Auditory & Visual Practical

Question 1

How is visual acuity measured?

Answer 1

Similar triangles

Question 2

What does the similar triangles theory tell us?

Answer 2

Represents the minimum distance on the retina necessary to allow discrimination between 2 points

Question 3

What refraction errors are there? Describe them and how they are corrected

Answer 3

• Myopia= short sighted, concave lens
• Emmetropia=normal, eye relaxed
• Hyperopia= long sighted, convex lens

Question 4

What is visual acuity?

Answer 4

Clarity of vision

Question 5

What does visual acuity depend on?

Answer 5

• the sharpness of the retinal focus within the eye
• the health and functioning of the retina
• the sensitivity of the interpretative faculty of the brain

Question 6

What is relative visual acuity?

Answer 6

Visual acuity of an uncorrected eye

Question 7

Describe regular astigmatism

Answer 7

• Refraction of meridian is different

- Curvature along each meridian is even

Question 8

Describe irregular astigmatism

Answer 8

-Curvature along each meridian is different

Question 9

What will be observed for short/long sighted people in the duo chrome test? Why?

Answer 9

• Coloured Snellen’s test
• Green light refracted more than red light
• Short=Red letters seem more clear
• Long= Green letters seem more clear

Question 10

Where is the blind spot?

Answer 10

Optic disc= blood vessels enter & leave & optic axons leave the eye

Question 11

What is the function of the semicircular canals?

Answer 11

• Give info about movements of the head occurring in the plane of each canal
• Anterior vertical, horizontal, posterior canals

Question 12

What is the sensory end organ? Where is it?

Answer 12

• Cupula

- In the ampulla of the canal

Question 13

How does cupola movement stimulate nerves?

Answer 13

• Movements of endolymph displace cupula in certain direction
• Stimulates nerve endings

Question 14

What components of the inner ear send impulses via the superior branch of the vestibular nerve?

Answer 14

• Anterior vertical ampulla
• Horizontal ampulla
• Utricle
• Anterior superior part of saccula macula

Question 15

What components of the inner ear send impulses via the inferior branch of the vestibular nerve?

Answer 15

• Posterior vertical ampulla

- Main portion of saccula macula

Question 16

What does the vestibule-ocular reflex connect?

Answer 16

• Shortest reflex connection

- Semicircular canals and ocular muscles

Question 17

What are the 3 neurons in the vestibule-ocular reflex?

Answer 17

• Primary vestibular-connects sensory cells in crista ampullaris with neurons in vestibular nuclei
• Secondary vestibular- send axons to oculomotor nuclei via ascending branch of medial longitudinal fasciculus
• Motor neurons- innervating various extra ocular muscles

Question 18

Where do the majoirty of the fibres from the SCC synapse?

Answer 18

-Medial & superior vestibular nuclei

Question 19

What 3 things need to be available for accurate sound localisation?

Answer 19

• Interaural phase timing differences (low frequencies)
• Interaural intensity/amplitude differences (high frequencies)
• Head related transfer function (how the external ear modifies sound)

Question 20

What are the 2 types of deafness?

Answer 20

• Sensorineural= injury or degeneration of the nerve elements on the cochlea/auditory nerve
• Conductive= disease of the middle ear interfering with transmission of sound to the cochlea

Question 21

What is conductive & sensorineural deafness in regards to tuning folk testing?

Answer 21

• C= subject deaf to air conduction but no deafness to bone conduction
• S=Deaf to both air & bone conduction