DR PRIYANKA

EMBRYOLOGY

OSTEOLOGY OF NOSE

MAXILLA

FRONTAL ( UNPAIRED )

ETHMOID ( “ )

SPHENOID ( “ )

INFERIOR TURBINATE

LACRIMAL

PALATINE

NASAL BONES

Sphenoid bone

Bone spanning the width of middle cranial fossa

Consists of central body and three processes; greater and lesser wings and pterygoidprocess (pos. view)

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Sphenoid Bone (Floor of Cranium) (Green Colored Bone)

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Maxilla

The largest bones of the face, except for the mandible and form, by their union, the whole of the upper jaw.

Each assists in forming the boundaries of three cavities, namely, the roof of the mouth, the floor and lateral wall of the nose, and the floor of the orbit.

Zygomatic, frontal, palatine and alveolar process Landmarks:

Infra Orbital foramen: hole below the orbit, for blood vessels and nerves

Alveolar process: arch of the maxilla containing the upper teeth

Palatine process: horizontal projection of the maxilla forming the anterior ¾ of the hard palate.

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Maxilla

Lacrimal canal : groove posterior to frontonasalprocess, lacrimalbone and lacrimalprocess of inferior turbinate

Infraorbitalforamen

Greater palatine canal

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Ethmoid Bone An irregularly shaped, spongy bone that provides the floor of the front part

of the skull and the roof of the nasal cavity.

The ethmoid consists of two masses of thin plates enclosing air cells and looks like a sieve.

Landmarks:

Lateral masses: form most of the wall between the nasal cavity and the orbits

Perpendicular plate: forms the superior portion of the nasal septum

Cribiform plate: forms the roof of the nasal cavity

Olfactory foramina: small holes within the cribiform plate for passage of the first cranial nerve (for smell)

Crista galli: upward extension of bone above the cribiform plate, acts as an anchoring point for one of the coverings of the brain.

Nasal concha (turbinates): two scroll-shaped projections with a mucus membrane on either side of the nasal septum. Function to cause air turbulence and trap inhaled particles.

Ethmoid bone - landmarks

Cribiform plates Forms roof of nasal

cavity, fits into the notch in frontal bone, foramina : olfactory nerve

Horizontal and vertical lamella lamella

Crista galli Attachment of the

dura mater which secures brain in cavity

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Nasal Bones

Bridge of nose

Internal surface : groove for anterior ethmoidal nerve

Superior border articulates with frontal bone

Lateral border : frontonasal process of maxilla

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Lacrimal BonesSmallest and most

fragile bone of the

face

Contains the lacrimal

sac and the naso-

lacrimal duct.

Orbital surface : posterior lacrimalcrest

Btwn anterior and posterior lacrimalcrest : lacrimal sac

Lacrimal bone

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Palatine bones

Fragile L shaped bone

It contributes to the

walls of three

cavities: the floor

and lateral wall of

the nasal cavity,

the roof of the

mouth, and the

floor of the orbit

Horizontal plate

Posterior section of hard palate

Perpendicular plate

Part of the posterolateralwalls of nasal cavity

Greater palatine canal

Orbital surface

Part of inferior medial aspect of orbit

Processes :

Orbital process

Sphenoid process

Between the two : sphenopalatine notch

Pyramidal process

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Inferior Nasal Conchae

Extends horizontally

along the lateral wall

of the nasal cavity

and consists of a

lamina of spongy

bone, curled upon

itself like a scroll.

Inferior Nasal Conchae

NOSE Consists of:

External Nose

Nasal cavity

The external nose :

Is a pyramidal projection

of face

tip

Root

dorsum

ala of nose bounding inferiorly a pair of nostrils

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EXTERNAL NOSEOsteocartilaginous

framework:

Bony pyramid –upper 1/3rd

Cartilaginous part –

lower 2/3rd

(Upper & lower

cartilaginous vault)

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BONY VAULT Formed by Nasal bones and frontal

process of maxilla

Paired nasal bones, each one is tapered, thin and bevelled below but gradually thickens upwards encroaching upon the nasal cavity

Two nasal bones form a crest in midline

Articulates

Upwards with nasal spine of frontal & perpendicular plate of ethemoid

Laterally with frontal process of maxilla (is thick below n thin above) by nasomaxillary suture

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Cartilaginous vault

UPPER CARTILAGENOUS VAULT Paired, Triangular ULC and part of

septal cartilages enclosed in common perichondrial sheath

Base at septum, Apex at pyriform fossa

Cephalic attachment to nasal bones Nasal bones overlap over ULC 1cm Held in place with intimate fusion

b/w perichondrium and periostium

Medial borders are thick and continuous with dorsal border of septal cartilage.

Laterally ULC are short of pyriform edge of maxilla, the gap is filled by dense fibrofatty tissue (empty triangle)

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Lowermost part of nasal fossae, bounded superiorly by caudal edge of ULC is vestibule.

Lined by thin skin having coarse hairs and sebaceous , sweat glands.

Internal nasal valve-triangular area bounded lat by caudal edge of ULC ,septum medially, nasal cavity floor inf,is narrowest part of nasal cavity

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LOWER CARTILAGENOUS VAULT Paired alar cartilages (few sesamoid

cartilages)

can move freely over ULC and septal

Contribute to formation of lobule, columella and ala.

Each one made up of single piece of C-shaped cartilage ,having parts medial, middle and lateral crura

Lateral crus - 1 mm in thickness

Starts at domal segment and arch outwardly convex

• Middle crus-

from columella to lateral crus

Divided into domal and lobular segment

Medial crus-

It starts at footplate and extends into columella

lies under the thin skin of columella and two med crura are attached by fibrous tissue and to lower end of septum by membranous septum

COLUMELLA Extends between upper lip and

tip of the nose Divided into three almost equal

parts , upper –lobular, middle and basal part –wider

Consist of paired medial crura with covered skin, variable length of crura may produce projecting or depressed tip

Anteriorly- diverging crura form an angle of 30 degrees for tip formation.

Posteriorly - also diverge to receive post septal angle, adjoining septal cartilage and anterior nasal spine.

Shape of columella depends on size and shape of medial crura.

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SOFT TISSUE COVERING Nasal skin : thick over-nasion,

supratip area and thin at rhinion over lower firmly adherent to

cartilages over nasal bones and ULC is mobile

Subcutaneous tissue covering thickens gradually downwards from rhinion: has 4 layers

1. Superficial panniculus2. Fibromuscular layer3. Deep fatty layer4. Periosteum/ perichondrium

Incisions in rhinoplasty are given deep to all these layers since blood vessels run in deep fatty layer.

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NASAL MUSCULATURE

Elevators: Procerus Levator labii

superioris alaquenasi

Depressors: Alar part of nasalis Depressor septiCompressor: Tranverse part of

Nasalis Compressor narium

minor Dilators:

dilator naris

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ARTERIAL SUPPLY

Dorsal and external nasal branch of ophthalmic artery

Infra orbital br. of maxillary artery

Lateral nasal and angular br. of facial artery

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Venous drainage

•External veins of nose drain to angular and opthalmic veins

NERVE SUPPLY TO EXTERNAL NOSE

Sensory supply:

By branches of ophthalmic and maxillary div. Of trigeminal

infra trochlear branch-skin of root and adjacent sides of nose

infra orbital, external nasal nerve- skin of lower half of nose

terminal branches of palatine nerves – skin of base of columella

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NERVE SUPPLY TO INTERNAL NOSE

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NASAL SEPTUM NASAL SEPTUM HAS 3 PARTS :

COLUMELLAR : Columellar septum. It is formed of

columella

Containing the medial crura of alar cartilages united

together by fibrous tissue and covered on either side by

skin.

Membranous septum. It consists of double layer of skin

with no bony or cartilaginous support. It lies between the

columella and the caudal border of septal Cartilage. Both

columellar and membranous parts are freely movable from

side to side.

Septum proper. It consists of osteocartilaginous

framework, covered with nasal mucous membrane.

Cartilagenous portion composed of quadrilateral cartliage,

contributions from lower and upper lateral cartilages.

Bony septum : mainly by perpendicular plate of

ethmoid and vomer

Minor contributions : crest of nasal bone

nasal spine of frontal bone

rostrum of sphenoid

crest of palatine bone

crest of maxilla

anterior nasal spine of maxilla

Bony septum: perpendicular plate of ethmoid forms

the superior and anterior bony septum, which is

continuous above with the cribriform plate and crista

galli.

Vomer defined as keel shaped bone, extends anteriorly

from spenoid and superiorly from nasal crest of

maxilla and palatine bone.

forms the posterior and inferior nasal septum and

articulates by its two alae with the rostrum of sphenoid

creating vomerinovaginal canals which transmit

pharyngeal branches of maxillary artery.

The upper margin expands which is connected to the upper lateral cartilages.

Bound firmly by collagenous fibres to the nasal bones And to the perpendicular plate of the ethmoid and vomer

Inferior border of vomer articulates with nasal crest formed by maxillae and palatine bones.

Anterior border articulates with perpendicular plate of ethmoid and septal cartilage inferiorly.

Posterior border forms the free edge

LATERAL WALL OF NOSE

The lateral wall of nose:

Maxillary bone

Ethmoid bone

Sphenoid bone

Inferior turbinate

Lacrimal bone

Palatine bone

The nasal turbinates are embryologically derived from a series of outgrowths from the foetal lateral nasal wall.

The outgrowths form a series of ridges, referred to as “ethmoturbinals” which are separated by furrows.

Each ridge has an anterior ascending portion and a posterior descending portion.

The uncinate process develops from the descending portion of the first ridge, which is also known as the “nasoturbinal”

The agger nasi develop from its ascending portion.

The second ridge forms the bulla lamella, or the bulla ethmoidalis when pneumatized.

The middle turbinate develops from the third ridge, which is the first permanent ethmoturbinal.

The fourth ridge, the second permanent ethmoturbinal, forms the superior turbinate.

Based upon this, variations in development and pneumatization of the ethmoturbinalsmay lead to anatomical variations within the bony structures of the ethmoidal complex.

Nasal turbinates:

The turbinates are the most prominent feature of the lateral nasal wall . They are usually three or sometimes four in number. These turbinates appear as scrolls of bone, delicate, covered by ciliated columnar epithelium. These turbinates sometimes may contain an air cell, in which case it is termed as a concha.

Inferior turbinate, meatus

Largest turbinate and largest meatus

Highest at the jnctn of ant and middle 3 rd (1.6-2.3 cm)

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/meatus

Portion of ethmoid bone

It recieves drainage from the frontal, maxillary and antethmoidal cells

hiatus semilunaris and ethmoid infundibulum.

maxillary hiatus.

ant and post fontanelles

recesses terminalis

MIDDLE MEATUS

Infundibulum – Air passage

connecting the maxillary sinus

ostium to middle meatus

Hiatus Semilunaris – Gap

between the uncinate process

and bulla ethmoidalis. Medially

it communicates with middle

meatus. Laterally & inf it

communicates with

infundibulum

Middle turbinate

3 parts

Anterior 1/3rd : saggital plane : cribriform plate at the junction of medial and lateral lamella

Middle 1/3rd : coronal plane; lamina papyracea : ground lamella / basal lamella

Posterior 1/3rd : horizontal plane : lamina papyraceaand perpendicular plate of palatine bone.

OSTEO MEATAL COMPLEX The osteomeatal complex is the key anatomic area

addressed by endoscopic sinus surgeons. Blockage of the

osteomeatal complex prevents effective mucociliary

clearance, thus leading to a stagnation of secretions and

therefore leading to recurrent or chronic sinusitis.

OSTEO MEATAL COMPLEX The OMC is bounded

medially by the middle

turbinate,

posteriorly and superiorly

by the basal lamella, and

laterally by the lamina

papyracea.

Inferiorly and anteriorly

the OMC is open.

OSTEO MEATAL COMPLEX

Uncinate process:

This is the most stable landmark in the lateral nasal wall.

Horizontal and vertical limb

It is a wing or boomerang shaped piece of bone. It attaches anteriorly to the posterior edge of the lacrimalbone, and inferiorly to the superior edge of the inferior turbinate .

Superior attachment of the uncinate process is highly variable, may be attached to the lamina palyracea ( 80 % ),or sometimes to the middle turbinate or lie freeewithin middle meatus

The configuration of the ethmoidal infundibulum and its relationship to the frontal recess depends largely on the behavior of the uncinate process

Variations in the superior insertion of the uncinate process are classified according to criteria developed by Landsber & Friedman

A: Type 1 (insertion into the lamina papyracea). B: Type 2 (insertion into the posterior wall of agger nasi

cell). C: Type 3 (insertion into the lamina papyracea and junction

of the middle turbinate with the cribriform plate). D: Type 4 (insertion in to junction of the middle turbinate

with the cribriform plate). E: Type 5 (insertion into the skull base). F: Type 6 (insertion into the middle turbinate)

Uncinate attached to lamina : frontal sinus drainage : medial to uncinate process

Attached to skull base : frontal sinus drains into infundibulum : disease from frontal sinus spreads to maxillary

The Agger Nasi Air Cell :

Its an ethmoturbinal remnant present in nearly all patients ( 93 % )

The ANC is the most constant and anterior of the ethmoidal air cells.

Located anterior to the vertical attachment of the middle turbinate to the skull base.

The degree of ANC pneumatization varies and has a significant effect on both the size of the frontal sinus ostium and the shape of the recess.

If the ANC is small, then the “beak” of the frontal process of the maxilla, lying anteriorlyand superiorly, will be prominent and extend posteriorly into the frontal recess, resulting in a narrow ostium.

If the ANC is large, the beak will be small, resulting in a wider ostium but potentially causing obstruction more inferiorly.

ETHMOID BULLA Well pneumatized most constant anterior ethmoid cell

8% rudimentary/ absent

Separated posteriorly from ground lamella by retrobullar recess

if does not extend upto skull base, suprabullar recess.

If both suprabullar and retrobullar recess are absent : semilunar space above and behind the bulla : sinus lateralis

Sinus lateralis opens into middle meatus by a cleft : hiatus semilunaris superioris

Frontal recess may drain into sinus lateralis

FRONTAL RECESS• The frontal recess is an hourglass like narrowing

between the frontal sinus and the anterior middle meatus through which the frontal sinus drains

• Bounded anteriorly by agger nasi cell

Posteriorly by bulla ethmoidalis

Laterally by lamina papyracea

Medially by middle turbinate, lateral wall of olfactory fossa.

Roof of frontal recess formed by fovea ethmoidalis: thick bone : resistance to injury

Anterior ethmoid artery runs across fovea ethmoidalis

When ther is a suprabullar recess : ethmoid artery will be in the frontal recess

Anterior ethmoidal artery may lie in a mesentry in 15-45% pts, suspended from the skull base.

Anatomical variants

Fronto-ethmoid/kunh cells/bulla frontalis

Are the anterior ethmoid cells which invade the frontal bone, bulging its floor

They are more easily demonstrated at saggital view, where they appear as ethmoid air cells located above the ethmoid bulla and as an extension towards the frontal sinus.

Depending on their size and pneumatization extent, such cells may affect the frontal sinus drainage.

These air cells, are categorized into four types depending on their number and degree of extension into the frontal sinus.

They are all located superior to the ANC.

Type 1 (most common): Single cell superior to the ANC that does not extend into the frontal sinus

Type 2: Two or more cells superior to the ANC that may or may not extend into the frontal sinus.

Type 3: Single frontal cell superior to the ANC that extends into the frontal sinus.

Type 4: Completely contained in the frontal sinus. This configuration is rare.

This is formed by lateral and posterior pneumatization of the most posterior ethmoid cells over the sphenoid sinus.

The presence of Onodi cells increases the chance that the optic nerve and / or carotid artery would be exposed in the pneumatized cell.

VARIATIONS OF THE CRIBRIFORM PLATE

The cribriform plate may present at variable levels and, it is classified according to the criteria developed by Keros.

It is based on the height of the olfactory fossa in relation to the roof of the ethmoid sinus as compared with the length of the lateral lamella of cribriformplate.

The higher the Keros grade, the greater the chance of injury of the cribriform plate and olfactory fossa.

A: Type 1 (lateral cribriform lamella of 1–3 mm, the cribriform plate and the ethmoid cell roof are practically parallel to each other).

B: Type 2 (lateral lamella of 4-7 mm, cribriform plate is much below the nasal cavity as compared with the ethmoid roof).

C: Type 3 (lateral lamella of cribriform plate of 8–16 mm, ethmoid cell roof is located much above the plate

Haller cell Infraorbital ethmoid cells

or Haller cellsareethmoid air cells located anteriorly to the ethmoidbulla, along the orbital floor, adjacent to the natural ostium of the maxillary sinus, which may cause mucociliary drainage obstruction, predisposing to the development of sinusitis.

VARIATIONS IN MIDDLE TURBINATE Concha bullosa is a

variation originated from pneumatization of the bone plate by extension of ethmoid sinus cells.

Such variation may be either uni- or bilateral.

Varied degrees of pneumatization of the concha may be observed, possibly causing middle meatus or infundibulumobstruction.

PARADOXICAL TURBINATES Paradoxical turbinates occur as the convexity of the middle

turbinate is directed towards the medial wall of the maxillary sinus.

Depending on the degree of curvature of the paradoxical turbinate compression of the infundibulum and sinusalobstruction may be observed.

A)horizontal uncinate

b)hypertrophy of lt uncinate.

C)pneumatisation of lt uncinate.

D)vertical lt uncinate.

ACCESSORY MAXILLARY OSTIA Accessory maxillary ostia are generally solitary, but

occasionally may be multiple.

Easily seen, circular : tunnel like, ovoid

Such variation may be congenital or secondary to sinusaldiseases.

Possible mechanisms involved in the development of such variation include:

main ostium obstruction, maxillary sinusitis or anatomical/pathological factors in the middle meatus, resulting in rupture of membranous areas.

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