Nasal cavity and paranasal sinuses

Nasal Cavity and Paranasal

Sinuses

Dr. Wael Mohamed Talaat

Assistant Professor of Oral and Maxillofacial

Surgery

University of Sharjah

Objectives

Knowledge of the anatomy of the

nasal cavity

Knowledge of the anatomy of the

paranasal sinuses and their dental

implications

Nasal Cavity

Is the nasal cavity closely related

to our practice ??

Why did a patient experience bubbling

of blood and escape of fluids through

his nostril following extraction of his

second upper molar ???

Functions

A passageway for air to lungs

Organ of smell

Filters impurities from inspired air

Warms and humidifies inspired air

Aids in phonation

Receives secretions from paranasal

sinuses

Receives secretions from nasolacrimal

duct

Bony framework

Nasal bone

Frontal process of the maxilla

Nasal process of the frontal bone

Bony Framework: Nasal Bone

Bony Framework: Nasal Bone

The two nasal bones form the upper part of the bridge of the nose. Each nasal bone is quadrilateral, being longer than it is wide.

The superior border articulates with the nasal part of the frontal bone.

The inferior border forms the superior boundary of the anterior nasal aperture.

The lateral border meets thefrontal process of the maxilla and the medial border meets its fellow in the midline.

Bony Framework:

Frontal process of the maxilla

Bony Framework:

Frontal process of the maxilla

The frontal process of the maxilla

projects postero-superiorly from the

body of the maxilla and is situated

between the nasal bone in front and

the lacrimal bone behind. The process

articulates apically with the frontal's

nasal part, the anterior border with the

nasal bone and the posterior border

with the lacrimal bone.

Bony Framework:

Nasal process of the frontal bone

The nasal part of the frontal bone is a

small, thin plate of bone that projects

antero-inferiorly in the midline

between the supra-orbital margins and

forms a small portion of the roof of the

nose.

Bony Framework:

Nasal process of the frontal bone

Cartilaginous framework

• Lateral Superior Nasal cartilage

• Greater Lower Nasal Cartilages

• Minor Alar Cartilages

• Septal Nasal Cartilages

Lateral Superior Nasal cartilage

Lateral Superior Nasal cartilage

Greater Lower Nasal

Cartilage

Lateral Superior & Greater Nasal cartilages

The lateral (upper) nasal cartilages

and the greater (lower) nasal

cartilages support the lateral surfaces

of the external nose. The lateral nasal

cartilages are triangular plates. They

are united in the midline with each

other and with the septal cartilage.

Minor Alar Cartilages

Minor Alar Cartilages

The minor alar cartilages are found at

the back of the major nasal cartilages,

embedded in fibrous tissue that

connects them to the maxilla.

Function

Extend to maintain the patency of the

anterior nares.

Septal Nasal Cartilages

Septal Nasal Cartilages

The cartilaginous elements form the lower part of the external nose and in the midline lies the septal cartilage. It is quadrangular and fits posteriorly into the notch between the perpendicular plate of the ethmoid bone and the vomer. The septal cartilage is also attached to the nasal crest of the maxilla and to the anterior nasal spine. The septal cartilage at the apex of the external nose is termed the 'columella'. The columellacan also be defined as the tip of the mobile part of the septum.

The entire nasal

cavity extends from

the nares (nostrils)

anteriorly to the

choanae posteriorly Choanae

•It is divided into 2

parts by an

osseocartilaginous

nasal septum

Each half of the nasal cavity has a:

Floor

Roof

Lateral wall

Septal wall

The Floor

Palatine process

maxilla

Horizontal plate

palatine bone

(the superior surface of

the hard palate)

http://www.netterimages.com/images/vtn/000/000/001/1966-150x150.jpg

The Roof Narrow

Formed by a number of bones and cartilages

Nasal Cartilages, Nasal, Frontal, Ethmoid,Sphenoid Bones

The Nasal Septum (the medial wall)

Divides the nasal cavity into right and left halves

It is part osseous and part cartilaginous

Perpendicular

Plate (ethmoid)

Vomer

Septal

Cartilage

The Lateral Walls

Marked by 3

projections:

◦ Superior concha

◦ Middle concha

◦ Inferior concha

The area below each

concha is referred to as a

meatus (passageway).

Superior Meatus

Middle Meatus

Inferior Meatus

Paranasal Sinuses

Paranasal Sinuses are air containing

bony spaces around the nasal cavity

Usually lined by respiratory mucous

membrane of ciliated columnar

epithelium

Four pairs of paranasal sinuses surround

the nasal cavities and are named from the

bones

in which they are located: maxillary,

frontal, sphenoid, and ethmoid sinuses.

The maxillary sinuses are located lateral to the nasal cavities. Each of the two sinuses is pyramidal in shape with the apex of each located near the zygomatic bone.

The maxillary sinus is the first of the

paranasal sinuses to develop, and its

growth ends with the eruption of the

third molars at approximately 20 years

of age

Roof: The roof of the

sinus is part of the floor of the orbit and contains the infra-orbital canal, which transmits the infra-orbital nerve and vessels.

Floor

The alveolar

process and part

of the palatine

process of the

maxilla form the

floor of the sinus,

which lies below

the level of the

floor of the nose

and is related to

the roots of the

teeth.

Apex:

The apex extends into the zygomatic process of the maxilla.

Anterior wall

The anterior wall of the maxillary sinus is the facial surface of the maxilla.

Posterior wall

The posterior wall

is the

infratemporal

surface of the

maxilla. The

posterior superior

alveolar nerve

and vessels pass

through canals in

the posterior

surface of the

sinus.

Medial wall:

The base or medial wall forms part of the lateral wall of the nose and has the opening (ostium) of the sinus.

√ Size varies from one person to another.

√ Asymmetry existed in the same individual.

√ Small in children and grows up with aging.

√ Average height is about 3.5 cm, depth 3.2 cm and width 2.5 cm.

√ Capacity of about 15 cc.

√ Divided into several compartments by bony septa (underwood’s septa).

√ Lined with pseduo-stratified columnar ciliary epithelium.

Pneumatization is the enlargement of

the sinus by resorption of the alveolar

bone that formerly served to support a

tooth or teeth

What might be the clinical implications

of maxillary sinus pneumatization ??

Each maxillary sinus communicates

with the nasal cavity by the ostium

which opens into the middle nasal

meatus under the overlapping middle

nasal turbinate. Although the ostium is

located at a higher level than the floor

of the maxillary sinus, the normal

sinus drains satisfactorily because of

the action of the cilia of the

pseudostratified columnar epithelium.

Kilic C et al, An Assessment of the

Relationship between the Maxillary

Sinus Floor and the Maxillary

Posterior Teeth Root Tips Using

Dental Cone-beam Computerized

Tomography, Eur J Dent. 2010

October; 4(4): 462–467.

N Mean Std. Dev. Minimum Maximum

R 1st pm 87 8.42 9.10 −1.32 28.52

R 2nd pm 87 3.75 6.67 −21.00 23.70

R 1st mo bm 87 1.77 6.10 −5.41 27.55

R 1st mo bd 87 0.70 4.69 −4.71 27.17

R 1 st mo pal 87 1.86 6.06 −4.22 29.46

R 2nd mo bm 87 0.42 2.85 −5.06 16.45

R 2nd mo bd 87 0.25 2.17 −5.97 8.76

R 2nd mo pal 87 1.06 2.36 −4.52 9.57

R 3rd mo bm 87 1.63 3.33 −2.67 8.41

R 3rd mo bd 87 0.62 3.40 −3.50 8.48

R 3rd mo pal 87 0.92 3.32 −2.87 8.54

Mean, standard deviation, minimum and maximum values obtained fromright premolar and molar teeth.

Their results showed that the distance

between sinus floor and root tip was

longest for the first premolar root tip

and shortest for the second molar

buccodistal root tip for both right and

left sides. No statistically significant

differences were found between the

right and left side measurements or

between female and male patients

(P>.05).

Ethmoid Air Sinus

Ethmoid Air Sinus

The ethmoid sinus is each of the two

paranasal sinuses within the ethmoid

bone, comprising the ethmoidal air

cells and filled with air. They lie

between the upper parts of the nasal

cavities and the orbits, and are

separated from these cavities by thin

bony laminae.

Sphenoid Air Sinus

Sphenoid Air Sinus

The two sphenoidal sinuses are

contained within the body of the

sphenoid and they vary in size and

shape; owing to the lateral

displacement of the intervening

septum.

Functions of Paranasal Sinuses

Humidifying and warming inspired air

Regulation of intranasal pressure

Increasing surface area for olfaction

Lightening the skull

Resonance

Absorbing shock

Frontal Sinus

Frontal Sinus

Within the frontal bone are two funnel-shaped cavities, termed the '

frontal air sinuses '.

They lie above and behind the superciliary arches immediately above

the roof of the nasal cavity and may extend into the medial part of the

roof of the orbit. In such cases, a thin layer of bone separates the sinus

from the floor of the cranial cavity and from the roof of the orbit.

Please answer question on slide 4.

Thank You