Nasal Cavity and Paranasal

Sinuses

I. Nasal Cavity

Opens on face through anterior nasal

apertures (nares, or nostrils)

communicates with nasopharynx through a

posterior opening, choanae.

Has a slight dilatation inside aperture of each

nostril, vestibule, is lined largely with skin containing hair, sebaceous

glands, and sweat glands.

A. Roof

Is formed by :

1. nasal,

2. frontal,

3. ethmoid (cribriform plate), and

4. sphenoid (body) bones.

cribriform plate transmits olfactory nerves.

B. Floor

Is formed by :

1. palatine process of maxilla and

2. horizontal plate of palatine bone.

Contains incisive foramen, which transmits :

i. nasopalatine nerve and

ii. terminal branches of sphenopalatine artery.

C. Medial wall (nasal septum)

Is formed primarily by :

1. perpendicular plate of ethmoid bone,

2. vomer, and

3. septal cartilage.

Is also formed by :

i. processes of palatine,

ii. maxillary,

iii. frontal,

iv. sphenoid, and

v. nasal bones.

D. Lateral wall

Is formed by : A. superior conchae of ethmoid bone

B. middle conchae of ethmoid bone and

C. inferior concha.

Is also formed by : i. nasal bone,

ii. frontal process and

iii. nasal surface of maxilla,

iv. lacrimal bone,

v. perpendicular plate of palatine bone, and

vi. medial pterygoid plate of sphenoid bone.

Contains following structures and their openings:

1. Sphenoethmoidal recess: • opening of sphenoid sinus.

2. Superior meatus: • opening of posterior ethmoidal air cells.

3. Middle meatus: i. opening of frontal sinus into infundibulum,

ii. openings of middle ethmoidal air cells on ethmoidal bulla, and

iii. openings of anterior ethmoidal air cells and maxillary sinus in hiatus semilunaris.

4. Inferior meatus: • opening of nasolacrimal duct.

5. Sphenopalatine foramen: • opening into pterygopalatine fossa; transmits sphenopalatine artery and nasopalatine nerve.

II. Subdivisions and Mucous Membranes

A. Vestibule

• Is dilated part inside nostril that is bound by alar cartilages and lined by skin with hairs.

B. Respiratory region

• Consists of lower two thirds of nasal cavity.

• Warms, moistens, and cleans incoming air with its mucous membrane.

C. Olfactory region

• Consists of : 1. superior nasal concha and

2. upper one third of nasal septum.

• Is innervated by olfactory nerves, • convey sense of smell from olfactory cells and enter cranial cavity through cribriform plate of ethmoid bone to end

in olfactory bulb.

III. Blood Supply to Nasal Cavity

Occurs via following routes:

A. ophthalmic artery.

B. maxillary artery.

C. facial artery

III. Blood Supply to Nasal Cavity

A. ophthalmic artery.

lateral nasal branches of

i. anterior ethmoidal a

ii. posterior ethmoidal a

B. maxillary artery

sphenopalatine a

i. posterior lateral nasal brs

ii. posterior septal brs

C. maxillary artery

descending palatine artery greater palatine branch

(its terminal branch reaches lower part of nasal septum through incisive canal).

D. facial artery

1. septal branch of superior labial a

2. lateral nasal branch.

IV. Nerve Supply to Nasal Cavity

A.SVA (smell) sensation “

• is supplied by olfactory nerves for olfactory area.

B. GSA sensation “

• is supplied by

1. ophthalmic nerve 1. anterior ethmoidal branch

2. maxillary nerve 1. nasopalatine,

2. posterior-superior lateral nasal branches ,

3. posterior-inferior lateral nasal branches

• via pterygopalatine ganglion; and

4. anterior-superior alveolar branch of infraorbital nerve.

V. Paranasal

Sinuses

V. Paranasal Sinuses

Consist of 1. ethmoidal,

2. frontal,

3. maxillary, and

4. sphenoidal sinuses.

Are involved in a reduction of weight and resonance for voice.

A. Ethmoidal sinus

•Consists of numerous ethmoidal air cells,

•are numerous small cavities within ethmoidal labyrinth between orbit and nasal cavity. •Its infection may erode through thin orbital plate of ethmoid bone into orbit.

Can be subdivided into following groups:

1. Posterior ethmoidal air cells, • drain into superior nasal meatus.

2. Middle ethmoidal air cells, • drain into summit of ethmoidal bulla of middle nasal meatus.

3. Anterior ethmoidal air cells, • which drain into anterior aspect of hiatus semilunaris in middle nasal meatus.

B. Frontal sinus

Lies in frontal bone

opens into hiatus semilunaris of middle nasal meatus by

way of frontonasal duct (infundibulum).

Is innervated by supraorbital branch of ophthalmic nerve.

C. Maxillary sinus

Is largest of paranasal air sinuses

is only paranasal sinus that may be present at birth.

Lies in maxilla on each side, lateral to lateral wall of

nasal cavity and inferior to floor of orbit,

drains into posterior aspect of hiatus semilunaris in

middle nasal meatus.

D. Sphenoidal sinus

Is contained within body of sphenoid bone.

Opens into sphenoethmoidal recess of nasal cavity.

Is innervated by:

1. branches from maxillary nerve

2. posterior ethmoidal branch of nasociliary nerve.

•pituitary gland lies above this sinus

• can be reached by transsphenoidal approach,

which follows nasal septum through body of

sphenoid.

• Care must be taken not to damage cavernous

sinus and internal carotid artery.

VI. Development of the Nasal Cavity

A. Nasal pits are ectoderm-lined depressions that result from proliferation of mesenchyme in lateral and medial nasal

swellings. nasal pits deepen, form blind sacs, and rupture to form nostrils.

B. Oronasal membrane initially separates nasal cavities from oral cavity, but its rupture allows communication between nasal and

oral cavities through primitive choanae.

C. Nasal septum forms as a downgrowth from medial nasal process.

D. Lateral wall is formed as superior, middle, and inferior conchae.

E. Floor of nasal cavity is formed by fusion of medial nasal process (nasal septum) with palatine processes of maxilla.

F. Roof of nose is formed from lateral nasal processes.

G. Paranasal sinuses develop as diverticula of lateral nasal wall and extend into maxilla, ethmoid, frontal, and sphenoid bones.