Structural variations of the supratubal recess: the anterior epitympanic space

We sought to classify the shape and structure of the anterior epitympanic space (AES) and produce measurements of its dimensions together with its relationships with the facial nerve and geniculate ganglion.

The AES is limited by the middle cranial fossa superiorly, zygoma root anteriorly, cog posteriorly, chorda tympani laterally, facial nerve medially, and tensor tympanic semicanal inferiorly.

The AES was examined in 30 human temporal bones using two different methods. Twenty bones were cut vertically and a modified radical mastoidectomy was performed in the other 10 bones.

The AES showed two types in the vertically cut bones according to its shape and structure. Type I, found in 17 (85%) of the bones, showed two cavities that were separated by a bony landmark and the tensor tympanic fold. The name "supratubal ridge" is suggested for this bony landmark. In type II, which was seen in three (15%) of the bones, there was only one cavity. In the mastoidectomy group, again two types of AES were found: eight (80%) were type I and two (20%) were found to be type II. If we combine these findings with the vertically cut bones, we find that 25 (83.3%) possess an AES type I, whereas five (16.7%) are type II.

These variations in the structure of the AES and its close relationships with a number of vital structures such as the facial nerve, cochlea, and middle fossa dura must be taken into account during the surgical management of middle ear disease.