Descending Tracts Flashcards
what are descending tracts
Pathways to the spinal cord from cortex and brainstem
The brain “answers” back
what are the pathways fro motor control
final common path t alpha/gamma motor neurones
spinal cord contains central pattern generators
motor output of spinal cord controlled by higher centre in cortex and brainstem
what do alpha and gamma motor neurones control
alpha - contractile muscle fibres
gamma- spindle function
what si path from cortex t sp cord
corticospianl
what is the path from midbrain to sp cord
tectospinal
what is the path from pons to sp cord
reticulospinal
what is the path from medulla to sp cord
vestibulospinal
where about are descending tracts
lateral and ventral columns
what are in the lateral columns mostly
corticospinal
what are in brain stem tracts ventral columns
tectojpinla, reticulospinal, vestibulospinal
where is info usually fed in sp cord
into ventral horn
what is the route of the cortiospinal trcts
pyramidal cells motorcortex internal capsule cerebral peduncles split tract pyramids later corticospinal tract
what does corticospinal tract control
fine distal flexors
what does corticospinal tract consist of
50% primary CTX
50% SMA somatosensory
3% Betz cells
single neuron
what happens to 85% of neurons and where
crosses sides between medulla and spinal cord
what ar basal ganglia
series of grey matter structures in brain
what portion of the peduncle contains corticospinal tract
middel 3rd segment
cortex to BS
what ar the other two segments of the midbrain peduncle
frontopontine and temporoontien
where does the corticospinal tract spot into fibres
in pons
where des the cirticospinal that go thro when at the medulla
pyramids - pyramidal tract
what is the smooth bit across the medulla
where 85% cross over called decussation of pyramids
what happens to the corticopinal tract in a stroke or cerebrovascular accident
- lesion
- internal capsule - bleeding
- degeneration of corticospial tract
- effects on app side of body
- muscle rigidity and hyperreflctive
- upper motor neuron lesion
hat does corticospinal tract do
distal flexors
fine movements
what does reticulospinal tract do
lateral fine movement
medial proximal limb
repetitive movements
locomotion
what doe vestibulospinal tract do
lateral
proximal extensors
balance
what does tectospinal tract do
relations to light
auditory stimulus
controls neck region
where are the motor association areas
primary motor cortex - pre central gyrus
supplementary (repetitive moves)
premotor cortex (posture, locomotion, planning)
central sulcus (forma nd plan moves)
what happens to control the more neurons assc with it
finer control from pre central gyrus think homunculus
what is the corticobulbar tract
similar function to corticospinal but supplies motor inv to nuclei serving cranial nerves 3/4/5/6/7/9/10/11/12
what are the summary of assc features of motor control
motor cortex sp cord brainstem basal ganglia cerebellum thalamus
