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Substitute for The Ear and Hearing and Balance Lab

PLEASE DO NOT WRITE ON THIS PAPER. Return this paper with your answer sheet.

Directions: Use the information on the back and your textbook to answer the following questions.

1. What is the name of the instrument to view the ear?

2. What is the name of the glands that produce earwax?

3. What does the Weber Test determine?

4. If the Weber test is conducted and the tone is equally loud in both ears, what does this indicate?

5. If the tone is heard louder in one ear during the Weber test what does this indicate?

6. If sensorineural deafness is present in one ear, where will the tone be heard during Weber Test?

7. If conduction deafness is present, why will the sound be heard more strongly in the ear with hearing loss?

8. How do sound waves reach the cochlea when conduction deafness is present?

9. The Rhinne Test evaluates an individual’s ability to hear sounds conducted by air or bone. Do we normally hear sound coming through AIR to our inner ear or through BONE to our inner ear?

10. Through what do sound waves travel in the external auditory canal to the tympanic membrane?

11. Through what do vibrations travel through the middle ear to the oval window?

12. Through what substance do vibrations travel through the inner ear to the cochlea?

13. List, in order beginning with the external auditory canal, seven ear structures and substances through which vibrations travel from the external ear to the cochlear nerve.

14. What are the receptor cells, or hair cells, of the inner ear called?

15. Which ear structures are involved with conduction deafness?

16. Which ear structures are involved with sensorineural deafness?

17. What is the name of the fluid surrounding the membranes of the inner ear?

18. What is the name of the fluid inside the membranes of the inner ear?

19. Which part of the inner ear is involved with static equilibrium?

20. What do the receptors in for static equilibrium report?

21. Explain how the otoliths are involved in equilibrium.

22. What happens after the hair cells of the vestibule are activated?

23. Which part of the inner ear is involved with dynamic equilibrium?

24. What do the receptors for dynamic equilibrium report?

25. Explain the action of the endolymph of the semicircular canals when the head moves in an angular direction. (See also p. 269)

26. Using this information regarding movement of the endolymph, explain why you still feel like you are spinning after you get off a spinning ride at the fair? (p. 269)

27. What are the receptors found in muscles and tendons that report body position to the brain?

28. What are the receptors for vision found in the retina of the eye?

29. Maintaining body equilibrium and balance depends on a number of sensory receptors. Name the three different receptors involved in body equilibrium.

30. How do body movements and vision help with body equilibrium?

Hearing Acuity

Hearing acuity, or sharpness of hearing, is generally tested by decreasing the strength of sound waves until the tone is no longer heard. Often excess earwax, or cerumen, can become impacted on the tympanic membrane and decrease hearing acuity in the affected ear. An otoscope is the instrument used to view the external auditory canal and structures of the outer ear.

Weber Test

The Weber Test is used to determine conductive and sensorineural deafness . A tuning fork is struck and placed on the medial superior head. If the tone is equally loud in both ears, you have equal hearing or equal loss of hearing in both ears. Hearing the tone louder in one ear may indicate some degree of deafness. If sensorineural deafness is present in one ear, the tone will be heard in the UNAFFECTED ear but not in the ear with sensorineural deafness. If conduction deafness is present, the sound will be heard more strongly in the ear with hearing loss because the vibrations are traveling through the bone.

Rhinne Test

The Rhinne Test is used to compare bone- and air-conduction hearing. Normally, sound is heard by air conduction. Sound waves travel through air in the external auditory canal to reach the tympanic membrane, which then vibrates causing the bones, or ossicles (malleus, incus, stapes), of the middle ear to vibrate, which then taps the oval window, vibrating the perilymph, membranous labyrinth, and endolymph fluid of the inner ear. Conduction deafness occurs when something interferes with the conduction of sound vibrations to the cochlea of the inner ear (eardrum, ossicles, oval window). Sensorineural deafness occurs when there is a problem in the ability of the nerve impulse to travel to the brain (cochlea, cochlear nerve, or auditory cortex of the brain). A person who has conduction deafness will still be able to hear by bone conduction. On the other hand, individuals with sensorineural deafness cannot hear better by either conduction route.

Equilibrium

The equilibrium apparatus of the inner ear is in the vestibule and semicircular canals. The membranes within these structures are surrounded by a plasma-like fluid called the perilymph. The fluid within the membranes, the endolymph, contains the receptor cells (mechanoreceptors) called hair cells.

Within the membrane sacs of the vestibule are receptors for static equilibrium, which report on changes in the position of the head with respect to the pull of gravity. They provide information on which way is up or down and help us keep our head erect. Receptor cells (hair cells) are embedded in a jellylike material containing otoliths. As the head moves, these tiny stones (otoliths) roll in response to the pull of gravity, which causes the gel to slide over the hair cells. This event activates the hair cells which send impulses along the vestibular nerve to the cerebellum.

The dynamic equilibrium receptors are found in the semicircular canals. These receptors report on changes in angular or rotary movement of the head. When your head moves in an angular direction, the endolymph in the canals moves the jellylike material covering the hair cells. This stimulates the hair cells and impulses are transmitted along the vestibular nerve to the cerebellum of the brain.

The mechanoreceptors of the vestibule and semicircular canals usually act together. Additionally, the information these equilibrium senses provide is enhanced by the proprioceptors of the muscles and tendons and the photoreceptors of the eye. Therefore, body position (the tension of your muscles) as well as vision play an important role in equilibrium by providing the brain with additional information about how the body is positioned within the environment.

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