Figure 11-12. A frontal section of the human ear.
c. Auditory Ossicles. The auditory ossicles (OSSICLE = small bone) are
three very small bones which form a chain across the middle ear cavity. They join the
tympanic membrane with the medial wall of the middle ear cavity. In order, the ossicles
are named as follows: malleus, incus, and stapes. The malleus is attached to the
tympanic membrane. A sound stimulus is transmitted from the tympanic membrane to
the medial wall of the middle ear cavity by way of the ossicles. The ossicles vibrate
(mechanically oscillate) in response to the sound stimulus.
d. Auditory (Eustachian) Tube. The auditory tube is a passage connecting
the middle ear cavity with the nasopharynx. The auditory tube maintains equal air
pressure on the two sides of the tympanic membrane.
e. Association With Other Spaces. The middle ear cavity is associated with
other spaces in the skull. The thin roof of the middle ear cavity is the floor of part of the
cranial cavity. The middle ear cavity is continuous posteriorly with the mastoid air cells
via the antrum (an upper posterior recess of the middle ear cavity).