الفهرس 
Cadaveric studyOnly 14 pages are availabe for public view
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Abstract
This work was done to study the features of the mastoid process with special reference to Körner’s septum (KS) or petrosquamosal lamina. Its incidence, anatomical variations and attachments were recorded. Its clinical importance was also evaluated.
In the present work, 50 temporal bones were used during temporal bone dissection courses in Ain Shams University Specialized Hospital. Also 50 CT scans of temporal bone were examined for identification of KS. They were done for patients suspected to have inner ear diseases without history or signs of otitis media.
Mastoid exploration was done and proceeded to deeper planes to expose the mastoid antrum and air cells. The mastoid antrum could be located on the surface of the squamous part of temporal bone by the suprameatal (Macewen’s) triangle.
The mastoid cavity was bounded anteriorly by the descending part of the facial nerve canal and the posterior wall of the external auditory canal. Posteriorly was the sigmoid sinus plate, superiorly by the tegmen (dural plate) and inferiorly by the mastoid tip cells. Medially were the lateral and posterior semicircular canals. Anterosuperiorly was the mastoid antrum which communicated with the mastoid air cells.
Körner’s septum was identified in 16 out of 50 temporal bones (32%). In 9 cases the septum extended above the middle ear cavity and coursed inferiorly in the mastoid process to the mastoid tip dividing the process completely into a superficial compartment belonging to the squama and a deeper compartment belonging to the petrous part of temporal bone. KS was partially present in the upper part (4 cases) or in the lower part (3 cases) of the mastoid process.
Körner’s septum was identified in 15 out of 50 CT scans axial and coronal views of temporal bone (30%). The septum extended completely in 7 cases dividing the mastoid cavity into superficial and deep compartments. In 8 cases the septum was partially existing. It was found to be unilateral in most cases (10 out of 15 CT scans). The septum was observed as a bony lamina thicker than the wall of the adjacent mastoid air cells. No definite relationship was noted between the presence of KS and the mastoid process pneumatization.
In both temporal bone specimens and CT scans KS was noted extending from the attic anteriorly through the mastoid antrum. The septum was attached anteriorly to the posterior wall of external auditory meatus, posteriorly to the lateral part of sinus plate, superiorly to the lateral part of tegmen and inferiorly to the mastoid tip.
Mastoid air cells derived from superficial cell compartment, lateral to KS and also lateral and posterior to the sigmoid sinus were named retro-sinus air cells and those found in the mastoid tip were named mastoid tip cells. These cells were divided by the digastric ridge into superficial and deeper cells. Mastoid air cells lying deep to Körner’s septum were derived from the petrous portion of temporal bone. The labyrinth lay between the deeper mastoid cells and the petrous bone air cells. In a well pneumatized temporal bone the petrous cells could be tracked and opened from deeper mastoid cells by following some routes or cell tracks around the labyrinth.
from the present study it is concluded that Körner’s septum is an anatomic handicap predisposing the individual to chronic otitis media, cholesteatoma and adhesive otitis media, because the septum contributes to attic blockage.
Also Körner’s septum may give a false impression to otologists during opening the mastoid antrum that the deep compartment of the antrum had been explored whereas the septum may hide cholesteatoma or cholesterol granuloma behind it which may be missed especially if the superficial compartment was sclerosed.
Preoperative CT scans of temporal bones are needed to avoid entering a false antrum or injury to the facial nerve in presence of Körner’s septum.