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ORAL CAVITY

Opening of parotid gland. ORAL CAVITY. Divided into : Vestibule : -A slit-like space bound by lips and cheeks externally and by gums and teeth internally -The parotid duct opens into the vestibule, opposite the upper second molar tooth Oral cavity proper : Boundaries :

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ORAL CAVITY

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  1. Opening of parotid gland ORAL CAVITY • Divided into: • Vestibule: • -A slit-like space bound by lips and cheeks externally and by gums and teeth internally • -The parotid duct opens into the vestibule, opposite the upper second molar tooth • Oral cavity proper: • Boundaries: • -Anterolateral: gums and teeth • -Posterior: oropharyngeal isthmus • -Roof: hard and soft palate • -Floor: tongue and mucosa covering • the floor of the mouth • Frenulum linguae: • A median fold of mucosa connecting the undersurface of the tongue to the floor of the mouth Frenulum linguae • Sublingual fold: • A small ridge on each side of the frenulum linguae. • The fold is raised by the sublingual gland • The medial end of the fold presents the sublingual papilla, which carries the opening of the submandibular duct Sublingual fold Sublingual papilla

  2. LIPS • Two folds surrounding the oral fissure • Each lip is connected to the gum by a median fold of mucosa (labial frenulum) • The outer surface of the upper lip presents a median depression called the philtrum • Layers of the lip: • Skin • Muscle layer (Orbicularis oris ms.) • Submucosa (containing mucous glands) • Mucosal lining labial frenulum

  3. PALATE • Forms the roof of the mouth • Divided into: • Hard palate (ant. 2/3) • Soft palate (post. 1/3) Bony palate • Hard palate: • Has a bony skeleton formed by the bony palate • Covered by dense fibrous tissue with a surface mucosal membrane • Presents a median raphe • Its mucosal covering is thick and corrugated anteriorly (smooth posteriorly) • The mucosa contains mucous palatine glands

  4. Soft palate • A mass of soft tissue extending backwards and downwards from the posterior border of hard palate betweennasopharynx and oropharynx • Continuous on the sides with the pharyngeal wall • Covered by mucosa which encloses: • Palatine aponeurosis • Muscles • Palatine glands • Vessels • Nerves nasopharynx Soft palate oropharynx Palatoglossal arch Soft palate • The free inferior border of soft palate projects in the median plane forming the uvula • Two mucous folds extend laterally from the uvula to the pharynx: • -Palato-glossal arch (anteriorly) which contains palatoglossus muscle • -Palato-pharyngeal arch (posteriorly) which contains palatopharyngeus muscle • The 2 folds enclose the palatine tonsil Palatopharyngeal arch Palatine tonsil

  5. Palatoglossal arch & muscle Palatopharyngeal arch & muscle

  6. Palatine aponeurosis: • A horizontal fibrous sheet which is attached to the posterior border of hard palate • It gives origin or insertion to all muscles of the palate • Palatine muscles: • Tensor palati • Levator palati • Palatoglossus • Palatopharyngeus • Musculus uvulae

  7. Palatoglossus: O: palatine aponeurosis I: side of the tongue A: elevates the posterior part of the tongue N: cranial accessory n. Pharyngeal isthmus Palatopharyngeus: O: palatine aponeurosis I: posterior border of thyroid cartilage and wall of pharynx A: approximate the palatopharyngeal arches to close the pharyngeal isthmus N: cranial accessory nerve Palatine tonsil Musculus uvulae: O: posterior nasal spine I: mucosa of the uvula A: elevates the uvula N: cranial accessory nerve Tensor & levator palati Musculus uvulae Palatoglossus Palatopharyngeus

  8. Auditory tube Tensor palati Levator palati Palatine aponeurosis Superior constrictor of the pharynx Palatopharyngeus Buccinator Stylohyoid ligament Mylohyoid Stylopharyngeus Middle constrictor of the pharynx Geniohyoid Hyoglossus muscle Thyroid cartilage

  9. Nerve supply of the palate: • Sensory: • Greater palatine • Lesser palatine from the sphenopalatine ganglion • Nasopalatine • Glossopharyngeal nerve • Motor: • All muscles of the palate are supplied by cranial part of accessory n. Except tensor palati (supplied by mandibular n.) • Secretomotor: (to the palatine glands) • Postganglionic fibers from the sphenopalatineganglion (carried by the lesser palatine n.) Nasopalatine n. Sphenopalatine ganglion Greater & lesser palatine n.

  10. Arterial supply of the palate: • Greater (and lesser) palatine a. (from maxillary a.) • Palatine branch of ascending pharyngeal a. (from ECA) • Ascending palatine a. (from facial a.) • Venous drainage • Pharyngeal & pterygoid plexuses of veins Ascending pharyngeal a. ECA Ascending palatine a. Greater & lesser palatine a. Facial a.

  11. Functions of the soft palate: • The soft palate is raised to close the pharyngeal isthmus during the following: • Swallowing, to prevent regurgitation of food and fluid into nasopharynx • Speech, to produce explosive sounds • Blowing, to prevent escape of air into the nasopharynx

  12. TONGUE Foramen caecum Lingual tonsil • A muscular organ which lies mostly in the floor of the mouth • It has an apex, base, dorsum and a ventral surface • Mucous membrane of the tongue • On the dorsum: • Ant. 2/3 (palatine part): covered by a great number of lingual papillae • Post. 1/3 (pharyngeal part): smooth mucosa that shows irregular elevations which cover lymphoid follicles (lingual tonsil) • On the ventral surface: • Covered by smooth mucosa and shows the frenulum linguae Vallate papillae Palatine part Fimbriated fold Frenulum linguae Deep lingual vein, art and lingual nerve • The palatine and pharyngeal parts are separated by a V-shaped groove called the sulcus terminalis • The apex of the sulcus terminalis is directed backwards and shows a median depression called the foramen caecum • 8-12 large papillae (vallate papillae) are arranged in a single row in front of the sulcus terminalis

  13. MUSCLES OF THE TONGUE • Extrinsic muscles: • Palatoglossus • Styloglossus • Genioglossus • Hyoglossus • The extrinsic muscles move the tongue Sup & inf. long. intrinsic Vertical intrinsic • Intrinsic muscles: • Superior & inferior longitudinal: shorten the tongue • Transverse: narrows the tongue • Vertical: flattens the tongue • The intrinsic muscles shape the tongue Transverse intrinsic • Glands of the tongue • Mucous, serous and muco-serous • The mucous glands open on the inferior surface of the tongue • The serous glands open near the vallate papillae

  14. Arterial supply of the tongue: • Lingual artery (from ECA): main source • Twigs from tonsillar branch of facial a. • Twigs from ascending pharyngeal a. • Venous drainage of the tongue: • Profunda linguae vein: receives the sublingual v. and continues backwards (superficial to hyoglossus) as the vena comitans of hypoglossal nerve • Lingual veins: venae comitantes of the 2nd part of lingual artery (deep to hyoglossus), they receive the dorsalis linguae veins. • Lingual vein: is formed at the posterior border of hyoglossus by the union of lingual veins and vena comitans of hypoglossal nerve, and drains into IJV Dorsal lingual v. Profunda linguae v. Sublingual vessels IJV Lingual artery (2nd part) Hypoglossal n. Vena comitans of hypoglossal n.

  15. Nerve supply of the tongue: • Sensory: • Ant 2/3: general sensations (lingual n), taste sensation (chorda tympani) • Post 1/3: general & taste sensations (glossopharyngeal n.) • Most posterior part of the tongue: general & taste sensations (sup laryngeal branch of vagus) • Motor: all muscles of the tongue are supplied by hypoglossal n, exceptpalatoglossus m (cranial accessory) • Secretomor: postganglionic fibres to the lingual glands from the submandibular ganglion

  16. PHARYNX • A musculo-membranous tube • It extends behind the nose, mouth and larynx • About 12cm long, and extends from the base of the skull to the 6th cervical vertebra (opposite the lower border of cricoid cartilage) N a s a l c a v i t y • Attachment of the pharynx • Medial pterygoid plate & pterygoid hamulus • Pterygomandibular raphe • Mandible • Side of the tongue • Hyoid bone • Thyroid cartilage • Cricoid cartilage M o u t h Larynx 6th cervical vertebra

  17. Relations of the pharynx: • Ant: nasal cavity, mouth & larynx • Post: vertebral column, separated by prevertebral fascia, longus colli and longus capitis ms. • Superiorly: basilar parts of sphenoid and occipital bones • Inferiorly: continuous with the osophagus • Laterally: • -styloid process and structures attached to it • -CCA, ICA & ECA (including ascending pharyngeal and ascending palatine arteries) • -medial border of parotid gland • -thyroid gland, recurrent laryngeal n, superior laryngeal n. nasopharynx oropharynx Styloid process laryngopharynx

  18. Divisions of the pharynx: • Nasopharynx • Oropharynx • Laryngopharynx Pharyngeal tonsil Tubal elevation Salpingopalatine fold Pharyngeal recess Opening of auditory tube • 1. Nasopharynx: • Lies behind the nasal cavity, above the level of soft palate • Communicates anteriorly with the nasal cavity through the post nasal apertures • Communicates inferiorly with the oropharynx through the pharyngeal isthmus Salpingopharyngeal fold Palatine tonsil Pharyngeal tonsil Salpingopharyngeus Medial end of auditory tube • Features of the nasopharynx: • Opening of the auditory tube • Tubal elevation: formed by the bulging medial end of the auditory tube • Salpingopharyngeal fold (overlying salpingopharyngeus ms) • Salpingopalatine fold • Pharyngeal recess: depression behind the tubal elevation • Pharyngeal tonsil (adenoids): a collection of lymphoid follicles at the junction of posterior wall and roof

  19. 2. Oropharynx: • Lies behind the oral cavity • Extends from the soft palate to the upper border of epiglottis • Communicates with the mouth through the oropharyngeal isthmus • Communicates with the nasopharynx through the pharyngeal isthmus • The lateral wall of oropharynx lodges the palatine tonsil Pharyngeal tonsil Base of skull Nasal septum Styloid process Tubal elevation Parotid Soft palate Opening of auditory tube Pharyngeal recess Salpingo-pharyngeal fold Tongue Epiglottis Palato-pharyngeal fold Palatine tonsil Osophagus Trachea

  20. Palatine tonsil: • A collection of lymphoid follicles on the lateral wall of oropharynx • Lies in a recess called tonsillar recess • The tonsillar recess is bound by palatoglossal arch anteriorly and palatopharyngeal arch posteriorly • The medial surface of the tonsil shows 12-15 orifices leading to tonsillar crypts • The lateral surface is separated from the superior constrictor muscle by a fibrous capsule • The capsule is pierced by the arteries supplying the tonsil • The lateral surface is related to the paratonsillar vein Pharyngeal tonsil Tubal elevation Opening of auditory tube Soft palate Palatine tonsil Pharyngeal recess Palatopharyngeal fold Palatoglossal fold

  21. Arterial supply of the palatine tonsil: • Tonsillar artery: a branch of facial a. • Tonsillar branches of • -ascending palatine (from facial a.) • -ascending pharyngeal (from ECA) • -lesser palatine a (from maxillary a.) • Nerve supply of the palatine tonsil: • Tonsillar branches of • -glossopharyngeal n. • -lesser palatine nerves • Venous drainage of the palatine tonsil: • Veins of the tonsil drain into the paratonsillar veinwhich drains into the pharyngeal plexus of veins Glossopharyngeal n. & its tonsillar branch ECA Ascending pharyngeal a Ascending palatine a Tonsillar a Facial a

  22. Waldeyer’s ring • A ring of lymphoid tissue at the entry of nose and mouth into the pharynx • The ring is formed by: • Pharyngeal tonsil, superiorly • Palatine tonsil, on each side • Lingual tonsil, inferiorly Pharyngeal tonsil Palatine tonsil Lingual tonsil Median glossoepiglottic fold Valecula Lateral glossoepiglottic fold Pharyngeal tonsil Palatine tonsil Palatine tonsil Lingual tonsil • The pharyngeal (posterior) part of the tongue is connected to the epiglottis by 3 folds of mucosa: • Median glosso-epiglottic fold • Two lateral glosso-epiglottic folds • The depression between the lateral and median glossoepiglottic folds is called the valecula

  23. 3. Laryngopharynx • Lies behind the larynx • Extends from the upper border of epiglottis to the lower border of cricoid cartilage • Its anterior wall is formed of: • Laryngeal inlet • Mucosa covering the back of cricoid cartilage • The depression lateral to inlet is called the piriform fossa • The piriform fossa is bound by: • Aryepiglottic fold medially • Lamina of thyroid cartilage laterally epiglottis Laryngeal inlet Aryepiglottic fold Piriform fossa Thyroid lamina Back of cricoid cartilage

  24. Wall of the Pharynx • The wall of the pharynx is formed of the following layers: • Mucosa • Inner fibrous layer: called the pharyngobasilar fascia • Muscle layer: consisting of the following muscles: • Superior constrictor • Middle constrictor • Inferior constrictor • Stylo- • Palato- -pharyngeus • Salpingo- • Outer fibrous layer: called the buccopharyngeal fascia Superior constrictor stylopharyngeus Middle constrictor Inferior constrictor Superior constrictor salpingopharyngeus salpingopharyngeus palatopharyngeus Middle constrictor stylopharyngeus palatopharyngeus Inferior constrictor stylopharyngeus

  25. Superior constrictor • Origin • posterior border of medial pterygoid plate, • pterygoid hamulus, • pterygomandibular raphe, • posterior end of mylohyoid line, • side of the tongue (glossopharyngeal part) • Insertion: pharyngeal raphe • which is attached superiorly to the pharyngeal tubercle Medial pterygoid plate Pterygoid hamulus Pterygomandibular raphe Glossopharyngeal part of sup constrictor Pharyngobasilar fascia Pharyngeal tubercle Pharyngeal raphe

  26. Middle constrictor: • Origin: • Lower part of stylohyoid ligament • Lesser & greater horns of hyoid bone • Insertion: pharyngeal raphe Stylohyoid ligament • inferior constrictor: • Origin: • Oblique line of thyroid cartilage (thyropharyngeus) • Side of cricoid cartilage (cricopharyngeus) • Insertion: pharyngeal raphe Middle constrictor Hyoid bone Thyropharyngeus Thyroid cartilage Cricopharyngeus

  27. Salpingopharyngeus • O: auditory tube • I: wall of the pharynx • A: elevates the wall of the pharynx during swallowing Salpingopharyngeus • Palatopharyngeus • O: palatine aponeurosis • I: posterior border of thyroid cartilage and wall of the pharynx • A: elevates the wall of the pharynx during swallowing to close the pharyngeal isthmus Palatopharyngeus Stylopharyngeus • Stylopharyngeus • O: styloid process • I: posterior border of thyroid cartilage and wall of the pharynx • A: elevates the pharynx during swallowing • N: glossopharyngeal n.

  28. Structures passing in relation to the constrictor muscles • 1. Between the base of the skull and superior constrictor, the space is closed by the pharyngobasilar fascia and gives passage to: • Auditory tube • Levator palati • Ascending pharyngeal artery Pharyngobasilar fascia Auditory tube Levator palati Ascending Pharyngeal a Glossoph. n

  29. 2. Between superior and middle constrictors • Stylopharyngeus • Glossopharyngeal nerve • 3. Between middle and inferior constrictors • Superior laryngeal vessels • Internal laryngeal nerve • 4. Deep to the lower border of inferior constrictor • Inferior laryngeal vessels • Recurrent laryngeal nerve Superior constrictor Sup laryngeal vessels & Internal laryngeal nerve Glossoph. n Middle constrictor Inferior constrictor Stylopharyngeus Recurrent laryngeal n

  30. Pharyngeal plexus of nerves: • Lies on the outer wall of the pharynx • Formed of the following nerves: • 1. Pharyngeal branch of vagus (containing fibers of cranial accessory) • Constitutes the motor component of the plexus • Supplies ALL muscles of the pharynx EXCEPTstylopharyngeus (supplied by glossopharyngeal n) • 2. Pharyngeal branches of glossopharyngeal nerve: • Constitute the sensory component of the plexus • 3. Laryngo-pharyngeal branches from the superior cervical sympathetic ganglion • Constitute the sympathetic component of the plexus Pharyngeal plexus of nerves

  31. Arterial supply of the pharynx • Ascending pharyngeal (ECA) • Ascending palatine (facial) • Tonsillar branch of facial • Artery of pterygoid canal (maxillary) • Pharyngeal branch of maxillary Artery of pterygoid canal & Pharyngeal branch of maxillary Ascending pharyngeal a Ascending palatine a • Pharyngeal plexus of veins • Lies on the outer wall of the pharynx • Receives veins from: • Pharynx • Soft palate • Tonsils • Drains by pharyngeal veins into the IJV Greater palatine a Tonsillar branch of facial a

  32. Mechanism of swallowing • First stage: (voluntary) • Driving the food bolus into the oropharynx • The tongue is raised up against the hard palate, from tip and extending backwards, driving the food bolus backwards • The food bolus is compressed in a groove on the dorsum of the tongue • More pressure of the dorsal surface of the tongue against the hard palate (tongue is pulled up and backwards by the styloglossi) pushes the bolus backwards into oropharynx

  33. Second stage (involuntary) • Closure of pharyngeal isthmus • The soft palate is raised up (levator palati) and makes contact with the posterior pharyngeal wall (contraction of palatopharyngeus) closing off the pharyngeal isthmus • Closure of laryngeal inlet • The epiglottis is tipped down closing the laryngeal inlet (but not completely) • Approximation of the aryepiglottic folds prevents entry of food into larynx • A stripping wave moves down the pharyngeal wall pushing the food bolus down • Closure of oropharyngeal isthmus • The soft palate is pulled down, approximated to the tongue and pressed against it by the stripping wave, thus the oropharyngeal isthmus is closed off

  34. Third stage (involuntary) • The thyropharyngeus part of inferior constrictor contracts, while the cricopharyngeusrelaxes pushing the bolus down the osophagus • Failure of relaxation of cricopharyngeus leads to herniation of the mucosa between thyro- and cricopharyngeus parts of the inferior constrictor forming a small pouch

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