Anatomy and physiology of oral cavity oropharynx waldeyer’s

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  • 1.  Pharynx is a conical fibromuscular tube forming upper part of air and food passages.  Divisions:Nasopharynx Oropharynx Hypo/laryngopharynx.  Structure of Pharyngeal wall.  From outwards:4 layers Mucous membrane Pharyngeal aponeurosis Muscular coat Buccopharyngeal fascia.
  • 2.  Extension:  Plane of hard palate above to the plane of hyoid bone below.  Lies opposite to the oral cavity with which it communicates thro’ oropharyngeal istmus.  Boundries of istmus: Above:soft palate Below:upper surface of tongue. Either side:palatopharyngeal arches.
  • 3.  Posterior wall:related to retropharyngeal spaces and lies opposite to the 2nd and upper part of 3rd cervical vertebrae.  Anterior wall:deficient above where oropharynx communicates with oral cavity but below (a)Base of tongue:posterier to circumvallate papillae (b)Lingual tonsils:one on either side situated on base of the tongue. (c) Valleculae:cup shaped depression lying b/w the base of the tongue and anterior surface of epiglottis.
  • 4.  Each is bounded medially by the median glossopharyngeal fold and laterally by pharyngoepiglottic fold.These are seat of retention cyst.  Lateral wall: (a)Palatine tonsil (b)Anterior pillar formed by palatoglossus muscle. (c)Postreior pillar formed by palatopharyngeus muscle.  Both the anterior & posterior pillar diverge from soft palate & encloses triangular depression called Tonsillar fossa where tonsil is situated.
  • 5.  Oropharynx Jugulo digasic node.  Soft palate,lateral & posterior pharyngeal walls and base of the tongue retro and para pharyngeal nodes jugulodigastic and posterior cervical groups.  Base of the tongue bilaterally
  • 6.  As a conduit for passage of food and air.  Helps in the pharyngeal phase of deglutition.  Forms part of vocal tract for certain speech sounds.  Helps in appreciation of taste:taste bubs present on the base of tongue,soft palate,anterior pillars &post pharyngeal walls.  Provides local defence & immunity.
  • 7.  Two in number.  Each is ovoid mass of lymphoid tissue situated in the laterel wall of oropharynx b/w the anterior & posterior pillars.  Actual size is bigger than that appears from the surface as tonsil extends upwards into the soft palate,downwards into the base of the tongue &anteriorly into the palatopharyngeal arch.  Tonsils have: Two surfaces:medial & lateral. Two poles:upper and lower.
  • 8.  Medial surface:covered by st.sq.non keratinised epithelium which dips into the surface of tonsils as crypts.  Openings of 12 to 15 crypts can be seen on the medil surface of tonsils.  One of them in the upper part of the tonsil is very large & deep & called as Crypta Magna/Intra tonsillar cleft which represents the ventral part of 2nd pharyngeal pouch.  From the main crypts arise secondary crypts within the substance of tonsils.  Crypts may be filled with cheesy material consisting of epith cells,bacteria & food debris which can be expressed by the pressure over anterior pillar.
  • 9.  Lateral surface:presents a well defined fibrous capsule.  B/w the tonsil & the bed of the tonsil is the areolar tissue which makes it easy to dissect the tonsil in the plane during tonsillectomy.  Also the site for collection of pus in peritonsillar abscess.  Some fibres of palatoglossus &palatophartngeal muscles are attached to the capsule of the tonsil.
  • 10.  Upper pole:extends into the softpalate.  Its medial surface covered by semilunar fold extending b/w anterior & posterior pillars & enclosing a potential space called supratonsillar fossa.  Lower pole:attached to the tongue.A triangular fold of mucous membrane extends from anterior pillar to antero inferior part of tonsil & encloses a space called anterior tonsillar space.  The tonsil seperated from the tongue by sulcus called tonsillolingual sulcus which may a seat of carcinoma.
  • 11.  Bed of the tonsil: Formed by superior constrictor & styloglossus muscle.  The glossopharyngeal nerve & styloid process if enlarged may lie in relation to the lower part of tonsillar both these structures can be surgically approached thro’ tonsil bed after tonsillectomy.  Outside the superior constrictor,tonsil is related to the facial artery,submandibular salivary gland,posterior belly of digastic muscle,medil pterygoid muscle & the angle of mandible.
  • 12.  5 arteries:  Tonsillar branch of facial artery:Main artery.  Ascending pharyngeal artery from external carotid artery.  Ascending palatine a branch of facial artery.  Dorsal lingual branches of lingual artery.  Descending palatine branch of maxillary artery.  Venous drainage:tonsillar vein:paratonsillar vein:common facial vein:pharyngeal venous plexuses.
  • 13.  Lymphatic drainage: Lymphayics from tonsil Deep cervical nodes particularly jugulodigastic nodes below the angle of mandible.  Nerve supply:lesser palatine branches of sphenopalatine ganglion(5th CN) & glossopharyngeal nerve provide sensory nerve supply.
  • 14.  Protective role & act as sentinals at the portal of air & food passages.  Crypts:increase the srface area for contact with the foreign substances.  Tonsils are larger in childhood 7 gradually dicrease in size by the time of puberty.  Removed when themselves become seat of infection.