Functional neuroanatomy of movement disorders Flashcards
features of UMN lesion
weakness, spasticity, clonus, and hyperreflexia, hypotonia
babies have low muscle tone
what is a monosynaptic reflex
The monosynaptic stretch reflex, or sometimes also referred to as the muscle stretch reflex, deep tendon reflex, is a reflex arc that provides direct communication between sensory and motor neurons innervating the muscle.
LCST decussation
medulla
fibres from motor cortex, motor area, premotor cortex, somatosensory cortex, parietal lobe and cingulate gyrus
where is the primary motor cortex found
precentral gyrus of the frontal lobe
what does the primary motor cortex do
Generates signals execute movement opposite side of body
what does the secondary motor area include
posterior parietal cortex
premotor cortex ( anterior to primary MC)
supplementary motor area SMA above and medial to premotor area
the secondary motor area includes is involved in motor planning
the posterior parietal Cortex is involved in the secondary motor area what does it do
- transforms visual info into motor commands eg steering hand to glass in space. It sends signals to premotor cortex and SMA
what does the premotor cortex do
sensory guidance of movement controlling proximal and trunk muscles (orientation of body before reaching for the glass)
what does the supplementary motor area SMA do
planning complex movements and coordinates two handed movements - tai chi, double handed tennis stroke
the supplementary motor areas sequences of movement form memory. how does normal movement occur
start in premotor cortex and SMA goes
BG receive input from …….. …….. …….. e.g. premotor cortex & supplementary motor areas (SMAs - sequences of movements from memory)
Integrates these signals & feeds back to pre-motor cortex via …………
Pre-motor cortex then activates the primary motor cortex (to execute movement) & the cerebellum (to coordinate & fine-tune the movement)
BG also have access to descending pathways for axial & proximal limb muscle control
BG receive input from cortical motor areas, e.g. premotor cortex & supplementary motor areas (SMAs - sequences of movements from memory)
Integrates these signals & feeds back to pre-motor cortex via thalamus
Pre-motor cortex then activates the primary motor cortex (to execute movement) & the cerebellum (to coordinate & fine-tune the movement)
BG also have access to descending pathways for axial & proximal limb muscle control
wha is BSS
Brown-Sequard syndrome (BSS) is a rare neurological condition characterized by a lesion in the spinal cord which results in weakness or paralysis (hemiparaplegia) on one side of the body and a loss of sensation (hemianesthesia) on the opposite side.
UMN
cortical grey matter - cell bodies
white matter tracts - myelin
spinal tracts
LMN ventral horn of spinal cord cauda equina peripheral nerve ( spinal and cranial) neuromuscular junction alpha * muscle fibres force) and gamma motor neurones ( innervate fibres in muscle spindles - measuring length and stretch of the muscle)
UMN lesion
Paralysis of movement rather than individual muscles
Hypertonic muscles (spasticity) after a couple of days
‘Hopping rabbit’ posture
Moderate muscles wasting
Tendon reflexes increased & modified
Babinski sign
clonus
LMN lesion
Paralysis of individual muscles
Hypotonic muscles (flaccidity)
Pronounced muscle wasting
Tendon reflexes absent
what is the SMA
sequences of movements from memory – choreography like martial arts forms/kata, dance like Strictly (GABA)
BG & Cerebellum integrates these signals & feeds back to pre-motor cortex via thalamus
BG also have access to descending pathways for axial & proximal limb muscle control
Damage leads to spontaneous & inappropriate movement
putamen and the caudate
striatus ( corpus striatum)
putamen and the globus pallidus
lentiform nucleus
caudate nucleus runs in the wall of what ventricle
lateral ventricle
major role of the basal ganglia
imitation and termination of movement
neuronal activity in putamen seen before body movements
neuronal activity in caudate seen before eye movements
also involved in initiation and termination of some cognitive functions
the basal ganglia is a collection of nuclear masses in the forebrain what is contained in the basal ganglia
caudate nucleus
putamen
globus pallidus
amygdala is anatomically and embryonically similar but functionally part of the limbic system
2 functionally related midbrain structures - substantia nigra and sub thalamus
caudate nucleus it tadpole shaped - where is it found in comparison to the BG
most superior to BG
above and lateral to the thalamus and medial to internal capsule
enlarged head at the front which is continuous with the putamen
what is the limbic system mad of
hippocampus, amygdala and hypothalamus
motivation dn mood
what “loops does the limbic system have”
Motor loop
Oculomotor loop
Prefrontal loop – attention, planning, focus concentration
Limbic loop – emotional function – link between movement and emotion
what is Korsakoff syndrome and what causes it
Korsakoff Syndrome. Korsakoff syndrome is a chronic memory disorder caused by severe deficiency of thiamine (vitamin B-1). Korsakoff syndrome is most commonly caused by alcohol misuse, but certain other conditions also can cause the syndrome.
high dose of thiamine
substantia nigra does what
send dopaminergic neurones to basal nuclei
black substance due to melanin projecting to corpus striatum of BG - largest nucleus of the midbrain
what is the subthalmus
The subthalamus is the most ventral part of the diencephalon.
two problems causes by BG dysfunction
either hyperkinetic e.g. Parkinson’s - reduced or slow movement
hyperkinetic disorder - excessive abnormal spontaneous movement
Chorea
rapid, involuntary dancing movements eg Huntington’s disease
Ballismus
severe chorea with thrashing motions
Athetosis
Involuntary writhing (twisting & turning) movements of limbs & neck
symptoms of Parkinsons
Tremor Slow, pill-rolling Asymmetrical Worse at rest Reduced on movement/distraction
Bradykinesia (slowness of movement) Slow shuffling gate Expressionless face with reduced blinking Quiet monotonous speech Micrographia (spidery writing)
Rigidity
lead-pipe rigidity in limbs, trunk & neck
cogwheel rigidity = rigidity + tremor
falls and dementia
BG goes light what has happened
Degeneration of dopamine producing neurons (neuropigmented cells) in the pars compacta region of substantia nigra
- loss of melanin
an example of a hyperkinetic disorder is Huntington’s disease - autosomal domino so 50%
caused by what
loss of GABA releasing neurone of the corpus striatum
chorea is primary feature
dementia, unsteadiness and speech problems
no effective treatment
what is Wilsons disease
Wilson disease is a rare genetic disorder characterized by excess copper stored in various body tissues, particularly the liver, brain, and corneas of the eyes. The disease is progressive and, if left untreated, it may cause liver (hepatic) disease, central nervous system dysfunction, and death.
Researchers have determined that Wilson disease is caused by disruption or changes (mutations) of the ATP7B gene, which plays an important role in the movement of excess copper from the liver to the bile to eventually be excreted from the body through the intestines.
liver transplant
what separates the cerebellum from the cerebrum
transverse fissure and tentorium cerebelli
median region separated from pons and medulla by 4th ventricle
what does each cerebellar lobe do
Anterior lobe & posterior lobe = subconscious skeletal muscle movement Flocculonodular lobe (inferior surface) = equilibrium & balance
what is a cerebellar peduncle
A cerebellar peduncle is a nerve tract that permits communication between the cerebellum and the other parts of the central nervous system.
sup - efferent outpoin t
mid and inf afferent input from eyes , limbs etc
sup cerebellar peduncles goes to where
midbrain
mid c peduncles comes from voluntary motor signals from pons but where does inf c peduncles come from bringing vestibular apparatus of inner ear and body proprioceptors
and axons from medulla and spinocerebellar tracts of spinal cord to cerebellum
medulla
DANISH
D ysdiadokokinesis A taxia Uncoordinated, staggering, broad-based gait Finger-nose ataxia (past-pointing) Heel-knee-shin ataxia Falls N ystagmus (Involuntary, rapid, rhythmic eye movement)
I ntention tremor
S peech disturbance (dysarthria)
H ypotonia
