F1i: Structure and function of the nose


  • Breathing is via nose/mouth → both airways converging in the oropharynx
  • Nose consists of bony & cartilaginous sections
  • Bony section

→ Superior half

→ Nasal bone & frontal maxilla bone

  • Cartilaginous

→ Inferior half

→ Cartilaginous portions are connected to each other & bones by a tough fibrous membrane

  • 2 nostrils = openings of nose
  • Nostrils separated by NASAL SEPTUM
  • Nostrils open into VESTIBULES → 2 NASAL CHAMBERS
  • Nasal cavity separated from cranial cavity by CRIBIFORM PLATE
  • CRIBIFORM PLATE is perforated, many small openings to allow OLFACTORY N (CN I) passage
  • Nasal Chambers contain 3 passageways KA SUPERIOR, MIDDLE, INFERIOR CONCHAE (conch seashell shape)
  • Posterior to these are OVAL shaped orifices KA CHOANAE (1.5 – 3cm diameter); openings allow air passage. Once air has passed through CHOANAE it is in the upper resp tract; THE PHARYNX
  • Paranasal sinuses
    • 4 empty air spaces which open/drain into nasal cavity
    • Named for their location
      • FRONTAL
      • SPHENOID
      • ETHMOID



  • For air to pass from environment → lungs

Humidify & Filter Air

  • Stratified squamous epithelium at entrance to nasal cavity
  • Contain sebaceous glands + NOSE HAIRS which filter out inhaled particles
  • Main nasal passage → RESPIRATORY MUCOSA
  • Pseudo-stratified ciliated columnar epithelium
  • Contain:
    • GOBLET CELLS → secrete mucous which traps inhaled particles (dust, bacteria)
    • SEROUS GLANDS → produces watery fluid with bacterial enzymes
    • CILIA → mucociliary rhythmical actions transport secreted mucous + trapped particles to throat where it is swallowed

Humidifying Air

  • Thin walled veins line nasal epithelium
  • Heat is transferred from blood to warm inspired air
  • Turbinate structure allows ↑SA for this


  • Olfactory receptors for smell located in nose
  • Olfactory nerve transmits these via nasal passage

Resonating Chamber for Speech

  • Sinuses lighten the skull
  • Also act as a resonating chamber for speech