motor control disorders ect ppt2 (same lecture) Flashcards
what does the concept of “hierarchical organisation” of motor control refer to?
higher order areas of hierarchy are involved in more complex tasks
(PROGRAMME and DECIDE ON movements, COORDINATE muscle activity)
lower level areas of hierarchy: lower level tasks (EXECUTION of movement)
what does the concept of functional segregation refer to?
motor system organised in a number of different areas that control different aspects of movement
where does the motor cortex (primary and non primary) receive information from? where does it send info to?
-from other cortical areas (thalamus)
-sends to thalamus and brainstem and spinal cord
what areas sometimes mediate transfer of info from motor cortices to brainstem and thalamus?
basal ganglia (for thalamus)
cerebellum (for both)
they adjust the commands sent
where does the brainstem send info to?
spinal cord to stimulate muscles of body, or straight to muscles of face head and neck to move these regions
2 major types of descending tracts
pyramidal and extrapyramidal (refers to whether they pass through pyramids in medulla)
which are the extrapyramidal tracts ?
vestibulospinal
tectospinal
reticulospinal
rubrospinal
role of extrapyramidal tracts?
involuntary (automatic) movements FOR BALANCE, POSTURE and LOCOMOTION
think of EXTRA: einai ta extra, fine tuning, isoropia klp)
where do extrapyramidal tracts start and end?
start brainstem nuclei end spinal cord
which are the pyramidal tracts
corticospinal (Body)
coritcobulbar (face)
role of pyramidal tracts
voluntary movements of body and face (think of pyramidal: pyrinika: basics)
pathway of corticospinal tract of UPPER motor neurons up to where they link to lower motor neurons;
1) upper motor neurons (in primary motor cortex)
2) midbrain (cerebral peduncle)
3) medulla in pyramids
4) 85-90% decussate in medulla BEFORE they enter spinal cord : forming lateral corticospinal tract in spinal cord
(going to limb muscles)
- the rest doesnt cross- stays as it is and forms anterior corticospinal tract in spinal cord
(going to trunk muscles)
5) then they link to lower motor neurons once in spinal cord
(Note; pyramids are only in medulla, dont continue in spinal cord thats why the tracts turninto anterior and lateral and not called pyramidal anymore)
what is the homunculus?
Represents the proportional amount of brain (in somatosensory or motor cortices -theres a diffirent humunculus for each) devoted to that part of body
(think H for HUMUNGUS HANDS): BECAUSE the sketch has huge hands einai san terataki see slide 10
what is somatotopy
Represents location of part of body on brain NOT AMOUNT devoted to it
role of corticobulbrar tract
Principal motor pathway for voluntary movements of the face (and neck)
what are some areas/ types of nuclei in brain that are components of the basal ganglia?
caudate nucleus + putamen nucleus
(these two make the “striatum”)
globus pallidus
thalamus
what does a nucleus in neuro terms refer to (just for my understanding not from slide)
In neuroanatomy, a nucleus typically refers to a collection of neurons (nerve cells) located within the central nervous system that have a similar structure and function.
These nuclei are often grouped together based on their anatomical location
what do motor nerves from these nuclei do?:
1)occulomotor nuc, throchlear, 2)trigeminal motor nucleus,
3)abducents,
4)facial,
5)hypoglossal
eye movements
muscles of jaw
eye movements
muscles of face
tongue
role of vestibulospinal tract
Stabilise head during body movements, or as head moves
Coordinate head movements with eye movements
Mediate postural adjustments
role of reticulospinal tract
Changes in muscles tone associated with voluntary movement
(ex. Standing one leg, when walking, reaching, its controlling trunk muscles so you stay stable)
Postural stability
role of tectospinal tract
orientation of head and nech during spine movements
rubrospinal tract role
In humans mainly taken over by corticospinal tract
but one thing it does:
Innervate lower motor neurons of FLEXORS (thats a unique thing) of the upper limb
where do each of the extrapyramidal tracts originate in (in brainstem as seen previously) but where specifically for each
tectospinal tract: superior colliculus of midbrain
reticulospinal: medulla and pons
red nucleus of midbrain for rubrospinal
didnt find smth for vestibulospinal in my flashcards, chatgpt : medulla and pons
which is the most primitive descending tract? (develops first in babies ect)
reticulospinal
what does it mean in general to have negative signs of upper motor neuron lesions?
Loss of voluntary motor function:
what are the types of negative signs of upper motor neuron lesions?
1) Paresis: graded weakness of movements
2) Paralysis (plegia): complete loss of voluntary muscle activity
NOTE:”graded” implies that the weakness is not uniform but can range from mild to severe,
what does it mean in general to have positive signs of upper motor neuron lesions?
generally: abnormal increased motor function due to loss of inhibitory descending inputs
specific positive signs of upper motor neuron lesions
Spasticity: increased muscle tone
Hyper-reflexia: exaggerated reflexes
Clonus: abnormal oscillatory muscle contraction
Babinski’s sign (sharp object on sole thing) normal adult is fingers to curl down
what is apraxia
A disorder of skilled movement. Patients are not paretic but have lost information about how to perform skilled movements
LESION IN which area gves you apraxia
supplementary motor area - SMA)
- is basically in premotor cortex
- in terms of lobes its a little on inferior parietal and on frontal
what are the most common causes of disease in these areas that can cause apraxia? (go to ppt to see mri)
stroke and dementia
lower motor neuron lesion symptom type in general
weakness
specific symptoms of lower motor neuron lesion
Hypotonia (reduced muscle tone)
Hyporeflexia (reduced reflexes)
Muscle atrophy
Fasciculations:
Fibrillations:
(remember: lower motor: hypo hypo Motor ff)
what is the difference between muscle fasciculations and fibrilations
Fasciculations are VISIBLE twitches of a motor unit after it has been DAMAGED and produces a spontaneous action potential.
fibrillations are NON VISIBLE twitches on individual muscle FIBRES (only with needle electromyography) that are SPONTANEOUS
difference between spasticity (thing seen in positive sign UPPER motor neurons) vs fasciculations
Spasticity: Spasticity refers to increased muscle tone or stiffness, often accompanied by involuntary muscle contractions.
Fasciculations are involuntary muscle twitches or contractions that can occur in SMALL BUNDLES of muscle fibers. - see a little twitch under skin type thing
what is motor neuron disease (MND) + most common form
Progressive neurodegenerative disorder of the motor system
Most common/ characteristic type: Amyotrophic Lateral Sclerosis
start- finsish of upper motor neurons
from motor cortex to brainstem
two types of lower motor neurons and what they innervate - only relevant areas to MND
brainstem lower motor neurons (innervate tongue/ face, upper limb, intercostal muscles (:through axon bundles)
and spinal cord lower motor neurons (innervate lower limb muscle)
MND upper motor neuron signs
Spasticity (increased tone of limbs and tongue)
Brisk limbs and jaw reflexes
Babinski’s sign
Loss of dexterity (dexiotita)
Dysarthria (difficulty speaking) (facial muscles)
Dysphagia (difficulty swallowing)
MND lower motor neuron signs
Weakness!!
Muscle wasting!!
Tongue fasciculations and wasting!!
Nasal speech!!
Dysphagia
!!: unnique compared to upper
what is the physiological problem in parkinsons disease
Degeneration of the dopaminergic neurons that originate in the substantia nigra and project to the striatum
what are the symptoms of parkinsons disease
bradykinesia
akinesia
hypomimic face
rigidity
tremor at rest (hand and then can spread to other areas later in disease)
what is akinesia parkinsons
difficulty initiating movement internally
what is rigidity parkinsons
increased muscle tone causing resistance to extenraly impose djoint movements
what is hypomimic face pakrinsons
face - expressionless, mask-like (absence of movements that normally animate the face)
what is the physiological pathology in huntington’s disease?
Degeneration of GABAergic neurons in the striatum (caudate and then putamen).
*(striatum is the name for caudate and putamen nuclei)
what is the cause of huntingtons disease? what kind of disease is it
Genetic neurodegenerative disorder
what chromosome is the issue in in huntingtons? what is the mutation? is it dominant or reccessive?
chromosome 4
so its autosomal + dominant
CAG repeat
what are the main presenting symptoms of huntingtons?
choreic movements
rapid jerky involuntary movements (hands and face affected first thne legs and resto of body)
unsteady gait
speech impairment
difficulty swallowing
what are some huntingtons symptoms in later stages?
cognitive decline
dementia
what part of the NS has usally been damaged in balism and how?
Usually from stroke affecting the subthalamic nucleus.
what is the main symptom of ballism
and what does the side of symtmtom onset tell you about pathology location
Sudden uncontrolled flinging of the extremities
(remember pic of ppt)
symptoms occur contralaterally
location of cerebellum in skull
posterior cranial fossa
what structure separates cerebrum from cerebelum
tentorium cerebelli
role of cerebellum and what happens when its damaged
Not thaaaat important just that it mediates the signals sent fromo brain down so harm in cerebellum is usually loss of skilled movement!!! Eg playing guitar, piano ext: loss of coordination and prediciton of movement: that’s what skills are about
what is the role of the cerebellum
Regulation of gait, posture and equilibrium
Coordination of head movements with eye movements
what is the result of vestibulocerebellum damage?
causes syndrome similar to vestibular disease leading to gait ataxia and tendency to fall (even when patient sitting and eyes open)
role of spinocerebellum
Coordination of speech
Adjustment of muscle tone
Coordination of limb movements
usual cause of vestibulocerebellum damage
tumour
usual cause of spinocerebellum damage
degeneration and atrophy
what happens when spinocerebellum is damaged
affects mainly legs, causes abnormal gait and stance (wide-based) (people have legs more spread than. normal
cerebrocerebellum role
Coordination of skilled movements
Cognitive function, attention,
processing of language
Emotional control
what is the consequence of damage in cerebrocerebellum
affects mainly skilled coordinated movements of the arms (tremor) and speech
when are the signs of cerebellar dysfuncitno apparen?
only on movement
what are the signs of cerebellar dysfunction
Ataxia
General impairments in movement coordination and accuracy. Disturbances of posture or gait: wide-based, staggering (“drunken”) gait
Dysmetria
Inappropriate force and distance for target-directed movements (knocking over a cup rather than grabbing it)
Intention tremor
Increasingly oscillatory trajectory of a limb in a target-directed movement (nose-finger tracking)
Dysdiadochokinesia
Inability to perform rapidly alternating movements (rapidly pronating and supinating hands and forearms)
Scanning speech
Staccato, due to impaired coordination of speech muscles
