Motor system Flashcards
Where are LMN cell bodies found ?
ventral horn or CN motor nuclei
What activates sensory neurones in the deep tendon reflex ?
muscle spindles
What happens to the hamstrings in patellar reflex action ?
they are inhibited via its LMNs
What happens to our primitive reflexes as we age ?
they disappear as maturation of UMN pathways
What are they symptoms of LMN damage ?
weakness , areflexia , wasting , hypotonia , fasciculations
Why do you get fasciculations in LMN damage ?
up-regulation of mus nAChrS to compensate
Where are UMNs originate from ?
Pre-central gyrus (motor cortex)
Where do UMNs synapse ?
Ventral horn or CN motor nuclei
What is the effect of UMNs on LMNs ?
Inhibition
What is the course of a UMN from the motor cortex?
- Corona radiata
- Internal capsule
- Cerebral peduncle
- Pons
- Medullary pyramids
- Decussation of the pyramids
- Lateral corticospinal tract
- ventral horn
- synaspe
What does the lateral corticospinal tract good at controlling ?
Fine motor control in limbs
how does the UMNs in the facial nerve innervate the various muscles ?
The superior facial nerve nucleus supplies the forehead and receives inputs from both hemispheres
the inferior facial nerves nucleus receives supply form the contralateral hemisphere
How do you tell UMN lesion in the face nerve from a true facial nerve palsy ?
UMN = forehead sparing whilst true palsy is all the face is gone
What are the symptoms of UMN damage ?
weakness
Hypertonia
hyperreflexia
Extensor plantar reflex (reverse to normal)
What is spinal shock?
due to UMN lesion . initially, flaccid paralysis but then hypertonia and hyperreflexia
