Anatomy Of Nose and paranasal sinuses With ImagingAAMIR YOUSUF PG ENT

OBJECTIVESEMBRYOLOGY GROSS ANATOMY MICROSCOPIC ANATOMY IMAGING

EMBRYOLOGY IN BRIEF

The development of NOSE starts at about 4th week of gestational age. Three prominences appear around stomatodaeum(future mouth). FRONTONASAL PROCESSmesoderm covering the developing forebrain proliferates,& forms downward projection that overlaps upper part of stomatodaeum. MANDIBULAR ARCHES(Rt & Lt).arising from 1st pharyngeal arch. Mandibular arch divides into maxillary and mandibular process.

4th-5th week

The Nose is derived from frontonasal process in 4thfetal week. 5th fetal week ectodermal plaques develop on lateral aspect of FNP & become paired NASAL PLACODES,early precursors of nares. End of 5th week these convex placodes develop into concave nasal grooves, the medial & lateral sides of placodes protrudes forwards to become Medial & Lateral Nasal Process. 6th fetal week nasal grooves become blind-ending Nasal Pits with forward &downward growth of maxillary process. 7th fetal week nasal pit deepens forms Nasal Sac which forms future nasal cavity.

6th -7th week

7th-8th fetal week lateral wall of nasal capsule begins to form series of ridges of mesenchymal tissue. 1st ridge, the maxilloturbinal(7th week)INFERIOR TURBINATE. 5 to 6 ridges appear superior to 1st (8th week)through regression & fusion, these ridges 3 to 4 ethmoturbinals. 1st ethmoturbinal (nasoturbinal)aggar nasi(ascending portion)..uncinate process(descending portion). 2nd ethmoturbinal .MIDDLE TURBINATE. 3rd forms SUPERIOR TURBINATE, rest regress or join supreme turbinate.

8th week

SUMMARY OF EMRYONIC PRECURSORS

PARANASAL SINUSES

Appear as outgrowths from nasal cavity. Frontal ,maxillary,& ethmoidal sinuses arise from evaginations of lateral nasal wall. Sphenoid sinus arises from a posterior evagination of nasal capsule. The sinuses begin to develop in 3rd fetal month & only ethmoidal & maxillary sinus, are present at birth. Maxillary sinus begins as an outpounching of lateral nasal wall at 10th fetal week. Ethmoidal sinus begins at 3rd month of fetal life.

Frontal sinus develops during 4th fetal month as an outpounching medial the most superior aspect of uncinate process. Sphenoid sinus are unique in that they arise from within the nasal capsule of embryonic nose. undeveloped until 3 yrs by 7 yrs pneumatization reaches sella tursica by age 9 to 12 it is generally complete

Gross anatomyEXTERNAL NOSE............

Anatomical landmarks. Nasion : midline point at which nasal bones join the frontal bone. Rhinion : inferior point of the midline suture between nasal bones where they meet the upper lateral cartilages. Dorsum of nose: ridge formed by the union of lateral surfaces of nose in the midline. Bridge of nose: anterior surface of nose formed by the nasal bones. Columella: midline nasal soft tissue anterior to septum separating the two nares. Alae nasi: wings of nose,(rounded eminences)at the

Nasal bony framework :Is pyramidal in shape..

Nasal bones(two) articulate with the nasal process of frontal bone superiorly & with the ascending processes of maxilla laterally.

These bones are thicker superiorly than inferiorly.

Their medial articular surfaces are wider & extend poster inferiorly into nasal cavity to form crest. This crest forms part of septum & articulates with : spine of nasal process of frontal bone perpendicular plate of ethmoid septal cartilage of nose

The piriform aperture is bounded by these bones and the alveolar processes of maxilla. The alveolar processes merge in midline to form the anterior nasal spine to which cartilaginous septum is attached.

Nasal cartilages

Upper lateral cartilage Lower lateral cartilage Accessory cartilageUpper lateral (triangular) cartilage: in shape boundaries

Lower lateral cartilage (greater alar or lobular cartilage)forms the shape of nasal tip & maintains patency of nostrils. Each comprises

Medial crus Lateral crus

Nasal septum

7 components. post.sup: per. plate of ethmoid. Anteriorly: septal cartilage. membranous septum medial crus of greater alar cart. Post. Inferiorly: vomer crest of maxillary bone crest of palatine bone

Perpendicular plate of ethmoidforms upper 1/3 or more of the nasal septum Unites sup. with cribrifom plate of ethmoid. Articulates with ant.supfrontal/nasal bone postcrest of sphenoid bone post.infvomer ant.infseptal cartilage

Vomer

Post inf portion of nasal septum Articulates with

Septal (or quadrangular) cartilageIs continuous with upper lateral cartilage towards bridge of nose. Membranous septum Its inferior portion, the columella,is supported by medial crura of alar cart. This Columella is connected by membrane to lower border of septal cartilage(mobile or membranous septum). Vomeronasal cartilage Is small bar of cartilage on either side of inf border of septal cartilage.

Nerve supply of septum

Anterior ethmoidal nerve.(ant sup) Ant sup alveolar(ant inf) Nasal branch of ant palatine nerve

Blood supply of septum

Sphenopalatine artery Ant & post ethmoidal artery Facial artery Superior labial artery branch(coronary art)

Muscles of the Nose Are arranged in two overlapping layers. All innervated by facial nerve. Dilators procerus dilator naris Constrictors nasalis depressor septi

Procerus: (Pyramidalis nasi)Is continuation of frontal muscle onto the nose Is attached to nasal bones & upper lat.cartilage Actionshortens or elevates nose

Dilator naris:(Levator labii superioris) Ant/post part Dilates nostrils/pulls upper lip

Depressor septi: Inserted into septum & back part of ala Arise from incisive fossa of maxilla Action draws ala of nose downwards constricts nares

The Nasalis (Compressor naris)

transverse partalar part

Blood supply of external noseorigin.. lateral nasal branch from angular (upper part of facial or ext maxillary). dorsal nasal artery infraorbital artery external nasal artery

Nerve supply of external noseSupratrochlear & infratrochlear branches of the ophthalmic nerve supply the skin of root,bridge,upper portion of side of nose Infraorbital branch of the maxillary nerve supply the skin on side of nearly the lower half of nose Ext.nasal branch of Ant. Ethmoidal nerve skin over dorsum to

tip

Lymphatic drainage

Main Submandibular/Submental nodes Bilateral drainage & flow to the parotid nodes

Nasal cavity

Paired cavities separated by nasal septum Ant .nares or nostrils are oval shaped Post nares or choanae is oval shaped nasopharyngeal opening of the cavity. Walls of nasal cavity: Medial..septum Lateral cartilaginous,membranous,bony structure. Floorant 3/4th palatal process of maxillary bone. post 1/4th horizontal process of the palatine bone

Roofant. Nasal bone, nasal spine of frontal bone, floor of frontal sinus midportion cribrifoms plate of ethmoid post..ant wall of sphenoid sinus and bone

Subdivision of nasal cavityOlfactory region Respiratory region olfactory region:-comprises superior nasal concha & corresponding opp.septum (olfactory slit). Features .. less vascular (yellow in colour) nerve cell bodies that give rise to olfactory nerve fiber(nonmylinated) Serous glands( of bowman)

Respiratory region

Remainder of nasal cavity Covered by mucous membrane(exp.vestibule) Highly vascular with mucous & serous glands Covered by pseudo stratified columnar ciliated epithelium

Lateral nasal wallFormed by 3 or 4 conchae(or turbinates) Named from below inferior,middle,superior,supreme conchae. Meatus refers to air spaces located beneath conchae Remaining nasal cavity posterior to turbinates is nasopharyngeal meatus. Inferior turbinate/meatus Largest turbinate. Separate bone covered by thick mucous membrane Nasolacrimal opening in anterior portion of lateral wall of inferior meatus Slit like opening is protected by fold of mucous membrane, the plica lacrimalis or valve of Hasner

Middle turbinate/meatusPortion of ethmoid bone Consists of two parts Lateral lamina/lamina basilaris Medial lamina/lamina ta Lateral lamina: Post part of middle turbinate Downwards/backwards from Ant ethmoidal roof to a small crest of Palatine bone.

Medial lamina : ant part of middle turbinate Ascends upwards lining ethmoid air cells Attached to roof of ethmoid at junction of fovea with cribrifom. Most superior portion of middle meatus is inferior to genu known as frontal recess..Ostia of frontal sinus and some ant ethmoidal cells are located here. Rest of middle meatus posteroinferiorly contains ethmoidal bulla uncinate process semilunar hiatus

Uncinate process:

Crescent shaped bone curved downward/backwards Variation of attachment lamina papyracea cribrifom plate middle turbinate Concha bullosa:(36%) Aerated middle turbinate/unilateral or bilateral May obstruct middle meatus osteomeatal complex(sinusitis) May get infected form mucocele

Paradoxical middle turbinate:

Greater curvature of middle turbinate is concave to middle meatus

Double middle turbinate:

Anteriorly bent UP may come in contact with middle turbinate Narrows middle meatus & appear as additional turbinate

Superior turbinate/meatus

Is appx. length of middle turbinate Starts about midde of lower turbinate & becomes continous with tham Sphenoethmoidal recess lies between superior & supreme turbinate supreme turbinate Unilaterally or bilaterally in 60% of individuals Ostia of pos. ethmoidal cells open into supreme meatus(75%)

Paranasal sinuses

Paranasal sinuses are air filled spaces in skull bones lined by mucosa and drain into nasal cavity.

Frontal sinusSeen in frontal bone Two sinuses are rarely symmetrical Dimensionsheight(28-32mm) width(24-26mm) depth(18-20mm) volume(6-7ml) May have septa which partially subdivide the cavity & interfere with drainage.

Bent and Kuhn classification of frontal cells. Type1single frontal recess cell above the agger nasi cell, but below the frontal sinus Type11tier of more than one cell in frontal recess above the agger nasi cell, but below the frontal sinus Type111large single cell pneumatizing cephaloid into frontal sinus Type1Vsingle isolated cell within the frontal sinus

Opening of the frontal sinus Drainage into frontal recess anterior to the infundibulum(55%) Drainage above but not into the infundibulum(30%) Drainage into infundibulum(15%) Drainage above the bulla(1%)

Blood supply of frontal sinus Supraorbital artery Supratrochlear artery Venous drainage Small vein that unites the Supraorbital and Superior ophthalmic veins. Nerve supply Supraorbital nerve(ophthalmic nerve) Supratrochlear nerve(ophthalmic nerve) Lymphatic drainage Submandibular nodes

Ethmoidal sinusesEthmoid means sieve like Ethmoid is trapezoid box narrow/taller anteriorly wide posteriorly(4-5cm AP 2-3cm high width 0.5cm ant/1.5cm p) Multiple air containing cells situated in ethmoidal labyrinth(3-18)

Boundaries of ethmoidal sinus

Classification of ant ethmoidal cells

Anterior group-(drains middle meatus) Middle group(drains-middle meatus) Posterior group(drains-superior meatus)

Bagatella et al classification of ant. group of cells pre infundibular group(0-1)agger nasi cells Lateral infundibular group(0-2) Post infundibular group(0-2) Bullar cells(2-5) Posterior ethmoidal cells Intramural cells Extramural cells Onadi cells posterior ethmoidal cells seen just in front of sphenoid Haller cell..ant ethmoidal cells seen anteriorly & below the orbit.

Blood supply of ethmoid sinus

Anterior ethmoidal artery(ophthalmic artery) Post. Ethmoidal artery Sphenoidal artery(maxillary artery)

Venous drainage

Nasal veins Ant. Ethmoidal vein Post. Ethmoidal vein

Nerve supply

Ant ethmoidal nerve Post etmoidal nerve Maxillary branch of trigeminal nerve

Lymphatics

ant.& middle ethmoidal cells-submandibular group Post ethmoidal retropharyngeal nodes

Sphenoidal sinus

Sphenoid means wedged(frotal,temporal,occipital) Right & left are rarely symmetrical in shape Pneumatization may extend into body of sphenoid bone pterygoid process basilar portion of occipital bone nasal septum/perpendicular plate of ethmoid Dimensions (L..4-44mm)( w..25-34mm)(h.. 533mm) volume (7.5ml)

Boundries Suppituitary/optic chisma LatICA/optic nerve/venous cavernosis Postbrain stem/basilar artery Floorvidian nerve

Types on basis of pneumatisation1.

conchal(3%)

2.

Presellar(11%)

Postsellar(86%)

Blood supply

Posterior ethmoidal artery(roof of sinus) Sphenopalatine artery(floor of sinus)

Nerve supply

Trigeminal (1/11 div)

Lymphatics

Retropharyngeal nodes

Maxillary sinus

Antrum of Highmore Largest pns/ pyramidal cavity in maxillary bone Dimensions : height(3.3cm) width(2-3cm) ant.post(3-4cm) volume(15ml)

Boundries

Ant..surface of maxilla Postinfratemporal fossa Medlat.wall of nasal cavity Supfloor of orbital cavity Inferioralveolar & palatine process of maxilla

Maxillary Ostia

3-4mm in diameter Post part of medial wall Drains into middle meatus through ethmoidal infundibulum

Accessory ostium: when present seen post to natural ostia Almost always circular Easily seen during endoscope Myerson1932-31%

Blood supply

Facial artery Infraorbital artery Greater palatine artery Sphenopalatine artery

Nerve supply

Greater palatine nerve Post lateral nasal nerves Superior alveolar (infraorbital nerve)

Microscopic anatomyHistological basis nasal cavity is divided into three: vestibular region(1-1.5cm) respiratory region olfactory region vestibular region: lined by keratinized stratified sq. epithelium,hair,sebaceous glands.

Respiratory region

Olfactory region

IMAGING OF NOSE & PNS

Plain sinus radiography Computed tomography Magnetic resonance imaging

Radiographic positions to study the paranasal sinuses are standardised around three positions: 1. Two anatomical - namely coronal and sagittal 2. One radiographic - termed as radiographic base line.. The various radiographic positions used to study paranasal sinuses are: 1. Occipito-mental view (Water's view) 2. Occipital-frontal view (Caldwell view) 3. Submento-vertical position (Hirtz position/jug handle) 4. Lateral view

FRONTAL

SINUS

sinus watersORBIT

view/occipETHMOID SINUS

itomental viewMAXILLARY SINUS

Infra orbital margin

Sinus Caldwell viewFRONTAL SINUS

ORBIT SPHENOID BONE

INFERIOR TURBINATE

MASTOID AIR CELLS

HARD PALATE

MANDIBLE

Lateral skull

CORONAL SUTURE

FRONTAL SINUS

FLOOR OF CRANIAL FOSSA

ETHMOID SINUS

MASTOID AIR CELLS

LAMBDOID SUTURE

MAXILLARY SINUS

HARD PALATE

SubmentoverticalMAXILLARY SINUS ETHMOID SINUS

LAT. PTYERGOID PLATE

EXT. AUDITORY CANAL

CT nose /pns/coronal

ct sinus axial view

Ct scan axial view

MAXILLARY SINUS

ct scan sinus axial view

ETHMOID SINUS

coronal cuts sinus

INFERIOR TURBINATE

Coronal view Of sinus

SPHENOID SINUS

coronal cut CT sinus

MRI nose/pns

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