The Fallopian canal
This canal begins at the anterior angle of the superior fossa of the internal auditory meatus, and passes directly outwards to the hiatus Fallopii; it then turns abruptly backwards and forms a horizontal ridge on the inner wall of the tympanum lying in the angle between it and the tegmen tympani. It passes immediately above the fenestra ovalis, and extends as far backwards as the entrance to the mastoid antrum; here it comes into contact with the inferior aspect of the projection formed by the external semicircular canal. It then tm-ns vertically downwards, running in the angle between the internal and posterior wall of the tympanum to terminate at the stylo-mastoid foramen.
The canal is traversed by the facial (seventh) nerve. Numerous openings exist in the walls of this passage. At the hiatus the greater and smaller superficial petrosal nerves escape from, and a branch from the middle meningeal artery enters, the canal. In the vertical part of its course the cavity of the posterior pyramid opens into it. There is also a small orifice by which the auricular branch of the vagus joins the facial, and near its termination the iter chordae posterius for the chorda tympani nerve leads from it into the tympanum.