The middle ear lays in the temporal bone between the tympanic membrane laterally & internal
The tegmental wall makes the roof, & thus separates it from the middle cranial fossa. It is
continuous with the bony lateral wall of the epitympanic recess, which in turn is continuos with
aditus to the mastoid antrum. The jugular wall makes the floor that separates it from the internal
Connected to the tympanic membrane laterally are the three auditory ossicles; the malleus, that
connect further to the incus & stapes that finally connects to the lateral wall of the internal ear at
the oval window. Anteriorly it is separated by a thin layer of bone from the internal carotid
artery, & also a smaller opening for the tensor tympani muscle & the entrance of the
pharyngotympanic tube leading to the nasopharynx. The pharyngotympanic tube extends
forward, medially, & downward & enters nasopharynx just posterior to to the interior meatus of
The promontory is a bulge in the medial wall produced by the basal coil of the cochlea.
Associated with the mucus membrane covering the promontory is a plexus of nerves, consisting
primarily of the tympanic branch of the glossopharyngeal nerve, CN IX, & branches from the
internal carotid plexus.
The oval window is posterosuperior to the promontory & is the attachment for the base of stapes.
The round window is posteroinferior to the promontory. The two muscles associated with the
ossicles are tensor tympani & stapedius. Tensor tympani lays in a bony canal above the
pharyngotympanic tube & stapedius has a small projection on the mastoid wall after originating
from inside the pyramidal eminence.