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Netter's Atlas Of Human Anatomy (5th Ed.).pdf
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5 Nasal Region

STUDYAIMS

At the end of your study, you should be able to:

Outline the structures that form the nasal region Describe the gross structure of the external nose Describe the nasal septum

Define the boundaries of the nasal cavity

Describe the structure of the nasal cavityincluding its blood supply, venous and lymphatic drainage, and innervation Describe the origin of the paranasal sinuses and their relationship to the nasal cavity

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GUIDE

Head and Neck: Nasal Region

Nasal region

External nose

Nasal cavities

Divided bynasal septum

Filter, humidifyand warm air

Contain specialised olfactorymucosa

Receive secretions from paranasal sinuses and nasolacrimal duct

Includes related paranasal sinuses

External Nose

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The nose is composed primarilyof cartilages except at the "bridge" of the nose where the nasal bone resides.Anteriorly, the air enters or leaves the nose via the nares, which open into the nasal vestibule, whereas posteriorlythe nasal cavitycommunicates with the nasopharynxvia paired apertures called the choanae.

Composed of bone and hyaline cartilage Bones

Paired nasal bones

Frontal processes of maxilla

Nasal part frontal bone

Cartilages

Paired lateral cartilages

Paired alar cartilages

Septal cartilage

Associated muscles dilate and flatten nares (nostrils)

Nasalis

Compressor nares

Dilator nares

Innervation ophthalmic and maxillarydivisions of trigeminal nerve (cranial nerve [CN] V1 and V2)

Blood supply

Ophthalmic artery

Facial artery

Venous drainage

Facial veins → internal jugular veins

Ophthalmic veins → cavernous sinus

Nasal septum

The nasal cavityis separated from the cranial cavitybyportions of the frontal, ethmoid, and sphenoid bones, and from the oral cavityinferiorlybythe hard palate.Anasal septum, usuallydeviated slightlyto one side or the other, divides the nasal cavityinto right and left chambers. The anterior third of the nasal septum is cartilaginous and the posterior two thirds is bony.

Divides nasal cavityinto two chambers

Composed of

Bone

Vomer

Perpendicular plate of ethmoid

Septal cartilage

Septal cartilage articulated with edges of bonyseptum

Nasal Cavity

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The lateral wall of the nasal cavityis characterized bythree shell-like conchae, or turbinates, that protrude into the cavity, and along with their covering of nasal respiratoryepithelium, theygreatlyincrease the surface area for warming, humidifying, and filtering the air.At the most superior aspect of the nasal cavityresides the olfactoryregion, with its olfactoryepithelium and specialized sensorycells for the detection of smells.

Each cavitynarrow above and wider below, separated from each other bynasal septum

Extend from nares to choanae

Naris = external opening of nose

Choana = opening into pharynx

Vestibule

First part of cavity

Lined with skin with hairs

Bounded laterallybyalar cartilages

Limen nasi

Crescentic line

Marks upper limit of vestibule

Nasal mucosa

Lines nasal cavities except for vestibule

Bound to periosteum and perichondrium of surrounding bones and cartilages

Extends into all chambers, cavities and sinuses communicating with nasal cavities

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Upper one third is olfactoryareas (mucosa)

Lower two thirds is respiratoryareas (mucosa) Boundaries (walls) of nasal cavity

Nasal conchae

Three horizontal projections from lateral wall

Superior, middle and inferior nasal conchae

Divide nasal cavityinto four areas

Superior meatus

Middle meatus

Inferior meatus

Sphenoethmoid recess Superior meatus

Between superior and middle conchae

Has openings from posterior ethmoidal sinuses Middle meatus

Wider and longer than superior

Depressed area-atrium-at anterior end

Ethmoid infundibulum at anterior end

Leads to frontonasal duct

Duct leads to frontal sinus

Ethmoidal bulla (swelling)

Rounded projection at inferior root of middle meatus

Represents bulge of ethmoid air cells (sinuses)

Groove called semilunar hiatus immediatelybeneath leads to infundibulum

Contains openings for frontal, maxillary, and anterior ethmoidal sinuses

Frontal sinus opening at anterior end of semilunar hiatus/infundibulum

Maxillarysinus opening at posterior end of semilunar hiatus

Variable openings for ethmoid air cells Inferior meatus

Below inferior concha

Receives nasolacrimal duct opens into anterior end Sphenoethmoidal recess:

Posterior and superior to superior concha

Receives opening of sphenoidal sinus Innervation

Posterior region of nasal cavity

Nasal septum: maxillarynerve (CN V2) → nasopalatine nerve to nasal septum

Lateral wall: lateral branches of lateral palatine nerve

Anterior and superior regions of nasal cavity: anterior and posterior ethmoidal nerves, branches of nasociliarynerve from ophthalmic nerve (CN V1)

Olfactoryepithelium innervated byolfactorynerve (CN I) Arterial supply

Sphenopalatine artery(branch of maxillaryartery)

Anterior and posterior ethmoidal arteries

Greater palatine artery

Superior labial and lateral nasal branches of facial artery Venous drainage

Plexus of veins beneath nasal mucosa drains to

Sphenopalatine veins

Facial veins

Ophthalmic veins Lymphatic drainage

Posterior nasal cavityto retropharyngeal nodes Anterior nasal cavityto submandibular nodes

Paranasal sinuses

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Sinus

Description

Frontal

Paired sinuses, lying anteriorlyin frontal bone and draining into semilunar hiatus of middle meatus

Ethmoid

Paired anterior, middle, and posterior sinuses in ethmoid bone; anterior and middle draining into middle meatus

 

(hiatus semilunaris and ethmoid bulla, respectively), and posterior, into superior nasal meatus

Sphenoidal

Paired sinuses, in sphenoid bone, draining into sphenoethmoidal recess

Maxillary

Paired sinuses, in maxilla, draining into middle meatus (semilunar hiatus); largest sinus (20-30 ml)

There are four pairs of paranasal sinuses, which are open chambers within several of the bones surrounding the nose and orbits. Theyare lined with respiratoryepithelium, assist in warming and humidifying the inspired air, and drain their mucus secretions into the nasal cavities. Blowing the nose clears the nasal cavityand sinuses of excess secretions.

Extensions of nasal cavityinto maxillary, ethmoid, frontal, and sphenoid bones

Lined with respiratoryepithelium

Present at birth and increase in size until adulthood

Air filled

Frontal sinuses (2)

Between inner and outer tables of frontal bone

Can be detected around age 7

Maxillarysinuses (2)

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Largest of paranasal sinuses

Occupymost of bodyof maxillae Ethmoidal sinuses

Several in number

Not well developed until after age 2 Sphenoidal sinuses

Derive from extensions of ethmoidal sinuses into sphenoid bone around 2 years of age

Numbers different on either side

Bonyseptum between two sides

Onlya thin plate of bone separates them from critical structures in the anterior and middle cranial fossae: optic nerves, pituitary gland, internal carotid arteries, cavernous sinuses

[Plate 46, Orientation of Nerves and Vessels of the Cranial Base]

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