anatomy and physiology of nose and paranasal sinuses

ANATOMY & PHYSIOLOGY

OF NOSE ANDPARANASAL

SINUSESBRIG ANWAR UL HAQ00923018513303

PAKISTAN

ANATOMY OF NOSEEXTERNAL NOSE

• Osteocartilagenous framework: Upper 1/3rd - BonyLower 2/3rd – Cartilagenous

• Bony frameworka) Nasal bonesb) Nasal processes of frontal bonec) Frontal processes of maxilla

APPLIED ANATOMY• Dangerous area of face- The lower part of

external nose and the upper lip. Infection may spread to cavernous sinus through inferior ophthalmic vein via anterior facial vein which have no valves

• Dangerous area of nose- olfactory area Infection may spread into meninges along the pia and arachnoid sheath of olfactory nerves. This area is also connected to superior sagittal sinus and cavernous sinus by venous channels

ANATOMY OF NOSEEXTERNAL NOSE• Cartilagenous frameworka) Upper lateral cartilagesb) Lower lateral cartilages (alar cartilages)c) Lesser cartilages (sesamoid cartilages)d) Septal cartilage

Clinical significance: limen nasi (nasal valve) is the narrowest area in the upper airway

ANATOMY OF NOSEEXTERNAL NOSE

• Nasal valve: Formed by lower edge of upper lateral cartilages, the anterior end of inferior turbinate and adjacent nasal septum.

• Cottle’s test: used in nasal obstruction due to abnormality of nasal valve.

ANATOMY OF NOSEEXTERNAL NOSE

• Nasal musculature:a) Procerusb) Nasalis (transverse and alar part)c) Levator labi superioris alaque nasid) Anterior and posterior dialator narise) Depressor septiNasal skin: skin over nasal bone and upper

lateral cartilage is thin and freely mobile while that on alar cartilages is thick and adherent and contains sebaceous glands

ANATOMY OF NOSEEXTERNAL NOSE

• Blood supply: – facial and ophthalmic arteries and

veins• Lymphatic drainage:

– preauricular– submandibular lymph nodes

ANATOMY OF NOSEINTERNAL NOSE

• It is divided into right and left nasal cavities by nasal septum.

Each nasal cavity consists of a) Skin lined portion-vestibule (contains

sebaceous glands, hair follicles, vibrissae)b) Mucosa lined portion-nasal cavity proper

ANATOMY OF NOSEINTERNAL NOSE

• Nasal cavity proper: bounded by lateral wall, medial wall, roof and a floor.

• Floor: Formed by– Palatine process of maxilla (anterior 3/4th )– Horizontal process of palatine bone (posterior

1/4th )

ANATOMY OF NOSEINTERNAL NOSE

• Roof: formed by– Anterior sloping part by nasal bones– Posterior sloping part by body of sphenoid– Middle horizontal part by cribriform plate of

ethmoid through which olfactory nerves enter the nasal cavity

ANATOMY OF NOSEINTERNAL NOSE

• Medial wall of nasal cavity (nasal septum)

ANATOMY OF NOSEINTERNAL NOSE (Septum)

• Nasal septum consists of three parts a) Columellar septumb) Membranous septum (lies between columella and

caudal border of septal cartilage)c) Septum proper: consists of osteocartilagenous

framework covered with nasal mucous membrane

ANATOMY OF NOSEINTERNAL NOSE(Septum)• Septum proper: principal constituentsa) Perpendicular plate of ethmoid postero-

superiorlyb) Vomer infero-posteriorlyc) Septal cartilage (quadrilateral cartilage)• These articulate with following bones to

complete the septum a) Superiorly-frontal bone, nasal bone,

rostrum of sphenoid.b) Inferiorly anterior nasal spine of maxilla,

nasal crest of maxilla and palatine bones

BLOOD SUPPLY-NASAL SEPTUM

• Little’s area: Situated in the antero-inferior part of nasal septum just above the vestibule. Four arteries-– anterior ethmoidal– septal branch of superior labial– septal branch of sphenopalatine– greater palatine

• anastamose here to form kiesselbach’s plexus.

BLOOD SUPPLY-NASAL SEPTUM

NERVE SUPPLY-NASAL SEPTUM

ANATOMY-LATERAL WALL OF NASAL CAVITY

ANATOMY-LATERAL WALL OF NASAL CAVITYa) Ascending process of maxillab) Nasal bonec) Ethmoidd) Medial part of maxillae) Inferior turbinatef) Perpendicular plate of palatine boneg) Medial pterygoid plate

ANATOMY-LATERAL WALL OF NASAL CAVITY• Three bony projections

– turbinates or conchae-• Superior (part of ethmoid) • Middle (part of ethmoid)• Inferior (separate bone)

• Sometimes 4th turbinate concha suprema

• Bellow and lateral to each turbinate – corresponding meatus

ANATOMY-LATERAL WALL OF NASAL CAVITY• Inferior meatus-

– nasolacrimal duct opens in its anterior part.• Middle meatus-

– consists of bulla ethmoidalis, hiatus semilunaris, infundibulum. Frontal, maxillary and anterior ethmoidal sinuses open into middle meatus.

ANATOMY-LATERAL WALL OF NASAL CAVITY• Superior meatus-

– Posterior ethmoidal sinuses• Sphenoethmoidal recess-

– Sriangular fossa above the superior meatus.– Sphenoidal sinus

ANATOMY-LATERAL WALL OF NASAL CAVITY

BLOOD SUPPLY-LATERAL WALL OF NASAL CAVITY

NERVE SUPPLY-LATERAL WALL OF NASAL CAVITY

AUTONOMIC NERVE SUPPLY- NASAL CAVITY

• Sympathetic supply- – Superior cervical sympathetic ganglion – Internal carotid plexus – vidian nerve – sphenopalatine ganglion.

AUTONOMIC NERVE SUPPLY- NASAL CAVITY

• Parasympathetic supply- – facial nerve – greater superficial petrosal nerve – vidian nerve – sphenopalatine ganglion.– Nasal branches from sphenopalatine ganglion

SENSORY NERVE SUPPLY-NASAL CAVITY• Common sensation

– Trigeminal nerve • ophthalmic • maxillary divisions.

• Special sensory (smell) – Olfactory nerves.

LYMPHATIC DRIANAGE-NASAL CAVITY

• Upper deep cervical nodes drain the nasal cavity directly or via the retropharyngeal nodes.

PARANASAL SINUSES-ANATOMY

• These are air filled spaces• Certain bones of skull• Direct communication with nasal cavity

through their ostia• Four on each side divided as

PARANASAL SINUSES-ANATOMY

a) Anterior group- a) Maxillaryb) Frontalc) Anterior ethmoidal

b) Posterior group- a) Posterior ethmoidb) Sphenoid

Development of Sinuses• Outpouching from mucus membrane of

nose• at birth:-Maxillary and ethmoidal present• At 6-7 yrs:- frontals and sphenoids• At 17-18 :- all full developed

Drainage

Objectives• To know anatomical location• Their connections & significance• Development• Neurovascular supply• Applied anatomy

Introduction

• Air containing cavities.

• Each sinus are named after the bone it resides in.

• 4 pairs :-• frontal • maxillary, ethmoidal,

sphenoidal

Lateral view

Anterior view

Maxillary sinuses

• Largest PNS• Pyramidal shape • Base pointing to

lateral wall of nose• Apex laterally in

the zygomatic process

• Capacity 15 ml

Relations • Anterior:-– Facial surface of

maxilla• Posterior:

– Infratemporal and pterygopalatine fossa

• Medial:- – Middle and inferor

meatus• Floor:-

– Alveolar and palatine processes of maxilla

• Roof:-– Floor of orbit

BLOOD SUPPLY MAX SINUS• Blood supply :

– Facial– infra orbital– greater palatine arteries.

• Lymphatic drainage : – Submandibular nodes.

• Nerve supply : – Infra orbital, anterior– middle and post superior alveolar nerves

Frontal sinus • Resides in frontal bone

• 2nd largest• Asymmetrical• Usually paired-

sometimes one, three or none!

Relations -Frontal Sinus• Anterior:-

– Skin over the forehead

• Inferior:-– Orbit & its contents

• Posterior:- – Meningeal and frontal lobe

of brain

Neurovascular supply• Blood supply –

– Supra orbital arteryAnterior ethmoidal arteries.

• Venous return –– Anastomotic veins in supra orbital notch, connecting

supra orbital and supra ophthalmic veins.

•  Lymphatic drainage – – Submandibular nodes.

• Nerve supply – – Supra orbital nerve traversing the floor of the sinus.

Ethmoidal sinuses• Resides in ethmoid

bone• 3 groups:-

– anterior – Posterior– sphenoethmoidal

recess• Number varies from

3-18• Present from birth

Relation(Ethmoids)

• Roof:- – anterior cranial fossa

• Lateral:- – orbit (separated by

lamina papyracea)• Optic nerve lies close

to posterior ethmoidal cells

Neurovascular supply(Ethmoids)• Blood supply :

– Sphenopalatine artery Anterior and posterior ethmoidal artery.

• Lymphatic drainage :– Submandibular nodes

Retropharyngeal nodes. 

• Nerves : – Anterior and posterior ethmoidal

nerves.Orbital branches of pterygopalatine ganglion..

OSTEOMEATAL COMPLEX• The middle meatus

– Space below and lateral to the middle turbinate,– Functionally referred as osteomeatal complex– Drainage pathways

• Anterior ethmoids• Maxillary • Frontal sinuses.

• The middle meatus – Pathophysiology of chronic rhinosinusitis.

OSTEOMEATAL COMPLEX-RELATED STRUCTURES

• Bulla ethmoidalis- The ethmoid bulla is one of the most constant and largest of the anterior ethmoid air cells. It is located within the middle meatus directly posterior to the uncinate process and anterior to the basal lamella of the middle turbinate.

OSTEOMEATAL COMPLEX-RELATED STRUCTURES

• Hiatus semilunaris- Hiatus semilunaris is a crescent shaped gap between the posterior free margin of the uncinate process and the anterior wall of the ethmoid bulla, through this passage the middle meatus communicates with the ethmoid infundibulum .

OSTEOMEATAL COMPLEX-RELATED STRUCTURES• Ethmoidal infundibulum - Ethmoidal

infundibulum is the funnel-shaped passage through which the secretions from various anterior ethmoid cells, the maxillary sinus, and, in some cases, the frontal sinus are transported or channeled into the middle meatus.

OSTEOMEATAL COMPLEX-RELATED STRUCTURES• Uncinate process- floor and medial wall of

infundibulum is formed by the uncinate process of the ethmoid. This structure is nearly sagittally oriented, nearly paralleling the ethmoidal bulla. It is approximately 3 to 4 mm wide and 1.5 to 2 cm in length.

Sphenoid sinus

• Resides in body of sphenoid

• Paired• Asymmetrical• Not present at birth

Relation(Sphenoid)• Lies below to sella turcica• Sphenoid effusion shows skull base fracture• Related to

– optic tractchiasma– internal carotid artery

Sphenoid Sinus• Blood supply :

– Posterior ethmoidal artery.• Lymphatic drainage

– Retropharyngeal nodes.• Nerve supply :

– Posterior ethmoidal nerve.

Microscopic Anatomy

• Lined by mucus membrane

• Ciliated columnar epithelium

• Goblet cells secretes mucus

• Cilia are more marked near ostia.

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Introduction• organ of smell• Organ of respiration• It warms, cleans and humidifies the

inspired air, cools and remove the water from the expired air

• It also adds quality to speech production

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Introduction• The ENT surgeon should distinguish

normal nasal function from pathological symptoms to prevent unnecessary surgery

• Although the nose is a paired structure divided coronally into two chambers, it act as a functional unit

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Function Mechanism

Respiration

Heat exchangeDirection of blood flowLatent heat of evaporationThermoregulation

HumidificationAnterior serous glandsMixed serous and mucus glandsCapillary permaebilityOther body fluids; e.g. tears

Filtration Airflow pattern: laminar/turbulent

Nasal resistance Anatomical, fixedNeurovascular, variable

Nasal fluids and ciliary fuction

Mucus, mucinsProtein including immunoglobulinsCiliary structure and function

Nasal neurovascular reflexes

ParasympatheticSympatheticSensory: axon reflexesSneezingCentral: pulmonary reflexesNasal cycle

Voice modification Nasal escape63

Olfaction

Stimulus Threshold and suprathresholdAdaptation, discrimination and classification

Pathways Neurones in contact with the external environmentTwo neurone peripheral pathway

Higher centresPerceived smell

Trigeminal input PainOlfaction and behaviour Pheromones

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Respiration• Air conditioning unit • Humidification• Heat transfer

– Temperature regulation• Filtration

– Inspired gases contain pollutants, domestic dust particles and pollen, industrial products, bacteria, viruses and tobacco smoke

• Bypasses during exercise• Temperature regulation

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I. Heat Exchange• Inspired air

– Vary from -50 to 50oc

Conduction, convection and radiation• Conduction occurs without flow when heat

is transferred by increased molecular movement

• A temperature gradient leads to convection of currents affect airflow in the nose turbulence

• Flow results in forced convection66

II. Humidification• Vaporization cools the surface • 10 percent of the body heat is lostInspiration• Saturation follows the temperature rise

rapidly

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II. Humidification• Energy required for:

– raising the temperature of inspired air (1/5)– The amount of energy is dependent on ambient

temperature and relative humidity of an inspired air

– Heat of evaporation (4/5)• 10% of body heat loss occurs through the

nose in humans• Air in post nasal space is approximately 31oC

and is 95% saturated2

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Expiration • expired air at the back of the nose

– slightly below body core temperature– saturated

• Some water condenses into the mucosa as the temperature drops along the nose

• The temperature in the anterior nose at the end of the expiration is 32oC and approximately 30oC at the end of inspiration

• Approximately 1/3rd of the water required to humidify the inspired air is recovered in this way

• People who breathe in through the nose and out through the mouth will dry the mucosa

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Water production• Water comes from the serous gland, which are extensive

throughout the nose• During nasal cycle, secretions are lower on the more

obstructed side• Additional water comes from the expired air, the

nasolacrimal duct and the oral cavity• Humidification is reduced by atropine probably acting on

the gland rather than the vasculature3

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III. Airflow• The airflow and the sensation of it are very different• Cold receptors sense airflow• Most of the work of heat and mass transport has

been performed on simple structures with constant cross sections.2

• The flow is turbulent, but is considered laminar at rest• The equations below describe flow, two for laminar

and one for the transition to turbulent flowAirflow : VA = constant

Bernoulli’s equation : P + ½ ρV2 = constant

Reynolds number : Re =

ρ = density (g m-1); V = velocity (m sec-1); A = cross-sectional area (m2); P = pressure (N m-2); d = diameter (m); ƞ = viscosity (g sec-1 m-1) 71

dVρƞ

• Gases flow faster through the choana4

• The characteristic of air flow were similar in different noses regardless of variety of nasal shape

• The cross-sectional flow is maximal at the centre and is zero at the edge

• Bernoulli equation is not strictly applicable since the energy overcoming the viscosity results in an irreversible drop in pressure

• The nose has variable cross section – the pressure and velocity will alter continuously within the system

• Because of the flow is turbulent in an irregular tube, the resistance is inversely proportional to the square of the flow rate5

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Inspiration• Airflow is directed upwards and backwards from the

nasal valve initially, mainly over the anterior part of the inferior turbinate

• It then splits into two, below and over the middle turbinate, rejoining into posterior choana

• Air reaches the other parts of the nose to a lesser degree• The velocity at the anterior valve is 12 - 18 m per sec

during quiet respiration

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Expiration• Expiration lasts longer than inspiration

and is more turbulent• Extrapulmonary airflow is turbulent

because of the direction changes, the calibre varies markedly and walls are not smooth. The surface area is enlarged by the turbinates and the microanatomy of the epithelium

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Nasal resistance• Differs between races• The nose accounts for up to half of the total

airway resistance• Produced by two resistors

– fixed: bone, cartilage and muscle– variable: mucosa

• High in infants (obligatory nose breathers)• Adult breath preferentially through the nose at

rest even though there is a significant resistance

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The anterior nasal valve• Narrowest part of the nose and less well defined

physilogically then anatomically• Greatest resistor – produces the most turbulent

airflow• Formed by the

– lower edge of the upper lateral cartilages– anterior end of inferior turbinate– adjacent nasal septum– surrounding soft tissues

• EMG – – contraction of the dilator naris – increases during exercise

• Alar collapse occurs after denervation77

Nasal cycle• alternate nasal blockage between passages• The changes are produced by vascular activity

particularly the volume of blood on the venous sinusoids (capasitance vessels)

• Cyclical changes - 4 to 12 hours• Can be demonstrated in over 80% of adults• Difficult to demonstrate in children• Nasal secretions are also cyclical with an

increase in secretions in the side with the greatest airflow3 78

Factors modify the nasal cycle• allergy• Infection• Exercise• Hormones• Pregnancy• Fear• Emotions• sexual activity• Vagal overactivity• Puberty

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•Sympathomymetic•Parasympathetic

IV. Protection of Lower Airway: Mechanical and Chemical

• Removing particles - 30 μm, – pollens from the inspired air

• Dust deposited in the nose• Inspired air travels through 180o and velocity drops

markedly just after the nasal valve• Turbulence increases deposition of particles• Particles in motion - carry on in the same direction• Resistance to change in velocity is greater in irregular

particles because of larger surface area and the number of facets

• Vibrissae will only stop the largest particles80

Nasal secretions• Composed of :–

– Mucus – Water– Glycoprotein – goblet cells– Water and ions –– Submucosal glands– Serous glands

• The anterior part of the nose

• Sinuses has fewer goblet cells and mixed glands

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Proteins in nasal secretion1. Lactoferrin

– Serous gland– Bind divalent metal ions – like transferrin in

the circulation– Lactoferrin and transferrin

• Prevent growth of certain bacteria,• Staphylococcus and pseudomonas

2. Lysozymes– Serous glands and tears– Act only on non capsulated bacteria

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3. Antiproteases– Produced by leukocytes– Increase with infection

4. Complement– C3 – produced by liver and locally by macrophages– Functions: lysis of microorganism, enhancing neutrophil function

(leukotaxis)

5. Lipids6. Ions and Water

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CiliaUltrastructure• Found on the surface of cells in the respiratory

tract• Function: to propel mucus backwards• All cilia have the same ultrastructure • Nasal cilia - relatively short at 5 μm, • Nasal cilia - with up to 200 per cell• 9 paired outer microtubules surround a single

inner pair of microtubules85

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FACTORS AFFECTING CILIARY ACTION

• Drying stops the cilia• Temperature below 10oC and above 45oC• Solutions above 5 % and below 0.2%• pH below 6.4 and above 8.5• Upper respiratory tract infection – damage the epithelium• Ageing

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FACTORS AFFECTING CILIARY ACTION

DRUGS• Acetylcholine - increases the rate• Adrenaline - reduces the rate• Propanolol – reduces the rate• Cocaine hydrochloride (>10%) – causes

immediate paralysis• Corticosteroids – reduces the rate

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V. Protection of Lower Airway: Immunological• IgA • IgE• IgM • IgG• Certain bacterial allergens are neutralized• The T and some B cells interact with microphages, • Dendritic cells are important in the allergic response• cytokines • Leukotrines

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VI. Vocal Resonance• Nose form resonating chamber for certain

consonants in speech• Phonating nasal consonants (M/N/NG) – • Many nasal condition affect the quality of

voice by blocking the passage of air• Rhinolalia clausa – too little air escapes

from the nose• Rhinolalia aperta – too much air escapes

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VII. Olfaction• Olfactory compound need high water and lipid

solubility• The solute in the mucus is presented to the

sensory mucosa

Olfactory area • Area: 200-400mm2

• Receptor cells

StimulusReact with lipid bilayer of the receptor cells at specific sites cells depolarization 91

Adaptation• Olfactoy responses show marked adaptation

and thresholds increase with exposure• Adaptation

– peripheral – central phenomenon

• Cross adaptations

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factors affecting threshold:• Changes in nasal mucus and its ph• Age – decreases the threshold • Hormones (sex hormones) – increases the

threshold

Olfactory pathways• Olfactory region (high up in nasal cavity)• Olfactory cells and cillia• Central process - olfactory nerves • Pass through the cribriform plate • Olfactory bulb• Olfactory tract • Prepyriform cortex • Amygdaloid nucleus where it reaches consciousness

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Disorders of smell• Anosmia: total loss of smell• Hyposmia: partial loss• Parosmia: perversion of smell –

– Interprets the odour incorrectly– Seen in

• Recovery phase of post influenzal anosmia,• Intracranial tumour

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Conclusion• An understanding of the physiology of the nose

is required to:– Evaluate nasal symptoms– Know its protective role in

• Health • Disease

– Determine the role of investigations in the assessment of airway function and mucociliary clearence

– Understand the action of drugs - nasal mucosa– Assess the smell and taste

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