It extends from: 
Anterior: Nostrils
Posterior : Choanae
It is divided by the 
Nasal Septum into
right and left halves.
It is narrow and 
arched.
It lies below the 
Anterior Cranial
Fossa.
It is formed of: 
Nasal cartilages. 
Nasal and frontal 
bones.
Cribriform Plate of
Ethmoid.
Body of sphenoid. 

It forms part of the 
roof of the oral
cavity.
It is composed of: 
Palatine process of 
maxilla .
Horizontal plate of 
palatine bone.
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It is formed of:
(1) Bony Part:
Perpendicular Plate of
Ethmoid: Superior
Vomer : posterior &
inferior.
(2) Septal Cartilage:
Anterior & inferior
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Irregular in contour .
It is interrupted by
Three Nasal ConChae.
Inferior: A separate
bone.
Middle: 
Superior: 
Are parts of Ethmoid
Bone
The Inferior Concha is
the largest.
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The nasal cavity is 
separated by the conchae
into Four Air Channels:
Superior 
Middle 
Inferior Meatuses. 
Spheno- Ethmoidal 
Recess : A triangular
fossa between superior
concha & roof of nose.
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It is above nostrils .
Lateral : ala of nose.
Above & Behind :
A curved elevation
“Limen Nasi”
It is lined by skin.
It has short hairs.
A depression between:
Middle meatus &
Vestibule
• Above : a ridge
“Agger Nasi”
1.
2.
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Bulla Ethmoidalis:
Dome shaped
elevation
Hiatus semilunaris:
Crescentic groove
below bulla.
Infundibulum:
Curved channel
Anterior to Hiatus.
Olfactory 
It lines : 
Roof. 
Upper surface of the 
superior concha.
Spheno-ethmoidal 
recess.
Corresponding area of
the nasal septum.
Respiratory : 
Lines the rest. 
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It posses special 
olfactory nerve
cells.
Their central 
processes are
Olfactory Nerves.
Which pass through
the Cribriform plate
of Ethmoid into the
Brain.
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A) Special :
Olfactory nerve
(B) General :
1. Ophthalmic Nerve:
. Anterior Ethmoidal:
It enters the nasal cavity
through a slit medial to
Crista Galli.
It gives the Internal Nasal to
the medial and lateral walls.
It terminates as the External
Posterior Ethmoidal: 
It enters the nasal 
cavity from the orbit.
It supplies the 
Ethmoidal cells and
Sphenoidal sinus. 
It does not extend 
into the nasal cavity
itself.
1. Nasopalatine: 
It is the largest branch. 
It passes through the 
incisive fossa to the roof
of the oral cavity.
It supplies the oral 
mucosa posterior to the
incisor teeth.
2. Posterior 
superior : lateral &
medial nasal
3. Posterior inferior
nasal:
From the greater 
palatine .
They supply the 
lateral wall.

From Pterygopalatine
ganglion.
Preganglionic: 
From the facial nerve
(greater petrosal).
Postganglionic : 
Through maxillary 
nerve.
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The Preganglionic 
synapse in the Superior
Cervical Ganglion.
The Post ganglionic 
fibers pass onto the
Internal Carotid Artery.
They join the Greater 
Petrosal to the
Pterygopalatine
Ganglion.
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1. Maxillary artery:
Sphenopalatine.
Greater palatine.
2. Facial artery:
Superior labial.
Lateral nasal.
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It is the terminal branch of
the maxillary A. in the
pterygopalatine fossa.
It is the most important
artery.
It gives:
Posterior lateral nasal.
Posterior septal branches.
It enters the floor of the
nasal cavity through the
incisive fossa and canal.
It supplies: 
Anterior part of the 
septum.
Adjacent part of the 
floor.

Anterior Ethmoidal.
Posterior
Ethmoidal.
They arise in the 
orbit from the
Ophthalmic Artery.
They supply : 
lateral and medial
walls.
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1. Anterior part of
septum (Little’s area):
• It is the major site of
Epistaxis.
• Anastomoses between:
• (1) Sphenopalatine
artery .
(2) Septal branch of
superior labial.
(3) Greater palatine.
(4) Anterior ethmoidal.
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2. Posterior part of
septum
(less common) :
Anastomoses
between branches
of Sphenopalatine
artery
1.
2.
3.
4.
5.
Facial vein.
Pterygoid plexus
An emissary vein.
It passes through the
foramen caecum and
joins the Superior
Sagittal Sinus.
This can be a route of
transmission of
infection to the cranial
cavity.
Vestibule:
Submandibular
nodes.
2. Rest of nasal
cavity:
Upper deep cervical
nodes.
1.
Ethmoidal Cells. 
Sphenoidal. 
Maxillary. 
Frontal sinuses. 
They are outgrowths 
from the nasal cavities
that erode into the
surrounding bones.
• Functions :
1. Lighten the weight of
skull
2. Add resonance to voice
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Lined with mucoperiosteum
and filled with air.
Open into lateral wall of
nasal cavity.
Innervated by branches of
the trigeminal nerve.
The maxillary and sphenoidal
are rudimentary at birth.
They enlarge after the 8th
year.
They are two in number. 
Most superior sinuses. 
Each is Triangular in 
shape.
Extension: 
Upward above the medial
end of the eye brow.
Backward into the medial
end of the roof of the
orbit.
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Drainage:
To the Infundibulum
of the middle meatus
through Frontonasal
duct .
Nerve supply:
Supraorbital nerve..
They are the largest. 
Fill the bodies of the 
maxillae.
Pyramidal in shape. 
Apex: 
In the zygomatic process
of maxilla.
Base : 
Forms to the lateral wall
of the nose.
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Roof :
Floor of orbit. (orbital plate
of maxilla)
Floor:
Alveolar process of maxilla.
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1.
The roots of upper
premolars & molars
project into the floor of
the sinus .
Infection of them can
cause Sinusitis
Extraction of a tooth
may result in a Fistula.
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Drainage:
Into Hiatus Semilunaris.
Nerve Supply:
Superior alveolar.
Infraorbital.
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Site : within ethmoid
bone
They are (3) groups:
Anterior.
Middle.
Posterior.
Drainage:
• Anterior :
Infundibulum.
• Middle :
• Bulla Ethmoidalis
• Posterior :
• Superior Meatus.
Nerve Supply:
Anterior & Posterior
Ethmoidal.
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The sinuses are separated
from the orbit by a thin
orbital plate of ethmoid
bone.
Infection can spread from
the sinuses into the
Orbit.
It can cause Orbital
Cellulitis.
Two in number.
 Site: within the
body of sphenoid.
Drainage:
Sphenoethmoidal
Recess.
Nerve supply :
Posterior Ethmoidal
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