Human Anatomy & Physiology (9th Edition)

Published by Pearson
ISBN 10: 0321743261
ISBN 13: 978-0-32174-326-8

Chapter 15 - The Special Senses - Review Questions - Critical Thinking and Clinical Application Questions - Page 589: 2


The source of the bacteria that caused Sally's mastoiditis and labyrinthitis was most likely her sore throat. Because the Eustachian tube connects with the middle ear it is not very difficult for bacteria in a sore throat to ascend to the middle ear. In this case the bacteria seems to ascend to and infected the middle ear. . This is the cause of the red and swollen ear drum since the tympanic membrane is the lateral border of the middle ear. . The dizziness and balance problems indicate that the infection had also proceeded medially and affected structures in the inner ear. These structures would include organs in the cristae of the semicircular canals and the maculae of the membranous labyrinth. The ear canal passes through the temporal bone. The mastoid bone is a part of the petrous section of the temporal bone . Because of the porous nature of the mastoid bone it is easy for bacteria in the middle ear or inner ear to find their way into the mastoid bone causing the inflammatory condition known as mastoiditis

Work Step by Step

The source of the infection is bacteria from an infected throat or pharynx. The route of the infection is the Eustachian tube. The dizziness is caused by inflammation of the semicircular canal and the vestibular apparatus of the middle ear. The pain in the ear lump ( mastoid process) is caused by movement of bacteria from the middle or internal ear into the mastoid bone of the temporal bone. The swollen red tympanic membrane was infected from the middle ear.
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