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Nasal Cavity & Paranasal sinuses
Head & Neck Unit – Lecture 9
‫ حيدر جليل األعسم‬.‫د‬
The Nose
Human Nose consists of external nose & nasal cavity; both
are divided by nasal septum into right & left halves.
External Nose
It has two elliptical orifices called Nostrils (or Nares).
Ala Nasi are rounded mobile lateral margin of external nose.
The framework of the external nose is made up above by nasal
bones, frontal processes of maxillae, and nasal part of frontal
bone. Below, the framework is formed of plates of hyaline
cartilage.
Blood Supply: is by
branches of ophthalmic,
maxillary & facial arteries.
Nerve Supply: is by
ophthalmic nerve (through
infra-trochlear & external
nasal nerve) and infraorbital branch of maxillary
nerve.
Nasal Cavity
Nasal cavity extends from nostrils in front to posterior nasal
apertures or (choanae).
Nasal choanae are oval-shaped openings between nasal
cavities and the nasopharynx.
Boundaries of Nasal Choanae:
Inferiorly: posterior border of
horizontal plate of the palatine bone;
Laterally: posterior margin of medial
plate of pterygoid process;
Medially: posterior border of vomer.
Roof: (Anteriorly: ala of vomer &
vaginal process of medial plate of
pterygoid process; Posteriorly: body
of sphenoid bone.
Nasal Cavity
Nasal cavity is divided into right & left halves by nasal septum that is
made up of septal cartilage, vertical plate of ethmoid, and vomer bone.
Nasal cavity consists of 3 regions:
1. Nasal vestibule : small dilated
space just internal to nostrils & is
lined by skin containing hair follicles;
2. Respiratory region: largest part of
nasal cavity. It has a large plexus of
veins in the sub-mucosa. It is lined by
respiratory epithelium composed of
ciliated and mucous cells.
3. Olfactory region: small region
located at apex of nasal cavity & is
lined by olfactory epithelium
containing olfactory receptors.
Function of Warm Blood and Mucus?
Nasal Cavity
Walls of Nasal cavity: each half of the nasal cavity has a floor, a roof, a
lateral wall, and a medial or septal wall.
Floor: palatine process of maxilla and
horizontal plate of palatine bone.
Roof: anteriorly beneath bridge of
nose by nasal and frontal bones, in
the middle by cribriform plate of
ethmoid, and posteriorly by body of
sphenoid.
Medial Wall: is formed by nasal
septum. The upper part is formed by
vertical plate of ethmoid & vomer.
Anterior part is formed by septal
cartilage. The septum rarely lies in
midline.
Nasal Cavity
Lateral Wall: it has three projections of bone called superior, middle &
inferior nasal conchae. The space below each concha is called a meatus.
1. Inferior Meatus: receives opening of lower end of nasolacrimal duct,
which is guarded by a fold of mucous membrane.
Nasal Cavity
2. Middle Meatus: lies below middle
concha. It has a rounded swelling
called bulla ethmoidalis formed by
middle ethmoidal air sinuses, which
open on its upper border.
Hiatus Semilunaris ia a curved
opening lying just below the bulla &
receives opening of maxillary sinus.
Infundibulum is a funnel-shaped
channel at anterior end of hiatus.
3. Superior Meatus receives
openings of posterior ethmoid
sinuses.
4. Sphenoethmoidal Recess: is a
small area above superior concha &
receives the opening of sphenoid air
sinus.
Nasal Cavity
Blood Supply to the Nasal Cavity
Arterial supply is from branches of maxillary & facial arteries (ECA). The most
important branch is sphenopalatine artery from maxillary artery that anastomoses
with septal branch of superior labial branch of facial artery in the vestibule (little’s
area) which is the area most commonly bleed (epistaxis)
Internal Carotid artery (ICA) also supplies nasal cavity through ethmoidal branches of
ophthalmic artery.
Venous Drainage of Nasal Cavity
Submucous venous plexus is drained by veins accompanying arteries.
Nerve Supply of the Nasal Cavity
Olfaction: (Smell) is carried by olfactory nerves that ascend from olfactory
mucous membrane through cribriform plate of ethmoid to olfactory bulbs
General sensation: is by branches of the ophthalmic & maxillary divisions of
trigeminal nerve.
Nerve Supply of the Nasal Cavity
Parasympathetic fibers: to all glands by in the facial nerve (through greater
petrosal nerve), which joins branches of the maxillary nerve in the
pterygopalatine fossa.
Sympathetic fibers are ultimately derived from superior cervical sympathetic
ganglion and postganglionic fibers reach the nasal cavities along blood vessels.
Lymph Drainage of the Nasal Cavity
Lymph vessels draining the
vestibule, end in submandibular
nodes. The rest of nasal cavity is
drained to upper deep cervical
nodes.
Paranasal Sinuses
They are cavities found inside the
maxillary, frontal, sphenoid and
ethmoid bones. They are lined
with mucoperiosteum & filled with
air. They communicate with nasal
cavity through relatively small
apertures.
Function of Paranasal Sinuses:
1. Act as resonators of voice.
2. Reduce weight of the skull.
3. Help in formation of facial
characteristics.
Paranasal
Sinuses
Maxillary Sinus: is pyramidal in shape within body
of maxillary bone. Roof is formed by floor of orbit,
and Floor is related to roots of the premolars and
molar teeth. The maxillary sinus opens into middle
meatus of nose through hiatus semilunaris.
Frontal Sinuses: are contained within frontal bone
and separated from each other by a bony septum.
Each sinus is roughly triangular, extending upward
above medial end of eyebrow and backward into
medial part of roof of orbit. Each frontal sinus
opens into middle meatus of the nose through the
infundibulum.
Sphenoidal Sinuses: lie within the body of
sphenoid bone. Each sinus opens into the
sphenoethmoidal recess.
Ethmoid Sinuses: are contained within ethmoid
bone, between nose & orbit. They are anterior,
middle and posterior. Anterior sinuses open into
the infundibulum; Middle sinuses into middle
meatus on bulla ethmoidalis; & Posterior sinuses
into superior meatus.
Paranasal Sinuses
End of the Lecture
GOOD LUCK