Fundus of internal acoustic meatus

The fundus of internal acoustic meatus is the lateral end of the internal aoustic canal.

It is closed by a vertical plate, which is divided by a horizontal crest, the transverse crest (falcifom crest, crista falciformis), into two unequal portions. Each portion is further subdivided by a vertical ridge into an anterior and a posterior part. In the portion beneath the crista falciformis are three sets of foramina; one group, just below the posterior part of the crest, situated in the inferior vestibular area (area cribosa media), consists of several small openings for the nerves to the saccule; below and behind this area is the foramen singulare, or opening for the nerve to the posterior semicircular duct; in front of and below the first is the tractus spiralis foraminosus, consisting of a number of small spirally arranged openings, which encircle the canalis centralis cochleæ; these openings together with this central canal transmit the nerves to the cochlea. The portion above the transverse crest presents behind, the superior vestibular area  (area cribrosa superior), pierced by a series of small openings, for the passage of the nerves to the utricle and the superior and lateral semicircular ducts, and, in front, the facial area (area facians), with one large opening, the commencement of the canal for the facial nerve (aquæductus Fallopii).