Chapter 16 Part 1

Question 1

Otolithic organs

Answer 1

Anatomic site of sensory receptors that respond to head position relative to gravity and to linear acceleration and deceleration of the head.

Question 2

Vestibular apparatus

Answer 2

Part of the inner ear that detects position and movement of the head; it consists of the semicircular canals, saccule, and utricle.

Question 3

Semicircular canals

Answer 3

Three hollow rings in the inner ear that are oriented at right angles to each other. Each canal contains the receptor mechanism for detecting rotational acceleration or deceleration of the head.

Question 4

Vestibular nuclei

Answer 4

Site of synapse between the first- and second-order neurons that convey information about head position and head movement.

Question 5

Vestibular ocular reflex (VOR)

Answer 5

Involuntary movements of the eyes that stabilize visual images during head and body movements;

Question 6

Semicircular canals:

Answer 6

rotational movement of the head

Question 7

Crista:

Answer 7

Is a body of supporting cells and sensory hair cells

Question 8

Three pairs of semicircular canals:

Answer 8

(1) Left with right horizontal canals
(2) Left anterior with right posterior
(3) Left posterior with the right anterior

Question 9

Utricle and saccule:

Answer 9

respond to head position relative to gravity and to linear acceleration and deceleration

Question 10

Otoconia:

Answer 10

calcium carbonite crystals that are more dense than the surrounding fluid and gelatinous support

Question 11

Conjugate

Answer 11

both eyes move in the same direction

Question 12

Vergence

Answer 12

eyes move toward the midline or away from the midline (convergence vs. divergence)

Question 13

Gaze stabilization

Answer 13

Keeping the position of the eyes stable during head movements to ensure that the environment does not appear to bounce

Question 14

Direction of gaze

Answer 14

Directing the gaze at visual targets

Question 15

Saccades

Answer 15

fast eye movements to switch gaze from one object to another

Question 16

Smooth pursuits

Answer 16

eye movements that follow a moving object

Question 17

Vergence movements

Answer 17

movement of the eyes toward or away from midline to adjust for different distances between the eyes and the visual target

Question 18

Utricular macula-horizontal

Answer 18

Responds maximally to head tilts that begin with the head in the upright position, as in bending forward to pick something off the floor
Respond to linear acceleration and deceleration

Question 19

Saccular macula- vertical

Answer 19

Responds maximally when the head moves from a laterally flexed position, as in moving from side lying to standing

Question 20

Semicircular canals are used to:

Answer 20

stabilize vision

Question 21

What is once major function of the vestibular nuclei?

Answer 21

coordinate movements of the eyes and head to allow for stable visual fixation during head movement.

Question 22

What are the two roles the vestibular system has in motor control?

Answer 22

gaze stabilization

postural adjustments

Question 23

Tracts for postural adjustments:

Answer 23

Lateral Vestibulospinal Tract: LMN to limbs and trunk

Medial Vestibulospinal Tract: adjust head

Question 24

Nasal retina

Answer 24

info crosses the midline in the optic chiasm and projects to the contralateral visual cortex

Question 25

Temporal retina

Answer 25

info continues ipsilaterally through the optic chiasm and projects to the ipsilateral cortex

Question 26

Primary visual cortex:

Answer 26

stimulates neurons that discriminate the shape, size, or texture of objects.

Question 27

Action Stream:

Answer 27

Is a stream of visual information that flows dorsally and used to direct movement

Question 28

Perception stream:

Answer 28

Is a stream of visual information that flows ventrally and used to recognize visual objects