Nose and paranasal cavity

NOSE AND PARANASAL CAVITY

ATIBA, P.M.

The Nose• Divided by Nasal

septum to right & left cavities

• Vary in size and shape depending on nasal cartilages

• Nares bounded by alae of nose

Nose and paranasal cavity 2

The Nose• Made of bony and

cartilaginous components

• Bony component –comprised of nasal, maxillae and frontal bones.


Cartilaginous component

• 2 lateral cartilages, 2 alar cartilages and 1 septal cartilage.

• Some smaller alar cartilages are also present.


Skin of the nose

• Thin - the bony part of the nose

• Thick – cartilaginous part with sebaceous gland

• Extends to vestibule via nares.


Muscles of Nose

• Nasal group of facial muscles move nose and skin around it

• Innervated by facial nerve.


Nasalis

• Largest, splits into transverse and Alar parts.

• Action: Transverse part compresses the nares. Alar part open the nares


The Nose• Superiormost of

nasal muscles.• Action:

(Contraction) Pulls the eyebrows downward to produce transverse wrinkles over nose


Depressor Septi Nasi• Assists the alar

part of the nasalis in opening the nostrils.

• Actions: It pulls the nose inferiorly, opening the nares.


PARANASAL SINUSES• Are air-filled

cavities produced by extension of the nasal mucous membrane into the bone around the nasal cavities


PARANASAL SINUSES

These bones are: frontal, ethmoid, sphenoid, maxilla.

The sinuses open into the nasal cavity through the lateral wall


PARANASAL SINUSES

The function of the sinuses is to make the skull lighter and add resonance to the voice

They are rudimentary or absent at birth and rapidly enlarge during 6-7 years


Frontal sinus

• Lies between outer and inner tables of the frontal bone, above the superciliary arch and root of the nose


Frontal sinus

• Appears rudimentary at birth, but is well developed by the 7th year and reaches full size after puberty


Frontal sinus• Drains through the

frontonasal duct into the ethmoidal infundibulum, which opens into the semilunar hiatus of the middle meatus


Frontal sinus

• Are innervated by branches of the supraorbital nerves (CN V1)


• Located in the lateral mass of the ethmoid bone, between the nasal cavity and the orbit.

• Comprises several cavities called ethmoidal cells

Ethmoidal sinuses


Ethmoidal cells

• Divided into anterior, middle and posterior groups of ethmoidal cells


Ethmoidal cells• Anterior cells open

into the middle meatus through the infundibulum

• The middle cells open directly into the middle meatus (form ethmoidal bulla)


Ethmoidal cells• The posterior cells

open directly into the superior meatus

• The ethmoidal cells are supplied by anterior and posterior ethmoidal branches of nasociliary nerve


Sphenoidal sinuses• Lie in the body of the

sphenoid bone, making it fragile

• Only thin plates of bone separate these sinuses from several important structures (Optic nerve, optic chiasma, pituitary gland, Internal Carotid Arteries, cavernous sinuses )


Ethmoidal cells

• These sinuses arise from a posterior ethmoidal cell that begins to invade the sphenoid bone at approximately 2 years of age


Ethmoidal cells

• Opens into the sphenoethmoidalrecess

• Supplied by posterior ethmoidal nerve


Maxillary sinuses

• Largest of the paranasal sinuses; located in the body of the maxilla; Have thin walls and following borders:


Boundary Maxillary Sinus• Superior - bony orbit

• Inferior - maxillary alveolar bone and corresponding tooth roots

• Medial - nasal cavity

• Lateral and anterior border are limited by the cheekbones.


Maxillary Sinus• Opens into the

middle meatus through the maxillary ostium

• Supplied by the anterior, middle and posterosuperior alveolar nerves (branch of maxillary nerve)


Applied Anatomy

• Sinusitis

• Variation in the frontal sinus

• Infections of the ethmoid (posterior) & sphenoidal sinuses may spread to vital organs like optic nerve causing blindness


Applied Anatomy• Infection of the

maxillary sinus more common because of its poor drainage, as a result of the location of the maxillary ostia


Applied Anatomy

• Transillumination impossible for the ethmoidal and sphenoidal sinuses


Documents

Nose and paranasal cavity