Nasal cavity

Nasal cavity

2. Nose, Nasal cavity
&
ParanasalSinuses

3. Nose
Only externally visible part of
the respiratory system
Has a free tipand is attached
to the forehead by the rootor
the bridge
Has two openings, the
anterior (external) nares or
nostrils, which lead to the
nasal cavity
Each nostril is bounded
laterally by the alaand
medially by the nasal septum
root
tip
external nares
septum
ala

4. Nose: Structure
Nose consists of bony &
cartilaginousframework
Formed aboveby the:
•Nasal bones
•Frontal processes of
maxillae
•Nasal part of frontal bone
Formed belowby plates of
hyaline cartilage, which
include upper& lowernasal
cartilagesand the septal
cartilage
Nasal part of
Frontal bone

5. Nasal Cavity
Extends from the
external (anterior)
nares to the posterior
nares (choanae)
Divided into right & left
halves by the nasal
septum
Each half has a:
Floor
Roof
Lateral wall
Medial wall (septum)

6. Roof
Is narrow & formed (from
behind forward) by the:
•Body of sphenoid
•Cribriform plate of
ethmoid bone
•Frontal bone
•Nasal bone & cartilage
Floor
•Separates it from the
oral cavity
•Formed by the hard
(bony) palate

7. Medial Wall (Nasal
Septum)
Osteocartilaginous
partition, only rarely lying
in the midline
Covered by the
mucoperiosteum
Formed:
•Superiorlyby the
vertical (perpendicular)
plate of ethmoid bone
•Posteriorlyby the vomer
bone
•Anteriorlyby the septal
cartilage

8. Lateral Wall
Shows three horizontal bony
projections, covered by
mucous membrane, the
superior,middle&inferior
conchae (turbinates)
The superior and middle
conchae are parts of the
ethmoid bone, whereas the
inferior concha is a separate
bone
The cavity below each
concha is called a meatus
and are named as superior,
middle& inferior
corresponding to the
conchae

9. The small space above
the superior concha is
called the
sphenoethmoidal recess
•The middle meatus is
continuous in front with a
depression called the
atrium
•Atrium is limited bove by
a ridge calledagar nasi
•Below and in front of
atrium, and just within
the nostril lies the
vestibule

10. The conchae
increase the surface
area of the nasal
cavity
Therecess& meati
receive the
openings of the:
Paranasal
sinuses
Nasolacrimal duct

11. Sphenoethmoidal
recess:Receives the
opening of the
sphenoidal sinus
Superior meatus:
Receives the opening
of the posterior
ethmoidalsinus
Inferior meatus:
Receives the opening
of thenasolacrimal
duct. The opening is
guarded by a valve, a
fold of mucous
membrane

12. Middle meatus:
•Shows a rounded eminence,
the ethmoidal bulla, caused by
the bulging of the underlying
middle ethmoidal sinus, which
opens on its upper border.
•A curved groove, hiatus
semilunaris, lies below the
bulla. Hiatus receives the
opening of the maxillary sinus
•Anterior end of hiatus leads to
funnel-shapedinfundibulum,
which receives the openings
of the frontal & theanterior
ethmoidal sinuses

13. Lining of the Nasal Cavity
Vestibuleis lined by
modified skin, and has
short, curved hair called
vibrissae
The roof, upper part of the
septum, upper surface of
the superior concha, and
the sphenoethmoidalrecess
are lined by the olfactory
mucosa
The rest of the cavity is
lined by the respiratory
mucosa
V
V
A

14. Olfactory Mucosa
Contains olfactory cells (bipolar sensory
ganglion cells), which serve as receptors for
olfactory stimuli.
Distinct smells are far more numerous than
tastes
The sense of smell plays a major role in the
flavor of foods and it is common for
individuals who lose their sense of smell to
report that food loses its taste. (food seems
somewhat tasteless when a person has
cold)
Most air breathed in normally flows through
the nose but only a small part reaches the
olfactory mucosa, enough to get a response
to an odor. Sniffing, however, increases the
flow of air over the smell receptor cells,
greatly increasing their exposure to odors.

15. Respiratory Mucosa
Pseudostratified ciliated columnar epithelium with
goblet cells
Rests on thick network of thin walled veins that
warms the air as it flows through the cavity
Glandsproduce ‘mucus’, which:
moisten the air
cleans the air by trapping the incoming bacteria
and foreign debris
Cilia help in moving the contaminated mucus
posteriorly towards the throat, where it is
swallowed and digested by the stomach juices

16. NerveSupply
Nasal cavity receives sensory&
visceralinnervation
Sensory innervation
Olfactory mucosasupplied by
olfactory nerves
Nerves of general sensation are
derived from opthalmic&
maxillary nerves
Anterior part supplied by the
anterior ethmoidal nerve
(branch of opthalmic nerve)
Posterior part supplied by
nasal, nasopalatineand
palatine branches (of maxillary
nerve)

17. Visceral Innervation
Sympathetic fibers arise from
neurons of superior cervical
ganglionand are distributed
through plexuses around the
arteries, supply mainly
vascular smooth muscle
Parasympathetic fibers arise
from neurons of the
pterygopalatine ganglionthat
course in the nasopalatine
nerve(branch of maxillary)
and its branches, supply the
mucosal glands.

18. Arterial Supply
Sphenopalatine artery (branch
of the maxillary artery) is the
main supply
Alar and septal branches of
superior labial artery (branch
of the facial artery)
Anterior & posterior ethmoidal
arteries (branches of the
ophthalmic artery)
The arteries make a rich
anastomosis in the region of
the vestibule, and anterior
portion of the septum

19. Venous Drainage:
Veins begin as a rich plexus in the submucosa,
accompany the corresponding arteries, and drain
into the facial, ophthalmic, and sphenopalatine
veins.
LymphaticDrainage:
The lymphatics from the:
Vestibule drain into the submandibularlymph
nodes
Rest of the cavity drains into the upper deep
cervicallymph nodes

20. Functions of Nose & Nasal Cavities
Air conditioning: warming, cleaning and
humidifying the inhaled air
Add resonance to the voice
Vocal sounds are also produced in the nasal
cavity thus aiding in vocalisation
Involved in the special sense of smell
Central role of the nose in facial appearance
??

21. Paranasal Sinuses
Air filled cavities located in the
bones around the nasal cavity:
ethmoid, sphenoid, frontal bones
& maxillae
Lined by respiratory mucosa
which is continuous with the
mucosa of the nasal cavity
Drain into the nasal cavity
through relatively small apertures
Drainageof the sinuses mainly
depends on the movement of the
cilia, which propel the mucus
toward their openings in the
nasal cavity

22. The development of sinuses
begins in 3-4 month, but only
maxillary& ethmoid sinuses
are present in rudimentary
form at birth. The frontal&
sphenoidalsinuses are not
clinically perceptible at birth
and can rarely be
demonstrated on plain x-ray
before two years of age.
Continue to grow postnatally
Enlarge appreciably after 8
th
year & become fully formed at
adolescence
M
E
From a 3 months old fetus, showing
ethmoid & maxillary sinuses

23. Functions
Lighten the skull
Act as resonant chambers for speech
The respiratory mucosal lining helps in
warming, cleaning and moistening the
incoming air

24. Maxillary Sinuses
•Located within the body of the
maxilla
•Pyramidalin shape with the base
forming the lateral wall of nose &
the apex lies in the zygomatic
process of the maxilla
•Roof: formed by the floor of the
orbit
•Floor: formed by the alveolar
border. Roots of 1
st
and 2
nd
premolars and the 3
rd
molar
(sometimes canines) project into
the sinus
•Opens into the middle meatus
through the hiatus semilunaris
•Supplied by superior alveolar &
infraorbital nerves
M

25. Frontal Sinuses
Twoin number
Located within the frontal
bone, separated from
each other by a bony
septum
Triangularin shape,
extending backward into
the roof of the orbit
Opens into the middle
meatusthrough the
infundibulum
Supplied by the
supraorbital nerve

26. Ethmoidal Sinuses
Locatedwithin the
ethmoid bone, between
the nose and the orbit
Divided into three
groups: anterior, middle
& posterior
Anterior group opens
into the infundibulum,
middleopens on the
bulla, and posteriorinto
the superior meatus
Supplied by the anterior
and posterior ethmoidal
nerves

27. Sphenoidal Sinuses
Twoin number
Located within the
body of sphenoid
Open into the
sphenoethmoidal
recess
Supplied by the
posterior ethmoidal
nerve

28. Clinical Notes
Epistaxis:Little’s area,
common site of bleeding from
nose
Inflammation of the nasal
mucosa, Rhinitis, results in
nasal congestion and excessive
production of mucus leading to
‘postnasal drip’
Infections of the nasal cavity
can extend to the:
Paranasal sinuses
Nasolacrimal duct &
lacrimal sac

29. Inflammation of mucosa of
the sinuses, Sinusitis, causes
excessive production of mucus
leading to obstruction of the
drainage of sinuses. This
results in headache and
change in the voice
Infection of frontal & anterior
ethmoidal sinuscan easily
spread to maxillary sinus
because of the location of
their openings
Infection of upper teethcan
lead to inflammation of the
maxillary sinus
Extraction of an infected
upper tooth may result in a
fistula

30. The maxillary sinus is most
commonly the site of infection
The inflamed mucosa results
in excessive production of
mucus as well as narrowing of
its opening in the nasal cavity
The position of the drain
causes problems in that
mucus can collect in the sinus
below the drain. In this
situation, the sinus will only
drain if the patient lies on
their opposite side.
Pressure from the trapped
fluid/mucus causes sinus pain

31. Thank You & Good
Luck