5. Motor system Flashcards
where do LMN axons project?
CNS and PNS
is the effect the same whether LMN cell body/ axon damaged in CNS/PNS?
yes
for skeletal muscle reflexes, why is inhibition needed to different segment on spinal cord?
to prevent antagonist msucle also contracting
most UMN projections to LMNs are inhibitory. in what situation is this not the case?
when movement is wanted, you get strong excitations instead
where is the lateral corticospinal tract?
lateral funicular of the cord
pathway of LCST
motor cortex descending to spinal cord
rubrospinal tract function
none in humans
reticulospinal tract
-pathway
-functions
-retinacular formation of brainstem to cord
-homeostasis, paralysis in REM sleep, muscle tone, inhibits LMNs
function of medial longitudinal fasciclus
integrates vestibular input to spinal cord, e.g. compensate posture for steep incline, or coordinate both eyes in any plane of head tilt
tectospinal tract
-pathway
-functions
-tectum of midbrain to spinal cord
-orienate towards interesting stimuli e.g a bang (reflex movement)
percentage of UMN axons that decussate at caudal medulla?
what happens to the other ones?
85%, form lateral corticospinal tract
15% form ventral corticospinal tract and decussate at level of LMN
which LMNs are supplied by
1. ventral corticospinal tract
2. lateral corticospinal tract
- trunk
- lower limbs
in a left UMN lesion, which regions of face are affected?
R lower face lost
R upper face spared (due to branch from R UMN intact)
components of spasticity
hyperreflexia
hypertonia
what type of ‘atrophy’ is described in UMN lesions?
disuse atrophy- cant really use affected limbs
