NC Exam 4

posture

inverted pendulum in the field of gravity

postural control

maintenance of body alignment and spatial orientation in order to put the body in a position to enable effective movement

posture problems

high center of mass/gravity
multiple joints
small support area

stability

a position that is resistant to disturbance or returns to its normal state after disturbance

over 50

humans center of gravity is ______% of standing height

center of pressure

point at which the force vector for ground reaction force is applied

sway

active search process

sway increases

closed eyes
standing on a narrow support/one foot
age, disorder

sway decrease

light finger touch
holding an object connected to the external world

center of gravity

_______ must remain within the base of support in order to maintain equilibrium

rambling

migration of the reference point
likely a reflection of the central search process
supraspinal process (active search by the brain)

trembling

likely a reflection of the mechanical properties of the effectors and reflex loops
subspinal process
more reflexive

vestibular hair cells

they are innervated by the peripheral ends of bipolar sensory neurons in the ampullary nerve

cupula

gelatinous, diaphragm like mass covering the ampullary crest

medulla

vestibular nuclei occupy a large part of the _____

semicircular canals

sensitive to angular acceleration of the head
fluid inside move when head rotates
fluid acts on cupula and displace hair cells, generating APs

otoliths

sensitive to linear acceleration of the head
gelationous substance conatining cyrstals of calcium carbonate that covers macula
otoliths deform gelatinous surface, bending hair cells, generating APs

necessary to maintain posture

adequate perception of a reference point or reference vertical
timely generation of appropriate muscle torques
control of posture under external and internal perturbations

postural perturbations

many voluntary movements are associated with changes in the activity of postural muscles, even before the movement begins

APAs

minimize perturbations to vertical posture

young people

slow forward or backward translations leads to an ankle strategy among _____
use hip when on a narrow surface or movement is fast
ankle is more effective but increases risk

old people

use a hip strategy

synergy

task specific organization of many elements by a controller
stabilize a value or a pattern of important performance variables

postural synergy

combo of control signals sent to several muscle to ensure stability of a limb or whole body either in anticipation of a predictable postural perturbation or in response to an actual perturbation

locomotion

an activity leading to a change in the location of the body in external space
velocity, stride length, relation between support and swing, relative timing of extremities (gait)

motor programming

central pattern generator
hypothetical neural structure that generates a neural activity
activity is transformed into rhythmic muscle activity
leading to rhythmic behavior

dynamic systems

rhythmicity of locomotion is caused by interaction of neural activity and the periphery (environment)

sherrington

wrong
locomotion was a pattern produced by alternating reflex responses
voluntary movement is a result of modulating reflexes

Brown

rhythmic motor pattern of locomotion was produced by a special neural network that could produce activity even in the absence of reflexes

crossed extensor and flexor

which two reflexes did sherrington hypothesize could control walking

central pattern generator

a hypothetical structure in the central nervous system that can generate patterned activity
can be driven by higher centers as well as by peripheral info
both sources of info can lead to gait changes

problems with CPG

undefined higher center
peripheral input could change the pattern of gait activity
difficult to determine if changes in gait are produced by higher center or peripheral input
many important variables lack a good definition

electrical stimulation

____ of certain brain, reticular formation, and spinal areas can induce locomotion

intraspinal drugs

locomotion and gait changes can also be induced by treadmill motion and by ___________
fictive locomotion can be seen

brown vs sherrington

the spinal cord is likely to contain one, two, or four central pattern generators
a cpg can driven by descending and ascending signals
it does not necessarily require either signal
it can produce different gaits

dynamic systems approach

better explains issues of stability (in M/L direction)
success in describing interlimb and inter joint coordination
can describe rather complex changes in behavior

motor programming

lacks coordination, all details of coordination are delegated by the ultimate controller

dynamic systems

coordination can emerge without supreme problem solver, but it lacks control

combination

all elements are linked and there is an upper neural structure that can send descending signals

0.5

COP shifts start ____s before stepping leg leave the ground

corrective stumbling reaction

occurs during locomotion
can be induced by a mechanical stimulus to the foot
represents a complex pattern of emg changes
leads to a quick step over the obstacle

kinesthesia

awareness of the position of the body segments in space and in relation to each other
allows us to perform movements without continuous visual control, to adjust patterns of control variables and perform tasks requiring multi-limb coordination
proprioceptors are the source of kinesthetic info

under isometric

______ conditions an increase in the level of muscle activation leads to an increase in the activity of the gamma system and an increase in the firing level of muscle spindle sensory endings
-may be interpreted by central nervous system as a joint motion corresponding to an increase in muscle length

under non-isometric

_______ conditions an increase in the level of muscle activation leads to muscle shortening accompanied by an increase in the activity of the gamma system
-may see the same average level of firing of muscle spindle sensory endings at different joint positions

joint torque

dependent on both muscle force and joint angle

efferent copy

represents a copy of a voluntary motor command
copy participates in deciphering the mixed info from peripheral receptors, thus reducing cognitive load
thalamus plays a large role

sufficient

each proprioceptor provides information that by itself is insufficient to extract values of joint angles or torques but the combined info is _____

neuromotor changes with aging

strength decline
longer reaction time
impaired control of posture/gait
impaired accurate control of force/movement
unintended force production

behavior changes with aging

weakness
slowness
higher variability
larger postural sway, delayed APAs

movement changes with aging

longer RT
slower movements
higher antagonist co contraction
higher safety margins
changed synergies

changes in motor units

decline in number if a motoneurons
muscle fiber denervation and atrophy
re-innervation by surviving motoneurons
higher innervation ratio
lack of smaller motor units

strength changes with age

muscle mass reduced
cross sectional area reduced
increase co activation

reflex changes with age

h reflex amplitude reduced
tendon tap reflex reduced
polysynaptic reflexes reduced
simple reaction time increased

posture changes with age

increased sway
loss of asynchronous involvement
switch from ankle to hip strategy
greater co activation
higher variability

motor consequences of DS

longer reaction time
longer movement time
irregular trajectories
high variability
preference for coactivation patterns: during movements, preprogrammed reactions, and anticipatory postural adjustments
high safety margin

practice and DS

can show significant improvement in motor performance with training/rehab especially with force production, speed of movement, coordination, and less co contraction

cerebellum

a lower _____ weight has been reported in persons w DS this could explain some of the difficulty with coordination

mononeuropathies

reduced amplitude of motor and/or sensory potentials
signs of denervation

carpal tunnel

entrapment of the median nerve at the wrist, most common mononeuropathy

diabetes

peripheral sensory neuropathy
peripheral motor neuropathy
atrophy of peripheral tissues - results in loss of balance and coordination with an increased probability of falls, fractures, and bruises

ALS

upper motor neuron syndrome
early symptoms include twitching, cramping or stiffness, muscle weakness, slurred and nasal speech, and difficulty chewing or swallowing

dysphagia

problems swallowing

dysarthria

problems speaking or forming words

spasticity

tight, stiff muscles

hyperreflexia

exaggerated reflexes

paresis

partial loss of voluntary control of muscle activity

plegia

total loss of voluntary motor control

para

two extremities are involved

hemi

half of the body (left or right) is involved

quadri

all four extremities are involved

multiple sclerosis

demyelination of axons within the CNS
autoimmune disorder, immune system attacks myelin sheath, leaving the axon exposed, causing it to harden

parkinsons

hypokinetic disorder, specifically effects dopamine production in the substantia nigra
brradykinesia, tremor, postural deficits (deficit in APA, increased PPR)

huntingdons

hyperkinetic disorder of the basal ganglia, specifically affects the caudate nucleus

chorea

generalized, irregular, restless, often pseudo purposive movements
-fidgeting hand movements, dancelike gait, clumsiness, slurry, speech

kinesthesia

what term describes awareness of the position of the body segments in space and in relation to each other

c

what happens to the activity of the muscle spindles during an isometric muscle action?
a. there is no activity
b. activity stays the same
c. activity goes up
d. activity goes down

lever/moment arm length

golgi tendon organs do not detect what variable that is important for calculating joint torque?

articular receptors

arent good in midranges

c

is joint position sense still present after a person has a joint replacement surgery?
a. no, the articular receptors are removed so there is no joint position sense
b. yes, the articular receptors are implanted back into the artificial joint
c. yes, other proprioceptors help with joint position sense
d. there is no way to answer

efferent copy, thalamus

this copy participates in deciphering the mixed info from peripheral receptors, this reducing the cognitive load
where would this copy be located?

e

which of the following changes occur to the neuromuscular system with aging?
a. decrease in strength
b. increased reaction time
c. impaired postural/gait control
d. worse control of muscle forces
e. all of the above

b, c, d

which of the following are observable movement changes that occur with aging?
a. increased coordination
b. slower movements
c. difficulty lifting/moving objects
d. increased postural sway
e. increased gait velocity
f. less movement variability

motor units as we age

fewer motor units are present
increased innervation ratio
smaller motor units are impacted more

muscle strength as we age

decreases
decrease in muscle mass
increased in co contraction ratio

walking as we age

wider base of support
shorter steps
slower walking velocity
more stooped posture

visual

what system is not developed at birth?

correct order of development

sitting unsupported, crawling, standing unsupported, walking

radiculopathy

spinal nerve root

neuropathy

axon

myasthenia gravis

neuromuscular synapse

MS

demyelination

ALS

neuron cell body

muscular dystrophy

skeletal muscle

duchenne

this disease affects young children between ages of 2-6, results in a breakdown of dystrophin and loss of skeletal muscle integrity

huntingdons

what disease of basal ganglia affects the caudate nucleus and is characterized by chore and dementia

MS

what disease is an autoimmune disorder in which the body's immune system attacks the myelin sheath of axons in the CNS, resulting in both sensory and motor issues

parkinsons

what is a disease of the basal ganglia that specifically affects the substania nigra, it results in slower movements

MS

with this disease, fatigue can be debilitating and not directly related to the amount of physical exertion

ALS

what disease affects the primary motor area of the cerebral cortex, and will eventually lead to paralysis and respirator dependence

parkinsons

hypokinetic