will actually narrow to form a canal and since that canal is found in the root you will call that one as the root canal okay the next portion that i will discuss is the blue arrow that is the apical foramin that is the part in the tooth where the blood vessels and the nerve will enter so that they can go to the root canal and end up into the pulp cavity the periodontal ligaments on the other hand are the fibrous tissues okay they are labeled in the picture they are fibrous tissues that will attach the tooth to the underlying bone okay so the bone could either be the maxilla or the mandible we will now discuss the hard parts of the tooth the structures that should protect the soft parts which we have already discussed in the previous slides okay we will first start with the enamel okay so the blue arrow is pointing to the enamel and it's very obvious in the picture that the enamel can only protect the crown of the tooth okay take note what makes the bones in the body hard is the composition called the calcium hydroxyapatite and bones in our body contain 70 calcium hydroxyapatite enamel on the other hand is composed of 96 to 98 percent calcium hydroxyapatite so meaning it's stronger than the bones in the body so therefore the hardest substance in the body is the enamel and the cell capable of producing enamel are called that is called ameloblast okay so it's easy to memorize okay the second hard part that we will discuss is the dentin it's a layer immediately below the enamel and what do you notice the dentine can protect the crown it can also protect the neck and it can also protect the root so that makes the dentin the most abundant substance that you can find in our tooth okay and then take note that this dentine only has 70 percent calcium hydroxyapatite so it is as strong as the bone okay and the cell that produces dentin is the odontoblast okay you have to take note of that okay so the crown of the tooth is protected by enamel and the underlying dentin okay so what will now protect the neck and the root if they don't have enough ml there's that structure we call the cementum ah okay the crown is protected by both enamel and then tin while the neck and the roof are protected by cementum and dentin so what covers the neck and the root of the tooth and connects it to the underlying bone via the periodontal ligaments is the cementum and the cell grab your emotions and the cell that produces the cementum is called cementoblast so i want you to take a look at this picture the blue arrow is pointing to the gingiva or the gum and then the red arrow is pointing to the tooth okay and the yellow arrow is pointing to the cement tomb okay the structure that will protect the the neck and the root of the tooth aside from the dentin we will now discuss the embryology of the teeth just like the salivary glands the teeth are derived from the oral cavity epithelium okay so the cells of the oral cavity epithelium will proliferate and as they proliferate they will invaginate into the underlying connective tissue or mesoderm take note the mesoderm is composed of what mesenchymal cells again the cells of the oral cavity epithelium will proliferate and as they do and as they proliferate they will invaginate into the underlying mesoderm or connective tissue okay and what will happen is as the cells of the oral cavity epithelium will proliferate the cells of the mesoderm which we call the mesenchymal cells will also try to differentiate and they will form what we call dental papilla or papillae okay again it starts with the proliferation of cells in the oral cavity epithelium the oral cavity epithelium will invaginate into the underlying mesoderm which is composed of mesenchymal cells the mesenchymal cells in the mesoderm will also differentiate okay and they will form the dental papilla so the first stage in the embryology of the tooth is the bud stage okay this is where the oral cavity epithelium will invaginate into the underlying mesoderm which is composed of what mesenchymal cells okay and take a look at this one huh this red arrow this red arrow showing you the invagination of the oral cavity epithelium to the under underlying masoderm or group of mesenchymal cells and the mesenchymal cells in the mesoderm will also try to differentiate and they will form what we call the dental papilla so the area pointed by the red arrow in the picture is the dental papilla and it is derived from the mesoderm and take a look at the shape of the the tooth at this stage they look it looks like a what a small bud that's why this stage is called bad stage the next stage is the cap stage okay this gap stage begins when i want you all to listen when the dental papilla okay will invaginate into the enamel organ enamel organ by the way is the structure that is formed when the lining epithelium or the oral cavity epithelium will invaginate into the underlying mesoderm okay so the entire structure above the dental papilla is called the enamel organ and it is derived from the oral cavity epithelium if the dental papilla will invaginate into the enamel organ it will actually cause the developing tooth to have as an appearance just like a cap that's why this stage is called tap stage and the area pointed by the red arrow is the dental papilla take note of that huh let's try to label the parts of the cup stage of the tooth okay let's start with this red arrow can you see group of tall columnar cells in there these tall columnar cells are the ones that will give rise to the future mellow blast okay and this group of columnar cells will be referred to as the inner enamel epithelium but there's also another group of tall columnar cells that you can find outside the cup okay and you will now call this one as the outer layer of enamel epithelium you can simply just call it outer enamel epithelium okay so please remember the dental popula the inner enamel epithelium which will give rise to the future ameloblast okay and then the outer enamel epithelium so this is actually a good picture of the cup stage of the embryology of the tooth do you know what will happen next this entire structure will detach from the oral cavity epithelium okay so again the entire cup stage of the developing tooth will detach from the overlying uh oral cavity between you and that will now proceed to the next stage that is called the bell stage in the bell stage the developing tooth has already detached itself from the overlying um oral cavity epithelium okay i want everybody to be remembered that the blue arrow is still the what outer in a mill epithelium okay and the red arrow is pointing to the inner enamel epithelium i hope uh you can still imagine the structures know from the previous slide so let's have this slide the red arrow is pointing to the inner enamel epithelium i hope you can remember that the inner enamel epithelium is composed of tall columnar cells which will eventually become the ameloblast okay and then this blue arrow is pointing to the dental papilla okay the one that will invaginate into the the enamel organ to form the cup stage okay take note the cells of the dental papilla will eventually give rise to the odonto blast okay so come to think of it the enamel no no the ameloblasts are derived from the oral cavity epithelium because they are derived from the enamel organ while the odontoblasts are derived from the mesoderm or the mesenchymal tissue which will eventually form the dental papilla i hope that makes sense so located on the outer part of the tooth you have the meloblast in the inner part of the tooth you have the odonto blast so let's apply what you have learned so far the cap stage will detach from the [Music] overlying oral cavity epithelium to form the bell stage okay and then this red arrow is pointing to the outer enamel epithelium okay and then this red arrow is pointing to the inner enamel epithelium which is composed of tall columnar cells which will eventually give rise to the ameloblast okay and then this blue arrow is pointing to the dental papilla and the cells in there will eventually become the odontoblast do you know what will happen the inner enamel epithelium and the dental papilla will eventually become bigger and the entire structure will pierce through the outer enamel epithelium okay so that it will what come out as a developing tooth okay so the outer enamel epithelium will just be broken down or pierced through by the developing inner enamel epithelium and dental papilla and as they do so okay this is how the developing tooth will look like okay so what is not shown in the picture is the outer enamel epithelium what is only shown here is the inner enamel epithelium and the underlying dental papilla so can you remember that the ameloblasts are found on the outer area of the developing tooth what while the odontoblasts are found in the inner area okay so number one you can see their group of tall columnar cells okay so most likely those are your ameloblasts okay take note of that ameloblast so since they are the meloblast the area labeled as number two is most likely the the the product that they will produce so number two is the enamel okay so number four take a look at number four you have their group of nucleated cells right so since they are found in the inner part of the developing tooth so most likely those are the odonto blast so number three is the secretory padak of odontoblast so most likely number three is the then tin so this is another good picture of a developing tooth the area labeled as and that ends our lecture on the histology of the oral cavity and its associated structures thank you very much for listening epithelium is composed of nucleated cells so most likely those are the ameloblasts okay and they are the ones producing the enamel the one that is colored black and and is found immediately below the enamel epithelium i want you to appreciate that the enamel is only present in the crown of the developing tooth okay and then i want you to take a look at the air label blast okay so those are your odento blasto meaning the yellow and the orange colored areas are representing the dentin and i want you to appreciate the dentin can actually be present from the crown and even up to the neck and the root of the the developing tooth okay so i hope i was able to impart to you my knowledge on the histology of the oral cavity and its associated structures if you answered filiform papillae you're correct because it's very obvious that this type of papillae are curved and they are highly keratinized and you do not see areas for taste buds right i want you to focus on the muscles immediately below the the filiform papillae can you appreciate that they are multinucleated and they have peripheral nuclei that will only tell us that the muscles of the tongue are really skeletal in type