The Nasal Cavity
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and orbit | Main Anatomy
Index | The ear
Last updated 30 March 2006
- The nose is the superior part of the respiratory tract
and contains the peripheral organ
- It is divided into right and left nasal
cavities by the nasal
- The nasal cavity is divided into the olfactory
area and the respiratory
- Noses vary considerably in size and shape, mainly as a
result of the differences in the nasal cartilages and the
depth of the glabella.
- The inferior surface of the nose is pierced by two
apertures, called the anterior
nares (L. nostrils).
- These are separated from each other by the nasal septum (septum nasi).
- Each naris is bounded laterally by an ala
(L. wing), i.e., the side of the nose.
- The posterior nares
apertures or choanae
open into the nasopharynx.
of the Nasal Septum (p. 754)
Click here for a diagram of
the nasal septum.
- This part bony, part cartilaginous septum divides the
chamber of the nose into two narrow nasal cavities.
- The bony part of the septum is usually located in the
median plane until age 7; thereafter, it often deviates
to one side, usually the right.
- The nasal septum has three main components: (1) the perpendicular plate of the ethmoid bone;
(2) the vomer, and (3)
the septal cartilage.
- The perpendicular plate,
which forms the superior part of the septum, is very thin
and descends from the cribiform
plate of the ethmoid bone.
- The vomer, which forms
the posteroinferior part of the septum, is a thin, flat
bone. It articulates with the sphenoid, maxilla and
Skeleton of the Nose (p. 754)
- The immovable bridge of the nose, the superior
bony part of the nose, consists of the nasal bones, the frontal
processes of the maxillae,
and the nasal part of the frontal bones.
- The movable cartilaginous part consists of five main
cartilages and a few smaller ones.
- The U-shaped alar nasal cartilages
are free and movable.
- They dilate and constrict the external nares when the
muscles acting on the external nose contract.
- The nasal cavities are entered through the anterior nares or nostrils.
- They open into the nasopharynx through the choanae.
The Roof and Floor of the Nasal Cavity (p.
- The roof is curved and narrow, except at the posterior
- The floor is wider than the roof.
- It is formed from the palatine
process of the maxilla and the
horizontal plate of the palatine
Walls of the Nasal Cavity (p. 758)
Click here for
a diagram of the lateral wall of the nasal cavity.
- The medial wall is formed by the nasal septum; it is
- The lateral wall is uneven owing to the three
longitudinal, scroll-shaped elevations, called the conchae (L. shells) or
turbinates (L. shaped like a top).
- These elevations are called the superior, middle and
inferior conchae according to their position.
- The superior and middle conchae
are parts of the ethmoid bone, whereas the inferior conchae are separate
- The inferior and middle conchae project medially and
inferiorly, producing air passageways called the inferior and middle meatus (L.
passage). Note: the plural of "meatus" is the
same as the singular.
- The short superior conchae conceal the superior
- The space posterosuperior to the superior concha is
called the sphenoethmoidal recess.
Click here to go to the meatus.
- Mucosa lines the entire nasal cavities except for the vestibule of the nose.
- The nasal mucosa is firmly bound to the periosteum and
perichondrium of the supporting structures of the nose.
- It is continuous with the adjoining cavities to which the
nasal cavity communicates (e.g., the nasopharynx and
- The inferior 2/3 of the nasal mucosa is called the respiratory area and air
passing over this is warmed and moistened before it
passes into the lungs.
- The superior 1/3 is called the olfactory
The Olfactory Area of Nasal Mucosa (p. 756)
- This area contains the peripheral organ of smell.
- Sniffing draws air into this area
- Olfactory receptor cells (from the olfactory nerve,
CN I, are located in the mucosa of this area in the nose.
Nerves to the Respiratory Area of Nasal Mucosa (pp.
- The mucous membrane of the nasal septum is supplied
chiefly by the nasopalatine nerve,
a branch of the maxillary
nerve (CN V2).
- Its anterior portion is supplied by the anterior ethmoidal nerve (a
branch of the nasociliary nerve)
which is derived from the ophthalmic nerve
- The lateral walls of the nasal cavity are supplied by
branches of the maxillary nerve (CN V2); the greater palatine nerve, and
the anterior ethmoidal nerve.
of the Nasal Mucosa (p. 758)
Click here for a
diagram on the innervation and blood supply of the mucosa of the
- The blood supply of the mucosa of the nasal septum is
derived mainly from the maxillary
- The sphenopalatine artery,
a branch of the maxillary, supplies most of the blood of
the nasal mucosa.
- It enters by the sphenopalatine
foramen and sends branches to the posterior
regions of the lateral wall and to the nasal septum.
- The greater palatine artery,
also a branch of the maxillary, passes through the incisive foramen to supply the
- The anterior and posterior
ethmoidal arteries, branches of the ophthalmic artery, supply the
anterosuperior part of the mucosa of the lateral wall of
the nasal cavity and nasal septum.
- Three branches of the facial artery
(superior labial, ascending palatine, and lateral nasal)
also supply the anterior parts of the nasal mucosa.
of the Nasal Mucosa (p. 758)
- The veins of the nasal mucosa form a venous network of
plexus in the connective tissue of the nasal mucosa.
- Some of the veins open into the sphenopalatine
vein and drain to the pterygoid
- Others join the facial
and infraorbital veins.
- Some empty into the ophthalmic
veins and drain into the cavernous sinus.
The Meatus of
Recess (p. 758)
- This space is posterosuperior to the superior concha.
- The sphenoidal sinus
opens into this recess.
Meatus (p. 758)
- This is a narrow passageway between the superior and
middle nasal conchae.
- The posterior ethmoidal sinuses
open into it by one or more orifices.
Middle Meatus (p. 758)
- This is longer and wider than the superior one.
- The anterosuperior part of this meatus lead into a
funnel-shaped opening, called the infundibulum,
through which the frontonasal duct
leads to the frontal sinus.
- There is one duct for each frontal sinus and since there
may be several, there may be several frontonasal ducts.
- When the middle concha is removed, rounded elevation
called the ethmoidal bulla
(L. bubble), is visible
- The middle ethmoidal air cells
open on the surface of the ethmoidal bulla.
- Inferior to this bulla is a semicircular groove called
the hiatus semilunaris.
- The frontal sinus opens into this hiatus
- Near the hiatus are the openings of the anterior ethmoid air cells.
- The maxillary sinus also opens into the middle meatus.
Meatus (p. 758)
- This is a horizontal passage, inferolateral to the
inferior nasal concha.
- The nasolacrimal duct
opens into the anterior part of this meatus.
- Usually, the orifice of this duct is wide and circular.
- These sinuses are air-filled
extensions of the respiratory part of the
- They are in the following bones, frontal, ethmoid,
sphenoid and the maxilla.
The Frontal Sinuses (pp. 760, 762)
- These are located between the outer and inner tables of
the frontal bone, posterior to the
The Ethmoidal Sinuses (p. 762)
- These comprise of several small cavities, called ethmoidal air cells, within
the ethmoidal labyrinth
(G. labyrinthos, a maze) of the lateral
mass of the ethmoid bone.
The Sphenoidal Sinuses (p. 762)
- These occupy a variable amount in the body
of the sphenoid bone and may extend into the
The Maxillary Sinuses (pp. 762-3)
- These are the largest pair of paranasal sinuses.
- They are pyramidal-shaped cavities that may occupy the
entire bodies of the maxillae.