BPK 105 Study Guide - Midterm Guide: Mastoid Cells, Ear Canal, Eardrum
27 Apr 2018
School
Department
Course
Professor
Module 5 - Objectives - Part 5
● Describe the structure and function of the middle and outer ear.
Middle Ear
- Medial to the tympanic membrane is the air-filled cavity of middle ear.
- Two covered openings on the medial side of the middle ear, the oval window and the
round window, connect the middle ear with the inner ear.
- middle ear contains three auditory ossicles (ear bones): the malleus, the incus, and
the stapes.
- bones transmit vibrations from the tympanic membrane to the oval window.
- malleus is attached to the medial surface of the tympanic membrane.
- incus connects the malleus to the stapes.
- base of the stapes is seated in the oval window, surrounded by a flexible ligament. A
- as vibrations are transmitted from the malleus to the stapes, force of the vibrations is
amplified about 20-fold bc the area of the tympanic membrane is about 20x that of the
oval window.
- Two small muscles in the middle ear, one attached to the malleus and the other to the
stapes, help dampen vibrations caused by loud noises, protecting the delicate inner ear
structures.
- two unblocked openings into the middle ear.
- One opens into the mastoid air cells in the mastoid process of the temporal bone.
- The other, called the auditory tube, or eustachian tube,
opens into the pharynx and
enables air pressure to be equalized between the outside air and the middle ear cavity.
- Unequal pressure between the middle ear and the outside environment can distort the
tympanic membrane, dampen its vibrations, and make hearing difficult.
- Distortion of the tympanic membrane also stimulates pain receptors associated with that
structure.
- That distortion is why, as a person changes altitude, sounds seem muffled and the
tympanic membrane may become painful.
- symptoms can be relieved by opening the auditory tube to allow air to enter or exit the
middle ear, such as by swallowing, yawning, chewing, or holding the nose and mouth
shut while gently forcing air out of the lungs.
External Ear
-Auricle: the fleshy part of the external ear on the outside of the head.
- opens into the external auditory canal, a passageway that leads to the eardrum.
Document Summary
Describe the structure and function of the middle and outer ear. Medial to the tympanic membrane is the air-filled cavity of middle ear. Two covered openings on the medial side of the middle ear, the oval window and the round window, connect the middle ear with the inner ear. Middle ear contains three auditory ossicles (ear bones): the malleus , the incus , and the stapes . bones transmit vibrations from the tympanic membrane to the oval window. Malleus is attached to the medial surface of the tympanic membrane. incus connects the malleus to the stapes. base of the stapes is seated in the oval window, surrounded by a flexible ligament. A as vibrations are transmitted from the malleus to the stapes, force of the vibrations is amplified about 20-fold bc the area of the tympanic membrane is about 20x that of the oval window.
