EMBRYOLOGICAL DEVELOPMENT &

ANATOMY OF NOSE

Presenter – Dr Pulkit AgarwalModerator – Dr G.S.Renukananda

EMBRYOLOGY 4th to 8th week from 5 Swellings

(Ectoderm)

1st Arch

Ectodermal thickenings(5th week)

6th week : ectoderm from Nasal placode invaginates to form oval nasal pits

12.5 mm Enbryo stage : Maxillary prominence grows medially

Nasal pits separate from stomodeum

Intermaxillary process (fusion of medial nasal process) central tissues pushed up to form nasal prominence

Globular process forms the philtrum (lateral angles of medial nasal process)By 7th week invaginates to form nasolacrimal duct

Canalisation may not complete till after birth

• Nasal Septum Development – 13.5 mm embryo stage (6th week)• Fusion of maxillary to frontonasal process. • Midline ridge from posterior end of frontonasal process forms

septum• 6th week• 15mm stage

Nasal pits deepen and coalesce (end of 6th week)

Primitive Choanae formed at 7th week

Primitive nasal septum is completely Cartilagenous

2 centres

Groove on which septal catilage sits

Lateral nasal processes – nasal alae and lateral nasal wallHard palate formed by around 8th and 9th week

Palatine shelf – Medial extensions of maxillary process

Fuses with septum forming 2 passages which opens into defintive choanae

Paraseptal Jacobsons cartilage invagination of ectoderm leads to Vomeronasal Organ

Disappears leaving a blind tubular pouch 2 – 6mm long

Jacobsons cartilage involutes leaving small cartilagenous bulge

VNO / Jacobsons organ is first stage of the accessory olfactory system, and contains sensory neurons that detect chemical stimuli mainly used to

detect pheromones found in many animals

ProcessesStructures

Formed Frontonasal Forehead, Bridge of nose,

medial and lateral nasal prominences

Maxillary Cheeks, Lateral portion of upper lip

Medial Nasal Philtrum of upper lip, Crest and tip of nose

Lateral Nasal Alae of nose, lateral nasal wall

Mandibular Lower lip and jaw

External Nose

Nasal Cavity

Nasal Septum

Lateral Wall

Anatomical Variations

ANATOMY

EXTERNAL NOSE :

Skin & Vestibule :

Skin :

Thickness of skin and soft tissue varies.

Over dorsum and side – thin and loose

Over tip & alar region – thick and adherent

Vestibule :

Anteriormost part of nasal cavity lined by stratified squamous keratined epithelium.

Demarcated by limen nasi

Lined by coarse vibrissae, glands

Blood supply ICA Ophthalmic Artery

Vth Ophthalmic nerve Anterior ethmoidal External nasal nerve (Dorsum, tip)

Vestibule of nose

Maxillary artery

ECA

VENOUS DRAINAGECorresponds to arteriovenous units.Frontomedian area drains into the facial vein Orbitopalpebral area – ophthalmic vein (cavernous sinus communication)

LYMPHATIC DRAINAGE

Submandibular and submental nodes and sometimes buccal nodes intervene

Nerve supply

Trigeminal Nerve

Ophthalmic Branch

Anterior Ethmoidal

Nasociliary

Maxillary Branch

External Nasal

Infratrochlear

Infraorbital nerve

Vestigial importance

Depresses SeptumTip of noseExpandes nares during forced inspiration

Transverse – Pyriform aperture to Dorsum of nose & Contracts nasal apertureAlar – beneath nasomaxillary suture line via short thin tendon to skin of nasal alae Contraction causes shortening and dilation of Nostril

Continuation of FrontalisShortens nose on contraction and also movements in region of eyebrows hence aka Depressor Glabellae

Frontal process of maxillaBlends with lateral crus of lower lateral cartilages & pulls it superiorlyAlso pulls lips superiorly helping in dilation

framework

Bony :

Nasal BoneNasal process of frontal BoneFrontal process of maxilla

Cartilagenous:

Paired upper lateral cartilages Septal Cartilage Paired lower lateral cartilage / Greater alar cartilage Minor accessory alar cartilages

Nasolacrimal Suture

Supported by Nasal Spine and perp. Plate

of ethmoid

Nasal bones are supporetd by perp plate

of ethmoid and nasal

spine both of which groove

the bone

Upto 15mm

Overlapped by Nasal bone, Maxilla, Alar cartilage

(Fibrous Cartilage)

Hyaline cartilages which may be ossified & prevent collapse of vestibule

Limen Nasi(Intercartilagenous

Incisions)

Overlapped by Nasal bone, Maxilla, Alar cartilage

(Fibrous Cartilage)

Medially continuous with septal cartilage which is bifid in this region

Limen Nasi(Intercartilagenous

Incisions)

Medial is loosely attached in midline anterior to Quadrangular Cartilage & contributes to Columella (area from tip to philtrum)

Medial Crus

Lateral Crus

Lower margin of lateral ascends away from margin of Nostril

Medial Crus

Lateral Crus

3 – 4 sesamoid cartilages present

Medial Crus

Lateral Crus

Nasal Cavity

Extension

(Broader)

Vertical Extent

Each half has a floor, roof lateral and medial wall.Floor – concave, Ant 3/4th – Palatine process of maxilla and posterior 1/4th by horizontal process of palatine bone12mm behind ant end, mucous memb dips overlying incisive canalContains terminal branches of Nasopalatine nerve, greater palatine artery & short mucosal stensons canal

HORIZONTAL PROCESS

Roof :

FrontonasalEthmoidalSphenoidal

Highest, Cribriform plate of ethmoid which is horizontal

Resp epithelium continuous with PNS, NLD & nasopharynx

Olfactory epithelium

Medial Wall = SeptumLateral Wall = Lateral Wall of Nose

Nasal septum

Cartilages –

Quadrilateral cartilageUpper and lower lateral cartilages contributionVomeronasal Cartilage

Membranous septum

Bones –

Perpendicular plate of ethmoidVomerTwo bony crests of the

maxilla and palatineRostrum of sphenoidNasal spine of frontal bone

3 – 4 mm centrally and 4 – 8 mm anteroinferiorly (footplate) Above dome of lower lateral cartilages, upper angle expanded forming anterior septal angle

QUADRANGULAR CARTILAGE

Perp Plate of ethmoid forms superior and anterior bony septumAbove is cribriform plate and cristae galliGrooves nasal bones

vomerPosterior and inferior septumWith 2 alae articulates with rostrum of sphenoid, forms vomerovaginal canals which transmit pharyngeal branch of maxillary arteryInferiorly – with both crestsAnterior – perp plate & septal cartilage

Post free edge of vomer

Blood Supply

Posteroinferior septum and anteroinferior face of sphenoid sinus

& posterior halves of middle & inf turbinates

b/o maxillary artery b/o ECA

Blood Supply

Supplies anteroinferior portion entering the nasal cavity via incisive canal

b/o maxillary artery b/o ECA

Blood Supply

Supplies anteroinferior portion entering the nasal cavity via incisive canal

b/o Facial artery b/o ECA

Blood Supply

b/o ICA

Sinusoidal system in nasal submucosa under autonomic control described well with turbinates but also seen in septum adjascent to inferior turbinate and most anterior part of septumRelated to control of airflow in nasal cavityIn 2/3rd seen in posterior septum

Nerve supply

Maxillary nerve (V2) supplies majority of septumNasopalatine nerve, posterosuperior nasal branch of maxillary nerve supplies bulk of bony septum entering via sphenopalatine foramen.Anterosuperior – anterior ethmoidal branch of nasocilairy nerve (V1 branch)Small Anteroinferior area supplied by anterior superior alveolar nerve

Anterior superior alveolar nerve

b/o pterygopalatine ganglion and carries both sensory and parasympathetic fibres

& also Vidian nerve

Nerve supply of septum

Sensory nerves accompanied by postganglionic sympathetic nerves to blood vessels and postganglionic parasympathetic secretomotor fibres pass to glands with the branches from the pterygopalatine ganglionOlfactory, respiratory and stratified squamous keratinised epitheliumSurface area increased by cilia on respiratory cellsNerve fibres from olfactory receptors are slim and bundled together in sets of 20 to pass through cribriform plate Carries dura, pia along Shearing may lead to CSF leak or destruction of olfaction

LYMPHATIC DRAINAGE Anteriorly – Submandibular LN

Posteriorly – Retromandibular & deep cervical LN

Lateral wall

Roof of posterior choanae

Straighter

1 cm

Atrium – Structureless areaShows bulge anterior to middle turbinate formed by agger nasi cellsRidge from agger nasi to apex of superior border of inferior turbinate which overlies NLD3 scrolls of turbinates. Occasionally supreme turbinate.Sphenoethmoidal recess above superior turbinate which forms niche between posterior ethmoidal cells and sphenoidal cellsFossa of rosenmuller forms a deep cleft behind torus tubarisAttachments of middle turbinate :Anterior 1/3rd – cribriform plate at jnct in saggital plane also takes a small anterior attachment to frontonasal process(maxilla)Middle 1/3rd – lamina papyracea in coronal plane (ground lamellae)Posterior 1/3rd – to lamina papyracea and the perpendicular plate of the palatine bone extending upto the roof of posterior choanae

Behind middle turbinate, most anteriorly – Uncinate processSeparated from well pneumatized ant ethmoidal cell (bulla) by hiatus semilunaris inferioris.Hiatus semilunaris leads into infundibulum

As per Naumann : Osteomeatal complex is complex microarchitectural pathway in ethmoid labyrinth that drains anterior group of paranasal sinuses and consists of frontal recess, ethmoid infundibulum, hiatus semilunaris, uncinate process, bulla ethmoidalis and middle meatus

Osteomeatal Complex

Uncinate process – sickle shaped, Horizontal and vertical parts & intermediate transitional partRetrobullar recess – Between bullae and ground lamellaeSuprabullar recesss – If bulla doesn’t extend till skull baseTogether form space above and behind the bulla called Sinus Lateralis of grunwald which opens in middle meatus via Hiatus semilunaris superiorisBoundaries :

Roof : Ethmoid foveaFloor : Ethmoid bullaPosteriorly : Ground lamellaAnteriorly : Frontal recessLaterally : Lamina papyraceaMedially : Middle turbinate

Infundibulum leads into the frontal recess

Frontal Recess :BoundriesAnteriorly : Agger Nasi cells (a part of Frontal recess)Posteriorly : Bulla Ethmiodalis (a suprabullar recess will open in posterior wall of frontal recess)Laterally : Lamina PapyraceaMedially : Middle turbinateSuperiorly : Opens via the frontal ostium into the frontal sinus

Frontal sinus opening is funnel shaped (FI) in posteromedial floor of sinus. Hour glass config.Upper end of Uncinate lies in frontal recess.Large no of anatomical variations but 80% attached to lamina papyracea in form of domeDome like attachement of uncinate in frontal recess described by Stammberger – eggshell in inverted cup

Recess enclosed within this dome is called recessus terminalisIn this case frontal sinus opens medial to uncinate processWell hidden by the uncinate process lies an opening of the maxillary sinusNormal ostium – 3D, Ovoid and tunnel likeAccessory osteum – 2D, CircularRelations of maxillary ostium are : Inferiorly is the inferior turbinate, 1 to 2 mm superiorly is the lamina papyracea and the orbit, posteriorly is the posterior fontanelle, 0.5 cm anteriorly lies the nasolacrimal ductAnterior fontenelle – AI to uncinatePosterior fontenelle – PS to uncinateBoth are just double layer of mucous membrane without underlying bone, thus if memb deficient can lead to accessory ostia

Bulla may drain into the middle meatus/hiatus semilunaris/ sinus lateralis

Frontal sinus drains into frontal recess medial or lateral to uncinate process depending on the mode of attachment of the uncinate process or suprabullar recess if present

Maxillary sinus – always in infudibulum

Sphenoid sinus – Sphenoethmoidal recess

Meatal Drainage

Inferior meatus :

NLD (Hasners valve)

Middle meatus :

FrontalAnterior ethmoidalMaxillary

Superior meatus :

Posterior ethmoidal

Sphenoethmoidal recess :Sphenoid

Arteries Of lateral and medial wall of Nose

Artery Branch of Supplies

Anterior ethmoidal & Posterior Ethmoidal arteries

Ophthalmic artery(ICA)Ethmoid and frontal sinuses, roof of the

nose, upper part of lateral wall and septum

Sphenopalatine artery Maxillary artery 3rd part (ECA)Mucous membrane, superior and

middle meatus, conchae and septum

Greater palatine artery Maxillary artery (ECA)Posterior part of lateral nasal wall (also

anteroinferior end of septum)

Superior Labial Facial artery (ECA) Region of vestibule of nose

Infraorbital artery, anterior and posterior superior alveolar arteries b/o Maxillary artery supply Maxillary sinusPharyngeal branch of maxillary sinus supplies sphenoid sinus

Nerve supply :

(V2)

(V1)

Anatomical Variations

DNS –AP deviations best seen in axial scansSpurs at vomerocartilagenous junction – Coronal scansNear OMC may lead to impaired drainage of sinusesConcha bullosa or HIT on roomy side may compromise OMCSeptum may be pneumatised

Agger Nasi cells – Can be hypoplastic or prominent leading to displacement of anterior attachment of middle turbinate posterosuperiorly

Uncinate process – Hypoplastic / laterally bent – Infundibulum narrow space difficult to enterMedially bent so much so to resemble anterior wall of bulla, or may be curled upon itself to appear like a duplicated middle turbinate

Variations attachment of Uncinate – • Skull base• Middle turbinate• Insertion of middle turbinate• May lie free in the middle meatus

May be pneumatisedUncinate if attached to skull base, frontal sinus drains into infundibulum and therefore diseases from the frontal sinus can spread directly to the maxillary sinus and vice versa

Middle turbinate :Pneumatised – concha bullosa (either from agger nasi/frontal reces or from anterior ethmoidal cells)Concha may obstruct airway, affect drainage of secretions and lead to chronic infections of sinusesOccasionally middle turbinate may pneumatise the vertical lamella of the middle turbinate to produce what is called the intralamellar cell of Grunwald

May take a paradoxical sharp bend laterally, often bilaterally leading to blockade of infundibulumCan sometimes curl upon itself to produce a concavity within it called turbinate sinus

Ethmoidal bulla :Hypoplastic or non pneumatised hillockMay be excessively pneumatised abutting against uncinate process anteriorly or the middle turbinate compromising infundibulum or middle meatus respectivelyThe sinus lateralis may extend laterally to pneumatise the roof of the orbit thus forming the supraorbital ethmoid cell. This cell is seen in coronal CT scan at the level of the bulla behind the frontal sinus

Ethmoid Air Cells :The anterior and posterior ethmoid air cells may pneumatise surrounding bones like lacrimal bone, maxilla, frontal bone, sphenoid to produce varying patterns of pneumatisation