Figure 3.

Posterior to anterior and lateral view of a pathological right ear after lateral epitympanic bone removal. The orange arrow indicates the direction of the air flow. An isthmus blockage (*) prevents air flow to the epitympanum, leading to pressure reduction inside the mastoid cavity and the epitympanum itself and consequently the creation of a retraction pocket of the tympanic membrane. Aes, anterior epitympanic space; et, Eustachian tube; fn, facial nerve; in, incus; is, isthmus; lsc, lateral semicircular canal; ma, malleus; pes, posterior epitympanic space; pr, promontory; teg, tegmen tympani; tf, tensor fold.