Friday, 27 May 2011

Mastoid air cell system


  1. Mastoid air cell system: Is considered to be an important contributor to the physiology of middle ear function. According to Tumarkin the mastoid air cell system served as an reservoir of air and serves as buffer system to replace air in the middle ear cavity temporarily in case of eustachean tube dysfunction. The mean volume of air in the mastoid air cell system could be about 5-8 ml. CT scan evaluation of temporal bone is considered to be the best modality to assess mastoid air cell system.
    The penumatization of mastoid air cell system can be divided into
    3 types:
    Sclerotic mastoid – Pneumatization is absent
    Diploic mastoid – Pneumatization partial
    Pneumatic mastoid – Full and complete pneumatization
    The mastoid air cell system is covered with highly vascular cuboidal epithelium. The contact between the blood vessels and the basement membrane is rather close resembling that of alveoli where extensive gaseous exchange takes place.
The mastoid air cell system is categorized according to various
regions of temporal bone. These include:
a. Squamo mastoid – This area include air cells around antrum, central mastoid tract and peripheral air cell tract.
b. Perilabyrinthine cells – These can be divided into supra labyrinthine and infralabyrinthine air cells
c. Petrosal air cells – Petrosal air cells and petrous apex air cells
d. Accessory air cells – These cells include zygomatic air cells, occipital air cells, squamous air cells and styloid air cells.

Patients with poor pneumatization of mastoid air cell system are more prone to develop adhesive otitis media following middle ear infections as the normal buffering system of the mastoid pneumatization is not adequate in them. Treatment of secretory otitis media with effusion is more effective in a patient with well developed mastoid air cell system when compared to that of patients with sclerosed ones.

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