Exercise 25: Special Senses: Hearing and Equilibrium

Question 1

Sound waves hitting the tympanic membrane initiate its vibratory motion. Trace the pathway through which vibrations and fluid currents are transmitted to finally stimulate the hair cells in the spiral organ. (Name the appropriate structures in their correct sequence.)

Answer 1

Tympanic membrane -> malleus -> incus -> stapes -> oval window -> perilymph -> vestibular membrane -> endolymph -> hair cell of the organ of Corti

Question 2

Explain how the basilar membrane allows us to differentiate sounds of different pitch.

Answer 2

The frequency is differentiated by the length and tension of the basilar membrane fibers; high pitch sounds make it close to oval window; low pitch further up basilar membrane near apex of cochlea

Question 3

Explain the role of the endolymph of the semicircular ducts in activating the receptors during angular motion.

Answer 3

Endolymph pushes scapula in direction opposite to that of angular motion; this movement depolarizes hair cells, resulting in impulse transmission up vestibular division of cranial nerve VIII

Question 4

Explain the role of the otoliths in perception of static equilibrium (head position).

Answer 4

When the head moves, otoliths move in response to variation in gravitational pull; as they deflect different hair cells, they hyper polarize hair cells and modify the rate of impulse transmission along vestibular nerve.

Question 5

When the tuning fork handle was pressed to the forehead during the Weber test, where did the sound seem to originate?

Answer 5

From the sides of the temples

Question 6

Indicate whether the result from the fusion of the ossicles relates to conductive deafness, sensorineural deafness, or both.

Answer 6

Conductive deafness

Question 7

Indicate whether the result from a lesion on the cochlear nerve relates to conductive deafness, sensorineural deafness, or both.

Answer 7

Sensorineural deafness

Question 8

Indicate whether the sound heard in one ear but not in the other during bone and air conduction relates to conductive deafness, sensorineural deafness, or both.

Answer 8

Sensorineural deafness

Question 9

Indicate whether the result of otitis media relates to conductive deafness, sensorineural deafness, or both.

Answer 9

Both

Question 10

Indicate whether the result from impacted cerumen or a perforated eardrum relates to conductive deafness, sensorineural deafness, or both.

Answer 10

Conductive deafness

Question 11

Indicate whether the result from a blood clot in the primary auditory cortex relates to conductive deafness, sensorineural deafness, or both.

Answer 11

Sensorineural deafness

Question 12

The Rinne test evaluates an individual’s ability to hear sounds conducted by air or bone. Which is more indicative of normal hearing?

Answer 12

Bone

Question 13

The Barany test investigated the effect that rotatory acceleration had on the semicircular canals. Explain why the subject still had the sensation of rotation after being stopped.

Answer 13

Subject had a viral labyrinthine disorder

Question 14

What is the usual reason for conducting the Romberg test?

Answer 14

To determine of proprioceptive impulses are being transmitted up the spinal cord to the brain properly