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

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The Nose• Made of bony and

cartilaginous components

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

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Cartilaginous component

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

• Some smaller alar cartilages are also present.

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Skin of the nose

• Thin - the bony part of the nose

• Thick – cartilaginous part with sebaceous gland

• Extends to vestibule via nares.

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Muscles of Nose

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

• Innervated by facial nerve.

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Nasalis

• Largest, splits into transverse and Alar parts.

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

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The Nose• Superiormost of

nasal muscles.• Action:

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

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Depressor Septi Nasi• Assists the alar

part of the nasalis in opening the nostrils.

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

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PARANASAL SINUSES• Are air-filled

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

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PARANASAL SINUSES

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

The sinuses open into the nasal cavity through the lateral wall

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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

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Frontal sinus

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

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Frontal sinus

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

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Frontal sinus• Drains through the

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

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Frontal sinus

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

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

• Comprises several cavities called ethmoidal cells

Ethmoidal sinuses

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Ethmoidal cells

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

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Ethmoidal cells• Anterior cells open

into the middle meatus through the infundibulum

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

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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

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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 )

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Ethmoidal cells

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

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Ethmoidal cells

• Opens into the sphenoethmoidalrecess

• Supplied by posterior ethmoidal nerve

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Maxillary sinuses

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

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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.

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Maxillary Sinus• Opens into the

middle meatus through the maxillary ostium

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

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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

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Applied Anatomy• Infection of the

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

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Applied Anatomy

• Transillumination impossible for the ethmoidal and sphenoidal sinuses

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