14 Movement pathways Flashcards
What are lower motor neurones?
Nerves from ventral grey horn via ventral roots to the motor end plates/neuromuscular junctions.
What do lower motor neurone lesions lead to?
Muscle wasting and weakness.
Hypotonia.
Absent tendon reflexes.
Fasciculation.
What do upper motor neurones do?
Influence LMNs.
Modify local reflex activity.
Superimpose complex patterns of movement.
What happens after damage to only the corticospinal tracts?
Initial flaccid paralysis and no tendon reflexes.
Movement is recovered but with spasticity and hypereflexia due to increased muscle tone (other pathways take over).
Fine motor movement is never regained.
What does the reticulospinal pathway control and where does it come from?
Voluntary movement, breathing, consciousness.
Brainstem reticular formation in pons and medulla.
What does the vestibulospinal pathway control and where does it come from?
Posture.
Vestibular nucleus in pons and medulla.
What does the rubrospinal pathway control and where does it come from?
Muscle tone.
Red nucleus in the midbrain.
What is the somatotopic representation in the internal capsule?
Face in genu.
Body through posterior limb (legs most near the back).
Describe the pathway of the UMNs in the corticospinal tract.
Through basis pedunculi/cerebral peduncles (midbrain level). Through pons. Through pyramids (medulla level). 85% of fibres decussate at closed medulla and enter lateral corticospinal tract. 15% descend ipsilaterally. Contact LMN in contralateral ventral grey horn.
Describe corticobulbar input into cranial nerve nuclei.
All are bilaterally served except…
Hypoglossal and lower facial nuclei which are only contralaterally served.
How do you differentiate between a supranuclear and a facial nerve lesion?
Supranuclear paralyses contralateral lower half of face only.
Facial nerve lesion paralyses whole of ipsilateral face.
