282 Introduction to Anatomy & Physiology Check Your Understanding 1. List the causes of deafness. 2. Define presbycusis. 3. Name the condition that causes ringing in the ears. 4. Why are infants and toddlers prone to otitis media? vestibular nerve or can result from an infection of the ear or a systemic infection. This condition can disrupt the normal function of the semicircular canals. Symptoms may include severe dizziness, nausea and vomiting, loss of hearing, loss of balance, tinnitus, and vertigo. Individuals with vertigo are unable to stand because their sense of orientation is severely compromised. Labyrinthitis is treated with antihistamines, medications to reduce dizziness and nausea, sedatives, and corticosteroids. Chronic inflammation of the semicircular canals of the inner ear is called Ménière’s (men- EERZ) disease. This disease causes periodic but severe vertigo, as well as progressive hearing loss. oval window a membrane-covered opening that connects the middle ear to the inner ear perilymph a clear fluid that fills the bony labyrinth semicircular canals inner ear channels containing receptor hair cells that play an important role in balance stapes one of the three ossicles tiny bone in the middle ear that attaches to the incus on one side and the oval window on the other tympanic cavity the middle ear tympanic membrane a sheet of tissue at the end of the auditory canal also known as the eardrum vestibule a chamber in the inner ear that contains the three semicircular canals vestibulocochlear nerve a cranial nerve that rises from the cochlear and vestibular nerves Know and Understand 1. What are the three anatomical regions of the ear? 2. Name the two terms used to describe the outer portion of the ear. 3. Where are the ceruminous glands located? 4. The Eustachian tube connects the middle ear to the _____. 5. Compare and contrast the function of the short, stiff hairs in the organ of Corti with that of its long, flexible hairs. 6. Describe the pathway of hearing. 7. Which part of the brain controls equilibrium? 8. What is the main function of the semicircular canals? 9. What is labyrinthitis? Mini Glossary Make sure that you know the meaning of each key term. auditory canal a short, tubelike structure that connects the outer ear to the eardrum auricle the irregularly shaped outer portion of the ear bony labyrinth winding tunnels located in the inner ear ceruminous glands secretors of cerumen, or earwax located in the auditory canal cochlea a snail-shaped structure in the inner ear that enables hearing cochlear duct the portion of the membranous labyrinth inside the cochlea endolymph a thick fluid inside the membranous labyrinth Eustachian tube a channel that connects the middle ear to the pharynx and serves to equalize pressure on either side of the tympanic membrane incus one of the three ossicles tiny bone in the middle ear that attaches to the malleus and transmits sound from the malleus to the stapes malleus one of the three ossicles tiny bone in the middle ear that transmits sound from the tympanic membrane to the incus membranous labyrinth membrane-covered tubes inside the bony labyrinth organ of Corti a spiral-shaped ridge of epithelium in the cochlear duct lined with hair cells that serve as hearing receptors ossicles the body’s three smallest bones—the malleus, incus, and stapes found in the middle ear LESSON 7.2 Review and Assessment Copyright Goodheart-Willcox Co., Inc.