ORAL CAVITY ANATOMY.pptx anatomy of oral

Anatomy of oral cavity

1. ANATOMY OF ORAL CAVITY MODERATOR : Dr. TANISHA PRESENTER : Dr. ESHITA

2. DEVELOPMENT OF ORAL CAVITY

3. 1. Early Oral Cavity Development (Week 4 ) Around the 4th week, the primitive oral cavity ( stomodeum ) appears as a shallow depression on the embryo’s surface . It is surrounded by five facial prominences: one frontonasal (above), two maxillary (sides), and two mandibular (below ). These are filled with mesenchyme derived from neural crest cells, which help shape facial structures . Maxillary and mandibular processes are from the first branchial arch .

4. 2. Breakdown of Oropharyngeal Membrane Initially separates stomodeum from the foregut; made of ectoderm (outer) and endoderm (inner ). Breaks down by the end of week 4, connecting oral cavity with pharynx . Adult remnant is just behind the third molar. 3. Fusion of Facial Prominences (Week 6 ) Mandibular processes fuse midline to form the lower jaw . Maxillary processes grow medially to meet medial nasal processes → upper lip formation.

5. 4. Upper Lip Development – Two Theories 1. Medial nasal processes form the middle part of the upper lip . 2. Maxillary processes overgrow to form the entire upper lip (supported by infraorbital nerve supply ). 5. Primary Palate (End of Week 5 ) Tissue beneath pits → primary palate . Initially only the anterior part of the oral cavity is separated . 6. Secondary Palate Formation (Weeks 6–12 ) Week 6–7: palatal shelves grow vertically Week 8: Shelves to elevate horizontally . Week 8–12: Shelves fuse with each other, nasal septum, and primary palate . A midline epithelial seam forms and degenerates, forming the complete secondary palate.

6. 7 . Ossification of the Hard Palate Occurs intramembranously from four centers (2 maxilla, 2 palatine ). Begins in week 8. No separate ossification center for the primary palate in humans . Posterior shelves form the soft palate and uvula. 8. Palatal Shelf Elevation Mechanism Occurs rapidly (minutes to hours). Likely driven by hydration of hyaluronan , collagen contraction, and tissue dynamics. Hyaluronan binds water and creates turgor pressure to lift shelves.

7. 9 . Shelf Fusion & Seam Degeneration Fusion starts in mid-palate and spreads . Epithelium adheres via glycoproteins and desmosomes . Seam removed by apoptosis, epithelial migration, and EMT (epithelial- mesenchymal transition ). 8. Muscle Development and Innervation Palatal muscles (except tensor veli palatini ) → lower arches → pharyngeal plexus . Tensor veli palatini → first arch → mandibular nerve (V3).

8. Development of tongue

9. Anterior Two-third: The two lateral lingual swellings overgrow the tuberculum impar and merge with each other to form anterior two-third of the tongue . The line of fusion of two lingual swellings in the median plane forms median sulcus on the dorsal surface of the tongue . The posterior one-third of the tongue including circumvallate papillae develops from cranial part of hypobranchial eminence . ⁠ The posterior most part of the tongue and epiglottis develop from the caudal part of the hypobranchial eminence.

10. ANATOMY OF ORAL CAVITY

11. The mouth is divided into two parts: Oral Vestibule – Between the lips or cheeks and the teeth lies a slit-like space Oral cavity proper – Extends from: Anterior – lips and cheeks Posterior – anterior tonsillar pillars ( palatoglossal arches)

12. LIPS T he lips are fleshy folds lines : 1. Externally : skin 2. I nternally : mucous membrane (labial mucosa) The labial mucosa is smooth and shows small elevations caused by underlying mucous glands.

13. MUSCLES OF THE LIPS : U pper lip: Depressor anguli oris , I ncisivus labii superioris L ower lip: L evator anguli oris , Z ygomaticus major , Incisivus labii inferioris The muscles of the mouth are capable of various movements : closing , protrusion and pursing of the lips.

14. Arterial supply : Superior and Inferior Labial Artery (Facial artery) Nerve supply : Sensory : >Upper lip : Infraorbital branch of maxillary nerve >Lower Lip : Mental nerve, terminal branch of inferior alveolar nerve b) Motor : Buccal and Mandibular branch of facial nerve Lymphatic Drainage : Upper lip and Lateral parts of lower lip : Submandibular lymph nodes Central part of lower lip : Submental lymph nodes

15. TEETH There are two generations of teeth : a) Deciduous (primary) dentition : 20 teeth – five in each jaw quadrant. b) P ermanent (secondary) dentition : 32 teeth - eight in each jaw quadrant . A complete permanent dentition is present when the third molars erupt at around the age of 18-21 years.

16. In both dentitions, there are three basic tooth forms: Incisiform teeth (incisors) : cutting teeth, having thin, blade-like crowns . Caniniform teeth (canines) : piercing or tearing teeth, having a single , stout, pointed, cone-shaped crown Molariform teeth (molars and premolars ): grinding teeth possessing a number of cusps separated by fissures.

17. Gingiva Gingiva is that part of oral mucosa which covers the alveolar processes of the jaws and surrounds the necks of teeth . C overed by keratinized epithelium,

18. CHEEK C overed externally by skin and internally by mucous membrane ( buccal mucosa) . M uscular skeleton : Buccinator muscle Internally , the pink mucosa of the cheek adheres firmly to the buccinator muscle.

19. BUCCINATOR ORIGIN : a)Outer surfaces of the alveolar processes of the maxilla and mandible by the side of the molar teeth. b )Anterior margin of the pterygomandibular raphe c )Additionally , a few fibres arise from a fine tendinous band that bridges the interval between the maxilla and the pterygoid hamulus INSERTION : C entral fibres : decussate, those from below crossing to the upper part of the mouth, those from above crossing to the lower part. Highest and lowest fibres : continue forwards to enter their corresponding lips without decussation .

20. FUNCTION : The buccinator muscle compresses the cheek against the teeth and gums during mastication and assists the tongue in directing food between the teeth. NERVE SUPPLY : B uccal branch of the facial nerve. ARTERIAL SUPPLY : Facial and Maxillary ( buccal branch) arteries.

21. S tructural landmarks visible : Parotid Pappila The parotid duct drains in the region of a small parotid papilla opposite the maxillary second molar tooth

22. b ) Pterygomandibular raphe : Behind the molar teeth, a fold of mucosa extending from the upper to the lower alveolus E xtends from the pterygoid hamulus to the back of the mylohyoid line . Raphe gives origin to the buccinator muscle from its anterior surface and the superior constrictor muscle from its posterior surface. The entrance to the pterygomandibular space lies lateral to the pterygomandibular raphe and medial to the ridge produced by the anterior border of the ramus of the mandible.

23. Arterial supply : Buccal branch of Maxillary artery Nerve supply : Sensory : Buccal branch of mandibular nerve Motor : Buccal branch of facial nerve Lymphatic drainage : Submandibular lymph nodes

24. HARD PALATE

25. HARD PALATE The skeleton of the hard palate is formed by: a) The palatine process of the maxillae b) The horizontal plates of the palatine bones. Epithelium : keratinized epithelium.

26. The periphery of the hard palate surrounding the necks of the teeth is termed as the gingiva . Oral mucosa is bound tightly to the underlying periosteum . Z one lacking submucosa runs anteroposteriorly in the midline as a narrow, low ridge : the palatine raphe. At the anterior extremity of the raphe behind the incisor teeth is a small prominence, the incisive papilla that covers the incisive fossa at the oral opening of the incisive canal. Radiating outwards from the palatine raphe in the anterior half of the hard palate are irregular transverse ridges or rugae .

27. A fibrous palatine aponeurosis is attached to the posterior border of the hard palate and extends to the soft palate : Represents : the expanded tendons of the tensor veli palatini muscles

28. Provides : fibrous skeleton of the soft palate that supports the palatine musculature. The palatine muscles are attached to the apponeurosis The boundary between the hard and soft palate may be distinguished by a change in colour , the soft palate being a darker red with a yellowish tint.

29. Arterial Supply : Greater palatine artery (third branch of maxillary artery) Nerve supply : a) Greater and lesser palatine nerve b) Nasopalatine branches of maxially nerve Lymphatic drainage : Jugulodiagastric lymph nodes

30. FLOOR OF ORAL CAVITY A small horseshoe-shaped region beneath the tongue M usculature : Mylohyoid muscle Near the base of the tongue in the midline, a fold of tissue called the lingual frenum is seen which extend onto the inferior surface of the tongue. The sublingual papilla is a conspicuous centrally positioned protuberance at the base of the tongue. The submandibular salivary ducts open into the mouth at this papilla. On either side of the sublingual papilla are the sublingual folds, beneath which lie the submandibular ducts and sublingual salivary glands.

31. MYLOHYOID MUSCLE : The main muscle forming the floor of the mouth : ATTACHMENTS : Origin : mylohyoid line of the mandible Insertion : i) The anterior and middle fibres from each side decussate in a median fibrous raphe that stretches f rom the symphysis menti to the hyoid bone. ii)The posterior fibres pass medially and slightly downwards to the front of the body of the hyoid bone near its lower border .

32. FUNCTION : Mylohyoid muscle elevates the floor of the mouth in the first stage of swallowing. It also aids in elevating the hyoid bone or depressing the mandible when the hyoid bone is fixed. NERVE SUPPLY : Mylohyoid branch of the inferior alveolar nerve BLOOD SUPPLY : a) Sublingual artery (Lingual artery ) b) Mylohyoid branch of the inferior alveolar (maxillary artery) c) Submental artery (facial artery)

33. TONGUE The tongue is a highly muscular organ of deglutition, taste and speech. It is partly oral and partly pharyngeal in position. It has : a) Dorsal and ventral surfaces b) Root c) Apex

34. The curved dorsum of the tongue shows: i)Anterior, oral part facing upwards ii)Posterior, pharyngeal part facing posteriorly The dorsum has a longitudinal median sulcus and is papillated A) DORSUM SURFACE :

35. 1. ORAL PART OF TOUNGUE : i) Forms the anterior two third of the tougue ii ) Sulcus terminalis : V-shaped groove From the foramen caecum (median depression) runs anterolaterally towards the palatoglossal arches iii) Relation : a) hard and soft palates above b) tapered tip or apex touching the incisor teeth c) free margin in contact with the gums and teeth

36. Types of papillae : a) Foliate : On each side, in front of the palatoglossal arch, are four or five vertical folds Leaf shaped b) Filliform : The keratinized filiform papillae are the most numerous. Minute conical or cylindrical projections A rranged in diagonal rows extending anterolaterally , parallel with the sulcus terminalis , except at the apex where they are transverse. H ave a masticatory function, appearing to increase the friction between the tongue and food, facilitating the movement of particles by the tongue within the oral cavity.

37. c) Fungiform : Scattered on the lingual margin but also irregularly on the dorsal surface, where they may occasionally be numerous . rounded (mushroom) shape and deep red colour Smaller than circumvallate papillae but larger than filliform papillae thin, non-keratinized epithelium d) Circumvillate : Cylindrical structures, 1-2mm in diameter V arying in number from about 8 to 12 Form a V-shaped row immediately in front of the sulcus terminalis . Each papilla is circumscribed by a groove A ll the papillae, except the filiform papillae bear taste buds.

38. 2. THE PHARYNGEAL PART OF TONGUE : L ying behind the sulcus terminalis F orms the base of the tongue Forms the anterior wall of the oropharynx Its mucosa is reflected on to the epiglottis posteriorly by a median and two lateral glossoepiglottic folds. The folds surround two depressions called as valleculae .

39. B) VENTRAL SURFACE Smooth purplish in colour Is reflected on to the oral floor and gums. Anteriorly is a median mucosal fold, the lingual frenum . Lateral to this fold on either side, a deep lingual vein is present . L ateral to the vein is a fringed mucosal ridge, the plica fimbriata .

40. MUSCLES OF TONGUE A) EXTRINSIC MUSCLES B ) INTRINSIC MUSCLES : a) Genioglossus muscle a) The superior longitudinal muscle b) Hyoglossal muscle b) The inferior longitudinal muscle c) Styloglossal muscle c) The transverse muscle fibres d) Palatoglossal muscle d) The vertical muscle fibres

41. GENIOGLOSSUS MUSCLE ORIGIN : Superior genial tectubercle (mental spine) behind the mandibular symphysis INSERTION : Superior fibres : ascend forwards to enter the whole length of the ventral surface of the tongue from root to apex, intermingling with the intrinsic muscles. Intermediate fibres pass backwards into the posterior part of the tongue Inferior fibres are attached to the upper anterior surface of the hyoid body near the

42. FUNCTION The genioglossus muscle brings about the forward traction of the tongue to protrude its apex from the mouth. Acting bilaterally, the two muscles depress the central part of the tongue Acting unilaterally, the muscle helps move the tongue to the opposite side . NERVE SUPPLY Hypoglossal nerve

43. HYOGLOSSUS Origin : the greater cornu and from the front of the body of the hyoid bone Insertion : side of the tongue between the inferior longitudinal muscle medially and styloglossus laterally . Function : D epresses the tongue. Nerve supply : Hypoglossal nerve.

44. STYLOGLOSSUS Origin : Apex of the styloid process (anterolateral aspect) Insertion : the substance of the tongue, decussating with fibres of hyoglossus . Function : Pull the tongue upwards and backwards. Nerve supply : H ypoglossal nerve

45. PALATOGLOSSUS Origin: P alatine aponeurosis Insertion : passes to the side of the tongue within the palatoglossal arch Function Acting bilaterally, the muscles narrow the oropharyngeal isthmus and can also help raise the sides of the tongue

46. a) The superior longitudinal muscle : Forms a thin stratum of longitudinal and oblique fibres lying beneath the lining of the dorsum of the tongue. b) The inferior longitudinal muscle : Narrow band of muscle beneath the inferior surface between the genioglossus and hyoglossus muscles. c) The transverse muscle fibres : Pass laterally from the median fibrous septum to the submucous fibrous tissue at the lingual margin. d) The vertical muscle fibres : Extend from the dorsal to the ventral aspects of the tongue in the borders of its anterior part . INTRINSIC MUSCLES

47. FUNCTION : When the superior and inferior longitudinal muscles contract, the tongue tends to shorten. The superior longitudinal fibres also pulls the apex and sides upwards to make the dorsum concave, while the inferior longitudinal fibres pull the apex down to make the dorsum convex. The transverse muscle contracts to narrow and elongate the tongue while contraction of the vertical muscle makes the tongue flatter and wider. Acting alone or in pairs and in endless combination, the intrinsic muscles give the tongue precise and highly varied mobil-ity , important not only in alimentary function but also in speech. NERVE SUPPLY : H ypoglossal nerve BLOOD SUPPLY : Lingual artery

48. ARTERIAL SUPPLY OF TONGUE The ventral surface of tongue : Lingual artery , external carotid artery D orsum of the tongue : Dorsal lingual afrtery Near the lingual frenum : Deep lingual artery (terminal part of the lingual artery) The root of the tongue : Tonsillar ascending palatine branches of the facial ascending pharyngeal arteries

49. NERVE SUPPLY OF TONGUE a)PRESULCAL (anterior two-thirds) : General Sensory : Lingual Nerve Special Sensory : Chorda Tympani b)POSTSULCAL (posterior one-third): General Sensory : Glossopharyngeal nerve Special Sensory : Glossopharyngeal nerve Motor supply : Hypoglossal Nerve

50. LYMPHATIC DRAINAGE OF TOUNGE C entral region: deep cervical nodes, especially the jugulodigastric and jugulo-omohyoid nodes. Dorsum of the tongue: jugulodigastric and jugulo-omohyoid lymph nodes . L ateral margin of the tongue: submandibular nodes, jugulodigastric or jugulo-omohyoid

51. ORAL MUCOSA It can be classified into : a) Masticatory mucosae b) Lining mucosae c) Specialized mucosae

52. 1. Masticatory mucosa : Covers the gingivae and hard palate. Keratinised squamous epithelium Has a dense fibrous lamina propria . Pink in colour . The masticatory mucosa is bound firmly to underlying bone or to the necks of the teeth

53. 2. Lining mucosa : Covers the : > internal surfaces of the lips and cheeks >floor of the mouth >soft palate >ventral surface of the tongue and >the alveolar processes (excluding the gingivae). Red in colour Non-keratinized, stratified, squamous epithelium L oosely fibrous and elastic lamina propria S ubmucosa contains some fat deposits and collections of minor mucous glands.

54. 3. Gustatory mucosa : Covers t he anterior two-thirds of the dorsum of the tongue The vermilion (red zone) of the lip that separates the skin from lining mucosa shares features of both lining and masticatory mucosa.