Pharynx

• Pharynx


  12-14cm Muscular tube that serves both respiratory and digestive functions by allowing passage of air, foods and liquids.

  • Extends from base of skull up to level of C6 where it continues as esophagus.
  • Divided into 3 main regions: nasopharynx, oropharynx and laryngopharynxs.
• Boundaries of pharynx

  • Sup: base of skull
  • Inferior: continues as esophagus at C6 level
  • Posterior: separated from cervical vertebra by prevertebral fascia and thin retropharyngeal space which is continue with posterior mediastenum.
  • Anterior: anterior wall is incomplete: comunicates with nasal cavity, larynx and oral cavity.
  • On each side it communicates with middle ear cavity through auditory tube
• Pharynx is attached to

  • Mandible
  • Tongue
  • Hyhoid bone
  • thyroid and cricoid cartilages
  • medisl pterygoid plate
  • pterygomandibular raphe
• Based on its anterior relationshipd pharynx are subdivided into 3 regions

  • Nasopharynx
  • Oropharynx
  • Laryngopharynx

  
• Nasopharynx boundaries

  • Anterior: posterior to the post opening of nasal cavity: choanae
  • Inferior: above level of soft palate.
  • Superior: Base of skull. pharyngeal tonsils
  • Lateral: pharyngeal opening of pterygotympanic tube. Space above and behind the tube: pharyngeal recess
  • Posterior: post pharyngeal wall
  • Features: pharyngeal tonsils (adenoids) at roof of nasopharynx and opening of the eustachian tube (connects nasopharynx to middle ear)

  
• oropharynx

  • Posterior to oral cavity extending from soft palate to level of hyoid bone.
  • Boundaries:

  Superior: inf suf of soft palate (separate oro from nasopharynx)

  Inferior: level of hyoid bone

  Anterior: oropharyngeal isthmus: opening btw oral cavity and oropharynx bordered sup by soft palate: inf by tongue and laterally by palatoglossal and palatopharyngeal arches.

  Posterior: post pharyngeal wall.
• • Palatine tonsils
  • Palatine tonsils: almond shaped paired lymphoid tissues located on lat wall of oropharynx, it occupies tonsillar sinus btw palatoglossal and palatopharyngeal arches.
  • 2 surfaces

  Medial suf: covered with stratified sqamous epithelium

  Has crypts 12-15, the most prominent of them is the crypta magna that represents the internal opening of 2 pharyngeal arch.

  Lat suf: covered with a sheet of fascia which forms the hemicapsule of the tonsil.

  
• The bed of palatine tonsil is formed from inside to outside

  • Pharyngobasilar fascia
  • Sup constrictor and palatopharyngeous muscle
  • Buccopharyngeal fascia
  • Styloglossus
  • Glossopharyngeal n

  Relations: Ant: palatoglossal arch with muscle

  Post: palatopharyngeal arch with muscle

  Upper pole: soft palate

  Lower pole: tongue
• ARTERIAL SUPPLY TO PALATINE TONSIL

  Main supply: tonsilar branch of facial artery

  Venous drainage: Paratonsillar vein/ palatine vein

  Nerve supply: glossopharyngeal n
• Bed of palatine tonsils

  
• Oropharynx has the following part:

  • soft palate
  • uvula: small conical projection hangi from post edge os soft palat.
  • base of tongue: post 1/3
  • lingual tonsil
  • vallecula: space btw tongue and epiglottis
  • Palatoglossus muscles
  • Palatopharyngeal muscles
  • Palatine tonsils
  • Posterior pharyngeal wall
• Waldeyers lymphatic ring

  • Collection of lymph nodes in pharynx
  • Nasopharyngeal node (adenoids)
  • tubal tonsil
  • Palatine tonsil
  • Lingual tonsil

  
• Palatine tonsil bed

  
• Laryngopharynx


  • Lower part of pharynx behind larynx
  • Extends from upper (epiglottis) to lower border (cricoid cartilag)
  • Ant wall: laryngeal inlet + post suf of cricoid and arytenoid cartilage
  • Post wall: supported main by C4 and C5. Formed by sup, mid and inf constrictors of pharynx.
• laryngopharynx has 3 parts

  • Pyriform sinus: right and left
  • Posterior cricoid area
  • Posterior pharyngeal wall

  Piriform sinues are two spaces on either side of pharyngeal inlet which channel swallowed materials around larynx unto esophagus.

  Bounded medially by aryepiglotic fold and laterally by the thyroid cartilage and thyrohyoid membrane.

  Beneath mucosa of sinus there the internal laryngeal n tat provides sensory supply to supraglottis and pyriform sinus

  
• Nerve supply of pharynx

  1. Pharyngeal plexus formed by:

  2. Pharyngeal branch of vagus carrying motor fibers of cranial accessory n

  3. Pharyngeal branch of glossopharyngeal n: sensory

  4. Pharyngeal branch of sup cervical ganglion
• Motor fiber through accessory n

  Supplies all pharynx muscles except stylopharyngeus (glossopharyngeal n)
• Inf constrictor


  Receives add supply from external and recurrent laryngeal N
• Sensory fibers


  Through glossophayngeal and vagus n.
• Nasopharynx


  Maxillary n throughout pterygopalatine ganglion.
• Soft palate and tonsils

  Lesser palatine and glossopharyngeal n.
• Parasympathetic secretomotor fiber


  Derive from lesser palatine branch of pterygopalatine ganglion
• blood supply to pharynx:

  1. ascending pharyngeal branch of external carotid
  2. ascending palatine and tonsilar branches of facial artery
  3. dorsal lingual branch of lingual artery
  4. Greater palatine, pharyngeal branch of maxillary artery

  Lymphatic drainage into retropharyngeal and deep cervical limph nodes