ANATOMY OF NOSE & PNSFUNCTIONS OF NOSE & PNS

Dr. Ajay Manickam Junior ResidentDept of OtorhinolaryngologyR G Kar Medical College

EMBRYOLOGY• Facial development takes place between 4 – 8 weeks of intra

uterine life• Face develops from 5 facial swellingsthat surround the

Primitive mouth by the end of 4th week Central unpaired frontonasal process Pair of maxillary process Pair of mandibular process

At 5th week thickening appear in fronto nasal process called nasal placodesAt 6th week nasal placode invaginates to form nasal pits6th and 7th week maxillary process increase in size to grow mediallyThey fuse with medial nasal process & then with lateral nasal process This separates nasal pits from stomadeum

Medial nasal process fuse with eachother to form inter maxillary processWhich forms central bridge of nose and the central portion of upper lip philtrumInter maxillary process grows backward to form nasal septumlateral nasal process enlarge to form alae, grow backward to form lateral nasal wall, which show ant post elevation to form turbinates.

• Maxillary process fuses with the lateral nasal process

• The junction is marked by a groove called nasolacrimal/ naso optic groove

• By 7th week groove invaginates into mesenchyme to form nasolacrimal duct

• Canalization continues throughout pregnancy and may not be complete till after birth

Anatomy of nose• Nose can be divided into external nose & nasal cavity• External nose consists of

External nares

• Oval apertures on the inferior aspect of external nose

• Held open by the alar cartilages and septal cartilages

• Inferior nasal spine and adjacent margins of maxillae

ANATOMY OF NOSE

• Nasal cavities are elongated wedge shaped spaces with large inferior base and narrow superior apex

• Ant apertures are the nares, open onto inferior surface of nose

• Post apertures are the choanae, which open into the nasopharynx

DIVISIONS OF NASAL CAVITY

• Nasal cavities• Lateral wall of

noseConchae divide nasal cavities into four air channelsConchae increase surface area of contact between lateral wall and respired air

Regions of Nasal Cavity

• Nasal vestibule• Respiratory region• Olfactory region

Skeletal framework of nasal cavities

• UNPAIRED- Ethmoid,Sphenoid,Frontal & Vomer• PAIRED- Nasal,Maxillary,Palatine,Lacrimal & Inf conchae

Ethmoidal Bone• Complex bone of skull• Contributes to roof, lateral wall,medial wall

of nasal cavity and contains ethmoidal cells

Ethmoidal bone• Cuboidal in shape• 2 ethmoidal labyrinths – united by cribriform

plate – separates nasal cavity from cranium• 2nd sheet – perpendicular plate descends

vertically from cribriform plate• Ethmoidal labyrinth 2 sheetsLateral sheet – orbital plateMedial sheet – upper part of lat wall of nose• Irregular projection the uncinate process• ArticulatesAnt – nasal spine of frontal bonePost – sphenoidal crest of sphenoid , vomerInf – ant – septal cartilage

Sphenoidal bone

• Closes the back of nasal cavity and separates it from ant and middle cranial fossa

• Lesser wing attached to body by two roots between which lies optic canal

• Medial pterygoid plate forms the lateral wall of post choana

• Inferomedian funnel shaped foramen vidian canal

• Supero lateral foramen is foramen of rotundum transmits maxillary nerve

Frontal bone

• Centre of frontal bone is a hiatus that’s filled with cribriform plate of ethmoid

• Either side of hiatus are aircells of ant & post ethmoidal cells

• Lateral border of these aircells articulate with lamina papyracea of ethmoidal bone

• At the junction of these suture lines lies ant and post ethmoidal foramina

• Anteriorly midline frontal bone elongated to form the nasal spine

Vomer

•  It is located in the midsagittal line, and articulates with thesphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.

• The vomer forms the posterior part of the nasal septum, with the anterior part formed by the ethmoid.

Nasal bone

• 2 small rectangular bones , forming bridge of nose

• 2 surfaces and 4 borders• External surface- covered by procerus and

nasalis muscle• Internal surface concave side to side,

groove for ant ethmoidal nerve• Superior border-frontal bone• Inferior border = upper lateral cartilage• Medial border –opposite nasal bone-part

of septum• Lateral border-frontonasal process of

maxilla

Maxillary bone

• Forms base of framework on which lat nasal wall is built

• Large opening in maxillary bone is closed off by processes of different bones

• Descending process - lacrimal bone ant

• Uncinate process - ethmoidal bone antinferiorly

• Maxillary process - inf turbinate inferiorly

• Perpendicular plate of palatine bone post

Maxillary Bone• Fronto nasal process of

maxilla• Medial surface of this process

has 2 crests• Ethmoidal crest- ant part of

middle turbinate is attached • Lower crest gives attachment

to inf turbinate• Immediately below frontonasal

process groove- canal for NLD

• Maxillary tuberosity- canal for greater palatine vessels

Palatine Bone• L shaped bone• Perpendicular plate- ant border of plate

has maxillary process, inferiorly continues with horizontal plate, superiorly with maxilla by orbital process and sphenoid by sphenoid process

• Horizontal plate- anteriorly articulates with horizontal process of maxilla to form floor, post free end

• Pyamidal process articulates with the notch between two pterygoid plates

Lacrimal Bone

• Smallest and most fragile cranial bone separates lacrimal fossa from nasal cavity

• Articulates anteriorly with frontonasal process,

• Orbital surface has a crest, between two crest is the lacrimal fossa containing sac

• Nasal surface of the lacrimal bone is pneumatised by an anteriorly migrated ethmoidal cell the agger nasi cell

Inferior conchal bone

• Separate scroll like bone• 3 processes• Anteriorly lacrimal process articulates

with descending process of lacrimal bone assists in NLD

• Ethmoidal process- articulates with ucinate process of ethmoid bone

• Maxillary process-forms part of inf meatus

Floor Of Nasal Cavity

• Smooth, concave, much wider than roof

• Consists of1. soft tissues of ext nose2. upper surface of palatine process of maxilla and horizontal plate of palatine bone, which together form hard palate

Roof Of Nasal Cavity

• Its narrow, highest in the central region, where it is formed by the cribriform plate of the ethmoid bone

• Anterior to cribriform plate roof slopes inferiorly to nares formed by

1.Nasal spine of frontal bone,nasal bone2.Septal cartilage and alar cartilage• Posteriorly roof slopes into choana

and formed by1.Ant surface of sphenoid bone2.Ala of vomer3.Vaginal process of medial plate of pterygoid

Medial wall of nose

• Mucosa covered surface of thin nasal septum, separates right and left nasal cavities

• Nasal septum consists of 1.Septal nasal cartilage anteriorlyPosteriorly 1.Vomer2.Perpendicular plate of ethmoid• Small contribution 1.nasal bone2.Nasal spine of frontal bone3.Nasal crests of maxillary and palatine bones4.Rostrum of sphenoid bone5.Incisor crest of maxilla

Lateral wall of nose • Formed by bone,cartilage,soft tissues

• Bony support for lateral wall of nose is provided by

1.Ethmoidal labyrinth and uncinate process2.Perpendicular plate of palatine bone3.Pterygoid process of the sphenoidal bone4.Medial surfaces of lacrimal bone5.Medial surface of maxillary bone6.Inferior concha

Lateral wall of nose • Inferior,middle,superior conchae extend medially across nasal cavity spreading into four air channels

• Lateral wall of middle meatus elevates to form dome shaped bulla ethmoidalis, middle ethmoidal cells ,which expands the medial wall of ethmoidal labyrinth

• Inferior to ethmoidal bulla is curved gutter semilunar hiatus, its anterior end forms channel the ethmoidal infundibulum, which curves upward and continues as the fronto nasal duct

Lateral wall of nose

• Naso lacrimal duct- under ant lip of inferior concha

• Frontal sinus- frontonasal duct and ethmoidal infundibulum into anterior end of semilunar hiatus

• Ant ethmoidal cells- drain into frontonasal duct or ethmoidal infundibulum

• Middle ethmoidal cells open onto ethmoidal bulla

• Posterior ethmoidal cells open onto lat wall of superior nasal meatus

• Maxillary sinus open into semilunar hiatus

Choanae • Choanae are rigid openings completely surrounded by bones

between nasal cavity and the nasopharynx• Margins formed by1.Post border of horizontal plate of palatine bone2.Medial plate of pterygoid process3.Medially by post border of vomer• Roof formed by1.Ant by ala of vomer2.Post by body of sphenoid

Gateways of nasal cavity

• Cribriform plate• Sphenopalatine foramen• Incisive canal• Small foramina in the lateral wall

Vessels • ECA- 1.Sphenopalatine artery 2.Greater palatine artery 3.Superior labial artery 4.Lateral nasal artery• ICA- Anterior and Posterior ethmoidal arteries

Blood supply• Spheno palatine.a terminal br of maxillary.a Post lat nasal br Post septal br• Greater palatine artery br of maxillary.a• Sup labial & lat nasal artery br of facial.a• Post ethmoidal & ant ethmoidal.a br of ophthalmic.a

Venous drainage• Veins pass with branches

that ultimately originate from maxillary artery, drain into pterygoid plexus of veins

• Veins from anterior region of nasal cavity join the facial vein

• Veins accompanying ant and post ethmoidal arteries tributaries of superior ophthalmic vein, largest emmissary vein drain into cavernous sinus

Innervation

• Olfactory nerve• Branches of ophthalmic and maxillary nerves for general

sensation• Parasympathetic• Sympathetic

• V1 Ant & post ethmoidal nerve• V2 Post sup lat nasal n Post sup medial nasal n Nasopalatine n Post inferior nasal n• Parasympathetic - secreto motor innervation of glands of

mucosa of nasal cavity & PNS Preganglionic – greater petrosal br of facial n Post ganglionic – join br of maxillary n• Sympathetic – regulates blood flow preganglionic – sup cervical sympathetic ganglion Post ganglionic – deep petrosal n join greater petrosal n

Blood & nerve supply of external nose• External nose

Para nasal air sinuses

• At birth the volume of cranial vault is 7 times that of facial skeleton

• This ratio decreases during infancy and childhood, as a result of growth of 4 pairs of PNS& development of teeth

• Sinuses develop from invaginations of nasal cavity that extend into the surrounding bone

• Maxillary and ethmoidal sinus develop in utero during 3rd and 5th fetal months

Embryology PNS

• With eruption of deciduous teeth, maxillary sinus enlarges to become 3 times longer, 5 times greater in height & width

• Ethmoidal sinus are small before the age of 2 years then grow rapidly 6-8 years, but donot complete the growth until puberty

• Around the 2nd year the most anterior ethmoidal cell grow into the frontal bone to form frontal sinus

• Frontal sinuses are visible in x ray from 7th year• Most posterior ethmoidal air cell grows into sphenoid bone to

form sphenoidal sinus

Frontal Sinus• Most superior , triangular in shape• Base of each triangle is oriented vertically in the bone, at the

midline above the bridge of nose apex is approximately 1/3rd way along the upper margin of orbit

• Drainage-middle meatus• Nerve- supra orbital nerve from ophthalmic nerve• Blood supply- ant ethmoidal artery branches

Ethmoidal air cells• 9-10th week of gestation, 6-7 folds appear in

lat wall of nasal capsule of foetus• Over next weeks folds fuse into 3-4

remaining crests with ascending anterior, and a posterior descending portion

• Ethmoidal air cells are divided into, anterior,middle posterior

• Anterior- ethmoidal infundibulum• Posterior- lat wall of sup nasal meatus• Middle- ethmoidal bulla• Nerve- ant&post ethmoidal branches of

nasociliary merve from ophthalmic nerve 7 maxillary nerve

• Blood- ant & post etmoidal arteries

Maxillary sinuses • First sinus to appear• Largest of all, pyramidal in

shape• Medial wall or base of

maxillary sinus formed by maxilla and by parts of inf concha, palatine bone

• Roof = related orbit• Anterolateral surface= roots of

upper molar and premolar teeth

• Posterior wall= infra temporal fossa

• Nerve- maxillary nerve-infra orbital & alveolar br

• Blood- maxillary a- infra orbital & sup alveolar br

Sphenoidal sinuses • Within body of sphenoid• Opens into roof of nasal cavity

via apertures on post wall of spheno ethmoidal recess

• Related above- pituitary gland &optic chiasm

laterally – cavernous sinus below & in front – nasal cavities• Nerve- post ethmoidal br ophthalmic N maxillary nerve• Blood- pharyngeal br maxillary

artery

Endoscopic anatomy

• 1st pass- endoscope is passed along floor of nasal cavity between inf turbinate & septum

• Structures studied are1.nasal septum2.Inf turbinate3.Post choana4.Post wall & roof of nasopharynx5.Eustachian tube opening6.Fossa of rosenmuller7.Opening of NLD- guarded by hasner’s valve

Endoscopic anatomy

• 2nd pass• Scope passed along floor upto post

choana, moved upward & medial to middle turbinatealong the roof of post choana and anterior surface of sphenoid

• Structures seen1.Superior turbinate and meatus2.Sphenoethmoidal recess3.Sphenoid ostium4.Below ostium woodruff plexus

Endoscopic anatomy

• 3rd pass- examine contents of middle meatus- by gently retracting middle turbinate by freer’s elevator

• Structures seen are1.Attachment of middle turbinate to cribriform plate2.Agger nasi cell3.Uncinate process4.Lamina papyracea5.Accessory ostium

Anatomical variations of middle turbinate• Ballooned out air cell enclosed in it, from

frontal recess, agger nasi cell, ant ethmoids, such a case middle turbinate is called concha bullosa

• Vertical lamella may be pneumatized to form intralamellar cell of grunwald

• May have paradoxical curve bending laterally

• Bifid • May attach to lat wall of maxillary sinus• Lower part of normally curved middle

turbinate may curve far laterally to produce a concavity within it called turbinate sinus

Histology

• Nasal septum• Mucous membrane is

predominantly respiratory with a small area of olfactory epithelium, adjacent to cribriform plate

• Composed of ciliated & nonciliated pseudostratified columnar cells,basal pluripotential stem cells & goblet cells

• Olfactory epithelium is composed of receptor cells, supporting cells with microvilli & basal stem cells, confering the capacity of regeneration

Histology

• Lateral wall of nose• Respiratory ciliated columnar epithelium, small variable

area superiorly of olfactory epithelium• Areas of squamous metaplasia are often found on the lateral

wall, particularly in areas subject to greatest airflow

Histology

• Frontal sinus - respiratory epithelium small number of goblet cells, sero mucinous glands

• Maxillary sinus - ciliated columnar epithelium with highest density of goblet cells seromucinous glands are infrequent

• Sphenoid sinus & ethmoid sinus – respiratory epithelium is same goblet cell population with least sero mucinous glands

Functions of Nose and PNS

1.Respiration• Heat exchange• Humidification• Filtration• Nasal resistance• Nasal fluids & ciliary functions• Nasal neurovascular reflex• Voice modification2. Olfaction • Two neurone peripheral pathway• Trigeminal input• Olfaction

Heat exchange • Temperature of inspired air vary from -50 –

50 degree C.• By the process of thermoregulation, latent

heat of evaporation, direction of flow of blood, heat exchange occurs

• Gas in the nose, arterial blood 2 fluids, that are in thermal, but not with direct contact

Humidification

• Vaporization cools the surface and 10% body heat is lost this way• Inspiration • Energy required for 2 function raising temperature of inspired air, latent

heat of evaporation• Despite variation in temperature of inspired air, air in post nasal space is

31degree C , 95% saturated• Expiration• Expired air at back of nose is slightly below body core temperature• As temperature drops along the nose , some water condenses to mucosa• Water production• Water comes from serous glands• Capillary leakage occurs during inflamation- additional water comes from

expiredair, NLD, oral cavity

Filtration • Airflow pattern• Inspiration• directed upwards and backwards mainly

over ant part of inferior turbinate• Then splits to two below and over middle

turbinate, rejoining post choana• Expiration• lasts longer• More turbulent

Nasal resistance • Difference exist between races• Nose accounts for upto half the total airway resistance• Resistance made of • 1. bone,cartilage,attached muscles• 2.variable , the mucosa• Nasal resistance is high in infants

Nasal fluids and ciliary functions• Nasal secretions 2 elements mucus &

water• Composition of mucus• Water & ions• Glycoproteins• Enzymes• Circulatory proteins• Proteins• Imunoglobulins• cells

Nasal immune system

• Surface propertiesMechanical

Physical characteristics of mucus• Innate immunity

Bacteriocidal activity in mucusProteins

cellular component• Acquired immunityIg A, IgM, IgE & IgG

LymphocytesPrimed macrophages

• Distant sitesAdenoids , LN, Spleen

Reflexes • Axon reflexes• Substance p vasodilator transmits anti dromic reflex• Initiated by mechanical irritation or histamine release• This amplifies the response• Nasopulmonary reflexes• Increasing airflow through one nose cause increased

ventilation on the homolateral lung• Blowing air through the nose causes bronchiole muscle to

relax on the same side and increases respiratory activity

Reflexes from nasal stimuli • Chemical, temperature change and physical stimuli cause

widespread cardiovascular and respiratory responses• Response ranges from sneezing to cardio respiratory arrest• Sneezing- change in respiratory rate with closure of larynx and

a variable cardiovascular response occurs• Sensory stimulation accompanied by lower cardiac output• Modification of submersion reflex

Nose and the voice• Nose adds quality by allowing air to

escape• Rhinolalaia clausa too little air escapes• Rhinolalia aperta too much escapes

Olfaction

• Stimulus – odours react with lipid bilayer of receptor cells at specific sites, causes k+ & cl – to flow out and depolarize cell

• Receptors – G protein coupled receptorsreact with specific adenyl cyclase

• Discrimination – man prefers to detect pleasantness of an odour

Olfaction

Trigeminal input• Most smell independent of trigeminal

nerve, but at high concentrations irritation occurs

• Patient who are anosmic notice only sweet,sour,salt & bitter & irritation.

• Irritation contributes to nature of smell

Olfaction areas of behaviour• Helps in recognizing food types & initiation

of digestion• Sexual behaviour• Territorial markings• Perception decreases with age and

neurodegenerative diseases• Olfaction is fully developed at birth, but

recognition and learning come late, probably after the age of 2 years

Physiological functions of sinuses• Vocal resonance• Dimnuition of auditory feedback• Air conditioning• Pressure damper• Reduction of skull weight• Floatation of skull in water• Mechanical rigidity• Heat insultation