Anatomy of lateral wall of nose with relevance
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June 2014, a ppt for DLO and MS ENT postgraduate students lecture by Prof Dr.G.Gananathan MS DLO FICS, then HOD & Prof of MMC, on endoscopic and ct relevence to lateral wall of nose and paranasal sinus.
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Anatomy of lateral wall of nose with relevance
- 1. Dr.G.Gananathan M.S, D.L.O.,F.I.C.S., Director & Professor Upgraded Institute of Otorhinolaryngology Madras Medical College, Chennai-03
- 2. A systemic approach to reading a CT PNS includes Evaluation of patient’s sinus anatomy with its variations Determinig the presence of disease Looking for potential areas of occlusionof drainage pathways Computer Tomography of Paranasal Sinuses
- 3. To master FESS Perfect anatomy Familiarization of radiological landmarks 3D reconstruction Cross sectional anatomy of FESS Handling of scope and instruments Not to panic when entering neighbouring areas Management of bleeding
- 4. Ask for 3 planes-coronal, axial and sagittal Axial view- Patient’s hard palate is perpendicular to the CT scanner table , so the External Auditory Canal is in line with the infra-orbital rim. Coronal view- Patient’s hard palate is parallel to the scanner table. Soft tissue and bone window settings Screening CT – 5-10mm , 1-2mm, 0.5mm Settings 1700-2300 HU , centre around +100 to +300 with 130 KV collimation of 2 x 1.5mm with rotation time of 1 second Protocol of CT
- 5. A patient undergoing FESS has to get a CT prior to the procedure after completion of maximal medical therapy. The scans are read twice : once to study the anatomy and its variations and then again to study the pathology It is advisable to start reading the scans from the scout view and then read it frame by frame without jumping erratically The navigation is complementary to the CT allowing the surgeon to orient himself in different planes intra-op When to Order CT
- 6. Scout film Frontal Sinus & Inferior turbinate First cut Following Scout Film - Nasal bone, Nasal septum & - Alar cartilage
- 7. Frontal Recess and T sign Nasofrontal beak, Nasolacrimal duct
- 8. Uncinate Process (dotted line) Crista galli & Suprabullar recess
- 9. Anterior Ethmoidal Artery Basal Lamella & Lamina Papyracea
- 10. Posterior Skull Base and Inferior Orbital fissure Orbital Apex, Sphenoidal Os & Planum Sphenoidale
- 11. Onodi cell, Vidian canal, Foramen Rotundum , Intersphenoidal septum, Anterior clinoid process & medial and lateral pterygoid plates Foramen Ovale & sphenoid sinus
- 12. AXIAL CUTS showing Sphenopalatine Foramen, Nasolacrimal duct, Globe, optic nerve Lamina papyracea And medial and Lateral rectii. Endoscopic view Showing sphenopalatine artery, Crista ethmoidale, Orbital fat, Medial rectus, Widened sphenoidal ostium.
- 13. Frontal Recess in Axial Cuts Axial cuts Showing Transition from frontal sinus to Frontal recess. Viewed from top Downwards. Anterior wall is Thicker. (Naso-Frontal Beak )
- 14. Frontal Recess Agger Nasi Cell & Concha bullosa
- 15. Frontal Air Cells Type I (Bipatite agger cell) Type II • Anterior & posterior group • Anterior group - 4 Types
- 16. Frontal Air Cells Type III (arrowheads) Type IV
- 17. Posterior- group -Supra Bullar cell
- 18. Posterior Frontal group-Frontal Bullar & Supra-orbital cells
- 20. Concha Bullosa
- 23. Haller cell
- 24. Onodi cell d NO- dehiscent optic nerve
- 31. Fibrous Dysplasia of Ethmoid Sinus
- 37. Fresh cadaver dissection platform to fine tune skills Fresh frozen preferred over formalin preserved as tissues are more pliable and anatomical details are closest to living tissues Nasal Endoscopy – 3 passes Cadaver Dissection
- 39. Note the following structures Inferior turbinate Middle turbinate Axilla of middle turbinate Uncinate process , Bulla ethmoidalis Accessory ostia Tubal elevation, Eustachian tube Fossa of Rosenmuller Superior turbinate, Sphenoidal os
- 40. 3 Passes First Pass Second Pass Third pass
- 41. Steps Lateralisation of Inferior turbinate at the level of anterior end of middle turbinate using Freer’s elevator (this increases room for manipulation in middle meatus) Indentify the free border of uncinate process Identify junction of the upper 2/3rdand loer 1/3rd of the uncinate process (corresponds Uncinectomy
- 43. Steps Mucosa of the medial surfaces of the horizontal portion of the uncinate is debrided away. Lower portion of uncinate bone is dissected away with sickle knife. The mucosa of the lateral surface of uncinate is retained. A vertical cut is made at its anterior end. A scissor is used to cut the mucosa , flush with the roof of the maxillary sinus as far as the accessory ostium The inferiorly based uncinate flap is now draped over the raw surface created over the superior aspect of the inferior turbinate. Middle Meatal Antrostomy
- 45. Boundaries Anteriorly : agger nasi Posteriorly: anterior ethmoidal artery Medially : middle turbinate Laterally : lamina papyracea Frontal Recess
- 47. Anterior Ethmoid The bulla is the largest anterior ethmoid air cell 6 walls Anterior wall Medial wall-related to the lateral wall of Hiatus Semilunaris Superioris Lateral wall- lamina payracea Posterior wall- related to retrobullar recess Superior wall – could be attached to skull base / related to suprabullar recess Inferior wall
- 49. Anterior ethmoidal neurovascular bundle running obliquely from posterior to anterior , and lateral to medial. Small portion of anterior fovea between posterior wall of frontal sinus and anterior ethmoidal artery.
- 50. Boundaries Anteriorly : ground lamella Posteriorly : anterior wall of sphenoid Laterally : lamina payracea Superiorly : posterior skull base Medially : superior turbinate Steps Identify ground lamellaand gentally slide Blakesley forceps along the horizontal attachment of middle turbinate. Perforate the basal lamella medially and inferiorly using the forceps. Remove all cells till the posterior skull base is identified. The skull base descends inferiorly towards the posterior aspect. Posterior Ethmoid
- 51. Intermediate approach Follow the inferior wall of bulla towards posterior end of middle turbinate. Use the debrider directed medially taking care not to damage the septal mucosa. The anterior end of superior turbinate is identified. Push superior turbinate gently laterally and identify the sphenoid os. Using forceps resect the inferior third of superior turbinate. Sphenoid os is visualized now. Using Stammberger mushroom punch forceps sphenoid os is widened. Sphenoid Sinus
- 52. Following structures are seen in sphenoid sinus Orbitel apex Optic nerve Internal carotid artery Sellar floor Structures in Sphenoid
- 53. Skull base
- 54. Structures identified in Skull Base Posterior ethmoidal neurovascular bundle Posterior fovea Anterior ethmoidal neurovascular bundle Anterior fovea Frontal recess