2009ë…„ 8›” Ethmoid bone dissection-lateral nasal sinus anatomy

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Text of 2009ë…„ 8›” Ethmoid bone dissection-lateral nasal sinus anatomy

2009 8 4

Nasal turbinate

Paranasal sinuses; frontal sinus, maxillary sinus, ethmoid sinus, sphenoid sinus

The Ostiomeatal Complex(OMC); air cells of anterior ethmoid and ostia ; middle meatus ; final sections of the common drainage and ventilation pathway of the frontal, maxillary, and anterior ethmoid sinuses

The Ostiomeatal Complex(OMC) 2Agger nasi cell Uncinate process Bulla ethmoidalis Hiatus semilunaris inferior Middle turbinate Maxillar sinus ostium Frontal sinus ostium

Agger nasi cell- located medial to lacrimal sac and fossa anterior to the uncinate process - product of pneumatization of the lacrimal bone

Uncinate process; sickle-shaped, thin, bony plate ; attachment anterior : anterosuperiorly, attached to the MT : form the inferomedial wall of agger nasi cell inferior : inferior turbinate and palatine bone posterior : parallel to the curvature of bulla ethmoidalis superior : attach to lacrimal bone base of the skull or LP always fuses with the MT anterosuperiorly

Uncinate process 2

Middle turbinate- conchal head, conchal neck, conchal sinus - conchal sinus, cavity between ethmoid bulla and MT - 3 discernible component 1st. Part ; anterior and medial position, sagittal plane attach vertically to the skull base, LT, lateral lamella 2nd. Part ; frontal plane attach laterally to the lamina papyracea in an oblique fashion 3rd. Part ; (basal lamella) horizontal plane attach laterally to the perpendicular plate of palatine

Middle turbinate 2Plane Vertical(Sagittal plane) Oblique(Frontal plane) Horizontal plane Attachment Crista ethmoidalis and the skull base Lamina papyracea Lamina papyracea & lamina perpendicularis

Three part Anterior 1/3 Middle 1/3 Posterior 1/3

Basal lamella1st. Uncinate process 2nd. Bulla ethmoidalis 3rd. Basal lamella of the middle turbinate 4th. Lamella of the superior turbinate 5th. Lamella of the supreme turbinate

Bulla Ethmoidalis- most constant landmark - Boundary anterior ; convex curvature posterior free border of UP superior ; Fovea posterior ; basal lamella(variable) lateral ; lamina papyracea medial ; covered by middle turbinate

Hiatus Semilunaris Inferior- sickle-shaped 2D cleft - average width, 1.5mm - between the ethmoidal bulla and free edge of uncinate process

Ethmoid infundibulum- well-defined 3D cleft between anterior wall of ethmoidal bulla and posterior wall of uncinate process - medial ; uncinate process lateral ; formed by LP, frontal process of the maxilla depth ; average depth, 2mm(variable, 0.5~10mm)

Hiatus Semilunaris Superior- between ethmoid bulla(anteriorly and inferiorly) and skull base(superiorly) and basal lamella(posteriorly)

Lateral sinus- not always present - boundary superior ; fovea inferior ; roof of the ethmoid bulla posterior ; basal lamella of the MT lateral ; lamina papyracea medial ; middle turbinate dorsal ; space between bulla ethmoidalis and basal lamella open ; between bulla ethmoidalis and middle turbinate

Lateral sinus 2- divided into suprabullar recess and retrobullar recess a. suprabullar recess ; a space bordered by the ethmoidal bulla(inferiorly) ethmoidal fovea(superiorly) b. retrobullar recess ; bordered by ethmoidal bullar(anteriorly) basal lamella(posteriorly)

Maxillary sinus ostium- usually located posterior and inferior at the angle formed by the ethmoidal bulla and uncinate process

Fontanelle area- 2 distinct areas on the lateral nasal wall where the nasal muconsa and mucoperiosteum of the maxillary sinus - anterior fontanelle : anterior and inferior to the inferior attachment of the uncinate process - posterior fontanelle : superior to the posterior insertion of the uncinate process

Frontal sinus ostium- located at the bulla-uncinate angle anteriorly and superiorly

Supraorbital Ethmoid air cell- arise from pneumatization of the orbital process of the frontal bone(15~21%) - located just posterior to the frontal sinus ostium - AEA, just posterior to the supraorbital cell

Anterior Ethmoid artery- orbital branch of ophthalmic a. exit the orbit through ant. Ethmoidal foramen pass into orbito-cranial canal in the roof of the ethmoid enter the lateral lamella and olfactory fossa

cf. posterior ethmoid artery : ophthalmic artery : posterior ethmoid canal - optic foramen(5~10mm)

Posterior ethmoid cell- larger in size, fewer in number than the anterior ethmoid cells - anterior ; basal lamella posterior ; anterior wall of sphenoid sinus lateral ; lamina papyracea medial ; superior meatus and superior turbinate superior ; fovea ethmoidalis inferior ; posterior part of middle turbinate

Sphenoethoidal cell(Onodi cell)- lateral and superior extension of posterior ethmoids - relation to the optic nerve and/or internal carotid artery

Roof of Ethmoids- anterior 2/3, frontal bone, fovea ethmoidalis - medially, join the lamina cribrosa - height of the roof(Keros)

Lateral lamella- thinnest at the location of anterior ethmoid arterial passage (0.05mm. 1/10 of thickness of fovea ethmoidalis)

Cribriform plate- perforated by the olfactory nerve fiber - attach to the crista gali and perpendicular plate middle turbinate lateral lamella

Olfactory fossa- located between the crista gali medially cribriform plate inferiorly lateral lamella laterally - olfactory bulb

Frontal recess- the space where the frontal sinus open - boundary anterior ; uncinate process and agger nasi cell posterior ; bulla ethmoidalis and suprabullar lamella lateral ; lamina papyracea medial ; hiatus semilunaris inferior or neck of MT inferior ; ethmoid infundibulum superior ; fovea ethmoidalis, supraorbital cell, anterior ethmoid artery, frontal ostium

Frontal recess

Frontal recess 2- size of the frontal recess, determined by the size of the surrounding anterior ethmoid air cell(bulla ethmoidalis, agger nasi cell, supraorbital cell and frontal cells)

Frontal cells- Kuhn type I : a single small cell above the agger nasi cell II : multiple small cells above the agger nasi cell III : a single large cell above the agger nasi cell extending to the frontal sinus IV : a single small cell inside the frontal sinus

Spatial relationship- superior ; anterior cranial fossa - anterior ; spheno-ethmoid recess, superior turbinate, and posterior ethmoid - inferior ; nasopharynx - posterior ; basi-sphenoid sella posterior cranial fossa - lateral ; middle cranial fossa, cavernous sinus

Classification: basis of pneumatization - conchal(2~3%) - presellar(11%) - sellar(86%)

Neurovascular relationship- optic nerve - internal carotid artery - maxillary nerve(V2) in the foramen rotundum - Vidian nerve in the pterygoid canal

Sphenoid sinus ostium- 1~5mm in size - round, oval or vertical cleft - located just medial to the posterior end of the superior turbinate - close to the midline in the anterior sphenoid wall at the junction of the upper 1/3 and lower 2/3

Supraoptic and Infraoptic recess- pnumatization extends into the lesser sphenoid wing (size and depth, degree of pneumatization of the anterior clinoid process)

Sphenoid rotrum- midline projection of anterior sphenoid wall - articulate, perpendicular plate of ethmoid and vomer

Sphenoethmoid recess - a space behind and above the most superior turbinate - boundary superior ; cribliform plate inferior ; nasopharynx anterior ; uppermost concha (superior or supreme turbinate) posterior ; anterior wall of sphenoid sinus medial ; nasal septum

Cavernous sinus - CN III, IV, V, VI - carotid artery

- Reference1) N.J. Bhatt Endoscopic Sinus Surgery new horizons p.48~51 2) 3) R. Kamel. Endoscopic anatomy of the lateral nasal wall, ostiomeatal complex and anterior skull base