Paranasal air sinus

paranasal sinus

1. PARANASAL AIR SINUS Dr. Payal Dash 1 ST year post graduate trainee Department of public health dentistry

2. CONTENTS Introduction Embryology Growth and development H istology Functions Evaluation of sinus Maxillary air sinus Frontal air sinus Ethmoidal air sinus Sphenoidal air sinus Applied anatomy Conclusion References

3. INTRODUCTION Paranasal sinuses are air filled spaces in certain skull bones. Embryologically developed as diverticula of mucous membrane of the nose. Bones containing air sinuses are called pneumatic bones . Classified as – Anterior group Maxillary ,frontal ,anterior ethmoidal air sinuses Posterior group Posterior ethmoidal air sinuses, sphenoidal

4. EMBRYOLOGY Begins at 3 rd month in- utero Outpouchings of superior and middle nasal meatus Two primary process- primary pneumatisation secondary pneumatisation SINUS PRIMARY PNEUMATISATION SECONDARY PNEUMATISATION MAXILLARY 10 weeks I.U. 5 th month I.U. SPHENOIDAL 4 th month I.U. 6-7 years ETHMOIDAL 4 th month I.U. 2 years FRONTAL 4 th month I.U. 6 months

5. GROWTH AND DEVELOPMENT SINUS STATUS AT BIRTH GROWTH FIRST RADIOLOGIC EVIDENCE MAXILLARY Present Volume : 6- 8 ml Rapid growth from birth to 3 years.Adult size-15 years 4-5 months after birth ETHMOID Present Anterior group-5*2*2mm Posterior group-5*4*2mm Adult size by 12 years 1 year FRONTAL Not present Invades frontal bone at 4 years and size increases till teens 6 year SPHENOID Not present Sella turcica - 7 years Dorsum sellae -late teens Basisphenoid - adult age Adult 15 years 4 year Source- Diseases of ear ,nose and throat and head and neck surgery 6 th edition- PL Dhingra , Shruti Dhingra

6. HISTOLOGY Microscopically 3 layers Epithelial layer Basal lamina Subepithelial layer including periosteum They are lined by pseudostratified columnar epithelium studded with mucus and serous glands

7. FUNCTIONS Air conditioning of inspired air Lighten the skull bones Resonance for voice Protection of orbit Provide extended surface for olfaction Provide local immunologic defence Act as buffers against trauma

8. EVALUATION OF SINUS Clinical examination- Inspection Palpation Percussion Transillumination Palpation Transillumination

9. Radiographs - Periapical , occlusal,lateral (intra-oral) Panoramic ,Water’s view, submentovertex (extra-oral)

10. CT scan and MRI Endoscopy

11. MAXILLARY AIR SINUS Also know as Antrum of highmore (1651) Largest of all Pyramidal in shape Capacity-15cc (average) Maxillary sinuses

12. BOUNDARIES APEX- zygomatic process of maxilla BASE- lateral wall of nasal cavity ROOF- floor of orbit FLOOR- alveolar process of maxilla situated 1.25cm below the level of nasal floor.

13. AVERAGE MEASUREMENTS Vertical - 3.5 cm Transverse - 2.5 cm Antero- posterior - 3.2 cm of base OPENING I n intact skull the size of opening is reduced to 3-4mm as it is overlapped

14. RELATIONS ANTEROLATERALLY POSTERIORLY Infra-orbital plexus of nerves Infratemporal Infra –orbital veins Pterygopalatine fossa Origin of muscles of upper lip Posterior superior alveolar vessels and nerves Anterior superior alveolar vessels and nerves in Canalis Sinusus ( a bony canal )

15. NEUROVASCULAR SUPPLY

16. FRONTAL AIR SINUS Resides in frontal bone. 2 nd largest Asymmetrical (triangular) On average vertically- 3cm antero-posteriorly - 3cm transversally- 2.5 cm

17. NEUROVASCULAR SUPPLY ARTERY- Supra-orbital branch of opthalmic artery VEIN- Junction of supra-orbital and superior ophthalmic vein LYMPH NODE Submanibular lymph nodes NERVE - Supra-orbital branch of frontal nerve

18. ETHMOIDAL SINUS Present in ethmoid bone Classified as Anterior -1-11 air cells Middle- 1-5 air cells Posterior-1-7 air cells Relations Superiorly-Cranial Cavity Inferiorly- Maxillary air sinus Anteriorly - External nose Medially- Nasal cavity Laterally- Optic nerve and nasolacrimal duct

19. NEUROVASCULAR SUPPLY

20. LYMPHATIC DRAINAGE Submandibular lymph nodes (anterior sinuses) Retropharyngeal lymph nodes(posterior sinuses) NERVE SUPPLY-

21. SPHENOIDAL SINUS Present in sphenoi d bone Pair of sinus separated by septum Approximately- 2*1.8*2cm

22. DRAINAGE SITES

23. APPLIED ANATOMY Maxillary sinus, frontal sinus Developmental anomalies Intrinsic diseases (originating from tissues within sinus) Extrinsic diseases (arising from odontogenic tissues)

24. APPLIED ANATOMY OF MAXILLARY SINUS Sphenopalatine fossa approached. Oro- antral fistula Infraorbital crescent Antral puncture APPLIED ANATOMY OF FRONTAL SINUS Frontal sinusitis Vacuum frontal headache Howarth operation Sinus gallop

25. DEVELOPMENTAL ANOMALIES Aplasia Agenesis Hypoplasia Crouzon syndrome Treacher collins syndrome Binder syndrome

26. MUCOSITIS Thickened sinus mucosa Normal mucosa thickness -1mm thick not seen in radiograph Inflamed (infectious or allergic )-10-15 times seen radiographically Detectable as noncorticated Band Radiopaque

27. SINUSITIS generalized inflammation of the paranasal sinus mucosa Causes blockage of drainage through the osteomeatal complex Pansinusitis 3 types- ACUTE,SUBACUTE,CHRONIC

28. ACUTE SINUSITIS AETIOLOGY A.EXCITING CAUSES Nasal infections Swimming and diving Trauma Dental infections B.PREDISPOSING CAUSES LOCAL GENERAL 1.Obstruction to sinus 1. Environment Ventilation and drainage 2. Poor general health 2.Stasis of secretions 3.Previous attack of sinusitis

29. PATHOLOGY OF SINUSITIS

30. ACUTE MAXILLARY SINUSITIS ACUTE FRONTAL SINUSITIS ACUTE ETHMOID SINUSITIS ACUTE SPHENOID SINUSITIS CLINICAL FEATURES Headache Pain Oedema of cheek Nasal discharge Frontal Headache Tenderness Oedema of upper eyelid Nasal discharge Pain Oedema of lids Nasal discharge Swelling of middle turbinate Pain Oedema of lids Nasal discharge Swelling of middle turbinate

31. CHRONIC SINUSITIS Infections lasting for months or years

32. CALDWELL-LUC(Anterior antrostomy ) operation

33. COMPLICATIONS OF SINUSITIS

34. POLYPS The thickened mucuous membrane of a chronically inflamed sinus forms into irregular folds called polyps .

35. ANTROLITH Radiographical features Location- maxillary sinus Periphery and shape-well defined ,smooth and irregular shape Internal structure- radiopaque ,homogenous or heterogenous

36. MUCOCELE Synonyms- pyocele , mucopyocele

37. BENIGN NEOPLASMS

38. PAPILLOMA Present in ethmoial /maxillary sinus Appear as isolated polyp in sinus Homogenous radiopaque

39. OSTEOMA Most common mesenchymal neoplasm Occur in frontal an ethmoidal sinuses Lobulated,sharp defined margin Homogenous and radiopaque

40. MALIGNANT NEOPLASMS

41. SQUAMOUS CELL CARCINOMA Occur in maxillary sinuses R adiopaque Destroy sinus walls, Bone destruction, Widening of periodontal Ligament space Floor destroyed

42. EXTRINSIC

43. PERIOSTITIS P resence of one or more halo layer of new bone indicates periosteum inflammation. Radiographic features- Periosteal new bone formation- T hin or thick radiopaque line (onion skin ) Centered directly above the inflammatory lesion

44. ODONTOGENIC CYSTS Radicular cyst Dentigerous cyst Mucus Retention Cyst

45. ODONTOGENIC TUMORS Ameloblastoma Myxoma Radiographic features oval or multilocular shape ,aggressive tumors lack border. Displace the floor of antrum Thinning of peripheral cortex Bony walls of sinus eroded . Tooth may be embedded

46. FIBROUS DYSPLASIA Radiographic features Posterior maxilla , not well defined Radiopaque - ground glass appearance , orange peel appearance

47. CONCLUSION

48. REFERENCES Gray’s anatomy 39 th edition Robbins and cotran 8 th edition Oral radiology by White and pharaoh 6 th edition Bailey and love’s short practice of surgery 24 th edition Textbook of oral an maxillofacial surgery by Kruger 6 th edition Oral and maxillofacial surgery by Daniel M. Laskin volume 1 Orbans oral histology and embryology