Chapter 16 Part 1 Flashcards Preview

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Flashcards in Chapter 16 Part 1 Deck (28):
1

Otolithic organs

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

2

Vestibular apparatus

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

3

Semicircular canals

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.

4

Vestibular nuclei

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

5

Vestibular ocular reflex (VOR)

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

6

Semicircular canals:

rotational movement of the head

7

Crista:

Is a body of supporting cells and sensory hair cells

8

Three pairs of semicircular canals:

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

9

Utricle and saccule:

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

10

Otoconia:

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

11

Conjugate

both eyes move in the same direction

12

Vergence

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

13

Gaze stabilization

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

14

Direction of gaze

Directing the gaze at visual targets

15

Saccades

fast eye movements to switch gaze from one object to another

16

Smooth pursuits

eye movements that follow a moving object

17

Vergence movements

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

18

Utricular macula-horizontal

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

19

Saccular macula- vertical

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

20

Semicircular canals are used to:

stabilize vision

21

What is once major function of the vestibular nuclei?

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

22

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

gaze stabilization
postural adjustments

23

Tracts for postural adjustments:

Lateral Vestibulospinal Tract: LMN to limbs and trunk
Medial Vestibulospinal Tract: adjust head

24

Nasal retina

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

25

Temporal retina

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

26

Primary visual cortex:

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

27

Action Stream:

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

28

Perception stream:

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