Lecture 7: Coordination and balance

Question 1

motor control

Answer 1

Motor control: ability of the central nervous system to control or direct the neuromotor system in purposeful movement and postural adjustment by selective allocation of muscle tension across appropriate joint segments

Question 2

Components of motor control

Answer 2

Normal muscle tone and postural response mechanisms

Selective movements

coordination

Question 3

Coordination

Answer 3

ability to execute smooth, accurate, controlled movement

Essence is the sequencing, timing, and grading of the activation of multiple muscle groups

Question 4

Dexterity

Answer 4

Skillful use of the fingers during fine motor tasks

Question 5

Agility

Answer 5

The ability to rapidly and smoothly initiate, stop, or modify movements while maintaining postural control

Question 6

balance

Answer 6

Balance: The condition in which all the forces acting on the body are balanced such that the center of mass (COM) is within the stability limits, the boundaries of the base of support (BOS)

Question 7

centre of mass

Answer 7

Centre of mass: uniquepoint at any given time where the weighted relative position of a distributed mass sums to zero. The midpoint of body mass in erect standing posture; the COM is located at the level of the second sacral segment

Question 8

base of support

Answer 8

Base of support: Refers to the area beneath a person that includes every point of contact that the person makes with the supporting surface

Question 9

Sensory systems for postural control

Answer 9

Sensory Systems for Postural Control
Vision
Somatosensory
Vestibular

Question 10

Focal vision

Answer 10

Focal vision: cognitive/explicit vision; what you are looking at directly .
plays a role in localizing features in the environment in our conscious reaction to visual events

Question 11

Ambient vision

Answer 11

Ambient vision: sensorimotor/implicit vision; Utilizes the entire visual field to provide information on the localizing features about the environment and to guide movements using largely unconscious awareness.

Question 12

What is the pathology associated with impaired ambient vision

Answer 12

Optic ataxia: The patient can recognize an object using focal vision but cannot use visual information to accurately guide the hand to the object (impaired ambient vision).

Question 13

What is the pathology associated with impaired focal vision

Answer 13

Visual agnosia: patient cannot recognize common objects, but can use the ambient visual system to reach and grasp an object or navigate an environment (impaired focal vision)

Question 14

vestibular system:
- function
- components

Answer 14

• stabilizes gaze during head movements via the vestibulocular reflex (VOR); assist with postural tone and postural muscle activation via the vestibulospinal reflex (VSR)
• semicircular canals and otolith organs

Question 15

semicircular canals

Answer 15

Semicircular Canals (SCCs): inner ear apparatus that detects angular acceleration. supports person in maintaining upright posture and balance.

Question 16

otolith organs

Answer 16

Otolith Organs: inner ear organ that detect linear acceleration and orientation of the head with reference to gravity. assists with balance and posture.

Question 17

What is the primary function of cerebellum

Answer 17

primary function of the cerebellum is regulation of movement, postural control, and muscle tone

rate,range and force of movement

Compares the commands for the intended movement transmitted from the motor cortex with the actual motor performance of the body segment

Question 18

cerebellar pathology

Answer 18

• Many of these impairments either directly or indirectly influence the patient’s ability to execute accurate, smooth, controlled movements

The motor deficits identified emphasize the crucial influence of the cerebellum on equilibrium, posture, muscle tone, and initiation and force of movement

Question 19

Basal ganglia 3 main nuclei

Answer 19

caudate nucleus
putamen
globus pallidus

Question 20

basal ganglia pathology

Answer 20

Patients with lesions of the basal ganglia typically demonstrate several characteristic motor deficits
1. Slowness of movement 2. Involuntary, extraneous movement 3. Alterations in posture and muscle tone

Question 21

Dorsal Column-Medial Lemniscal function

Answer 21

mediates sensations critical to coordinated movement such as proprioception, kinesthesia, and discriminative touch

Question 22

Dorsal Column-Medial Lemniscal Pathology

Answer 22

• Lack of joint position sense and awareness of movement, and impaired localized touch sensation
• Gait pattern is usually wide-based and swaying, with uneven step lengths and excessive lateral displacement
• Dysmetria
• Coordination and/or balance problems will be exaggerated when vision is occluded or when the patient’s eyes are closed

Question 23

Why does proprioception become poorer as a person gets older?

Answer 23

deterioration of the muscle spindles

Question 24

Why does the vestibulo-ocular reflex and vestibulospinal reflex deteriorate as a person gets older?

Answer 24

deterioration to the calcium carbonate crystals of the otolith

reduction in the number of hair cells in the inner ear

Question 25

Is there a relationship between changes in strength and ROM with measures of balance?

Answer 25

There is a correlation with strength and ROM with measures of stability eversion range of motion and plantarflexor strength is related to balance

Question 26

Is there a relationship between changes in ankle strength and ROM and risk of falls? What is the difference between non fallers and fallers

Answer 26

- Non fallers have greater ankle flexibility - Non fallers have less hallux valgus severity - Non fallers have more sensation in the first joint?

Question 27

Define: PAT compare PAT between younger and older adults

Answer 27

proprioceptive acuity thresholds: degrees of joint changes that a person can recognize There is a larger proprioceptive acuity threshold in older adults Older adults are less able to reproduce a joint position

Question 28

Dysdiadochokinesia

Answer 28

An impaired ability to perform rapid alternating movements This deficit is observed in movements such as rapid alternation between pronation and supination of the forearm

Question 29

Hypotonia

Answer 29

A decrease in muscle tone It is believed to be related to the disruption of afferent input from stretch receptors and/or lack of the cerebellum’s efferent influence on the fusimotor system

Question 30

Dysmetria

Answer 30

An inability to judge the distance or range of a movement It may be manifested by an overestimation (hypermetria) or an underestimation (hypometria) of the required range needed to reach an object or goal

Question 31

Dyssynergia

Answer 31

Describes a movement performed in a sequence of component parts rather than as a single, smooth activity For example, when asked to touch the index finger to the nose, the patient might first flex the elbow, and then adjust the position of the wrist and fingers, further flex the elbow, and finally flex the shoulder

Question 32

Rebound phenomenon

Answer 32

The loss of the check reflex or check factor, which functions to halt forceful active movements when resistance is eliminated When application of resistance to an isometric contraction is suddenly removed, the limb will remain in approximately the same position by action of the opposing muscles

Question 33

Tremor

Answer 33

An involuntary oscillatory movement resulting from contractions of opposing muscles

Question 34

Intention tremor

Answer 34

An intention tremor occurs during voluntary motion of a limb and tends to increase as the limb nears its intended goal or speed is increased

Question 35

Postural (static) tremor

Answer 35

Postural (static) tremor may be evident by back-and-forth oscillatory movements of the body while the patient maintains a standing posture

Question 36

Describe the finger to finger and nose to nose test objective: methodology what a positive sign is

Answer 36

objective: examine cerebellar function methodology Patient attempts to touch the index finger of the examiner with an outstretched arm. Requires the subject to fully extend arm and then flex elbow to bring finger back to their own nose. Fast response is encouraged as the examiner’s arm is moved horizontally Positive sign: - Delay in movement initiation - Terminal tremor – due to alternating contractions of agonist and antagonist - Dysmetria – inaccurate amplitude, impaired timing of muscle force

Question 37

Describe the heel to shin test objective: methodology what a positive sign is

Answer 37

objective: assess cerebellar function via coordination Procedure: - Patient supine and places heel on the shin of other leg near the knee - Slide the heel down the shin towards the foot Positive sign - Dysmetria – difficulty placing the heel (inaccurate amplitude) - Dyssynergia - method of getting the heal to shin (flexing the hip and knee in sequence rather than in one synergistic movement

Question 38

Describe the rebound test objective: methodology what a positive sign is

Answer 38

Procedure: - Patient performs an isometric contraction of the elbow flexors - Examiner initially resists force, then releases Positive - Patient cannot stop movement once resistance is removed - Rebound phenomenon – problem with braking of movement

Question 39

Describe the rapid alternating movements test objective: methodology what a positive sign is

Answer 39

objective: rule out or observe indications of a cerebellar pathology Procedure - Patient pats hand on a firm surface - Patient alternates between palm up and palm down (supination/pronation) Positive - Movement is performed slowly and with exaggerated supination and pronation - Disdiadochokinesia – difficulty performing rapid alternating movements

Question 40

What are the two movement strategies to control the COM over the BOS?

Answer 40

fixed support strategies: - ankle strategies and hip strategies change in support strategies - stepping strategy

Question 41

Describe the ankle movement strategy what when used

Answer 41

fixed support strategy for small forces that perturb your balance With forward sway, gastrocnemius is activated first, followed by hamstrings, then paraspinal muscles With backward sway, the anterior tibialis is activated first, followed by quadriceps, then abdominals The ankle strategy is a commonly used strategy when sway frequencies are low and disturbances of the COM are small and well within the limits of stability . Muscles are activated in a distal-to-proximal sequence

Question 42

Describe the hip movement strategy what when used

Answer 42

fixed support strategy used for unanticipated situations where larger forces are applied (ex: person bumps into you while walking, bus turns a corner fast). The hip strategy is typically recruited with faster sway frequencies and larger disturbances of the COM or when the support surface is small With forward sway abdominals are activated first, followed by quadriceps With backward sway, paraspinal muscles are activated first, followed by hamstrings. Hip strategies provide primary control for mediolateral stability Hip muscles (abductors and adductors) are activated to control lateral sway It has a proximal pattern of muscle activation before distal activation

Question 43

Describe the stepping strategy what when used

Answer 43

Realigns the BOS under the COM by using rapid steps or hops in the direction of the displacing force, for example, forward or backward steps In instances of lateral destabilization, the individual takes a side step or a cross step to bring the BOS back under the COM The stepping strategies are typically recruited in response to fast, large postural perturbations when ankle and hip strategies are not adequate to recover balance

Question 44

What are the common strategies for balance perturbations when sitting?

Answer 44

grasping (ex: edge of seat) or hooking the lower extremity around the legs of furniture

Question 45

What are the common strategies for balance perturbations when standing?

Answer 45

ankle/hip strategies or stepping strategies. depends on the weakness and limited ROM in ankle or hips

Question 46

Describe anticipatory postural control. How to test it?

Answer 46

Anticipatory postural control, the ability to activate postural adjustments in advance of destabilizing voluntary movements, should be examined For example, the therapist asks the patient while standing or sitting to raise both arms overhead or catch a weighted ball

Question 47

Dual task control how to test?

Answer 47

Dual task control: This is the ability to perform a secondary task (motor or cognitive) while maintaining standing or seated control For example, while standing the patient is asked to count backward from 100 by 7 (simultaneous verbal-cognitive task) or pour water into a glass (secondary motor task)

Question 48

Describe the romberg test objective methodology + or negative findings

Answer 48

Objective: assess dorsal column medial leminiscus tract for lesions by assessing person's proprioception and vestibular function methodology: During the test, the patient is instructed to stand with feet together, eyes open (EO) unaided for 20 to 30 seconds If the patient demonstrates significant sway or instability with EO, the test is over. The patient is then asked to stand with eyes closed (EC) Test is positive if sway is significantly worse or person loses balance with eyes closed compared to eyes open.

Question 49

Describe the functional reach test objective methodology describe the relationship between functional reach test scores and risk of falls?

Answer 49

objective: measure the limits of stability of individuals while reaching forward in a standing position Functional reach is the maximal distance one can reach forward beyond arm's length while maintaining a fixed base of support in the standing position no relationship between risk of falling

Question 50

Describe the Berg balance test objective: methodology

Answer 50

14-item scale that quantitatively assesses balance and risk for falls objective: designed to quantitatively assess balance in older adults It can also be used with patients post-stroke methodology: Items are scored from 0 to 4, with a score of 0 representing an inability to complete the task and a score of 4 representing independent item completion The greater the score, the better the balance. Components: - Sit to stand - standing unsupported - standing to sitting - standing unsupported with eyes closed - turning 360 degrees - standing on one leg

Question 51

Is the berg balance score a reliable outcome measure? Can the BBS be used to predict falls in older adults?

Answer 51

high interrater reliability; high inter rater reliability The evidence to support the use of BBS to predict falls is insufficient