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3. OBJECTIVES 1- Describe anatomy of the nose and paranasal sinuses. 2-Numerate Functions of the nose and paranasal sinuses.

4. Anatomy of the nose

6. A- External nose: It's pyramidal in shape; the skeletal framework maintains its shape Anterior nares: situated in the base of the nose & open downwards, they are separated by the columella. Bony constituents: support the upper part of the external nose, they are: Nasal processes of the frontal bone. Nasal bones. Ascending processes of the maxilla.

7. Cartilaginous constituents: support the lower part of the external nose, they are: Upper Lateral cartilages. Alar cartilage. Quadrilateral cartilage of the nasal septum. The cartilages & bone are connected with each other by continuous peri-chondrium & periosteum. Vestibule: is included in the external nose because it's lined with skin and contains sebaceous glands and hair (vibrissae).

9. B- Nasal Fossae the right & left nasal fossae (cavities) are separated by the nasal septum. The nasal fossae include only that part which is lined by or with mucous membranes. The nasal fossae communicated through the posterior choana with the nasopharynx posteriorly.

10. Each nasal fossa is bounded by: Floor: 1-Palatine processes of the maxilla (anterior 3/4). 2-Horizontal part of palatine bones (posterior 1/4). Roof: is very narrow & formed by: 1-Nasal process of frontal bone anteriorly. 2-Cribriform palate of ethmoid. 3-Body of sphenoid bone posteriorly

11. Medial wall: this is the nasal septum which lies in the midline or near the midline, it consists of: 1-Bony part which includes: A-Perpendicular plate of ethmoid (above & behind). B-Vomer (below & behind) 2- Cartilaginous part that includes: Quardrilateral cartilage in the angle between perpendicular plate of ethmoid & vomer.

13. Lateral wall: is formed by: 1-Medial wall of maxilla. 2-Lateral mass of ethmoid. 3-Lacrimal bone.

16. The main features of the lateral wall are: Three turbinates (superior, middle & inferior) the inferior turbinate is the largest. Three meati (superior, middle & inferior) each meatus lies below & lateral to the corresponding turbinate. Sphenoethmoidal recess lies above the superior turbinate and contains the ostium of the sphenoid sinus.

17. Superior meatus contains the ostia of posterior ethmoidal sinus. Middle meatus contains the ostia of maxillary, frontal & anterior ethmoidal sinuses. Inferior meatus receives the opening of the nasolacrimal duct. In the middle meatus there are: 1-Bulla ethmoidalis: which is round mass formed by anterior ethmoidal cells. 2-Haitus semilunaris: which is two dimentional space, lies between the anterior surface of bulla ethmoidalis & the posterior edge of unicinate process (uncinate process is part of ethmoid bone).

19. Paranasal Sinuses: These are air spaces within certain bones of the skull. There are four sinuses on each side (maxillary, ethmoid, frontal, sphenoidal sinuses) They are lined by mucous membrane continuous with that of the nose

21. Maxillary Sinus is pyramidal in shape, occupies the body of the maxilla, it's the largest sinus, the ostium is situated high up between the medial wall & roof; it opens in the middle meatus. Arterial blood supply: from facial artery, maxillary artery, infraorbital & greater palatine artery. Nerve supply: is by infraorbital, greater palatine & (anterior, middle and posterior) superior alveolar nerves.

22. Ethmoid Sinus consists of a number (7−15) of thin walled cavities within the lateral masses of the ethmoid bones. There are two group of cells: Anterior (small & numerous) → opens in the middle meatus. Posterior (large & few) → open in the superior meatus. Arterial blood vessels & nerves supply: is by anterior & posterior ethmoidal arteries & nerve.

23. Frontal sinus it occupies a very variable extent of frontal bone. They are often asymmetrical & separated by a thin bony septum it opens in the middle meatus. Arterial & nerve supply: is by supra-orbital arteries & nerves.

24. Sphenoid Sinus it occupies the body & sometimes the wings & pterygoid processes of sphenoid bone. They are rarely symmetrical and the right and left sinuses are separated by a septum. There are three types of sphenoid sinus pneumatization: 1- Conchal (1%) in which the sinus is rudimentary. 2- Pre-sellar pneumatization (40%) in which the sinus is pneumatized as far as the anterior bony wall of the pituitary fossa. 3- Post-sellar & occipital pneumatization (60%) in which pneumatization extend backward below the pituitary fossa. The ostium is situated in the upper part of anterior wall of the sinus & opens in the spheno-ethmoidal recess. Arterial blood & nerve supply: is from posterior ethmoidal arteries & nerve.

30. Lymphatic drainage of all paranasal sinuses: Anteriorly: is to submandibular glands. Posteriorly: to retropharyngeal lymph nodes & upper deep cervical lymph nodes. The epithelium which lines the nose and paranasal sinuses is pseudo-stratified columnar ciliated epithelium with goblet cells except the olfactory area (the roof of the nose, upper third of nasal septum & upper part of lateral nasal wall as far as, and include the superior turbinate), which is lined by olfactory epithelium.

31. The blood supply of the nasal septum & lateral nasal wall: Arterial blood supply of the nose is from branches of the external (90%) and internal (10%) carotid arteries. 1- Postero-inferiorly, the major blood supply is by sphenopalatine artery. 2- Antero-inferiorly is supplied by greater palatine artery & superior labial branch of facial artery. The above two are from the external carotid artery (90%). 3 -Postero-superiorly is supplied by posterior ethmoidal artery. 4-Antero-superiorly is supplied by anterior ethmoidal artery. The above two are from the internal carotid artery (10%).

33. Nerve supply of the nasal septum: mainly from the → maxillary division of the 5 th cranial nerve. Posteriorly → Nasopalatine nerve. Antero-superiorly → Anterior ethmoidal nerve. Antero-inferiorly → Anterior superior alveolar nerve.

34. Nerve supply of the lateral nasal wall: Mainly from the maxillary division of the 5 th cranial nerve. Posteriorly → Branches of pterygopalatine ganglia and anterior palatine nerve. Antero-superiorly → Anterior ethmoidal nerve. Antero-inferiorly → Anterior superior alveolar nerve and infraorbital nerve. The olfactory area (The roof, upper third of nasal septum& upper part of lateral nasal wall) is supplied by Olfactory nerve.

36. Physiology of the nose & paranasal sinuses:

37. Functions of the nose Provides airway for respiration. Filtration, warming & humidification of the inspired air. Voice modification. Collects the moisture from expired air to prevent excessive loss. Kills inspired bacteria & viruses. Transport mucous posteriorly to lubricate the pharynx. Olfaction.

38. Function of the paranasal sinuses: The functions of the sinuses are uncertain. There are several theories: Result of facial development. Air conditioning (warming & moistening of the inspired air). Lightening of the skull. Resonance of voice. Protection from sound transmission of one's own speech to the ear. Some influence on olfaction. Protection of eye from trauma.