Describe the anatomy osteomeatal complex.

The osteomeatal complex includes:

• Bulla ethmodalis
• Uncinate process
• Maxillary turbinate
• Ethmoid infundibulum.

It is important as ostium of frontal maxillary and anterior ethmoidal sinuses are present in this area.

Any anatomical variation mucosal swelling of osteomeatal complex can cause obstruction →stasis →repeated infection upstream sinuses.

Bulla ethmoidalis:

• Largest, constant anterior ethmoidal cell
• If not pneumatized, it may remain like a solid bony prominence.
• It may extend superiorly to base of skull and posteriorly to ground lamella

Retrobulbar recess+suprabulbar recess= Lateral sinus of Grunwald.

Lateral→ lamina papyracea

superior→ skull base

Inferior →Bulla

Medially→Opens into middle meatus

Uncinate process:

• Small thin lamina of ethmoid bone
• Forms floor and medial wall of the ethmoidal influndibulum
• Sickle shaped structure running from anterosuperior → posteroinferior direction.

2 borders	2 ends
Posterosuperior: free, sharp and virus|| to anterior surface of bulla ethmoidals	Posteroinferior end: attached to inferior turbinate and divides lower membranous part of middle meatus into anterior and posterior fontanella.
anteroinferior border: altache to lateral nasal wall.	Antero superior end: variable insection LP/skull base/MT accounts for the variation in the drainage of frontal sinus.

Middle turbinate:

• Attach to the lateral wall through ground lamella.
• Anterior 1/3 lie on sagittal plane →lateral edge of cribriform plate.
• Middle 1/3 lie on frontal plane →Lamina papyracea
• Posterior 1/3 runs horizontally →LP +medial wall of maxillary rimus.
• Fracture of Middle Turbinate can damage cribriform plate and cause CSF rhinorrhea and anosmia
• Paradoxical Middle Turbinate  can narrow middle meatus and affect ventilation
• Concha bullosa (pneumatization of MT): 30%
  • Usually asymptomatic
  • drains into the frontal recess directly through agger nast cells
  • affect ventilation of OMC and resuts s/s.

Hiatus semilunaris: 2 dimentional gap b/w Uncinate process and Bulla Ethmoidalis .

Opens laterally into 3 dimentional funnel shaped face called enthmoidal influndibulum.

Ethmoidal infundibulum:

Frontal sinus →opens into the anterosuperior part of infundibulium just posterior to posterior wall of agger nasi cell.

Anterior ethmoidal opens into infundibulum

Maxillary sinus:

• Natural ostium: opens in posterior infundibulum
• Accessory ostium:  4-5% in normal but increased to 25 % in Chronic rhinosinusitis
• Functional endoscopic sinus surgery(FESS) puts stress on this Osteomeatal comlex (OMC) and aims to restores normal sinus drainage and ventilation.

 

Tags: CSF Rhinorrhoea, MBBS Past Questions, MBBS Question Bank, MBBS Questions, MD Question Bank, MD Questions, Middle Turbinate, osteomeatal complex.