Neruo 5 Lesions of the Motor System Flashcards
Define a positive and negative sign of a neurological lesion?
Negative sign - Loss of function or capacity
Positive sign - Emergence of a feature e.g. tremor
Label the cerebellar functional divisions
What is the general function of each functional zone of the cerebellum?
vestibulocerebellum - Balance and ocular reflexes
spinocerebellum - Involved in Error correction
Cerebrocerebellum - Movement planning and motor learning, esp visually guided movements and coordination of muscle activation
Label the arteries that supply the cerebellum. From which arteries are these derived?
Which veins drain the cerebellum and where do these veins then drain into?
Superior and inferior cerebellar veins
drain into transverse and sigmoid sinuses
Give 3 common causes of cerebellar dysfunction
Tumours
Cerebrovascular disease
Genetic e.g. Friedrichs ataxia
Give 4 possible signs of damage to the cerebrocerebellum and spinocerebellum
ataxia, dysarthria and scanning speech, hypotonia, dysdiadochokinesia, inability to learn new movements
Give 2 signs of damage to the vestibulocerebellum
abnormal gait with a wide stance, and loss of balance
Label the anatomical divisions of the cerebellum
describe the embryonic development which leads to the cerebellum
Neural tube forms prosencephalon, mesencephalon, and rhombencephalon
Rhombencephalon splits into metencephalon (superior) and myelencephalon (inferior) - Metencephalon forms cerebellum
Give 6 signs of a UMN lesion
Hyperreflexia, hypertonia, spastic paralysis, babinski sign, myoclonus, choreas
What is a positive and negative sign of babinski?
Positive - abduction of toes and dorsiflexion of big toe
Negative - flexion of toes
What does a positive babinski mean?
UMN lesion in the corticospinal tract
Give 4 signs of LMN lesions
flaccid paralysis, denervation atrophy, areflexia / atonia, fasciculations
Explain why fasciculations occur in LMN lesions
deinnervation of muscles means nACHRs have become hypersensitive to any neurotransmitter substances or molecules even vaguely similar to ACh such as those found in the blood. Results in slight muscle contractions
In the case of LMN lesions, when is the damage irreversible?
If the cell body is damaged, no regeneration can take place.
How is micturition affected by a LMN lesion in S2-S4?
Overflow incontinence - autonomous bladder
Describe what spinal shock is. Why does it occur?
When descending tracts damaged, there is a recovery period of 4 - 6 weeks where there is flaccid paralysis and areflexia in the affected limbs. This is then replaced with spasticity and hyperactive deep reflexes.
It occurs because the loss of reflexes is due to loss of motor influences exerted by descending fibres. As these fibres degenerate the intact connections in the reflex circuits become dominant and show themselves as upper motor neurone signs
