Anatomy of Nose and Paranasal Sinus

Anatomy of Nose and Paranasal Sinus

The Nose

The nose consists of the external nose and the nasal cavity,
Both are divided by a septum into right and left halves.

External Nose

The external nose has two elliptical orifices called the naris (nostrils), which are separated from each other by the nasal septum.
The lateral margin, the ala nasi, is rounded and mobile.




External Nose

External Nose

The framework of the external nose is made up above by the nasal bones, the frontal processes of the maxillae, and the nasal part of the frontal bone.
Below, the framework is formed of plates of hyaline cartilage

External Nose

Blood Supply of the External Nose

The skin of the external nose is supplied by branches of the ophthalmic and the maxillary arteries.
The skin of the ala and the lower part of the septum are supplied by branches from the facial artery.

Nerve Supply of the External Nose

The infratrochlear and external nasal branches of the ophthalmic nerve (CN V) and the infraorbital branch of the maxillary nerve (CN V).


Nasal Cavity
The nasal cavity has
a floor,
a roof,
a lateral wall,
a medial or septal wall.

The Floor of Nasal Cavity

Palatine process maxilla

Horizontal plate palatine bone

The Roof of Nasal Cavity

Narrow
It is formed
anteriorly beneath the bridge of the nose by the nasal and frontal bones,
in the middle by the cribriform plate of the ethmoid,
posteriorly by the downward sloping body of the sphenoid

The Medial Wall of Nasal Cavity

The Nasal Septum
Divides the nasal cavity into right and left halves
It has osseous and cartilaginous parts

Nasal septum consists of the perpendicular plate of the ethmoid bone (superior), the vomer (inferior) and septial cartilage (anterior)

Perpendicular Plate (ethmoid)

Septal Cartilage
Vomer

The Lateral Walls of Nasal Cavity

Marked by 3 projections:
Superior concha
Middle concha
Inferior concha
The space below each concha is called a meatus.

The Lateral Walls of Nasal Cavity

The Lateral Walls of Nasal Cavity

• Inferior meatus: nasolacrimal duct
• Middle meatus:
• Maxillary sinus
• Frontal sinus
• Anterior ethmoid sinuses
• Superior meatus: posterior ethmoid sinuses
• Sphenoethmoidal recess: sphenoid sinus

Openings Into the Nasal Cavity

Nasolacrimal Canal drains into Inferior Meatus

Sphenoid sinus opens into sphenoethmoidal recess

Posterior ethmoidal air cells open into superior meatus

Anterior & middle ethmoid air cells, maxillary and frontal sinuses open into middle meatus

Blood Supply to the Nasal Cavity

Sphenopalatine a.

Maxillary a.

Netter, Frank H., Atlas of Human Anatomy. Ciba-Geigy Corporation, Summit, N.J. 1993. Plate 35.

Blood supply of the septum

Nerve Supply of the Nasal Cavity

The olfactory nerves from the olfactory mucous membrane ascend through the cribriform plate of the ethmoid bone to the olfactory bulbs .
The nerves of ordinary sensation are branches of the ophthalmic division (V1) and the maxillary division (V2) of the trigeminal nerve.

Nerve Supply of the Nasal Cavity

CN I – Olfactory Nerves (SVA)

Anterior ethmoidal branch of V1

Posterior nasal branches of V2

Cut nasopalatine branch of V2 to septum

Lymph Drainage of the Nasal Cavity

The lymph vessels draining the vestibule end in the submandibular nodes.
The remainder of the nasal cavity is drained by vessels that pass to the upper deep cervical nodes.


The Paranasal Sinuses

The Paranasal Sinuses

The paranasal sinuses are cavities found in the interior of the maxilla, frontal, sphenoid, and ethmoid bones .
They are lined with mucoperiosteum and filled with air.
They communicate with the nasal cavity through relatively small apertures.

Drainage of Mucus and Function of Paranasal Sinuses

The mucus produced by the mucous membrane is moved into the nose by cilliary action of the columnar cells.
Drainage of the mucus is also achieved by the siphon action created during the blowing of the nose.
Functions:
Resonators of the voice
They also reduce the skulls weight
Help warm and moisten inhaled air
Act as shock absorbers in trauma

Maxillary Sinus

Pyramidal in shape
Paired & symmetric
Located within the body of the maxilla behind the skin of the cheek.
The roof is formed by the floor of the orbit, and the floor is related to the roots of the 2nd premolars and 1st molar teeth.
The maxillary sinus opens into the middle meatus of the nose

Frontal Sinuses

Rarely symmetrical
Contained within the frontal bone .
Separated from each other by a bony septum.
Each sinus is roughly triangular
Extending upward above the medial end of the eyebrow and backward into the medial part of the roof of the orbit.
Opens into the middle meatus

Ethmoid Sinuses

They are anterior, middle, and posterior
They are contained within the ethmoid bone, between the nose and the orbit
Anterior & middle
Drains into middle nasal meatus
Posterior
Drain into superior nasal meatus
Separated from the orbit by a thin plate of bone so that infection can readily spread from the sinuses into the orbit

Sphenoidal Sinuses

Lie within the body of the sphenoid bone
Below sella turcica
Opens into the sphenoethmoidal recess above the superior concha

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