Lecture 12- Vision & Balance(LA)

Question 1

T/F: Visual system has direct access to vestibular nuclei (involved in balance)

Answer 1

T

Question 2

Vection is an illusion of self-motion while stationary caused by? What types?

Answer 2

Moving visual scenes Liner: like in a train Circular: sitting in a rotating cylinder

Question 3

What happens when we rotate at a constant velocity?

Answer 3

The sense of rotation is gradually replaced by a sense that the world is rotating around us.

Question 4

If you place someone in a centrifuge - what do they associate verticality with? Gravity, centrifugal force, resultant force?

Answer 4

Resultant *It is not gravity but FORCE in general with which we align our notion of what is “vertical”

Question 5

!How do we sense force? (4)

Answer 5

-Pressure on feet -Other body parts may take weight -Muscle reactions to maintain uprightness -MAJOR SOUCE: vestibular apparatus inside inner ear

Question 6

!What are the 3 main sources of orientation info?

Answer 6

1) Visual orientation info 2) Proprioceptive info (joint position, muscle force (via sensors in tendons)) 3) Vestibular system

Question 7

_ semicircular canals that sense? _ otolith organs that sense? Both in inner ear (each side of the head) found in?

Answer 7

3 - Rotation, angular acceleration 2 - Linear acceleration Petrous portion of temporal bone (hardest bone in skull - but still vulnerable to infection)

Question 8

!How can vestibular system be disrupted?

Answer 8

Deaf people lack the system, may be destroyed by gentamycin or related antibiotics, viruses

Question 9

What is affected if vestibular system is disrupted?

Answer 9

Swimming (disrupts proprioceptive and visual sources of “up” info), standing on one foot, walking in the dark

Question 10

What is presbycusis?

Answer 10

Hearing loss

Question 11

What happens to vestibular organs when excessive physical activity occurs?

Answer 11

Damage to vestibular organs. High impact aerobics can injure otoliths

Question 12

Bony labyrinth of vestibular system contains?

Answer 12

Perilymph

Question 13

Membranous labyrinth of vestibular system contains?

Answer 13

Endolymph

Question 14

Vestibular nerve is part of CN_

Answer 14

8 - same as auditory nerve but different termini

Question 15

Where do hair cells of all the labyrinth organs send their output to?

Answer 15

Vestibular nuclei in brainstem