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NOSE

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oseIntroduction:

The nose is the part of the respiratory tract superior to the hard palate

It contains the peripheral organ of smellComposition:

external nose

nasal cavity

the nasal cavity is divided into right and left cavities by the nasalseptum

Functions:

olfaction (smelling)

respiration (breathing) filtration of dust

humidification of inspired air

reception and elimination of secretions from the paranasal sinuses

and nasolacrimal ducts

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External Nose

is the visible portion that projects from the face

its skeleton is mainly carti laginous (small bony contributions are

present)

The part of the external nose that extends from the root of the nose

to the apex (tip) of the nose is called the dorsum

The inferior surface of the nose is pierced by two piriform

openings callednares (nostr i ls, anter ior nasal apertures)

The nares are bounded laterally by the alae (wings) of the nose

The superior bony part of the nose, including its root, is covered by

thin skin

The skin over the cartilaginous part of the nose is covered with

thicker skin, which contains many sebaceous glands

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The skin extends into the anterior part of the nasal cavity called the

vestibule of the nose

The vestibule of the nose has a variable number of stiff hairs called

vibrissae

These hairs are usually moist and these help to filter dust particles

from air entering the nasal cavity

Skeleton of the External Nose

composed of:I. bones

II. cartilages

The bony partconsists of the:

nasal bones

frontal processes of the maxillae

nasal part of the frontal bone

nasal spine

bony parts of the nasal septum

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The cartilaginous part of the nose consists of five main cartilages and

small minor cartilages:

two lateral cartilages,

two alar cartilages,

and one septal cartilage

3 or 4 minor alar cartilages

The U-shaped alar cartilages are free and movable; they dilate or

constrict the nares when the muscles acting on the nose contractNasal Septum

It divides the chamber of the nose into two nasal cavities

It has a:

bony part

a soft mobile cartilaginous part

The components of the nasal septum are

perpendicular plate of the ethmoid bone

Vomer bone

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septal cartilage

nasal crest of the maxillary bone

nasal crest of palatine bone

The perpendicular plate of ethmoid,vomer, nasal crests of maxi l laryand palatine bonesform the bony part of nasal septum

While the septal carti lageforms the carti lagenous part

The thin perpendicular plate of the ethmoid bone: forming the superior part of the nasal septum

descends from the cribriform plate

and is continued superior to this plate as the crista galli

The vomer: a thin flat bone, forms the posteroinferior part of the nasal

septum, with some contribution from the nasal crests of the maxillary

and palatine bones

The septal cartilage has a tongue-and-groove articulation with the edges

of the bony septum

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CLI NICAL ANATOMY

Nasal Fractures

Because of the prominence of the nose, fractures of the nasal bones are

common facial fractures in automobile accidents and sports (unless face

guards are worn)

Epistaxis (nosebleed) usually occurs

In severe fractures, disruption of the bones and cartilages results in

displacement of the nose.

When the injury results from a direct blow, the cribriform plate of theethmoid bone may also fracture

Deviation of the Nasal Septum

The nasal septum is usually deviated to one side or the other

This could be the result of a birth injury, but more often the deviation resultsduring adolescence and adulthood from trauma (e.g., during a fist fight)

Sometimes the deviation is so severe that the nasal septum is in contact with

the lateral wall of the nasal cavity and often obstructs breathing or

exacerbates snoring

The deviation can be corrected surgically

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Nasal Cavity

Divided into right and left halves by the nasal septum

The nasal cavity is entered anteriorlythrough the nares

It opens posteriorlyinto the nasopharynx through the choanae

Mucosa lines the nasal cavity, except for the nasal vestibule, which is

lined with skin

The superior one third of the nasal mucosa forms the olfactory area

The inferior two thirds of the nasal mucosa forms the respiratory area

The olfactory area contains the peripheral organ of smell; sniffing

draws air to the area

Air passing over the respiratory area is warmed and moistened before

it passes through the rest of the upper respiratory tract to the lungs

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Boundar ies of the Nasal Cavity

The nasal cavity has a:

roof

floor

medial wall

lateral wall

The roof:

is curved and narrow, except at its posterior end

it is divided into 3 parts frontonasal

ethmoidal

sphenoidal

They are named from the bones forming each part

The floor :

is wider than the roof

is formed by the;

palatine processes of the maxilla

horizontal plates of the palatine bone

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Th di l ll

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The medial wall :

formed by the nasal septum

The lateral walls:

are irregular owing to three bony plates, the nasal conchae, whichproject inferiorly, somewhat like louvers

Features on the lateral wall of the nasal cavity

There is the presence of nasal conchae and they curve inferomedially

The nasal conchae include;

Superior nasal concha

middle nasal concha

inferior nasal concha

The conchae or turbinates of many mammals (especially running

mammals and those existing in extreme environments) are highlyconvoluted, scroll-like structures that offer a vast surface area forheat exchange

Underneath each choncha in both humans with simple nasal conchaeand animals with complex turbinates is a recess or meatus{passage(s) in the nasal cavity}

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Th l it i th di id d i t 5

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The nasal cavity is thus divided into 5 passages:

1) a posterosuperiorly placed sphenoethmoidal recess

3 laterally located nasal meatus:

II) superiorIII) middle

IV) inferior

V) and a medially placed common nasal meatus into which the four

lateral passages open

The infer ior concha

is the longest and broadest and is formed by an independent bone (of

the same name, inferior concha) covered by a mucous membrane thatcontains large vascular spaces that can enlarge to control the caliber

of the nasal cavity

When infected or irritated, the mucosa may swell rapidly, blocking the

nasal passage(s) on that side

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The sphenoethmoidal recess :

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The sphenoethmoidal recess:

lying superoposterior to the superior concha,

receives the opening of the sphenoidal sinus, an air-filled cavity in thebody of the sphenoid.

The super ior nasal meatus :

is a narrow passage between the superior and the middle nasalconchae

The posterior ethmoidal sinuses open into this superior nasal meatus

through one or more orificesThe middle nasal meatus:

is longer and deeper than the superior one

The anterosuperior part of this passage leads into a funnel-shaped

opening, the ethmoidal infundibulumthrough which it communicateswith the frontal sinus through a passage known as the frontonasalduct

the anter ior ethmoidal cells opens on the ethmoidal infundibulumdirectly or opens indirectly on the frontonasal sinus

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The ethmoidal infundibulum leads inferiorly into a semicircular groove

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The ethmoidal infundibulum leads inferiorly into a semicircular groovecalled the semilunar hiatus

The maxi l lary sinus opens into the semilunar hiatus

superior to the semilunar hiatus is a rounded elevation called the ethmoidal

bulla The ethmoidal bulla is only visible when the middle concha is removed

The bulla is a swelling formed by middle ethmoidal cells that form theethmoidal sinuses

Anterior and inferior to the semilunar hiatus is a hooklike process called the

uncinate process of the ethmoid bone This process articulates with the inferior nasal concha

The infer ior nasal meatus:

is a horizontal passage inferolateral to the inferior nasal concha

The nasolacrimal duct, which drains tears from the lacrimal sac, opens intothe anterior part of this meatus

The common nasal meatus :

is the medial part of the nasal cavity between the conchae and the nasalseptum, into which the lateral recesses and meatus open

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The arter ial supply

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The arter ial supply

The arterial supply of the medialand lateral walls of the nasal cavity is

from five sources:

Anterior ethmoidal artery (from the ophthalmic artery)

Posterior ethmoidal artery (from the ophthalmic artery)

Sphenopalatine artery (from the maxillary artery)

Greater palatine artery (from the maxillary artery)

Septal branch of the superior labial artery (from the facial artery)

The anterior part of the nasal septum is the site (Kiesselbach area)of

an anastomotic arterial plexus involving all five arteries supplying the

septum

The external nose also receives blood from the 1st and 5th arterieslisted above plus

nasal branches of the infraorbital artery

lateral nasal branches of the facial artery

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Venous drainage

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Venous drainage

A rich submucosal venous plexus deep to the nasal mucosa drains into

the sphenopalatine, facial, and ophthalmic veins

Innervation

olfactory nerve

branches of the ophthalmic [V1] which include the anterior and

posterior ethmoidal nerves

maxillary [V2] nerves which include; posterior superior lateral nasal nerves

posterior superior medial nasal nerves

nasopalatine nerve

posterior inferior nasal nerves

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CLINICAL ANATOMY

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CLINICAL ANATOMY

Epistaxis

Epistaxis (nosebleed) is relatively common because of the rich blood

supply to the nasal mucosa In most cases, the cause is trauma and the bleeding is from an area in

the anterior third of the nose (Kiesselbach area)

Epistaxis is also associated with infections and hypertension

Spurting of blood from the nose results from rupture of arteries Mild epistaxis may also result from nose picking, which tears veins in

the vestibule of the nose

Rhinitis

The nasal mucosa becomes swollen and inflamed (rhinitis) during

severe upper respiratory infections and allergic reactions (e.g.,

hayfever)

Swelling of the mucosa occurs readily because of its vascularity

Infections of the nasal cavities may spread to the:

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Infections of the nasal cavities may spread to the:

Anterior cranial fossa through the cribriform plate

Nasopharynx and retropharyngeal soft tissues

Middle ear through the pharyngotympanic tube (auditory tube), whichconnects the tympanic cavity and nasopharynx

Paranasal sinuses

Lacrimal apparatus and conjunctiva