ANATOMY OF NOSE & OLFACTION midhun.pptx

PPT

1. ANATOMY OF NOSE & OLFACTION DR. MIDHUN BHASKAR . K

2. DEVELOPMENT OF NOSE Nose develops from numerous mesenchymal process around primitive mouth at 4 th week of gestation Neural crest cells proliferate nasal placode sinks nasal pits deepen nasal sac Adjacent mesoderm proliferate  medial & lateral nasal prominences of frontonasal process . Surrounds nasal sac & pits  nares

3. Maxillary process grows anteriorly & medially  fuse with nasal prominences & frontonasal process  closes off nasal pit  nasal cavity formed. Primitive nasal cavity & mouth separated by bucconasal memb  thins posteriorly  breaks down  choanae Failure of breakdown = choanal atresia

4. Frontal & maxillary process fuse Lateral 2/3 rd of upper lip Superior alveolar ridge Palatal shelves Medial nasal process fuse with maxillary process Philtrum Medial crus of lower lateral cartilage Lateral nasal prominences Nasal bone Upper lateral cartilage Lateral crus of lower lateral cartilage

5. Frontonasal process  posterior midline growth  septum of nose . Extends from roof of oral cavity to opening of rathke’s pouch. Maxillary process fuse with frontonasal process  primitive (1 ) palate

6. External nose Skin Thin over dorsum & sides of nose – loosely adherent Thick over nasal tip , alar cartilage – sebaceous glands (+) Hypertrophy of sebaceous gland in - rhinophyma

7. Muscles All muscles supplied by – facial nv br. Nasal elevators : procerus levator labii superioris alaeque nasi anomalous nasi

8. Depressors : alar nasalis depressor septi nasi Compressor : transverse nasalis compressor narium minor Dilator : dilator naris anterior (minor dilation only)

9. s/c tissue 4 layers : superficial fatty – connected to dermis fibromuscular – comprises nasal smas * deep fatty – have n/v bundles periosteal & perichondral – deepest layer In external approach rhinoplasty – dissection deep to 3 rd layer – minimize postop scarring & retraction – as smas & n/v bundles intact *smas – s/c Musculo aponeurotic system

10. Framework of ext nose Upper 1/3 rd – bony – 2 nasal bones meeting in midline - rests on nasal process of frontal bone - held btwn frontal process of maxillae Lower 2/3 rd - cartilagenous

11. Nasal cartilages Made of hyaline cartilage Attach to bones of ant. Nasal aperture 4 in no. – Upper lateral cartilage Lower lateral cartilage (alar cart) Septal ( quadrangular/quadrilateral) Sesamoid cartilage (lesser alar ) - >=2 in no Lower lat cart. – 3 crus – medial , intermediate & lateral - Forms natural arch of nasal ala (a/c alar cartilages )

12. Upper lat cart. – trapezoid shape -lower free edge – seen intranasally as limen nasi / limen vestibule Cartilages form – external & internal nasal valves

13. External nose Vestibule Anterior aspect of nasal cavity. Entry point of external nares into nasal cavity demarcated by limen nasi Limen nasi – site of marginal incision in externa approach rhinoplasty Lined by – keratinizing stratified squamous epithelium Hairs – vibrissae – covered by mucus layer – filter airborne particle during inspiration Sebaceous & sweat glands

14. External nasal valve Medial – septum Lateral – alar rim ( lateral crus , sesamoid complex , fibrofatty tissue ) Inferior – nasal sill If any absent – stenosis - dynamic wall collapse – increased on inspiration

15. Internal nasal valve Narrowest portion of nasal cavity – regulates air flow medial – septum Lateral – upper lat cart , head of inf. Turb Inferior – nasal floor Apex – 10 – 15 in Caucasian Any abn = nasal obstruction

16. Blood supply of ext nose Both eca & ica Alar region – angular a superior labial a - nasal side wall , ala – angular a , lat nasal br. Of angular a - nasal sill , columella – columellar br of sup labial a - ant nasal septum – septal br of sup labial a - dorsum , nasal side wall – anastomoses of 1) dorsal nasal br of ophthalmic a & 2) lat nasal br of angular a + - external nasal br of ant ethmoidal a, infraorbital a

17. Venous supply of ext nose Frontomedian area - facial vein Orbitopalpebral area – ophthalmic vein Upper lip & nose = danger area of face - facial vein communicates with cavernous sinus – via ophthalmic vein – valveless system

18. Nv supply of ext nose Skin of nasal root bridge – supratrochlear & infratrochlear br of ophthalmic nv upper part of side wall Remaining skin of nasal side wall – infraorbital br of maxillary nv Skin over dorsum , nasal tip – external nasal br of ant ethmoid nv

19. Lymphatic drainage of ext nose Submandibular ln Submental ln Have b/l drainage

20. Nasal cavity From External nares to posterior choanae – continuous with nasopharynx Divided into 2 by septum Nasal floor – concave side to side - flat Antero posteriorly - horizontally oriented Ant 3/4 th – palatine process of maxilla Post 1/4 th – horizontal process of palatine bone Roof – skull base Superiorly – superior septum , sup turb , upper aspect of middle turb lined by – olfactory epithelium Vestibule lined by – stratified squamous Other parts by – respiratory epithelium

21. Nv supply of nasal cavity Controlled by autonomic nv system Parasymp nv system - control nasal secretions - presynaptic - travel via vidian nv - synapse at sphenopalatine ganglion -post synaptic fibers to – nasal mucosa Sympathetic nv system - control degree of vascular tone - control turbinate congestion -synapse at sphenopalatine ganglion

22. Sensory innervation nasal mucosa - ophthalmic & maxillary divisions of trigeminal nv Pain, temp, touch – trigeminal nv via sphenopalatine ganglion Lateral wall , turbinates – posterolateral nasal nv from v2 , -ethmoidal nv from v1

23. Nasal septum 3 parts – bony , cartilaginous , membranous BONY SEPTUM Perpendicular plate of ethmoid Vomer Maxillary crest Palatine bone

24. Cartilagenous septum Septal cart / quadrilateral cart Septal cartilage – continuous with upper lat cart towards bridge of nose - sphenoidal process / septal tail –projection of sept cart - additional source of cartilage esp during revision rhinoplasty - inf attachment – to nasal crest of maxilla – bound by loose connective tissue – creates pseudoarthrosis – allows mobility of sept cart base during flexion – reduces risk d/t trauma Sup attachment - bound to nasal bones by collagenous fibers Membranous septum – connective tissue btwn septal cart & columella

25. Blood supply of septum Eca + ica Postero-inf septum – post septal a – basis of nasoseptal mucosal flap -br of sphenopalatine a (internal maxillary a - eca) Antero – inf septum – greater palatine a (internal maxillary a - eca) Caudal septum , columella – septal br of sup. Labial a ( facial a – eca ) Antero-sup & postero-sup : ant & post ethmoidal ( ophthalmic a – ica ) Kisselbach’s plexus – located along ant nasal septum @ little’s area - long capillary loops (+) - rich vascularity - mc site of epistaxis - anastomosis of – ant ethmoidal a - posterior septal a - septal br. Of superior labial a

26. Venous supply septum Sphenopalatine vessels  pterygoid plexus posteriorly  facial vein anteriorly

27. Lateral nasal wall Middle & superior turbinate = extension of ethmoid bone Inferior turbinate = embryologically independent bone Turbinates - filled with vascular channels & venous sinusoids -function : warm & humidify air : modify airflow resistance - under symp control – continuously dilate & constrict Nasal cycle – normal phenomenon – alternate congestion & decongestion of nasal cavity – every 0.5–3 hrs Turb hypertrophy = turb chronically congested / hypertrophied d/t inflammatory rhinitis

28. Inferior meatus – btwn inf turb & lnw -nasolacrimal duct opening – called hasner’s valve (not true valve but mucosal fold) MIDDLE TURBINATE – ATTACHED TO LNW BY BONY LAMELLA – GROUND/BASAL LAMELLA –ATTACHED IN ‘S’ SHAPED MANNER Middle meatus – btwn mid turb & lnw - maxillary sinus + ant ethmoidal sinus + frontal sinus openings *UNCINATE PROCESS – HOOK LIKE FROM ANT-SUP TO POST-INF *INFUNDIBULUM – MEDIALY : UNCINATE PROCESS , LATERALLY : LAMINA PAPYRACEA maxillary ostia – lower infundibulum

29. Bulla ethmoidalis – ethmoidal cell behind uncinate process. Space between both = hiatus semilunaris Space above bulla = suprabullar recess Space behind bulla = retrobullar recess Both combined = lateral sinus ( sinus lateralis of Grunwald ) Agger nasi = elevation ant to attachment of middle turb . - when pneumatized, agger nasi cell communicate with frontal sinus

30. Superior turbinate – post & sup to middle turb - sphenoid ostia lies medial to it Superior meatus – btwn sup turb & lnw - post ethmoidal sinus opening (1-5 in no) -onodi cell = post ethmoid cell that may grow posteriorly by side of sphenoid sinus . Optic nv may be in its lateral wall Sphenoethmoidal recess – above sup turb - opening of sphenoid sinus Supreme turbinate – sometimes present above sup turbinate

31. Blood supply of lnw Eca + ica Major bs = sphenopalatine a(eca) - ligate all br during sx – if not - ligate internal maxillary a Small area in ant part of lnw- facial a (eca) Inf part near palate – greater palatine a (eca) Superior lateral wall – ant & post ethmoidal a ( ica)

32. olfaction Well developed in lower animals Olfactory neuroepithelium – 2 cm 2 in upper recess of nasal cavity lining cribriform plate , sup & middle turbs , septum – majority in olfactory cleft Pseudostratified columnar epithelium – supported by vascular lamina propria

33. 6 diff type of cells – - bipolar sensory neuron – derived from olfactory placode (cns origin) - sustentacular ( supporting) cells – insulates bipo cells from each other , regulates mucus prodn , transports molecules across epithelium , detoxifies & degrades odorants - duct cell of bowman – mucus secretion -microvillar cell – sends microvilli into mucus - horizontal (dark) basal cells – stem cells in basement membrane -globose (light) basal cells – multipotent cells. Can make horizontal cells too

34. olfactory receptor cells in 6 millions Neurotransmitter = glutamate , dopamine Peripheral process of receptor cells in – nasal mucosa - expands into ventricle with cilia Central process of receptor cells = olfactory nv (12-20 in no ) – passes thru cribriform plate of ethmoid  mitral cells of olfactory bulb . Olfactory bulb - in ventral surface of frontal lobes over cribriform plate 1 st synapse forms – glomeruli in bulb 2 nd order neurons = mitral cells , tufted cells Axons of mitral cells = olfactory tract  prepiriform cortex & amygdaloid nucleus No synapse in thalamus- directly to cortex

35. Higher order brain regions - piriform cortex - olfactory tubercle - entorhinal area - amygdaloid cortex - corticomedial nuclear grp of amygdala 3 rd order projections – to hypothalamus , thalamus , hippocampus , orbitofrontal cortex

36. reference Scott-brown’s 8 th edition

37. Thank you