ANATOMY OF NOSE&

PARANASAL SINUS

Objectives Anatomy of external nose & osseocartilaginous framework

Anatomy of septum & lateral nasal wall

Anatomy of paranasal sinuses

Functions of nose & paranasal sinuses

External nose Pyramidal in shape

Root up and the base directed downwards

Bony part

Cartilaginous part-upper lateral cartilage lower lateral ( alar ) cartilage sesamoid cartilages septal cartilage

Internal nose Nasal septum divides the internal nose into right and left nasal

cavities

Communicate with the exterior through anterior nares (nostrils)

Communicate posteriorly with the nasopharynx through choanae

Anterior and inferior skin-lined portion – vestibule

Posterior mucosa-lined portion - nasal cavity proper

Nasal valve Laterally by the lower border of upper lateral cartilage

and fibro fatty tissue & anterior end of inferior turbinate

Medially by the cartilaginous nasal septum

Caudally by the floor of pyriform aperture

Area of maximum airflow resistance in the nasal cavity

Nasal septum Columellar septum

Membranous septum

Septum proper-perpendicular plate of ethmoid -vomer - quadrangular cartilage

Other bones make very small contributions, include crest of nasal bones, crests of palatine and maxilla nasal spine of frontal bone ,the anterior nasal spine of maxillarostrum of sphenoid, and

Lateral nasal valve

Ostiomeatal complex

Blood supply of nose

Nerve supply

Paranasal sinuses Anterior group

Posterior group

Maxillary sinus(Antrum of Highmore)

first to develop in human fetus

Largest paranasal sinus (15 ml capacity in adult)

It occupies the body of maxilla

Pyramidal shape. The base faces towards lateral wall of nose and apex is directed laterally into the zygomatic process

FRONTAL SINUS Situated above and deep to the supraorbital margin

It lies between the inner and outer tables of the lower part of frontal bone

Ostium of frontal sinus is situated in its floor and opens into the frontal recess

ETHMOID SINUS Thin walled air cavities in lateral masses of ethmoid bone.

They vary in number (3–18)

Lie between upper third of lateral nasal wall and the medial wall of orbit

Clinically they are divided into two groups: anterior and posterior

Anterior ethmoid group opens into the middle meatus

Posterior ethmoid group opens into the superior meatus and some in sphen oethmoidal recess

Sphenoid sinus Two sphenoid sinuses, one on each side are rarely symmetrical

They occupy body of sphenoid bone

Are separated by a thin bony septum, which is usually obliquely situated

The ostium, which is situated in the upper part of anterior wall, drains into spheno ethmoidal recess

Agger nasi cells: These are most anterior of anterior ethmoid cells and lie in close proximity of frontal recess

They are situated just anterior to anterosuperior attachment of middle turbinate

Ground (Basal) lamella: This bony insertion of middle turbinate into the skull base and lateral nasal wall separates anterior from posterior ethmoid cells

Ground lamella can be divided into three parts Anterior one-third inserts into lamina cribrosamiddle one-third (oblique anterosuperior to postero inferior course) into lamina papyracea posterior one-third horizontal part inserts into lateral nasal wall

Haller cells: These ethmoid cells extend into the roof of maxillary sinus in the region of maxillary sinus ostium

Onodi cells: These are posterior ethmoid cells and extend either laterally or superiorly along the sphenoid sinus

The optic nerve can lie within them

Onodi cells must be recognized during the endoscopic sinus surgery on posterior ethmoid to avoid optic nerve injury.

FUNCTIONS OF PARANASAL SINUSES RESPIRATION

OLFACTION

PROTECTION OF LOWER AIRWAYS

VOCAL RESONANCE

HUMIDIFICATION OF AIR