Find the full compiled notes on Nasal cavity and paranasal sinuses

1. NASAL CAVITY &
PARANASAL SINUSES
ONANUGA I.O.
BMS 2.1

2. INTRODUCTION
• The two nasal cavities are the
uppermost parts of the
respiratory tract.
• They are elongated wedge-
shaped spaces with a large
inf. base & a narrow sup.
apex and are held open by a
skeletal framework (bone &
cartilage).
• Apertures (Ant. & Post.)
Seprated from:
• Oral cavity by the hard
palate;
• Cranial cavity by parts of the
frontal, ethmoid & sphenoid.
• Lat. to them are the orbits.
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3. Regions
3
• Nasal vestibule, small dilated space
internal to naris, lined by skin &
contains hair follicles;
• Respiratory region, largest part of
the nasal cavity, has a rich
neurovascular supply, lined by
ciliated epithelium and mucous
cells;
• Olfactory region, at the apex of
each nasal cavity, contains the
olfactory receptors.
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4. Nasal Mucosa
• Mucosa lines the nasal cavity, except for the nasal
vestibule, which is lined with skin.
• Mucosa is firmly bound to the periosteum and
perichondrium of the supporting bones and
cartilages.
Mucosa is continuous with the lining of all the
chambers with which the nasal cavities communicate:
• Nasopharynx posteriorly,
• Paranasal sinuses superiorly and laterally, and
• Lacrimal sac and conjunctiva superiorly.
• The inferior 2/3 of NC is the respiratory area and the
superior 1/3 is the olfactory area.
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5. Skeletal framework
• Unpaired
ethmoid,
sphenoid,
frontal bone &
vomer;
• Paired nasal,
maxillary,
palatine,
lacrimal bones &
inferior conchae.
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6. Skeletal frame work
6
Perpendicular plate
articulate:
• Postly, sphenoidal
crest on the body of
sphenoid bone;
• Antly, nasal spine on
the frontal bone and
the two nasal bones;
• infely, septal cartilage
(ant) & vomer (post).
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7. ROOF • Is narrow and is highest in central
regions-formed by the cribriform plate &
foramen for the anterior ethmoidal
nerve & vessels.
Ant. to cribriform plate, the roof is formed
by:
• Nasal spine of frontal bone& nasal
bones;
• Lateral processes of the septal cartilage
& major alar cartilages of the external
nose.
Posteriorly, the roof slopes inferiorly to the
choana and is formed by:
• Anterior surface of the sphenoid bone;
• Ala of the vomer and sphenoidal process
of the palatine bone;
• Vaginal process of the medial plate of the
pterygoid process.
The opening between sphenoidal sinus &
spheno-ethmoidal recess is on the post
slope of the roof.
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8. FLOOR
• The floor is smooth,
concave, and much
wider than the roof. It
consists of: soft tissues
of the external nose;
• Formed by the upper
surface of the palatine
process of the maxilla &
the horizontal plate of
the palatine bone, which
together form the hard
palate.
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9. Medial wall
9
The MW of each NC is the
mucosa-covered surface of the
thin nasal septum.
Nasal septum consists of
• Septal nasal cartilage
anteriorly;
• Posteriorly-vomer & the
perpendicular plate of EB;
• small contributions by the nasal
bones and the nasal spine of
frontal bone;
• Nasal crests of the maxillary
and palatine bones, rostrum of
the sphenoid bones, and the
incisor crest of the maxilla20/12/2016

10. LATERAL WALL
• LW is complex, formed by
bone, cartilage & soft
tissues.
Bony support is provided by:
• Ethmoidal labyrinth &
uncinate process;
• Perpendicular plate of the
palatine bone;
• Medial plate of the
pterygoid process of the
sphenoid bone;
• Medial surfaces of the
lacrimal bones and
maxillae;
• Inferior concha.
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11. Lateral wall
• In the external nose, LW is
supported by cartilage
(lateral process of the
septal cartilage and major
and minor alar cartilages)
and by soft tissues.
• The surface of the lateral
wall is irregular in contour
and is interrupted by the
three nasal conchae.
• Conchae extend medially
across the nasal cavity,
separating it into four air
channels (IM,MM,SM &
SER). 1120/12/2016

12. Lateral wall• Inf. to the attachment of the
middle concha & ant to the
midpoint of the concha, the
lateral wall of the middle
meatus elevates to form the
dome-shaped ethmoidal
bulla-EB (formed by
underlying middle ethmoidal
cells).
• Inf. To EB is a curved gutter
(the hiatus semilunaris),
which is formed by the
mucosa& spans a defect in the
bony wall between EB &
uncinate process below.
• Ant. end of the hiatus
semilunaris forms a channel
(the ethmoidal infundibulum),
which curves suply &
continues as the frontonasal
duct to open into the frontal
sinus.
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13. Lateral Wall
• Characterized by 3 curved
shelves of bone (conchae),
which project
infriomedially across the
nasal cavity.
• The med, ant& post
margins of the conchae are
free.
• Meatus:
• Inferior nasal meatus;
• Middle nasal meatus;
• Superior nasal meatus;
• Spheno-ethmoidal recess.
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14. PARANASAL SINUSES
Develop as outgrowths from
the nasal cavities and erode
into the surrounding bones.
• Lined by respiratory
mucosa, which is ciliated
and mucus secreting;
• Open into the nasal
cavities;
• Innervated by branches of
the trigeminal nerve.
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15. PARANASAL SINUSES
15
• FS drains onto lateral wall of the
middle meatus via frontonasal duct.
• FSes are innervated by branches of
supra-orbital from V1. & supply by
branches of ant. ethmoidal arteries.
• MS opens near the top of the base,
which grooves the lateral wall of
the middle nasal meatus.
• MSes are innervated by infra-orbital
& alveolar branches of V2, and
receive their blood from the infra-
orbital and superior alveolar
branches of the maxillary arteries.
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16. Ethmoidal cells
• Ethmoidal cells fill the ethmoidal labyrinth.
ECs are formed by a variable number of individual air chambers,
which are divided:
• Ant. ECs open into the ethmoidal infundibulum or the
frontonasal duct;
• Middle ECs open onto the ethmoidal bulla, or onto lateral wall
• Post. ECs open onto the superior nasal meatus.
ECs are innervated by:
• Ant. & post. ethmoidal branches of nasociliary nerve from V1
& V2 via orbital branches from the pterygopalatine ganglion.
• ECs receive their blood supply through branches of the ant. &
post. ethmoidal arteries.
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17. Paranasal sinus drainage
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18. Sphenoidal sinuses
Open into the roof of the
NC via apertures on the
post. wall of the spheno-
ethmoidal recess.
Innervation is provided by:
• Post. ethmoidal branch
of the V1;
• V2 via orbital branches
from the pterygopalatine
ganglion.
SSes are supplied by
branches of the pharyngeal
arteries from the maxillary
arteries.
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19. External nose
• Extends the nasal
cavities onto the
front of the face &
point inferiorly.
• Pyramidal in shape
with its apex
anterior in position.
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20. External nose
• The bony parts are where the nose is continuous with the
skull-here the nasal bones and parts of the maxillae and
frontal bones provide support;
• Anteriorly, support is provided by lateral processes of the
septal cartilage, major alar and 3 or 4 minor alar
cartilages, and a single septal cartilage in the midline that
forms the anterior part of the nasal septum.
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21. Nares
• The nares are oval
apertures on the inferior
aspect of the external
nose and are the
anterior openings of the
nasal cavities.
• They are held open by
the surrounding alar &
septal cartilages, and by
the inferior nasal spine
and adjacent margins of
the maxillae. 2120/12/2016

22. Nares
Although the nares are
continuously open, they
can be widened further
by the action of the
related muscles of facial
expression:
• Nasalis muscle,
• Depressor septi nasi,
• Levator labii
superioris alaeque
nasi.
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23. Choanae
Oval-shaped openings between the
nasal cavities and the nasopharynx.
Unlike the nares, the choanae are rigid
openings completely surrounded by
bones that form the margins:
• Inferiorly-post border of the
horizontal plate of palatine bone;
• Laterally-post margin of the medial
plate of the pterygoid process;
• Medially-post border of the vomer.
The roof of the choanae is formed:
• Anteriorly-ala of the vomer and the
vaginal process of the medial plate
of the pterygoid process;
• Posteriorly-body of the sphenoid
bone.
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24. Apertures
• Cribriform plate (fibers of the
olfactory nerve, anterior ethmoidal
nerve & accompanying vessels).
• Sphenopalatine foramen
(sphenopalatine branch of the max
artery, nasopalatine & superior nasal
branches of the max nerve),
• Incisive canal (nasopalatine nerve-NC
to OC, terminal end of the greater
palatine artery-OC to NC),
• Small foramina (internal nasal
branches of the infra-orbital nerve of
V2, , alar branches of nasal artery
from the facial artery, inferior nasal
branches from the greater palatine
branch of V2.
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25. Arteries
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26. Vasculature and Innervation of the Nose
Blood to the medial and lateral walls is from 5 sources:
1. Ant. ethmoidal artery (ophthalmic a.)
2. Post. ethmoidal artery (ophthalmic a.)
3. Sphenopalatine artery (maxillary a.)
4. Greater palatine artery (maxillary a.)
5. Septal branch of the superior labial artery (facial a.)
• The ant. part of the nasal septum is the site
(Kiesselbach area) of an anastomotic arterial plexus
involving all 5 arteries supplying the septum.
• The external nose also receives blood from 1&5
arteries listed plus nasal branches of the infraorbital
artery and the lateral nasal branches of the facial
artery. 2620/12/2016

27. Veins
• A rich submucosal venous
plexus deep to the nasal
mucosa drains into the
sphenopalatine, facial and
ophthalmic veins.
• This venous plexus is an
important part of the body's
thermoregulatory system,
exchanging heat and warming
air before it enters the lungs.
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28. Nerve supply
Nasal mucosa can be divided into:
• Posteroinferior and anterosuperior portions (by an oblique line
passing approximately through the apex of the nose &
sphenoethmoidal recess.
Nerve supply of the posteroinferior portion of nasal mucosa is chiefly
from
• Maxillary nerve, via nasopalatine nerve to the nasal septum, and
• Greater palatine nerve via Post, Sup ,Lat & Inf. lateral nasal
branches to the lateral wall.
Nerve supply of the anterosuperior portion is from
• Ophthalmic nerve (CN V1) via ant. & post ethmoidal nerves,
• branches of the nasociliary nerve.
• Most of the external nose (dorsum and apex) is also supplied by CN
V1 (via the infratrochlear nerve and the external nasal branch of
the anterior ethmoidal nerve),
• Alae are supplied by the nasal branches of the infraorbital nerve
(CN V2).
 The olfactory nerves, concerned with smell 2820/12/2016

29. Nerves
s
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30. Lymphatics
• Lymph from anterior regions
drains forward onto the face by
passing around the margins of
the nares ultimately connect
with the submandibular nodes.
• Lymph from posterior regions of
the nasal cavity and the
paranasal sinuses drains into
upper deep cervical nodes.
Some of this lymph passes first
through the retropharyngeal
nodes.
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31. Rhinitis
• The nasal mucosa becomes swollen and inflamed (rhinitis) during
severe upper respiratory infections and allergic reactions (e.g.,
hayfever). Swelling of the mucosa occurs readily because of its
vascularity. Infections of the nasal cavities may spread to the:
• Anterior cranial fossa through the cribriform plate.
• Nasopharynx and retropharyngeal soft tissues.
• Middle ear through the pharyngotympanic tube (auditory tube),
which connects the tympanic cavity and nasopharynx.
• Paranasal sinuses.
• Lacrimal apparatus and conjunctiva.
Epistaxis
• Epistaxis (nosebleed) is relatively common because of the rich blood
supply to the nasal mucosa.
• In most cases, the cause is trauma and the bleeding is from an area in
the anterior third of the nose (Kiesselbach area).
• Epistaxis is also associated with infections and hypertension. Spurting
of blood from the nose results from rupture of arteries.
• Mild epistaxis may also result from nose picking, which tears veins in
the vestibule of the nose. 3120/12/2016