乳突洞・上鼓室のドレナージ—解剖学的考察

DRAINAGE OF THE MASTOID ANTRUM AND THE EPITYMPANUM. AN ANATOMICAL STUDY

　鼓室成形術を成功させる要因のなかでもつとも大切なものの1つは，耳管の機能が良いことである。耳管機能不全があると，術創の滲出液の排出がうまくつかず，新しくつくつた鼓室に空気が入らず，結局鼓膜の癒着や炎症の再発におわる。耳管機能障害を手術的に改善しようとする試み^1）が報告されているが，きわめて悪い例は，幸いにして少数であり，鼓室成形術の適応とならない症例の数は多くはない。

　近年外耳道を保存したり，外耳道を除去した場合でも骨片や軟骨片，筋膜などをつかつて外耳道を再建する術式（closed method）が多く行なわれるようになつた^2）〜4）。外耳道が形成されると術創の治癒がはやく，創の清潔が簡単にたもたれ，したがつて耳漏の再発も少ない。

　Various structures that may cause problems in air exchange and disturbances of diffusion in the middle ear cleft were studied by means of human temporal bones. The narrowest portion was the attic floor occupied by articulation of the malleus and incus. A narrow but constantly opened space was found only on the medial side of this articulation. The anterior attic wall was found to be composed of a thin bony plate. This anterior attic bony plate decended from the tegmen tympani extending from the facial canal to the scutum. The plate measured 2 to 3 mm in height and separated the attic and the supratubal space of the mesotympanum. The removal of this bony plate was necessitated to attain a wider communication between the attic and the mesotympanum.

　Distribution of the ciliated cells in the middle ear mucosa was also observed in 2 temporal bones using scanning electron microscope. Presence of a fairly good number of the ciliated cells on the aditus ad antrum and the anterior part of the promontory seemed to be effectively functioning for the middle ear drainage.