Flashcards in Movement pathways and centre Deck (54)
What are lower motor neurons (LMNs) ?
neurons that originate from the brain stem and spinal cord
What are the components to the lower motor neuron (LMN)?
1. spinal nerve
2. ventral root
3. dorsal root ganglion
4. dorsal root
5. dorsal grey horn
6. ventral grey horn
What are lower motor neuron lesions due to?
1. peripheral nerve injury - crush or poliomyelitis
What do lower motor neuron lesions lead to?
1. muscle wasting
2. muscle weakness/ reduced power
4. absent tendon reflexes
5. fasciculations/ fibrillation
What are fasiculations?
small uncontrollable localised contractions
What is an example of a descending mortor pathway?
upper motor neurons (UMNs)
What 2 types of descending motor pathways are there?
1. corticospinal - cortex to spine - spinal nerves
2. corticobulbar - cortex to brainstem - cranial nerves
What does the descending motor pathways/ upper motor neurons do?
1. influence LMN activity
2. modify local reflex activity
3. superimpose more complex patterns of movement
How many important descending pathways are there and what are they named after?
named after origin
What is the typical route for descending patwhays/ upper motor neurons?
1. cerebral cortex
2. precentral gyrus
3. internal capsule
4. brainstem/spinal cord
Do all descending pathways work separately or together?
What are the descending pathways often referred to as?
What happens initially if there is damage to the corticospinal tract only?
1. flaccid paralysis of opposite limbs
2. loss of tendon reflexes
What happens after several days to a week if there is damage in the corticospinal tract only?
1. motor function recovers
2. but there is hypertonia
What happens in the long term if there is damage to the corticospinal tract?
2. hyperreflexia - increased reflexes
3. left with pernamanet inability to carry out fine movements of hands and feet
What do other pathways seem to do if there is damage to the corticospinal tract only?
appear to take over most corticospinal functions
What type of homunculus do you have?
2. motor homunculus
Where is the somatosensory homunculus?
in the post-central gyrus
Where is the motor homunculus?
in the pre-central gyrus
What is the order of the motor homunculus in the pre-cnetral gyrus medial to lateral?
What is the order of the somatosensory homunculus in the post-central gyrus medial to lateral?
Where does the descending pathway (descending corticospinal/bulbar fibres) or upper motor neuron travel?
1. from pre central gyrus to internal capsule
What is the internal capsule?
deep bundle of white matter between the deep nuclei
What is the structure of the internal capsule?
1. anterior limb of internal capsule
2. lower limb of internal capsule
Where do descending fibres for the body go?
posterior limb of the internal capsule
Where do descending fibres fro the face and muscles of the head go?
What is the structure of the brainstem?
1. cerebral peduncle
2. basal pons
How does the descending pathway travel from internal capsule to spinal cord?
in the brainstem from cerebral peducnle to basal pons to pyramids and to contralateral spinal cord
How does the corticospinal pathway travel from cortex to spinal cord?
1. pre-central gyrus in cortex
2. inetrnal capsule
3. basis peduncles
5. pyramidal decusstaion
6. lateral corticospinal tract