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1. NOSE

3. Nose
Introduction:
• The nose is the part of the respiratory tract superior to the hard palate
• It contains the peripheral organ of smell
Composition:
• external nose
• nasal cavity
 the nasal cavity is divided into right and left cavities by the nasal
septum
Functions:
• olfaction (smelling)
• respiration (breathing)
• filtration of dust
• humidification of inspired air
• reception and elimination of secretions from the paranasal sinuses
and nasolacrimal ducts

4. External Nose
• is the visible portion that projects from the face
• its skeleton is mainly cartilaginous (small bony contributions are
present)
• The part of the external nose that extends from the root of the nose
to the apex (tip) of the nose is called the dorsum
• The inferior surface of the nose is pierced by two piriform
openings called nares (nostrils, anterior nasal apertures)
• The nares are bounded laterally by the alae (wings) of the 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

7. • The skin extends into the anterior part of the nasal cavity called the
vestibule of the nose
• The vestibule of the nose has a variable number of stiff hairs called
vibrissae
• These hairs are usually moist and these help to filter dust particles
from air entering the nasal cavity
Skeleton of the External Nose
composed of:
I. bones
II. cartilages
 The bony part consists of the:
 nasal bones
 frontal processes of the maxillae
 nasal part of the frontal bone
 nasal spine
 bony parts of the nasal septum

10. • The cartilaginous part of the nose consists of five main cartilages and
small minor cartilages:
 two lateral cartilages,
 two alar cartilages,
 and one septal cartilage
 3 or 4 minor alar cartilages
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
• It divides the chamber of the nose into two nasal cavities
• It has a:
 bony part
 a soft mobile cartilaginous part
The components of the nasal septum are
 perpendicular plate of the ethmoid bone
 Vomer bone

11.  septal cartilage
 nasal crest of the maxillary bone
 nasal crest of palatine bone
 The perpendicular plate of ethmoid, vomer, nasal crests of maxillary
and palatine bones form the bony part of nasal septum
 While the septal cartilage forms the cartilagenous part
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 tongue-and-groove articulation with the edges
of the bony septum

14. CLINICALANATOMY
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)
• 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

15. Nasal Cavity
• Divided into right and left halves by the nasal septum
• The nasal cavity is entered anteriorly through the nares
• It opens posteriorly into the nasopharynx through the choanae
• Mucosa lines the nasal cavity, except for the nasal vestibule, which is
lined with skin
• The superior one third of the nasal mucosa forms the olfactory area
• The inferior two thirds of the nasal mucosa forms the respiratory area
• The olfactory area contains the peripheral organ of smell; sniffing
draws air to the 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

19. Boundaries of the Nasal Cavity
 The nasal cavity has a:
 roof
 floor
 medial wall
 lateral wall
The roof :
• is curved and narrow, except at its posterior end
• it is divided into 3 parts
 frontonasal
 ethmoidal
 sphenoidal
• They are named from the bones forming each part
The floor:
• is wider than the roof
• is formed by the;
 palatine processes of the maxilla
 horizontal plates of the palatine bone

21. The medial wall :
formed by the nasal septum
The lateral walls :
• are irregular owing to three bony plates, the nasal conchae, which
project inferiorly, somewhat like louvers
Features on the lateral wall of the nasal cavity
• There is the presence of nasal conchae and they curve inferomedially
• The nasal conchae include;
 Superior nasal concha
 middle nasal concha
 inferior nasal concha
• The conchae 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
• Underneath each choncha in both humans with simple nasal conchae
and animals with complex turbinates is a recess or meatus
{passage(s) in the nasal cavity}

24. • The nasal cavity is thus divided into 5 passages:
1) a posterosuperiorly placed sphenoethmoidal recess
 3 laterally located nasal meatus:
II) superior
III) middle
IV) inferior
V) and a medially placed common nasal meatus into which the four
lateral passages open
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

27. 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
• The posterior ethmoidal sinuses open into this superior nasal meatus
through one or more orifices
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 through a passage known as the frontonasal
duct
• the anterior ethmoidal cells opens on the ethmoidal infundibulum
directly or opens indirectly on the frontonasal sinus

30. • The ethmoidal infundibulum leads inferiorly into a semicircular groove
called the semilunar hiatus
• The maxillary sinus opens into the semilunar hiatus
• superior to the semilunar hiatus is a rounded elevation called the ethmoidal
bulla
• The ethmoidal bulla is only visible when the middle concha is removed
• The bulla is a swelling formed by middle ethmoidal cells that form the
ethmoidal sinuses
• Anterior and inferior to the semilunar hiatus is a hooklike process called the
uncinate process of the ethmoid bone
• This process articulates with the inferior nasal concha
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
The common nasal meatus :
• is the medial part of the nasal cavity between the conchae and the nasal
septum, into which the lateral recesses and meatus open

33. The arterial supply
The arterial supply of the medial and lateral walls of the nasal cavity is
from five sources:
• Anterior ethmoidal artery (from the ophthalmic artery)
• Posterior ethmoidal artery (from the ophthalmic artery)
• Sphenopalatine artery (from the maxillary artery)
• Greater palatine artery (from the maxillary artery)
• Septal branch of the superior labial artery (from the facial artery)
 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 the 1st and 5th arteries
listed above plus
• nasal branches of the infraorbital artery
• lateral nasal branches of the facial artery

35. Venous drainage
• A rich submucosal venous plexus deep to the nasal mucosa drains into
the sphenopalatine, facial, and ophthalmic veins
Innervation
• olfactory nerve
• branches of the ophthalmic [V1] which include the anterior and
posterior ethmoidal nerves
• maxillary [V2] nerves which include;
 posterior superior lateral nasal nerves
 posterior superior medial nasal nerves
 nasopalatine nerve
 posterior inferior nasal nerves

37. CLINICALANATOMY
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
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

38. 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