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

3.  Nose consists of bony &
cartilaginous framework
 Formed above by the:
• Nasal bones
• Frontal processes of
maxillae
• Nasal part of frontal bone
 Formed below by plates of
hyaline cartilage, which
include upper & lower nasal
cartilages and the septal
cartilage
Nasal part of
Frontal bone

4.  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)

5.  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

6.  Medial Wall (Nasal
Septum)
 Osteocartilaginous
partition, only rarely lying
in the midline
 Covered by the
mucoperiosteum
 Formed:
• Superiorly by the vertical
(perpendicular) plate of
ethmoid bone
• Posteriorly by the vomer
bone
• Anteriorly by the septal
cartilage

7.  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

8.  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 called agar nasi
• Below and in front of
atrium, and just within
the nostril lies the
vestibule

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

10.  Sphenoethmoidal
recess: Receives the
opening of the
sphenoidal sinus
 Superior meatus:
Receives the opening
of the posterior
ethmoidal sinus
 Inferior meatus:
Receives the opening
of the nasolacrimal
duct. The opening is
guarded by a valve, a
fold of mucous
membrane

11.  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-shaped infundibulum,
which receives the openings of
the frontal & the anterior
ethmoidal sinuses

12.  Vestibule is 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 sphenoethmoidal recess
are lined by the olfactory
mucosa
 The rest of the cavity is
lined by the respiratory
mucosa
V
V
A

13.  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.

14.  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
 Glands produce ‘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

15.  Nasal cavity receives sensory &
visceral innervation
Sensory innervation
 Olfactory mucosa supplied 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, nasopalatine and
palatine branches (of maxillary
nerve)

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

17.  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

18. Venous Drainage:
 Veins begin as a rich plexus in the submucosa,
accompany the corresponding arteries, and drain
into the facial, ophthalmic, and sphenopalatine
veins.
Lymphatic Drainage:
 The lymphatics from the:
 Vestibule drain into the submandibular lymph nodes
 Rest of the cavity drains into the upper deep cervical
lymph nodes

19.  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
 ??

20.  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
 Drainage of the sinuses mainly
depends on the movement of
the cilia, which propel the mucus
toward their openings in the
nasal cavity

21.  The development of sinuses
begins in 3-4 month, but only
maxillary & ethmoid sinuses
are present in rudimentary
form at birth. The frontal &
sphenoidal sinuses 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 8th
year & become fully formed at
adolescence
M
E
From a 3 months old fetus, showing
ethmoid & maxillary sinuses

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

23. • Located within the body of the
maxilla
• Pyramidal in 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 1st and 2nd
premolars and the 3rd molar
(sometimes canines) project into
the sinus
• Opens into the middle meatus
through the hiatus semilunaris
• Supplied by superior alveolar &
infraorbital nerves
M

24.  Two in number
 Located within the
frontal bone, separated
from each other by a
bony septum
 Triangular in shape,
extending backward into
the roof of the orbit
 Opens into the middle
meatus through the
infundibulum
 Supplied by the
supraorbital nerve

25.  Located within the
ethmoid bone,
between the nose and
the orbit
 Divided into three
groups: anterior,
middle & posterior
 Anterior group opens
into the infundibulum,
middle opens on the
bulla, and posterior
into the superior
meatus
 Supplied by the
anterior and posterior
ethmoidal nerves

26.  Two in number
 Located within the
body of sphenoid
 Open into the
sphenoethmoidal
recess
 Supplied by the
posterior ethmoidal
nerve

27.  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

28.  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 sinus can easily
spread to maxillary sinus
because of the location of
their openings
 Infection of upper teeth can
lead to inflammation of the
maxillary sinus
 Extraction of an infected
upper tooth may result in a
fistula

29.  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