Maxillary Air Sinus

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Maxillary Air sinusMaxillary Air sinus

(Antrum of Highmore)(Antrum of Highmore)


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AIR SINUSAIR SINUS

These are air filled hollow space present within the boneThese are air filled hollow space present within the bonearound the nasal cavity called as paranasal air sinuses.around the nasal cavity called as paranasal air sinuses.

The sinuses areThe sinuses are (1) Frontal air sinus(1) Frontal air sinus

(2) Maxillary air sinus(2) Maxillary air sinus

(3) Sphenoidal air sinus(3) Sphenoidal air sinus

(4) Ethmoidal air sinus(4) Ethmoidal air sinus

These sinus forms various boundaries of the nasal cavity & allThese sinus forms various boundaries of the nasal cavity & all

these sinus communicate with each other and open into thethese sinus communicate with each other and open into thelateral wall of the nasal cavity.lateral wall of the nasal cavity.


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FUNCTION OF AIR SINUS :

(1)Humidification of inspired air

(2)Filtration of air

(3) It provides resonance to voice.

(4) It lightens the bone.

(5) It act as thermal insulator to protect organ such as the eyeand cranium from variation in intranasal temperature.

(6) Sinus increase the surface area of the skull

(7)Assist in olfaction

(8)Absorption of shock to the face/ skull.


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MAXILLARY AIR SINUS :

Definition: An antrum is a hallow cavity within thebody of the maxilla.

Maxillary air sinus known as antrum of Highmore,named after an english antomist Nathaniel Highmorewho was described it.

It is the largest paranasal sinus.


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ANATOMY OF THE MAXILLARY AIR SINUS :

pyramidal in shape with the base of the pyramid forming

the lateral nasal wall and apex at the root of the zygoma.

Volume : 10-15 ml (in adult antrum)

Size : Dimension of sinus are

Height 3.5 cm

Width 2.5 cm

Anteroposterior Depth 3.2 cm


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EMBRYLOGY:

The sinus are rudimentary or even absent at birth.

They enlarge rapidly at the age of 6 to 7 months.

The maxillary air sinus formed first among the other paranasal sinus.

It start as a shallow groove on the medial surface of the maxilla during the

fourth month of intrauterian life.

Present as small cavity at birth.

From birth to adult life the growth of sinus due to enlargment of bone.

It reach maximum size by around 18 years of age.

In old age it enlarge due to resorption of the surrounding cancellous bone.


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ROOF OF THE ANTRUM :

- Formed by floor of the orbit.

- Thin plate of orbital plate of maxilla.

- It lodges the infraorbital canal and groove

which lodges the infraorbital nerve.

FLOOR OF THE SINUS:

- Alveolar process of the maxilla.

- its level is lower than the level of the floor

of the nose.

- Closely related to root apices of themaxillary premolar and molar.


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ANTERIOR WALL:

-Formed by the facial surface of the maxilla.

- Canine fossa is an important structure of this wall.

POSTERIOR WALL:

- Formed by sphenomaxillary ( pterygomaxillary) wall of the maxilla

- A thin plate of bone separate the antral cavity from the infratemporal

fossa.

MEDIAL WALL :

- Lateral wall of the nasal cavity.

- the opening of the antrum in the middle meatus at the lower part of the

hitus semilunaris.

- The opening of the sinus is closer to the roof and thus at a higher levelthan the floor.


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Drainage of the sinusDrainage of the sinus

Opens into the middle meatus of the nasal cavityOpens into the middle meatus of the nasal cavitythrough the hiatus semilunaristhrough the hiatus semilunaris

It is at a higher level than the floor of the sinusIt is at a higher level than the floor of the sinus


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HISTOLOGYOFTHEMAXILLARYAIRSINUS:

the sinus is lined by respiratory mucosa which ispseudostratified ciliated columnar epithelium.

Presence of

Goblet cells

The ciliated movement help in removal of mucussecretion towards the osteum.


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BLOODANDNERVESUPPLY:

Arterial supply :- Facial artery - Infraorbital artery - Greater palatine artery Venous drainage:- Facial vein - pterygoid venous plexus

Lymphatic Drainage :- sumbmandibular lymph node.

Nerve supply:- Infraorbital nerve

- Anterior superior alveolar nerve - Middle superior alveolar nerve - posterior superior alveolar nerve


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CLINICALIMPOTANCE

Dental infection: Infection from the maxillary premolar

and molars can easily communicate and infect the maxillary

antrum.

Oroantral Communication: Traumatic extraction ofmaxillary teeth can cause oroantral communication.

Root Pieces: Root pieces of maxillary teeth may sometimes

be accidentally forced into the maxillary antrum.

Continuous pneumatization of sinus with the loss of teeth

(recess)


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Maxillary Sinusitis : Because of the thickned and inflammedsinus lining compresses the nerve supply of the maxillary

posterior teeth causing tenderness of the maxillary teeth.

The Maxillary Artery can be approached through the

posterior wall of the maxillary antrum for ligation.

The infraorbital and superior alveolar vessels are freqently

ruptured in maxillary fracture causing the hemotoma

formation in the antrum.


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Maxillary Air Sinus

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