L3 Reflexes

Question 1

Balance, postural stability

Answer 1

maintaining stability in an upright posture to keep the body up against gravity

Question 2

Center of mass

Answer 2

single point at which the entire mass of an object lies

Question 3

Base of support

Answer 3

all points of body contact with supporting surface
described, visualized as area enclosed within the perimeter of all points of contact

Question 4

Limits of stability

Answer 4

maximum distance a person can intentionally move or displace thier COM in each direction without losing balance

Question 5

Postural REsponses

Answer 5

developed during childhood, these reflexive/stereotypical response occur to certain sensory stimuli

Question 6

Righting reactions

Answer 6

Orient head in space, orient body in relation to head and the support surface.

Occur in response to visual, vestibular, somatosensory cues

Question 7

Somatosensory cues

Answer 7

body on head righting

Question 8

Protective Reactions

Answer 8

Prevent fall after COM moves beyond LOS

Reach to prop on surface by one or more extremity to prevent injuries, avoid falls, reset BOS

develops 6-9 months anteriorly, 10-12 months posteriorly

Question 9

Equilibrium Reactions

Answer 9

-integration of righting and protective reactions
-multidirectional responses to intrinsic/extrinsic forces
-involves trunk rotation in conjunction w/extension and abduction

becomes adaptable at 1 year, declines later in life

Question 10

Mild perturbation causes…

Answer 10

righting reaction

Question 11

Moderate perturbation causes

Answer 11

equilibrium reaction

Question 12

Strong perturbation causes

Answer 12

protective responses

Question 13

Ankle Strategy

Answer 13

utilized with subtle balance responses to environment

shifts a person’s COM toward center of BOS for increased postural stability

works from distal to proximal

Question 14

Hip strategy

Answer 14

utilized when greater force reactions needed than ankle strategy to keep from falling

proximal to distal muscle activation

Question 15

Stepping Strategy

Answer 15

occurs to recover stability when COM becomes suddenly outside of BOS, occurs when ankle/hip strategies don’t work

Question 16

Afferent sensory system

Answer 16

Vision, Vestibular, Somatosensory

CNS regulates goal-directed postural control and automatic postural responses with integrated info from all three systems

Question 17

Vision Sensory Input

Answer 17

Environmental info, particularly for orientation

Involved in static and dynamic conditions
Begins in early development
Navigation of obstacles, objects in environment

vision helps with negotiation of movement parameters

Question 18

Vestibular Sensory Input

Answer 18

-Semicircular canals and otolith organs in the inner ear
-Position of the head relative to gravity
-Stabilization of gaze during head movements
-Regulation of postural tone and muscle activation
-used most when other systems are limited

Question 19

Somatosensory Sensory Input

Answer 19

-Cutaneous touch, pressure from skin
-proprioceptive, kinesthetic info from muscle spindles, golgi tendon organs, joint capsule receptors

Question 20

Aging and Sensory Systems

Answer 20

decline in each system
increased difficult for elderly to maintain balance because of decreased sensory input

Question 21

Posturography

Answer 21

objective data obtained via computerized balance assessment, force platform

examines location of center of pressure, postural sway, limit of stability

Question 22

Static Posturography

Answer 22

Maintains quiet stance while on force platform

Visual feedback provided via computer monitor to keep cursor within central target box

Question 23

Dynamic Posturography

Answer 23

standing on force platform, and shifting their COP towards ends of BOS