21. Functions of the nose, anatomy and physiology of the nose and paranasal sinuses.

What are the parts of the external nose

• paired nasal bones, lateral cartilages, alar cartialges

• blood supply- angular artery, posterior nasal artery, infraorbital artery

• venous drainage- facial vein and superior opthalmic vein

• sensory innervatioin- opthalmic nerve, maxillary nerve

• morot innervation- facial nerve

What are the parts of the nasal cavity

• dividede into R and L by nasal septum

• opens posteriorly through the choana into the nasopharynx

• contains 3 conchae

Describe the 3 conchae

• superior

  • projects over superior nasal meatus

  • communicates with posterior ethmoidal air cells and sphenois sinus

• middle

  • projects over middle nasal meatus

  • communicates with anterior ethmoidal air cells, frontal sinus and maxillary sinus

• inferior

  • projects over inferior nasal meatus

  • contains opening of nasolacrimal duct

Describe the physiology of the nose

1. inspiration, air into nasal vestibule in laminar flow

2. when it reaches nasal valve→ turbulent flow

   1. slows down velocity of inspired air

3. prolongs time of contact with nasal mucosa

4. more time for nose to clean, humidify and warm the inspired air

What is the function of the nose

• cleaning, humidifying and warming air

• speech resonation, olfaction

• defence

Decribe the defences of the nose

• mechanical

  • mucociliary apparatus- phisically cleans air

• cellular defence

  • phagocytic cells

• humoral defence

  • IgA synthesis from paraglandular plasma cells

• specific defence

  • Waldeyer’s ring- antigen presentation

What are the paranasal sinuses

• air filled cavities that communicate with the nasal cavities

• lined from respiratory epithelium, ciliated pseudostratified columnar epithelium

What are the 4 paranasal sinuses

• frontal

  • blood supply- opthalmic artery

  • innervation- 1st ivision of CN V

• ethmoid sinus

  • divided into anterior, middle and posterior ethmoidal air cells

  • middle ethmoidal air cells from ethmoidal bulla

  • innervation- 1st division of CN V

• sphenoid sinus

  • blood supply- sphenopalatine artery

  • innervation- 1st and 2nd division of CN V

• maxillary sinus

  • behind lies pterygopalatine fossa

  • blood supply- internal maxillary artery

  • innervation- 2nd division of trigeminal nerve, infraorbital nerve

What is the physiology of the paranasal sinuses

• humidifies and heats inhaled air

• immunological defence

• lightens weight of skull

• speech resonance