Nasal Cavity, paranasal sinuses and pharynx

• PHARYNX

  • Muscular tube adjoining the oral and nasal cavity to the larynx and oesophagus
  • Ends at inferior border of cricoid cartilage
  • 3 subdivisions:
  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• NASOPHARYNX

  • Continuous with the nasal cavity
  • Respiratory function
  • Lined with respiratory epithelium
  • Posterosuperior nasopharynx contains the adenoid tonsils
• OROPHARYNX

  Between the soft palate and the superior border of epiglottis

  Structures:

  Posterior third of tongue

  Lingual tonsils

  Palatine tonsils

  Superior constrictor muscle

  Waldeyer’s ring

  Involved in swallowing
• LARYNGOPHARYNX

  • Between superior border of epiglottis and inferior border of cricoid cartilage
  • Continuous with the oesophagus
  • Communicates with the larynx via the laryngeal inlet
  • Contains the middle and inferior pharyngeal constrictors
• What are the three divisions of the pharynx?

  Nasopharynx, oropharynx, laryngopharynx.
• Where is the nasopharynx?


  Upper part of the throat, behind the nose. Nasal choanae to soft palate.
• What is the function of the nasopharynx?


  Respiratory - conditions inspired air and propagates into larynx
• Which cell type lines the nasopharynx?

  Pseudostratified columnar epithelium and goblet cells.
• Where is the oropharynx?

  Back of the throat. From soft palate to superior border of epiglottis.
• What are the contents of the oropharynx?

  Posterior third of the tongue, lingual and palatine tonsils and superior constrictor muscles.
• What is the function of the oropharynx?

  Voluntary and involuntary swallowing, allows food to be safely delivered to the oesophagus.
• Waldeyer's ring

  paired palatine tonsils, adenoid tonsils and lingual tonsil
• Nose

  • olfaction (smell)
  • respiration
  • filtration of dust
  • humidification and warmth
  • reception and elimination of secretions (from paranasal sinuses and lacrimal ducts)
• External nose has 5 cartilages

  • septal, lateral nasal major and minor, alar, and vomeronasal

  Nares (nostrils) are bound by alae.

  Skin extends into vestibule and has hairs for filtration.
• External nose bones:

  • Nasal
  • Maxillary
  • Frontal
  • Septum
• Nasal septum

  • Ethmoid
  • Vomer
  • Cartilage
  • Maxilla and palatine bones nasal crests
• Nasal cavity

  • divided by septum
  • entry - nares
  • exit to nasopharynx - choanae
  • lined by mucosa
  • pseudostratified ciliated columnar cells with goblet cells
  • except vestibule
  • continuous with pharynx and paranasal sinuses, lacrimal sac and conjunctiva
  • olfactory area - superior 1/3
• Conchae/turbinate

  • increased surface area for heat exchange
• meatus

  • recess underneath conchae
  • common nasal meatus - nasal passageway
  • mucosa can swell blocking passages
• Paranasal sinuses

  • air filled extensions of nasal cavity
  • named by the bones which they occupy
  • Maxillary and sphenoidal small at birth, others develop later (about 8 years old)
  • can be hyperaerated
• Paranasal sinuses
• Paranasal sinuses

  • frontal
  • maxillary
  • ethmoid
  • sphenoid
• Drainage of sinuses

  • sphenoethmoidal recess
  • sphenoid sinus
  • superior meatus
  • posterior ethmoidal
  • middle meatus
  • anteriorly is the ethmoidal infundibulum
  • drains frontal sinus and anterior ethmoid
  • semilunar hiatus and ethmoid bullae
  • drains maxillary sinus
  • drains middle ethmoid sinus
  • inferior meatus
  • nasolacrimal duct
• Arterial supply

  • kiesselbach's area (little's area)
  • anastomotic plexus on septum
  • external nose
  • from anterior ethmoid and septal and infraorbital and facial
  • submucosal venous plexus
  • thermoregulation
• Venous drainage external nose

  • cavernous sinus
  • ophthalmic veins
  • pterygoid plexus
  • facial vein
• Nerve supply

  • maxillary and opthalmic branches
  • most of external nose by ophthalmic
  • olfactory nerve
• Sphenoid sinus

  • only thin bone separating from
  • optic nerves and chiasm
  • pituitary gland
  • internal carotid arteries
  • cavernous sinus
  • transsphenoidal surgery
• Maxillary sinus

  • forms wall of nasal cavity and floor of orbit
  • posterior molar teeth can project into
  • drains via maxillary ostium into semilunar hiatus of middle meatus
  • most commonly infected (uphill drainage)
• Ethmoid sinus

  • direct passage to anterior cranial fossa through cribriform plate
  • infection can spread from ethmoiditis
  • fracture of cribriform plate can lead to CSF rhinorrhoea
  • similar to otorrhoea
  • can test glucose content - highly unreliable
  • beta-2 transferrin
  • single best test - high sensitivity and specificity
  • no localising information though - use imaging
• Nasal and facial fractures can lead to septal deviation.
• Rhinitis

  • upper respiratory tract infections and allergy
  • sinusitis
• Infection spreading

  • intracranially
  • cribriform plate
  • retropharyngeal
  • middle ear
  • pharyngotympanic (eustachian) tube
  • lacrimal apparatus and conjunctiva
  • orbital
  • thin ethmoidal walls
  • teeth to sinus or sinus to teeth
  • maxillary sinus and molar teeth
  • same nerve supply - superior alveolar nerves
• Pharyngeal muscles

  • longitudinal muscles internal to circular layer (opposite to rest of GI tract)
• Internal longitudinal layer Pharyngeal muscles

  • palatopharyngeus
  • stylopharyngeus
  • salpingopharyngeus
  • elevate larynx and shorten and widen pharynx during swallowing and speaking
• External circular layer pharyngeal muscles

  • pharyngeal constrictors
  • superior, middle and inferior
  • inferior has sphincteric function
  • involuntary sequential contraction to propel food bolus
  • pharyngeal nerve plexus from vagus, glossopharyngeal and sympathetic cervical ganglia
  • gaps between allow passage of nerves and arteries etc.
• Swallowing - 3 phases

  1. voluntary chewing and pushing into oropharynx
  2. involuntary - soft palate seals off nasopharynx, larynx elevates, widens pharynx
  3. involuntary - sequential contraction of pharyngeal constrictors causes peristalsis into oesophagus
• Tonsillar (Waldeyer's) ring (aggregated lymphoid tissue)

  • pharyngeal tonsils (adenoids)
  • roof and post wall nasopharynx
  • tubal tonsil
  • near eustachian tube orifice
  • palatine tonsils
  • each side of oropharynx, between palatine arches
  • lingual
  • posterior part of tongue
• Pharyngeal plexus

  • vagus - motor
  • all muscles of pharynx and soft palate except stylopharyngeus (IX) and tensor veli (V3)
  • some motor to inferior constrictor also from external and recurrent laryngeal branches
  • glossopharyngeal - sensory
  • some nasopharyngeal sensation from V2 also
  • Gag reflex
• Arterial supply and venous drainage of pharynx

  • tonsillar branch of facial artery as well as multiple other arterial branches
  • ascending and descending palatine, lingual, ascending pharyngeal
  • large paratonsilar vein to pharyngeal venous plexus
  • highly vascular, can bleed a lot at or after surgery
  • tonsilar lymphatic vessels to jugulodigastric cervical lymph node
• The fauces, isthmus of fauces or the oropharyngeal isthmus, is the opening at the back of the mouth into the throat. It is a narrow passage between the velum and the base of the tongue.