Transcript Clinical Anatomy of Nasal Cavity and Olfaction

Anatomy
Chapter 7- Part 8
Clinical Anatomy of Head:
Nasal Cavity
Associate Professor
Dr. Podcheko
SJSM
2015
Intended Learning Outcomes:
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To know clinical anatomy of :
NOSE
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External Nose
Nasal Cavities
Vasculature and Innervation of Nose
Paranasal Sinuses
Clinical correlations related to the nasal cavity anatomy
Nose
•The nose is the part of the respiratory tract superior to the
hard palate and contains the peripheral organ of smell.
•It includes the external nose and nasal cavity, which is divided
into right and left cavities by the nasal septum.
•The functions of the nose are olfaction (smelling),
respiration (breathing), filtration of dust, humidification of
inspired air, and reception and elimination of secretions from
the paranasal sinuses and nasolacrimal ducts.
External Nose
•The external nose is the visible portion
that projects from the face; its skeleton is
mainly cartilaginous.
•Noses vary considerably in
size and shape, mainly
because of differences in these
cartilages.
•The dorsum of the nose
extends from the root of the
nose to the apex (tip) of the
nose.
•The inferior surface of the nose is
pierced by two piriform (pearshaped) openings, the nares
(nostrils, anterior nasal apertures),
which are bound laterally by the alae
(wings) of the nose.
External Nose
•The superior bony part of the nose, including its
root, is covered by thin skin.
•The skin over the cartilaginous part of
the nose is covered with thicker skin,
which contains many sebaceous
glands.
•The skin extends into the vestibule of
the nose, where it has a variable
number of stiff hairs (vibrissae).
•Because they are usually moist, these
hairs filter dust particles from air
entering the nasal cavity.
•The junction of the skin and mucous
membrane is beyond the hairbearing area.
Skeleton of the External Nose
•The supporting
skeleton of the nose
is composed of bone
and hyaline cartilage.
•The bony part of
the nose consists of
the nasal bones,
frontal processes of
the maxillae, the
nasal processus of
the frontal bone and
its nasal spine, and
the bony parts of the
nasal septum.
Skeleton of the External Nose, contd.
•The cartilaginous
part of the nose
consists of five main
cartilages: two
lateral cartilages,
two alar cartilages,
and one septal
cartilage.
•The U-shaped alar
cartilages are free and
movable; they dilate or
constrict the nares
when the muscles
acting on the nose
contract.
Nasal Septum
•The nasal septum divides the chamber of the nose into two nasal
cavities and has a bony part and a soft mobile cartilaginous part.
•The main components of the nasal septum are the perpendicular
plate of the ethmoid, the vomer, and the septal cartilage.
•The thin perpendicular plate of the ethmoid bone, forming the
superior part of the nasal septum, descends from the cribriform
plate and is continued superior to this plate as the crista galli.
•The vomer, a thin flat bone, forms
the posteroinferior part of the
nasal septum, with some
contribution from the nasal crests
of the maxillary and palatine
bones.
•The septal cartilage has a tongueand-groove articulation with the
edges of the bony septum.
Clinical Correlates: Nasal Fractures
•Because of the prominence of the nose, fractures of the nasal
bones are common facial fractures in automobile accidents and
sports (unless face guards are worn).
•Fractures usually result in deformation of the nose, particularly
when a lateral force is applied by someone's elbow, for example.
•Epistaxis (nosebleed) usually occurs.
•In severe fractures, disruption of the
bones and cartilages results in
displacement of the nose.
•When the injury results from a
direct blow, the cribriform plate of
the ethmoid bone may also fracture.
Deviation of the Nasal Septum
•The nasal septum is usually deviated to one side or the other.
•This could be the result of
a birth injury, but more
often the deviation results
during adolescence and
adulthood from trauma
(e.g., during a fist fight).
•Sometimes the deviation is
so severe that the nasal
septum is in contact with the
lateral wall of the nasal cavity
and often obstructs breathing
or exacerbates snoring.
•The deviation can be corrected
surgically.
Nasal Cavity
•The term nasal cavity, divided into right and left halves by the
nasal septum, refers to either the entire cavity or one of its halves,
depending on the context.
•The nasal cavity is entered anteriorly through the nostrils.
•It opens posteriorly into the
nasopharynx through the
choanae.
•Mucosa lines the nasal
cavity covered with ciliated
columnar epithelium
containing goblet cells and
serous glands. The serous
glands produce a fluid
containing lysozymes which
are bacteriocidal
•Nasal vestibule is lined with
skin.
Nasal Cavity, contd.
•The nasal mucosa is firmly bound to the periosteum and
perichondrium of the supporting bones and cartilages of the nose.
•The mucosa is continuous with the lining of all the chambers
with which the nasal cavities communicate: the nasopharynx
posteriorly, the paranasal sinuses superiorly and laterally, and the
lacrimal sac and conjunctiva superiorly.
Nasal Cavity, contd.
•The inferior two thirds of the
nasal mucosa is the
respiratory area and the
superior one third is the
olfactory area.
•Air passing over the
respiratory area is
warmed and moistened
before it passes through
the rest of the upper
respiratory tract to the
lungs.
•The olfactory area contains the peripheral organ of smell; sniffing
draws air to the area
Boundaries of the Nasal Cavity
•The nasal cavity
has a roof, floor,
and medial and
lateral walls.
•The roof of the
nasal cavity is
curved and narrow,
except at its
posterior end; it is
divided into three
parts (frontonasal,
ethmoidal, and
sphenoidal)
named from the
bones forming
each part.
1
2
3
Boundaries of the Nasal Cavity
•The floor of the nasal cavity is wider than the roof and is formed
by the palatine processes of the maxilla and the horizontal plates
of the palatine bone.
•The medial wall of
the nasal cavity is
formed by the nasal
septum.
•The lateral walls of
the nasal cavity are
irregular owing to
three bony plates, the
nasal conchae, which
project inferiorly,
somewhat like
louvers (window blinds)
Features of the Nasal Cavity
•The nasal conchae
(superior, middle, and
inferior) curve
inferomedially, hanging
like short curtains.
•The conchae (shells)
or turbinates of many
mammals (especially
running mammals and
those existing in
extreme
environments) are
highly convoluted,
scroll-like structures
that offer a vast
surface area for heat
exchange.
Features of the Nasal Cavity
• Each nasal conch with surrounding structures forms a recess
and/or meatus which underlies each of the conchae
•The nasal cavity is
divided into five
passages: a
posterosuperiorly
placed
sphenoethmoidal
recess, three laterally
located nasal meatus
(superior, middle,
and inferior meatus),
and a medially
placed common
nasal meatus into
which the four
lateral passages
open.
common nasal
meatus
Features of the Nasal Cavity
•The inferior concha is the
longest and broadest and
is formed by an
independent bone (of the
same name, inferior
concha) covered by a
mucous membrane that
contains large vascular
spaces that can enlarge to
control the caliber of the
nasal cavity.
•When infected or
irritated, the mucosa
may swell rapidly,
blocking the nasal
passage(s) on that
side.
Features of the Nasal Cavity
The
sphenoethmoidal
recess, lying
superoposterior
to the superior
concha, receives
the opening of
the sphenoidal
sinus, an air-filled
cavity in the body
of the sphenoid.
The superior nasal meatus is a narrow passage between the superior
and the middle nasal conchae into which the posterior ethmoidal
sinuses open by one or more orifices.
Features of the Nasal Cavity
•The middle nasal meatus is longer and deeper than the
superior one.
•The anterosuperior part of this passage leads into a funnel-shaped
opening, the ethmoidal infundibulum, through which it communicates
with the frontal sinus.
•The passage that
leads inferiorly from
each frontal sinus to
the infundibulum is
the frontonasal duct.
Features of the Nasal Cavity
•The semilunar hiatus (hiatus semilunaris) is a semicircular groove
into which the frontal sinus opens.
•The ethmoidal bulla (bubble), a rounded elevation located superior
to the hiatus, is visible when the middle concha is removed.
•The bulla is formed by middle ethmoidal cells that form the ethmoidal
sinuses.
Features of the Nasal Cavity
•The inferior nasal meatus is a horizontal passage inferolateral to the
inferior nasal concha.
•The nasolacrimal duct, which drains tears from the lacrimal sac, opens
into the anterior part of this meatus.
Vasculature and Innervation of the Nose
The arterial supply of the medial and lateral walls of the nasal cavity is
from five sources:
1. Anterior ethmoidal artery (from the ophthalmic artery).
2. Posterior ethmoidal artery (from the ophthalmic artery).
3. Sphenopalatine artery (from the maxillary artery).
4. Greater palatine artery (from the maxillary artery).
5. Septal branch of the superior labial artery (from the facial artery).
Vasculature and Innervation of the Nose
•The first three arteries (anterior ethmoidal artery, posterior ethmoidal artery and
sphenopalatine artery) divide into lateral and medial (septal) branches.
•The greater palatine artery reaches the septum via the incisive canal through the
anterior hard palate.
•The anterior part of the nasal septum is the site (Kiesselbach area) of an
anastomotic arterial plexus involving all five arteries supplying the septum.
•The external nose also receives blood from first and fifth arteries listed above plus
nasal branches of the infraorbital artery and the lateral nasal branches of the facial
artery.
Vasculature and Innervation of the Nose
•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.
•Venous blood from the external nose drains mostly into the facial vein via
the angular and lateral nasal veins [lies within the ‘danger area’ of the face
because of communications with the cavernous (dural venous) sinus].
Innervation of the Nose
•Nerve supply - the nasal mucosa can be divided into posteroinferior
and anterosuperior portions by an oblique line passing approximately
through the apex of the nose and the sphenoethmoidal recess.
•The nerve supply of the posteroinferior portion of the nasal mucosa is
chiefly from the maxillary nerve, by way of the nasopalatine nerve to
the nasal septum, and posterior superior lateral nasal and inferior
lateral nasal branches of the greater palatine nerve to the lateral wall.
Innervation of the Nose
•The nerve supply of the anterosuperior portion is from the
ophthalmic nerve (CN V1) by way of the anterior and posterior
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), but the alae are supplied by the nasal
branches of the infraorbital nerve (CN V2).
Innervation of the Nose
•The olfactory nerves, concerned with smell, arise from cells in the
olfactory epithelium in the superior part of the lateral and septal
walls of the nasal cavity.
•The central processes of these cells (forming the olfactory nerve)
pass through the cribriform plate and end in the olfactory bulb, the
rostral expansion of the olfactory tract.
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.
•Paranasal sinuses.
•Middle ear through the pharyngotympanic tube (auditory tube),
which connects the tympanic cavity and nasopharynx.
•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.
Question:
 A young child is brought to your office by his
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mother, who is concerned about his frequent
nosebleeds. Nosebleeds often arise from the
anteroinferior part of the nasal septum, which is
richly vascularized and exposed to the drying
effect of air. Which of the following arteries
directly supplies that part of the septum?
External carotid artery
Anterior ethmoidal artery
Lesser palatine artery
Infraorbital artery
Paranasal Sinuses
•The paranasal sinuses are air-filled extensions of the respiratory part
of the nasal cavity into the following cranial bones: frontal, ethmoid,
sphenoid, and maxilla.
•They are named according to the bones in which they are located.
•The sinuses continue to invade the surrounding bone, and marked
extensions are common in the crania of older individuals.
Sinusitis
•Because the paranasal sinuses are continuous with the nasal cavities
through apertures that open into them, infection may spread from the
nasal cavities, producing inflammation and swelling of the mucosa of
the sinuses (sinusitis) and local pain.
•Sometimes several sinuses are inflamed (pansinusitis), and the
swelling of the mucosa may block one or more openings of the
sinuses into the nasal cavities.
Frontal Sinuses
•The frontal sinuses are between the outer and the inner tables of the
frontal bone, posterior to the superciliary arches and the root of the
nose.
•Frontal sinuses are usually detectable in children by 7 years of age.
•Each sinus drains through a frontonasal duct into the ethmoidal
infundibulum, which opens into the semilunar hiatus of the middle
nasal meatus.
•The frontal sinuses are innervated by branches of the supraorbital
nerves (CN V1).
Variation of the Frontal Sinuses
•The right and left frontal sinuses are rarely of equal size, and the
septum between them is not usually situated entirely in the median
plane.
•The frontal sinuses vary in size
from approximately 5 mm to
large spaces extending laterally
into the greater wings of the
sphenoid.
•Often a frontal sinus has two
parts: a vertical part in the
squamous part of the frontal
bone and a horizontal part in the
orbital part of the frontal bone.
•One or both parts may be
large or small.
•When the supraorbital part is large, its roof forms the floor of the
anterior cranial fossa and its floor forms the roof of the orbit.
Ethmoidal Cells
•The ethmoidal cells (sinuses) are small invaginations of the mucous
membrane of the middle and superior nasal meatus into the
ethmoid bone between the nasal cavity and the orbit.
•The ethmoidal cells usually are not visible in plain radiographs
before 2 years of age but are recognizable in CT scans.
•The anterior ethmoidal cells drain directly or indirectly into the
middle nasal meatus through the ethmoidal infundibulum.
Ethmoidal Cells
•The middle ethmoidal cells open directly into the middle meatus and are
sometimes called ‘bullar cells’ because they form the ethmoidal bulla, a swelling on
the superior border of the semilunar hiatus.
•The posterior ethmoidal cells open directly into the superior meatus.
•The ethmoidal cells are supplied by the anterior and posterior ethmoidal branches
of the nasociliary nerves (CN V1).
Infection of the Ethmoidal Cells
•If nasal drainage is blocked, infections of the ethmoidal cells
may break through the fragile medial wall of the orbit.
•Severe infections from
this source may cause
blindness because some
posterior ethmoidal cells
lie close to the optic
canal, which gives
passage to the optic
nerve and ophthalmic
artery.
•Spread of infection
from these cells could
also affect the dural
nerve sheath of the
optic nerve, causing
optic neuritis.
Sphenoidal Sinuses
•The sphenoidal sinuses are located in the body of the sphenoid
and may extend into the wings of this bone.
•They are unevenly divided and separated by a bony septum.
•Because of this extensive pneumatization (formation of air cells
or sinuses), the body of the sphenoid is fragile.
Sphenoidal Sinuses
•Only thin plates of bone separate the sinuses from several important structures:
the optic nerves and optic chiasm, the pituitary gland, the internal carotid arteries,
and the cavernous sinuses.
•The sphenoidal sinuses are derived from a posterior ethmoidal cell that begins
to invade the sphenoid at approximately 2 years of age.
•In some people, several posterior ethmoidal cells invade the sphenoid, giving
rise to multiple sphenoidal sinuses that open separately into the
sphenoethmoidal recess.
•The posterior ethmoidal
arteries and posterior
ethmoidal nerve supply
the sphenoidal sinuses.
Maxillary Sinuses
•The maxillary sinuses are the largest of the paranasal sinuses.
•They occupy the bodies of the maxillae and communicate with
the middle nasal meatus.
Maxillary Sinuses
•The apex of the maxillary sinus extends toward and often into the
zygomatic bone.
•The base of the maxillary sinus forms the inferior part of the lateral
wall of the nasal cavity.
•The roof of the maxillary sinus is formed by the floor of the orbit.
•The floor of the maxillary sinus is formed by the alveolar part of the
maxilla.
•The roots of the
maxillary teeth,
particularly the
first two molars,
often produce
conical elevations
in the floor of the
sinus.
Maxillary Sinuses
•Each maxillary sinus drains by one or more
openings, the maxillary ostium (ostia), into the
middle nasal meatus of the nasal cavity by way
of the semilunar hiatus.
•The arterial supply of the
maxillary sinus is mainly from
superior alveolar branches of the
maxillary artery; however,
branches of the descending and
greater palatine arteries supply the
floor of the sinus.
•Innervation of the maxillary sinus is
from the anterior, middle, and
posterior superior alveolar nerves,
which are branches of the maxillary
nerve.
Infection of the Maxillary Sinuses
•The maxillary sinuses are the most commonly infected, probably
because their ostia are commonly small and are located high on
their superomedial walls.
•When the mucous membrane of the sinus is congested, the
maxillary ostia are often obstructed.
•Because of the high location of the ostia, when the head is erect
it is impossible for the sinuses to drain until they are full.
•When lying on one's side only the upper sinus (e.g., the right
sinus if lying on the left side) drains.
•A cold or allergy involving both
sinuses can result in nights of
rolling from side-to-side in an
attempt to keep the sinuses
drained.
•A maxillary sinus can be
cannulated and drained by passing
a cannula from the nostrils through
the maxillary ostium into the sinus.
Relationship of the Teeth to the Maxillary Sinus
•The close proximity of the three maxillary molar teeth to the
floor of the maxillary sinus poses potentially serious problems
•During removal of a molar tooth, a fracture of a root
may occur.
•If proper retrieval methods are not used, a piece of the root
may be driven superiorly into the maxillary sinus.
•A communication may be created between the oral cavity and
the maxillary sinus as a result, and an infection may occur.
•Because the superior alveolar nerves (branches of the
maxillary nerve) supply both the maxillary teeth and the
mucous membrane of the maxillary sinuses, inflammation of
the mucosa of the sinus is frequently accompanied by a
sensation of toothache in the molar teeth.
 A patient presents to your office with nasal congestion,
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postnasal drip, and extremely uncomfortable pain and
pressure in her "cheekbone" (the region between her
eye and upper teeth). You determine that she has a
severe sinus infection. Which of her paranasal sinuses is
most likely involved with this infection?
A. Ethmoidal
B. Maxillary
C. Sphenoidal
D. Frontal
Teaching Point: Nasal congestion and postnasal drip are
signs of an infection. The pain in her maxillary area pinpoints
the location of the infection to the maxillary sinus.
Transillumination of the Sinuses
•Transillumination of the maxillary sinuses is performed in a
darkened room.
•A bright light is placed in the patient's mouth on one side of
the hard palate.
•The light passes through the maxillary sinus and appears as a
crescent-shaped, dull glow inferior to the orbit.
•If a sinus contains excess fluid, a mass, or a thickened
mucosa, the glow is decreased.
Transillumination of the Sinuses
•The frontal sinuses can also be transilluminated by
directing the light superiorly under the medial aspect of
the eyebrow, normally producing a glow superior to the
orbit.
•Because of the great
variation in the development
of the sinuses, the pattern and
extent of sinus illumination
differs from person to person.
•The ethmoidal and
sphenoidal sinuses cannot be
examined by
transillumination.
END