Paranasal sinuses 1 Paranasal sinuses Are air filled

Paranasal sinuses 1

Paranasal sinuses • Are air filled cavities found in the interior of frontal, maxillary, sphenoid and ethmoid bones • They communicate with nasal cavity through small openings or apertures • Maxillary and sphenoid rudimentary at birth, enlarge at 8 years and fully formed in adolescent 2

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functions of sinuses – Resonating chamber for voice – Decrease weight of skull – Warm & moisten air – Shock absorbers – Immune system 5

Maxillary sinuses • Are the largest sinuses • Paired, one on each side and equal size. • Pyramidal in shape with the body forming the lateral wall of the nose, and apex in zygomatic process of maxilla • Superolateral surface (Roof) is related to orbit • Anterolateral surface is related below to roots of upper molar and premolar teeth and to face in front • Posterior wall is related behind to infratemporal fossa 6

• Sinus opens into middle meatus of the nose through hiatus semilunaris • Is innervated by infraorbital and alveolar branches of maxillary nerve • Blood supply infra – orbital and superior alveolar branches of maxillary arteries 7

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Frontal sinuses • Two, contained within frontal bones • Are variable in size, most superior and second largest • Each is triangular in shape, extending upward above medial end of eyebrow and backward into medial part of the roof of orbit • Each drains onto lateral wall of middle meatus via frontonasal duct • Innervation by branches of supra – orbital nerve from ophthalmic nerve • Blood supply – branches of anterior ethmoidal arteries 10

Ethmoidal sinuses • Are formed by variable number of individual air chambers divided into anterior, middle and posterior groups bases on the location of their apertures on lateral wall of nasal cavity • Anterior group opens into ethmoidal infundibulum or frontonasal duct • Middle group onto ethmoidal bulla or lateral wall just above ethmoidal bulla • Posterior group onto lateral wall of superior nasal meatus 11

• Ethmoidal sinuses are innervated by anterior and posterior branches of nasociliary nerve from ophthalmic nerve • Maxillary nerve from via orbital branches from pterygopalatine ganglion • Blood supply is from branches of anterior and posterior ethmoidal arteries 12

Sphenoidal sinuses • They are two located within the sphenoid bone • Opens into the roof of nasal cavity through the apertures on the posterior wall of spheno – ethmoidal recess • Relations – above to cranial cavity (pituitary gland to optic chiasma – Laterally tocranial cavity esp cavenous sinuses – Below and infront to nasal cavities 13

• Innervation is provided by – Posterior ethmoidal branch of ophthalmic nerve – Maxillary nerve via orbital branches from pterygopalatine ganglion • Blood supply is via branches of pharyngeal arteries from the maxillary arteries 14

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