Tongue, Taste Buds and Taste PDF

Tongue, taste buds and taste [Oral & Dental Sciences] Miss H Rogers GDC ILOS 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica;on to pa;ent management 1.1.6 Describe relevant and appropriate physiology and explain its applica;on to...

Tongue, taste buds and taste [Oral & Dental Sciences] Miss H Rogers GDC ILOS 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica;on to pa;ent management 1.1.6 Describe relevant and appropriate physiology and explain its applica;on to pa;ent management Related topics:  Epithelium  Muscles  Floor of the mouth  Regional anatomy  Oral Mucosa Aim To gain an overview of the structure and func;ons of the tongue, and its varia;ons in appearance Learning Outcomes By the end of this lecture you should be able to: 1. Describe the structures and func;ons of the tongue and taste buds 2. Describe the muscles of the tongue (intrinsic and extrinsic), including their nerve innova;on and blood supply 3. Describe how the sensa;on of taste is created 4. Recognise the varia;ons in the tongue’s appearance in both health and disease The Tongue: In health 4 Grab a mirror and take a look at your tongue! Look at all the surfaces, consider the shape, colour, texture- how would you describe it?  Tongue- Comes from the Greek Glossus It is a moveable muscular organ, comprising of a root, body and ;p (apex). It has a curved dorsal surface and an inferior ventral surface. FuncCons How many did you get…  Mas;ca;on  Kissing  Taste  Sensi;vity Protective function  Swallowing  Suckling  Oral Hygiene  Swallowing reflux , ensuing nothing Defence sharp or going to chock  Speech Structures Qu: Which structures of the tongue are you able to label? -Palatineonsil asi Lingual surface tra La - -Dorsune - Apex It iP  EpigloQs PalaCne Tonsil Lingual Tonsil Root/Base Sulcus Terminalis (Posterior 1/3) Dorsum/Dorsal surface Lateral border Body Ventral surface (Anterior 2/3) (on underside) Median Lingual Sulcus Lingual Papillae Apex (Cp)  These surfaces need to be checked in examination Ventral surface Dorsum/Dorsal surface Lateral border  Epithelium covering dorsum of the tongue - Keratinzed stratified squamous epithelium also know as masticatory muscos. Dorsum The dorsum of the tongue is divided into two sec;ons: Anterior two thirds Root/Base (oral/body) Posterior one third (Posterior 1/3) (pharyngeal/base) Body The two parts are separated by: (Anterior 2/3) sulcus terminalis (a triangle-shaped landmark) Tissue if the tongue fuse here during development foramen caecum Small depression at the apex of sulcus terminalis Ventral Surface This surface is covered during your lecture ‘FOM and Palate’ Can you remember any of the structures? Lingual frenum, sublingual caruncles, lingual Veins, pelicans fimbriata What type of mucosa covers the ventral Deep Lingual Veins Plicae Fimbriate surface? Non keratinzed stratified squamous epithelium (Smbriated fold) Please refer to the FOM and Lingual Frenum 13 palate lecture for more informa;on on these structures Lateral Border The main features are the ridges along the border made up of foliate papillae Have another look in the mirror Are you able to iden;fy these features on your own tongue? Lingual Papillae 16 There are 4 types of lingual papillae located on the dorsum of the tongue: Filiform Fungiform Circumvallate Foliate  Filiform most numerous on the tongue , they’re small and conical in shape 2-3mm in diameter. Cover the whole surface of the body of the tongue. Gives the rough appearance and texture. If increase of No taste buds keratin present in noticed tongue Filiform papilla. may appear white. Function ; mechanical and aiding food back to pharynx for swallowing. Outer layer of the papilla are keritnized epithelium sitting over a core of lamina propria.  Less numerous, fungi shaped. Visible as small visible raised red dots 1mm in Fungiform diameter. Scattered all over mucus membrane mainly tip and lateral borders. Think outer layer or keratinized epithelium, Not found near sulcus terminalis. layering over a more vascular lamina. Hence why they are more red. Function ; contain a few taste buds, involved in taste sensation.  Larger than other papilla , 3-5 mm in diameter. Can be seen when tounge is arched and extended. 7-15 large raised mushroom like structures. Circumvallate Located infront of sulcus terminalis. When tounge is relaxed not visible, sitting in trench. They have outer layer of kertiznized epithelium. 100s of taste buds located at base of walls of epithelium. Sulcus Terminalis Circumvallate Papillae Von ebner glands secreted serous saliva into trenches where circumvallate papilla are , this it to flush out and clean trenches near taste pours , in order to produce new taste sensations.  Leaf like papilla, present lateral borders of the tongue. Consist of 4-11 parallel ridges. Foliate Few taste buds present. Outer layer or keratnized epithelium. Taste Buds 23 Taste buds are barrel-shaped organs and are composed of 30-80 spindle-shaped cells that extend from the basement membrane to the epithelial surface of the lingual papillae. The lingual papillae associated with taste buds: Fungiform Foliate Circumvallate Turnover of taste bud cells is rapid, approximately 10 days.  Within each taste bud there are two types of cell:  Suppor;ng cells  Taste cells SupporCng Cells These support the taste bud and are usually located on the outer por;on of the taste bud Taste Cells Usually located in the central por;on of the taste bud The taste pore is an opening in the most superbcial por;on of the taste bud Superbcial taste receptors make contact with dissolved molecules of food at the taste pore producing a taste sensa;on Taste cells are also associated with sensory neuron processes in the inferior por;on of the taste bud among the cells which receive messages of taste sensa;on by way of the receptors. The messages are then sent by way of the nerve to the central nervous system where it is iden;bed as a certain type of taste Taste (GustaCon) Official name for taste 29 Why do we have taste? Safety Foods that are: Sweet, umami or low salt- indicate nutrient rich foods Bieer, sour or highly salty- indicate poten;ally toxic or spoiling foods Physiological Taste starts diges;on and is closely linked to the other 4 senses… Sight, smell and the sounds of food prepare the body by increasing saliva cow and s;mula;ng gastric juices. When food enters the mouth, touch allows the body to know what type of saliva is most appropriate. In order to be able to experience taste, saliva needs to be present as substances can only be tasted in soluCon. Remember, the taste receptors in the taste bud make contact with dissolved molecules of food. What does this mean for pa;ents with xerostomia or reduced saliva produc;on? Poor taste. How might people compensate for a lack of taste and how could this have an impact on their oral health? Adding extra flavours, over flavouring food, eg, more sugar or salt this negative Impacts general health and more sugars can increase risk of dental caries. Taste Mapping Not true ! Lack of evidence regarding this. Muscles of the tongue 33 Divided into 2 groups: Extrinsic muscles (originate outside the tongue and inserted into it) Intrinsic muscles (contained en;rely within the tongue) Extrinsic Function - alter the position of tongue. These muscles alter the posi;on of the tongue Genioglossus Hyoglossus Palatoglossus Styloglossus Genioglossus Origin The superior genial tubercle (on the inferior aspect of the mandible) InserCon Into the whole surface of the tongue AcCon Pulls tongue forward to protrude from the mouth. Whole muscle can depress and form a concavity on its dorsal surface Hyoglossus Origin The hyoid bone InserCon The ventral side of the tongue AcCon Depresses the tongue and assists in retrac;on Palatoglossus Lies within the palatoglossal arch (see palate lecture) Origin Small narrow muscle arising from the aponeurosis of the sof palate InserCon Side of the tongue, and blends with the intrinsic muscles AcCon Lifs up the tongue, closing og the mouth from the pharynx e.g. during swallowing Styloglossus Origin A short muscle origina;ng at the styloid process InserCon Blends with the inferior longitudinal muscle, and the hyoglossus. AcCon Draws the tongue upwards and backwards  Intrinsic These muscles alter the shape of the tongue Superior Longitudinal Muscle Inferior Longitudinal Muscle Ver;cal Muscle Transverse Muscle Superior Longitudinal Muscle Origin The sub mucosa of the Superior Longitudinal Mu posterior por;on of the tongue InserCon The apex and anterolateral margins of the tongue AcCon Shortens the tongue Turns the ;p and the sides upwards Inferior Longitudinal Muscle Origin Root of the tongue and the hyoid bone InserCon Into the apex of the tongue AcCon Shortens the tongue Pulls the ;p and sides Inferior Longitudinal Muscle downwards VerCcal Muscle Origin Root of the tongue and Vertical (& Transverse) genioglossus muscle Muscle InserCon Lingual aponeurosis AcCon Flaeens and broadens the tongue Transverse Muscle Origin Fibres which originate in the median lingual septum Transverse (& Vertical) Muscle InserCon Pass laterally to insert into the side of the tongue AcCon Narrows and lengthens the tongue This video is a good visual walk through to summarise the extrinsic and intrinsic muscles of the tongue: heps://www.youtube.com/watch?v=umNW_PvKsPE Nerve InnervaCon & Blood Supply 46 Nerve InnervaCon Tongue The tongue has both a sensory nerve supply Posterior 1/3 and a motor nerve supply. Sensory and Taste: Glossopharyngeal nerve xI Glossopharyngeal Nerve (IX) Muscles. Anterior 2/3 Motor supply: Lingual nerve Sensory: Trigeminal nerve v Hypoglossal nerve (XII), except the Palatoglossus which is supplied by the Vagus nerve (X) Lingual nerve Taste: (Trigeminal Nerve Facial nerve VII V) Chorda Tympani Lingual nerve (Facial nerve VII) & Lingual nerve Blood Supply Blood supply reaches the tongue via the Lingual artery (a branch of the external caro;d artery) Deep lingual artery External carotid artery Lingual artery Blood Supply The tongue drains principally through the lingual vein Deep lingual veins Lingual vein The Tongue: ‘Abnormal’ appearance 50 Geographic Tongue Benign condi;on Caused by incamma;on of the tongue Smooth irregular red patches and white wavy lines, which may change posi;on Appearance likened to a Further informa;on: map- hence the name Oral Health Founda;on ‘geographic’ No treatment, advise to NORD avoid acidic and spicy foods to reduce soreness GlossiCs Incamma;on causing swelling , redness and Iron debciency anaemia [full ar;cle] Lef: before treatment, Right: afer treatment changes in the surface texture Can be categorised into acute, chronic, atrophic and median rhomboid Several causes including, Median Rhomboid Glossi;s but not limited to: Further informa;on: Anaemia Sharabim, A.F. & Winters, R. Glossi;s. [Updated Nov 30 2020]. In: StatPearls Celiac disease [Internet] Trauma Lu, S. (2016) Percep;on of iron debciency from oral mucosa altera;ons that s how a high prevalence of Candida infec;on. Allergic reac;on Piercings According to a poll undertaken by the Oral Health Founda;on, tongue piercings are the most popular oral piercing.  How might they impact on oral hygiene? Secondary local factor - plaque retentive factors Can damage teeth  How might they impact on the integrity of the teeth? Wear facets present on teeth Snake Eyes Need help? See a list by Colgate of the risks involved with oral piercings, or an ar;cle by dentalcare.com on the implica;ons for dental professionals Venom Black Hairy Tongue Overgrowth of cells crea;ng elongated papillae. Food, bacteria and yeast becomes trapped and causes discoloura;on. Smoking, an;bio;cs and radiotherapy can also contribute to the appearance. Treated by cleaning the surface of the tongue with a toothbrush or tongue scraper, and making lifestyle changes. Squamous Cell Carcinoma  Squamous cell carcinomas (SCC) make up 95% of oropharyngeal cancers. [Cancer Research UK]  Most common site (40%) is the tongue, on the posterior lateral border or ventral surface. SCC lesion This will be covered in more detail during your Dental Speciali;es module in Year 2 Reconstruc;on of the tongue following removal of SCC  lottS Summary- test yourself! Epis palaxiesil # 1. Try labelling this tongue diagram again. Compare it to the one you LinguaSusSes labelled at the start. How does it compare? porsum - 2. List the 4 digerent types of lingual papillae- highlight the ones that contain taste buds. - -Lateral Folate papilla median Fungiform papilla lingual Tip/ApeX Circumvallate papilla Filiform papilla. sulcus Revision Prep! Use the table below, or create your own, to summarise the muscles of the tongue Muscle Origin Insertion Action Innervation Blood Supply Muscles of the tongue Muscle Intrinsic / Origin Insertion Action Nerve Blood extrinsic Innervation supply Geniglossus extrinsic The superior Whole surface of the Pulls tongue Hypoglossal nerve Lingual artery genial tubercle. tongue. forwards to protrude from the Inferior aspect of mouth. (Stick the mandible. tongue out) Whole muscle can depress and form a con cavity on its dorsal surface. Hyoglossus Extrinsic Hyoid bone Ventral surface if the Depresses the Hypoglossal nerve Lingual artery tongue. tongue and assists in retraction. Plataoglossus Extrinsic Small narrow Side of tongue and Lifts up the tongue Vagus nerve Lingual artery muscle arising blends with the , closing off the from the intrinsic muscles mouth form the aponeurosis of the pharynx eg, during soft palate. swallowing. Stylogolssus Extrinsic Originating at the Blends with inferior Draws the tongue Hypoglossal nerve Lingual artery styloid process. longitudinal muscle upwards and and hyoglossus backwards. Superior Intrinsic The sub mucosa of The apex and Shorten the tongue. Hypoglossal nerve Lingual artery longitudinal the posterior anterolateral margins Turns the tip and muscle portion of the of the tongue. sides upwards. tongue. Inferior Intrinsic Root of tongue Into the apex of Shortens the Hypoglossal nerve Lingual artery longitudinal and the hyoid tongue tongue. muscle bone Pulls the tip and sides downwards. Vertical muscle Intrinsic Root of the tongue Lingual aponeurosis Flattens and Hypoglossal nerve Lingual artery and genioglossus (Thickend lamina broadens the muscle propria of the tongue. underside of the dorsum) Transverse Intrinsic Fibers which Pass laterally to insert Narrows and Hypoglossal nerve Lingual artery muscle originate in the into the side of lengthens the median lingual tongue. tongue. septum. (Center of tounge )  Addi)onal Resources YouTube Development of the tongue (NB: try not to get overwhelmed by the detail- check out the anima=ons) h@ps://youtu.be/NzLySYOBjRY Sam Webster- Muscles of the tongue (anatomy) h@ps://youtu.be/lATWhP0wJ5c Ar)cle InformedHealth.org [Internet]. Cologne, Germany: Ins=tute for Quality and E[ciency in Health Care (IQWiG); 2006-. How does the tongue work? 2011 Dec 19 [Updated 2016 Aug 23]. Available from: h@ps://www.ncbi.nlm.nih.gov/books/NBK279407/  Website KenHub- Muscles and Taste Sensa=on of the Tongue h@ps://www.kenhub.com/en/library/anatomy/muscles-and-t aste-sensa=on-of-the-tongue KenHub- Tongue h@ps://www.kenhub.com/en/library/anatomy/tongue References Bath-Balogh, M. & Fehrenbach, M.J. Dental Embryology, Histology, and Anatomy. Elsevier. 2006. Gravina, S. A., Yep, G. L., & Khan, M. (2013). Human biology of taste. Annals of Saudi medicine, 33(3), 217–222. h@ps://doi.org/10.5144/0256-4947.2013.217 KenHub h@ps://www.kenhub.com/