Nasal cavity


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Nasal cavity

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Nasal cavity

  1. 1. Nose, Nasal cavity&Paranasal Sinuses
  2. 2. Nose Only externally visible part ofthe respiratory system Has a free tip and is attachedto the forehead by the root orthe bridge Has two openings, theanterior (external) nares ornostrils, which lead to thenasal cavity Each nostril is boundedlaterally by the ala andmedially by the nasal septumroottipexternal naresseptumala
  3. 3. Nose: Structure Nose consists of bony &cartilaginous framework Formed above by the:• Nasal bones• Frontal processes ofmaxillae• Nasal part of frontal bone Formed below by plates ofhyaline cartilage, whichinclude upper & lower nasalcartilages and the septalcartilageNasal part ofFrontal bone
  4. 4. Nasal Cavity Extends from theexternal (anterior)nares to the posteriornares (choanae) Divided into right & lefthalves by the nasalseptum Each half has a: Floor Roof Lateral wall Medial wall (septum)
  5. 5.  Roof Is narrow & formed (frombehind forward) by the:• Body of sphenoid• Cribriform plate ofethmoid bone• Frontal bone• Nasal bone & cartilage Floor• Separates it from theoral cavity• Formed by the hard(bony) palate
  6. 6.  Medial Wall (NasalSeptum) Osteocartilaginouspartition, only rarely lyingin the midline Covered by themucoperiosteum Formed:• Superiorly by thevertical (perpendicular)plate of ethmoid bone• Posteriorly by the vomerbone• Anteriorly by the septalcartilage
  7. 7.  Lateral Wall Shows three horizontal bonyprojections, covered bymucous membrane, thesuperior, middle & inferiorconchae (turbinates) The superior and middleconchae are parts of theethmoid bone, whereas theinferior concha is a separatebone The cavity below eachconcha is called a meatusand are named as superior,middle & inferiorcorresponding to theconchae
  8. 8.  The small space abovethe superior concha iscalled thesphenoethmoidal recess• The middle meatus iscontinuous in front with adepression called theatrium• Atrium is limited bove bya ridge called agar nasi• Below and in front ofatrium, and just withinthe nostril lies thevestibule
  9. 9.  The conchaeincrease the surfacearea of the nasalcavity The recess & meatireceive theopenings of the: Paranasalsinuses Nasolacrimal duct
  10. 10.  Sphenoethmoidalrecess: Receives theopening of thesphenoidal sinus Superior meatus:Receives the openingof the posteriorethmoidal sinus Inferior meatus:Receives the openingof the nasolacrimalduct. The opening isguarded by a valve, afold of mucousmembrane
  11. 11.  Middle meatus:• Shows a rounded eminence,the ethmoidal bulla, caused bythe bulging of the underlyingmiddle ethmoidal sinus, whichopens on its upper border.• A curved groove, hiatussemilunaris, lies below thebulla. Hiatus receives theopening of the maxillary sinus• Anterior end of hiatus leads tofunnel-shaped infundibulum,which receives the openingsof the frontal & the anteriorethmoidal sinuses
  12. 12. Lining of the Nasal Cavity Vestibule is lined bymodified skin, and hasshort, curved hair calledvibrissae The roof, upper part of theseptum, upper surface ofthe superior concha, andthe sphenoethmoidal recessare lined by the olfactorymucosa The rest of the cavity islined by the respiratorymucosaVVA
  13. 13. Olfactory Mucosa Contains olfactory cells (bipolar sensoryganglion cells), which serve as receptors forolfactory stimuli. Distinct smells are far more numerous thantastes The sense of smell plays a major role in theflavor of foods and it is common forindividuals who lose their sense of smell toreport that food loses its taste. (food seemssomewhat tasteless when a person hascold) Most air breathed in normally flows throughthe nose but only a small part reaches theolfactory mucosa, enough to get a responseto an odor. Sniffing, however, increases theflow of air over the smell receptor cells,greatly increasing their exposure to odors.
  14. 14. Respiratory Mucosa Pseudostratified ciliated columnar epithelium withgoblet cells Rests on thick network of thin walled veins thatwarms the air as it flows through the cavity Glands produce ‘mucus’, which: moisten the air cleans the air by trapping the incoming bacteriaand foreign debris Cilia help in moving the contaminated mucusposteriorly towards the throat, where it isswallowed and digested by the stomach juices
  15. 15. Nerve Supply Nasal cavity receives sensory &visceral innervationSensory innervation Olfactory mucosa supplied byolfactory nerves Nerves of general sensation arederived from opthalmic &maxillary nerves Anterior part supplied by theanterior ethmoidal nerve(branch of opthalmic nerve) Posterior part supplied bynasal, nasopalatine andpalatine branches (of maxillarynerve)
  16. 16. Visceral Innervation Sympathetic fibers arise fromneurons of superior cervicalganglion and are distributedthrough plexuses around thearteries, supply mainlyvascular smooth muscle Parasympathetic fibers arisefrom neurons of thepterygopalatine ganglion thatcourse in the nasopalatinenerve (branch of maxillary)and its branches, supply themucosal glands.
  17. 17. Arterial Supply Sphenopalatine artery (branchof the maxillary artery) is themain supply Alar and septal branches ofsuperior labial artery (branchof the facial artery) Anterior & posterior ethmoidalarteries (branches of theophthalmic artery) The arteries make a richanastomosis in the region ofthe vestibule, and anteriorportion of the septum
  18. 18. Venous Drainage: Veins begin as a rich plexus in the submucosa,accompany the corresponding arteries, and draininto the facial, ophthalmic, and sphenopalatineveins.Lymphatic Drainage: The lymphatics from the: Vestibule drain into the submandibular lymphnodes Rest of the cavity drains into the upper deepcervical lymph nodes
  19. 19. Functions of Nose & Nasal Cavities Air conditioning: warming, cleaning andhumidifying the inhaled air Add resonance to the voice Vocal sounds are also produced in the nasalcavity thus aiding in vocalisation Involved in the special sense of smell Central role of the nose in facial appearance ??
  20. 20. Paranasal Sinuses Air filled cavities located in thebones around the nasal cavity:ethmoid, sphenoid, frontal bones& maxillae Lined by respiratory mucosawhich is continuous with themucosa of the nasal cavity Drain into the nasal cavitythrough relatively small apertures Drainage of the sinuses mainlydepends on the movement of thecilia, which propel the mucustoward their openings in thenasal cavity
  21. 21.  The development of sinusesbegins in 3-4 month, but onlymaxillary & ethmoid sinusesare present in rudimentaryform at birth. The frontal &sphenoidal sinuses are notclinically perceptible at birthand can rarely bedemonstrated on plain x-raybefore two years of age. Continue to grow postnatally Enlarge appreciably after 8thyear & become fully formed atadolescenceMEFrom a 3 months old fetus, showingethmoid & maxillary sinuses
  22. 22. Functions Lighten the skull Act as resonant chambers for speech The respiratory mucosal lining helps inwarming, cleaning and moistening theincoming air
  23. 23. Maxillary Sinuses• Located within the body of themaxilla• Pyramidal in shape with the baseforming the lateral wall of nose &the apex lies in the zygomaticprocess of the maxilla• Roof: formed by the floor of theorbit• Floor: formed by the alveolarborder. Roots of 1st and 2ndpremolars and the 3rd molar(sometimes canines) project intothe sinus• Opens into the middle meatusthrough the hiatus semilunaris• Supplied by superior alveolar &infraorbital nervesM
  24. 24. Frontal Sinuses Two in number Located within the frontalbone, separated fromeach other by a bonyseptum Triangular in shape,extending backward intothe roof of the orbit Opens into the middlemeatus through theinfundibulum Supplied by thesupraorbital nerve
  25. 25. Ethmoidal Sinuses Located within theethmoid bone, betweenthe nose and the orbit Divided into threegroups: anterior, middle& posterior Anterior group opensinto the infundibulum,middle opens on thebulla, and posterior intothe superior meatus Supplied by the anteriorand posterior ethmoidalnerves
  26. 26. Sphenoidal Sinuses Two in number Located within thebody of sphenoid Open into thesphenoethmoidalrecess Supplied by theposterior ethmoidalnerve
  27. 27. Clinical Notes Epistaxis: Little’s area,common site of bleeding fromnose Inflammation of the nasalmucosa, Rhinitis, results innasal congestion and excessiveproduction of mucus leading to‘postnasal drip’ Infections of the nasal cavitycan extend to the: Paranasal sinuses Nasolacrimal duct &lacrimal sac
  28. 28.  Inflammation of mucosa ofthe sinuses, Sinusitis, causesexcessive production of mucusleading to obstruction of thedrainage of sinuses. Thisresults in headache andchange in the voice Infection of frontal & anteriorethmoidal sinus can easilyspread to maxillary sinusbecause of the location oftheir openings Infection of upper teeth canlead to inflammation of themaxillary sinus Extraction of an infectedupper tooth may result in afistula
  29. 29.  The maxillary sinus is mostcommonly the site of infection The inflamed mucosa resultsin excessive production ofmucus as well as narrowing ofits opening in the nasal cavity The position of the draincauses problems in thatmucus can collect in the sinusbelow the drain. In thissituation, the sinus will onlydrain if the patient lies ontheir opposite side. Pressure from the trappedfluid/mucus causes sinus pain
  30. 30. Thank You & GoodLuck