Motor Systems Pt 2

what does damage to the higher centers cause

distinct signs and symptoms

• involuntary movements

• incoordination

• difficulty initiating movment

• lsowed or diminished movement

• altered muscle tone 

basal nuclei def

gray matter collections that form a subcortical, unconscioius motor system in the base of the cerebrum

division of the 6 strcutres of the basal nuclei

• 4 forebrain structures

• 1 structure of the diencephalon

• 1 brainstem area

6 structures of the basal nuclei

• caudate nucleus

• nucleus accumben

• utamen

• globus pallidus

• subtalamic nuclei

• substantia nigra

striatium structures of basal nuclei

• cuadate nucleus

• nucleus accumbens

• putamen

lentiform nucleus of the basal nuclei 

• putamen

• globus pallidus 

function of basal nuclei

primarily associated with motor control, but also play a role in cognition, emotions and motivation 

function of basal nuclei in movement

responsible for starting and stopping movement by balancing inhibitory and excitatory imulses 

autonomic motor patterns in basal nuclei

habits, and cognitive processes that involve timing of motor responses

basal nuclei feebback loop with cortex

cortex → BN → thalamus → cortex

major neurotransmitters in BN

• dopamine (excitatory)

• ach (inhibitory)

what do diseases of the BN result in

• involuntary movements (too much excitatory)

• problems initiating movement (too much inhibitory)

• disturbance in muscle tone (too much/too little)

hyperkinetic disorders

excessive movment and decreased muscle tone

hypokinetic disorders  are characterized by

impaired initiation of movement, bradykinesia, and increased muscle tone 

dystonia

disturbances in muscle tone

chorea is characterized by

continuous, rapid movmeents of the face, tongue, or limbs

which hyperkinetic disorder has a dance-like quality

chorea 

hyperkinetic disorders 

• chorea 

• huntington’s disease

• athetosis

• hemiballism

movements of chorea

• distal- hand foot

• proximal- shoulder shrugs, moving hips

• facial grimacing 

huntington’s disease def

chronic, degerative inherited disease that alos involves progressive dementia and mood alterations

when do symtpoms appear huntingtons

between ages 30-50

where is huntington’s degeneration in BN 

striatums but also in cortex 

athetosis def

slow, continuous, writihing movement of extremities

quality of movement athetosis

twisting or turning

athetosis lesion location

striatium

what characterizes hemiballism

violent thrashing of an extremity contralateral to the lesion

lesion hemiballism 

lesion of the subthalamus 

when is hemiballism most common

older adults who have had strokes of the subthalamus

hypokinetic disorders

• parkinson’s disease

• dystonia

what cuases parkinson’s disease

loss of dopamine-containing cells in the substantia nigra of the midbrain

what does lack of dopamine lead to in parkinsons

hypokinesia

rigidity in parkinsons

hypertonicity in all muscles, though strentght and reflexes typically normal

uniform rigidity 

plastic or lead pip 

cog-heel rigidity 

can be interrupted by a series of brief relaxations 

names for slow and reduced movementes

bradykinesia and hypokinesia

how does bradykinesia manifest in parkinson’s

difficulty initiating movement, decreased arm swing during gait, and akineseia in the face

akenesia in the face

lack of facial expression

most common movement disorder

tremor

what characterizes tremors 

rhythmic movements due to alternating contractions between agonist and antagonist muscles 

resting tremor

stop once voluntary movement is initiated and increased with emotional stress 

most common drug parkinson’s

sinemet

what does sinemet contain

L-DOPA and carbidopa

effect of L-DOPA

converted into dopamine in the brain

effect of carbidopa

inhibits breakdown of dopamine

side effects of sinemet 

decreased appetite, nausea, increased sex intered, reduced control of bp 

last resort for BN disorders

surgical lesions of the BN and thalamus

LVST big in parkinson's

high effort/ large amplitude moements while focusing on the sensory awareness of movement bigness

what characterizes dystonia 

sustained muscle contractions resulting in abnormal postures and repeated dytonia

focal dystonia def

movement disorder where an unwanted muscle contraction, or twitching, leads to an involuntary movement

Tics def

repetive, brief, rapid, involuntary and purposeless movements involving single or gorups of muscles

tics that are fragments of movements or throughts

• echolalia

• coprolalia

echolalia

• involuntary repetition of words just spoken by another person

copralalia

involuntary utterance of curse words 

tourettes syndrome 

• inherited disorder with childhood onset 

• likely a BN disorder involving motor and vocal tics 

OCD def

menatal illness in which person has obsessive thoughts, fears, and worry and then develops behavioral compulsions to attempt to diminish the worry

3 primary brain areas in OCD

• orbital frontal cortex-mistake feeling

• cingulate gyrus- triggers anxiety

• cuadate nucleus- a

c

cerebellum

little brain which has striking similarieties to the cerebrum

structure of cerebellum

2 cerebellar hemispheres with the vermis in the middle

deep areas of the cerebellum name

medullary center

coritcla ridges of cerebellum

folia

the cerebellum work on an _____ basis with regards to the body

ipsilateral

what does the cerebellum process 

all sensory information 

why is the cerebellum considered part of motor system

bc cerebellar damage produces disorders of movment

cerebellum is responsible for ___ of movement

synergy

synergy of movement

all componenets of movement are working together smoothly

1. equilibrium

2. control of muscle tone and posture

3. coordination of voluntary movements

2 areas of cerebellum 

superficial and deep areas 

cerebellar cortex contains 

purkinje cells 

purkinje cells 

designed like a tree to take in and integrate a large amount of information- axons project from the cerebellar cortex to deeper areas

medullary center contains

deep cerebellar nuclei which project out of the cerebellum

3 lobes of cerebellu

1. flocculonodular lobe

2. anterior lobe

3. posterior lobe 

what do the anterior and posterior lobes make up 

body of the cerebellum 

3 longitudinal zones of cerebellum

1. vermis

2. medial hemispheres

3. lateral hemispheres

3 cerebelar peduncles 

1. inferior cerebellar peduncle

2. middle cerebellar peduncle

3. superior cerebellar peduncle

inferior cerebellar peduncle

mainly inputs to the cerebellum from the spinal cord and brainstem (position sense)

middle cerebellar peduncle

mainly inputs to the cerebellum from the pontine nuclei

pontine nuclei

project info from the cerebral cortex

superior cerebellar peduncle

mainly efferent pathways from the cerebellum to the midbrain and thalamus which project to the cerebral cortex

basic flow of info through the cerebellum 

1. inferior and middle cerebellar peduncles contain inputs that bring info to cerebellum

2. info makes its way to cerebellar cortex

3. purkinje cells in the cerebellar cortex project to deep cerebellar nuclei found in the medullary center

4. deep cerebellar nuclei project out of the cerebellum through the superior cerebellar peduncles to various sites in the brainstem and thalamus (to give movement feedback) 

function of the lateral hemispheres in the cerebellum 

involved in planning and programming of voluntary movements, particularly learned and skillfull movements that become more precise with practice 

medial hemisphere function cerebellum

involved in adjusting limb movements as an error-detecting device 

what do the medial hemispheres of the cerebellum detect 

compare what you thought you were going to do with what is actually going on in your body and correct the movement if there is a problem 

what is the vermis involved in

postural adjustments and stereotyped movements 

what is the flocculus and vermis involved in

equilibrium and eye tracking movements

2 main functions of the cerebellum

motor learning and cognitive functions

common cerebellar signs

• hypotonia

• ataxia

hypotonia 

decreased 

ataxia 

loss of muscle coordination to produce smooth movements; most common sign of cerebellar dysfunction 

dysmetria

erorrs in appropriate distance of movement

dysdiadochokinesia

impaired ability to produce rapid alternating movements

intention tremor

tremor that occurs when attempting to make a voluntary movement

scanning speech

impaired ability to smoothy modulate speech

gait ataxia 

characterized by unsteady walking with a wide base of support

truncal ataxia

characterized by jerky, unsteady movements of the trunk

optic ataxia

characterized by jerky, unsteady movements of the eyes 

cerebellar hypoplasia

underdevelopment of cerebellum

friedreich’s ataxia

rare, inherited degenerative disease involving the spinal cord, peripheral nerves, and cerebellum 

acquired conditions of the cerebellum

MS, cerebellar stroke, TBI, tumors, alchoholism

anterior lobe syndrome

often found in people with chronic alchoholism due to degeneration of the cerebellar cortex that starts anteriorly in the anterior lobe and works posteriorly

levels of motor system involved in motor control

• higher centers (cortex, basal nuclei, cerebellum, thalamus)

• descending pathways (CST, CBT)

• built in patterns (reflexes and CPG)