Paranasal sinuses

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 8years and fully formed in adolescent

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

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

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

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

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

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

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 and to optic chiasma Laterally tocranial cavity esp cavenous sinuses Below and infront to nasal cavities

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