ANATOMY OF THE NOSE

The first part of the upper respiratory tract consists of paired nasal cavities divided from each other sagittally by the nasal septum and housed in a bony and cartilaginous framework that extends anteriorly as the external nose.

The two halves of the nasal cavity open onto the face through the nares, and are continuous posteriorly with the nasopharynx through the posterior nasal apertures or choanae

The cavity is divisible into three regions, the nasal vestibule anteriorly, the chemosensory olfactory area posterosuperiorly and the respiratory region between them which constitutes the majority of the nasal cavity.

The anterior nasal vestibule narrows posteriorly to form the nasal valve (the narrowest portion of the nasal airway).

A series of air-filled expansions, the paranasal sinuses, lie within either the lateral walls of the nasal cavities, or in communication with them in adjacent bones.

The Nose:

Nose (formed by the ethmoid, spehnoid,nasal,lacrimal,maxilla, zygomatic and vomer bones)

External : Is pyramidal in shape with the

root directed upwards.Consists of an osteocartilaginous

framework covered by skin,muscles and connective

tissue.

Internal:Divided into the vestibule,

olfactory region and nasal cavity proper. The vestibule is lined by skin and contains vibrissae,the olfactory region contains the

olfactory nerves and the nasal cavity proper is lined by respiratory epithelium.

Skeletal framework:

Coronal section :

The skin of the nose receives its blood supply from branches of the facial & infraorbital (branch of maxillary artery) (facial and maxillary arteries being branches of external carotid artery), ophthalmic (branch of internal carotid) arteries. The alae and lower part of the nasal septum are supplied by lateral nasal and septal branches of the facial artery The dorsal nasal branch of the ophthalmic artery and the infraorbital branch of the maxillary artery supply the lateral aspects and the dorsum of the nose.

The venous networks draining the external nose do not run parallel to the arteries. Instead, they correspond to arteriovenous territories of the face: thus, the frontomedian region of the face, including the nose, drains to the facial vein, and the orbitopalpebral area of the face, including the root of the nose, drains to the ophthalmic veins. The connections of the veins of the nose, upper lip and cheek with the drainage area of the ophthalmic veins are clinically significant.

Lymph drainage is primarily to the submandibular group of nodes. Lymph draining from the root of the nose drains to superficial parotid nodes.

The nasal muscles are innervated mainly from the buccal branches of the facial nerve. The nasal skin is innervated by the infratrochlear and external nasal branches of the nasociliary nerve, and from the nasal branch of the infraorbital nerve.

THE EXTERNAL NOSE:

External carotid artery> Facial artery > lateral nasal arteries + septal branches supplying the ala and the lower,external nasal septum.

External carotid artery > Maxillary artery > infraorbital artery supplying the lateral and dorsal part of the nose.

Internal Carotid Artery > opthalmic artery > dorsal nasal artery supplying the dorsum and lateral aspect of the nose.

Frontomedian part of face including nose >facial veins Orbitopalpebral part including the root of the nose >

ophthalmic veins. Root of the nose > lymph nodes of the superficial parotid

nodes Rest of the EXTERNAL nose > mainly to the submandibular

lymph nodes Trigeminal nerve > Ophthalmic nerve> nasociliary +

infraorbital nerves > nasociliary gives infratrochlear and external nasal nerves and infraorbital nerve gives off its nasal branch> supply the skin of the external nose.

Facial nerve > buccal branches > supply the musculature of the external nose.

Summary of Blood supply, lymphatic drainage and nerve supply:

External nose: Upper one third : bonyLower two thirds: cartilaginous

Bony part : Two nasal bones resting on the nasal processes of the frontal bones, held between the two frontal processes of the maxilla.

Cartilaginous part:• Upper Lateral cartilages: Extend from the undersurface of the nasal

bones to the alar cartilages, fuse in the midline with the septal cartilage and themselves, their lower border forming the limen vestibuli intranasaly.

• Lower lateral or alar cartilages: U-shaped, lateral crus forms the ala and medial crus runs in the columella, lateral crus overlapping the lower edge of the upper lateral cartilage on each side.

• Lesser alar or sesamoid cartilages: Lie above and lateral to the alar cartilages, two or more in number.

• Septal Cartilage: Runs from the nasal bones to the nasal tip, supports the dorsum of the cartilagnious part of nose.

Descriptions of the parts of the nose :

It is clearly evident from the above diagram that most of the nostril is not formed by cartilage. The cartilages are adjoined to the nearby bones by periosteum and perichondrium, whereas most of the free edge of the nostril is formed by fibrofatty tissue and not the alar cartilage.

Muscles: These are procerus, nasalis, levator labii superioris alaeque nasi, anterior and posterior dilators and depressor septi. These are not of much importance in humans.

Nasal skin: It is mobile and thin over the bony part and the upper lateral cartilage. The skin overlying the rest of the cartilaginous part is thick and adherent and contains sebaceous glands.

Remaining parts of external nose :

The nasal cavity is an irregular space between the roof of the mouth and the cranial base, divided by a vertical osseocartilaginous septum that is approximately median in position. The bony septum reaches the posterior limit of the cavity, which leads into the nasopharynx through a pair of posterior nasal apertures, or choanae, lying above the posterior hard palatal border. The medial border of the choanae is formed by the posterior edge of the vomer, and its posteroinferior boundary by the horizontal plate of the palatine bone with the nasal crest of the palatine bone. Lateral to the ala of the vomer the choanae are bounded superiorly by the vaginal processes of the pterygoid processes above, and by the perpendicular plates of the palatine bones laterally. The size of each choana is not usually affected by deviations of the nasal septum.

The cavity is wider below than above, and widest and vertically deepest in its central region. It communicates with the frontal, ethmoidal, maxillary and sphenoidal paranasal sinuses. The posterior nasal apertures are oval openings separated by the posterior border of the vomer, each being limited below by the horizontal plate of the palatine bone, above by the sphenoid and laterally by the medial pterygoid plate. In the adult each is c.2.5 cm in vertical height and 1.3 cm transversely. The vomerovaginal and palatovaginal canals are found in the roof of this region.

Each half of the nasal cavity has a roof, floor, lateral and medial (septal) walls.

Nasal Cavity :

Boundaries of the Choanae:

Is divided into two halves : the right and the left, by the nasal septum.

Has two pairs of openings, the anterior one communicates with the outside and consists of the nostrils. The posterior one opens into the nasopharynx and consists of the posterior nasal apertures or the choana.

Consists of the vestibule, which is lined by skin and contains the vibriasse,sebacious glands and hair follicles, the chemoreceptive olfactory region and the nasal cavity proper (or respiratory region) which is lined by ciliated columnar epithelium.

Internal nose :

Vestibule : It is lined by skin. It contains sebaceous glands, hair follicles and

vibrissae. Its upper limit on the lateral wall is the limen nasi

or the nasal valve which is formed by the caudal margin of upper lateral cartilage. Its medial wall is formed by the columella and the lower part of the nasal septum upto its mucocutaneous junction.

The limen nasi is a structure that has no importance in humans, but is fairly important in other mammals.

Consists of four parts: lateral wall, medial wall, roof and floor.

Laterall wall contains the turbinates which are important from the perspective that the openings of the sinuses are near them.

Medial wall is the part that supports the framework of the nose and contains the keiselbach’s plexus.

The roof contains the olfactory part of the nasal cavity.

The floor is formed by the palatine bones and the palatine processes of the maxilla and separates the nasal cavity from the oral cavity.

Nasal cavity proper:

Contains three, and sometimes even four, turbinates. Spaces below each choncha or turbinate is called a meatus, which has openings of different sinuses. Chonchae are bony projections covered by mucous membranes. They serve to increase the surface area.

The chonchae include : Inferior, middle and superior turbinates.

The meatuses include the inferior, middle and superior meatus.

The space above the superior turbinate is the sphenoethmoidal recess and receives the opening of the sphenoidal sinus.

Lateral nasal wall :

Bony support for the lateral wall is provided by: the ethmoidal labyrinth and uncinate process;

the perpendicular plate of the palatine bone; the medial plate of the pterygoid process of

the sphenoid bone; the medial surfaces of the lacrimal bones and

maxillae; the inferior concha.

The lateral wall:

Inferior turbinate : • It is a separate bone, lying above the inferior meatus.• Openings associates with it include that of the nasolacrimal duct

which opens into the terminal end of the inferior meatus and is gaurded by a mucosal valve known as Hasner’s valve.

Middle turbinate: • It is part of the ethmoid bone. The basal or ground lamella attaches

it to the lateral wall in an s-shaped manner. • In the anterior third it is in the sagittal plane and is attached to the

lateral edge of cribriform plate. In the middle third, it lies in the frontal plane and is attached to the lamina papyracea while in its posterior third, it runs horizontally and forms the roof of the middle meatus and is attached to lamina papyracea and medial wall of maxillary sinus.

• The ostia anterior to the basal lamella form anterior group of paranasal sinuses and vice versa.

Features of the lateral wall:

Middle meatus includes:oThe uncinate processoBulla ethmoidalisoHiatus semilunarisoOpening of maxillary sinus, anterior ethmoidal air cells and middle ethmoidal air cells.oAtriumoAgar nasioInfundibulum

Uncinate process: • Hook like structure• Runs in an anterosuperior to posteroinferior direction. • The posterosuperior border is sharp and runs parallel to the

anterior border of bulla ethmoidalis.• The anteroinferior border is attached to the lateral wall,

posteroinferior end is attached to the inferior turbinate dividing the lower middle meatus into anterior and posterior fontanalle. The fontanel area does not have any bone and is made of only membrane, leading into the maxillary sinus if perforated.

• Upper attachment of the uncinate process shows a lot of variation and may be inserted into the lateral nasal wall,upwards into the base of the skull or medially into the medial turbinate. This accounts for variations in drainage of frontal sinus (refer to the next slide).

Features of the Lateral Wall (continued):

Variations in the upper attachment of the uncinate process :

Hiatus semilunaris superior: • Cleft-like space between the bulla and skull base and opening into

middle meatus.Hiatus semilunaris inferior:• Is a two dimensional space located between the bulla and the

uncinate process.• Has a width of 1-2 mm.Infundibulum:• Medial wall: uncinate process & frontal process of maxilla and

sometimes even the lacrimal bone• Lateral wall : lamina paryracea• In its lower part, it contains the natural opening of the maxillary

sinus. Accessory ostia/ostium are sometimes seen in anterior and posterior fontanel.

Bulla Ethmoidalis:• It is an ethmoidal cell right behind the uncinate process.• Its anterior surface forms the posterior boundary of the hiatus

semilunaris. • It may be a pneumatized cell or a bony prominence.• It may extend superiorly to the skull base and posteriorly to fuse

with ground lamella.

• A space behind or about the bulla is called suprabullar or retrobullar recess.

• Suprabullar and retrobullar recess together form the lateral sinus, whose boundaries are : skull base superiorly, lamina papyracea laterally, middle turbinate medially and the bulla inferiorly.

• The lateral sinus is known as the sinus lateralis of Grunwald.• The sinus lateralis may extend posteriorly up to the basal

lamina of middle turbinate.Atrium : It is a shallow space right above the vestibule and in

front of the middle turbinate.Agger Nasi : • It is an elevation anterior to the attachment of the middle

turbinate.• It contains air cells when pneumatised, the agger nasi cells,

which communicate with the frontal recess. When the agger nasi is enlarged, it can encroach onto the frontal recess area thus causing mechanical obstruction to the drainage of the recess due to constriction.

Concha bullosa: A ballooned out middle turbinate due to pneumatisation is concha bullosa. Its drainage is into frontal recess directly or through the agger nasi cells.

Haller cells : These are air cells located in the roof of the maxillary sinus and can be pneumatised from the anterior or posterior ethmoid cells. When enlarged, they encroach onto the ethmoid infundibulum and cause interference in the drainage of the maxillary sinus.

Superior turbinate: It is an ethmoturbinal too and is located posterosuperior to the middle one. It can also be pneumatized by one or more cells.

Superior meatus : It is the space below the superior turbinate and it receives the opening of the posterior ethmoid cells, the number of which varies from 1-5.

Onidi cell: is a posterior ethmoidal cell which may grow posteriorly by the side of the sphenoid sinus or superior to it for a distance no greater than 1.5 cm from the anterior surface of sphenoid. It is surgically important because the optic nerve may be related to its lateral wall.

Sphenoethmoidal recess: This is the space between the roof and the superior turbinate and it receives the opening of the sphenoid sinus.

Supreme turbinate: It is sometimes present above the superior turbinate and has a narrow meatus beneath it. It is important from the perspective that when present, the sphenoid sinus opening is located near it. The exact location is such that the sphenoid sinus opening is located medial to the superior OR supreme turbinate in the sphenoethmoidal recess. It can be located endoscopically about 1 cm above the upper margin of posterior choana close to the posterior border of the septum.

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Suprabullar/Retrobullar Recess

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Natural Ostium -Haller’s cellsAccessory Ostium

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Frontal SinusOstiumFrontal recess Boundaries Dumbbell shapeSinus LateralisFrontal Bulla

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The Onodi Cell

Medial wall: (The following diagram contains only the bony part, the septal cartilage is missing)

As you can see in this diagram, the medial wall has a bony part and a cartilaginous part. The bony part contains the ethmoid and the vomer, with only minor contritbutions from other bones.

It is relatively featureless as compared to the lateral wall.

It has two parts: Cartilaginous part : made of the nasal septum cartilage.Bony part: Main contributions are from the ethmoid’s

perpendicular plate anterosuperiorly and the vomer posteroinferiorly. Other bones make minor contributions to the septum at the upper and lower limits of the medial wall. The nasal bones and the nasal spine of the frontal bones are anterosuperior, the rostrum and crest of the sphenoid bone are posterosuperior, and the nasal crests of the maxillary and palatine bones are inferior (Correspond with the diagrams in the previous slides).

Medial wall (explained) :

Other features of the medial wall :• The surface contains grooves related to the nasopalatine

nerves and accompanying vessels. • Above the incisive canals, at the lower edge of the septal

cartilage, there is sometimes a depression pointing downwards and forwards: it occupies the position of the nasopalatine canal which connected the nasal and buccal cavities in early fetal life. A minute orifice may be seen leading back into a blind tubule, 2-6 mm long, on each side of the septum near this recess. The tubules house the vomeronasal organ, a paired accessory olfactory organ similar to the olfactory epithelium in amphibians and reptiles, but believed to be vestigial in man.

• The nasal septum is often deviated - more usually to the left - and particularly affects the perpendicular plate of the ethmoid.

Roof:

The roof is horizontal in its central part but slopes downwards in front and behind.

The anterior slope is formed by the nasal spine of the frontal bones and by the nasal bones, which contribute to the external nose.

The central horizontal region is formed by the cribriform plate of the ethmoid bone which separates the nasal cavity from the floor of the anterior cranial fossa. The cribriform plate contains a separate anterior foramen for the anterior ethmoidal nerve and vessels, and numerous small perforations which transmit the olfactory nerves.

The posterior slope is formed by the anterior aspect of the body of the sphenoid - interrupted on each side by an opening of a sphenoidal sinus - and the sphenoidal conchae or superior conchae. The alae of the vomer and the sphenoidal processes of the palatine bones lie below.

Roof of the nasal cavity:

Floor (superior view) :

The floor of the nasal cavity is smooth, concave transversely, and slopes up from anterior to posterior apertures.

It constitutes the upper surface of the hard palate. Anteriorly, the palatine processes of the maxillae

and, behind them, the horizontal plates of the palatine bones, articulate in the midline and with each other. The nasal floor is therefore crossed at the junction of its middle and posterior thirds by the palatomaxillary suture.

Anteriorly, near the septum, a small infundibular opening in the nasal floor leads into the incisive canals that descend to the incisive fossa: the opening is marked by a slight depression in the mucosa.

Floor:

Blood Supply of the Nose

• ANTERIOR AND POSTERIOR ETHMOID ARTERIES: o Both of them come from the Internal Carotid via the Ophthalmic

Artery. o The Ethmoid Arteries leave the orbit through anterior posterior

ethmoid foramina in the cribriform plate of the ethmoid bone. o After leaving the orbit, they travel through the anterior cranial

fossa, underneath the dura before going through the Ethmoid Foramina. o That means that overall blood supply from the internal carotid is as

follows: Internal Carotid Artery ------> Middle Cranial Fossa ------> Optic Canal ------> Opthalmic Artery ------

> Ethmoid Arteries ------> through anterior posterior ethmoid foramina in cribriform plate ------> Anterior

Cranial Fossa ------> Anterior and Posterior Ethmoid Foramen ------> Nasal Cavity o Both of the Ethmoid Arteries divide into septal and lateral branches,

to supply the medial and lateral walls of the nasal cavity.

Blood Supply :

• Principle Blood Supply to NOSE: o INFERIOR 1/3 OF NOSE -- External Carotid: Facial Artery ------> Angular Artery ------> Lateral Nasal

Artery Sphenopalatine Artery ------> Posterior Lateral Nasal

Arteries Sphenopalatine Artery ------> Posterior Septal Artery o SUPERIOR 1/3 OF NOSE -- Internal Carotid: Ophthalmic

Artery ------> Dorsal Nasal Artery ------> bridge of the nose. • Additional Blood Supply to NOSE: This covers the

INFERIOR 2/3 OF NOSE with additional blood supply. o Internal Carotid ------> Ophthalmic Artery ------> Anterior

Ethmoidal Artery ------> Lateral Branch of Anterior Ethmoid Artery ------> External Nasal Artery o External Carotid ------> Maxillary Artery ------>

Infraorbital Artery

• Principle Blood Supply to the NASAL CAVITY: o Anterior Ethmoidal Artery, from Opthalmic, is the largest

contributor. o Posterior Ethmoidal Artery contributes a little less in the

posterior region. o Sphenopalatine Artery is a terminal branch of the

Maxillary Artery: Maxillary ------> Sphenopalatine Foramen ------> Sphenopalatine Artery ------> Lateral and

Septal branches • INTERNAL/EXTERNAL CAROTID ANASTOMOSES IN THE

NOSE: o Angular Artery (from Facial) <====> Dorsal Nasal (aka

Infratrochlear) Artery (from Ophthalmic) o Lateral and Septal Branches of Ethmoid Arteries (from

Ophthalmic) <====> Lateral and Septal Branches of Sphenopalatine Artery (from Maxillary)

Venous Supply of the Nose:

Nerve Supply of the Nose:

• Nasopalatine Nerve: From Maxillary (V2). o It is given off at the Sphenopalatine Ganglion. o It carries sympathetics from the Deep Petrosal Nerve and

parasympathetics from the Greater Petrosal Nerve o It enters the nose through the Sphenopalatine Foramen,

where it gives off lateral and septal branches to provide visceral motor (GVE) innervation to the nasal mucosa. Sympathetic (deep petrosal) = inhibition of nasal mucosa Parasympathetic (greater petrosal) = secretomotor

stimulation of nasal mucosa o It will continue down Septal Wall of nose, through the

Incisive Foramen, right behind the incisors (front teeth). There it will provide sensory innervation to the anterior

portion of the hard palate.

Nerve Supply:

• Anterior Ethmoid Nerve: Provides sensory innervation to internal nose, plus some innervation to external nose.

o It divides into Medial and Lateral Internal Nasal Nerves.

• Infraorbital: From Maxillary (V2), provides some sensory innervation to inferior part of external nose via External Nasal branches.

o The Infraorbital may anastomose with the Infratrochlear, from Ophthalmic (V1), over the surface of the nose.

o So, the external surface of the nose potentially has dual innervation.

Lymphatic supply of the Nose: