TBL Upper Lower Neuron and pathways Flashcards
What symptoms will a lower motor neuron lesion result in?
paralysis
muscle atrophy
areflexia and atonia
ipsi deficit in spinal cord
What symptoms will a upper motor neuron lesion result in?
paresis (weakness) no atrophy hyperreflexia, hypertonia, spacisticy Contra deficit above decussation ipsi deficit below decussation
What symptoms will a basal ganglia lesion result in?
no paralysis no atrophy Parkinson's: rigidity, resting tremor, bradykinesia Huntingtons: chorea hyerkinesia COntra
What are descending tracts?
motor tracts
What are ascending tracts?
sensory tracts
What is the Dorsal column medial leminiscus pathway ( TVP Body and Head)?
Peripheral afferent neuron (1 neuron)-> DRG-> up dorsal column-> synapse at gracilis and cuneate nuclei (in medulla)->decussation -> medial leminiscus (2nd order neurons)-> VPL of thalamus-> to primary sensory cortex (3rd order neuron) to posterior limb of internal capsule
Describe the spinothalamic pathway (P +T Body and Head)
peripheral afferent neurons (1st order)-> DRG-> synapse in dorsal horne-> (2nd order) deccusate-> ascend via spinal thalamic tract-> synapse in VPL of thalamus-> (3rd order) axons ascend from VPL of thalamus through the posterior limb of internal capsule to the cortex
What happens if you injury the DCML pathway?
you lose TVP
What if you get a lesion in the spinal cord of the DCML pathway?
ipsilateral loss of TVP
What happens if you have an injury to the ALS pathway?
loss of P and T
What happens if you have lesion on spinal cord of ALS pathway?
loss of P and T on contralateral side
Decribe the Trigeminal TVP pathway
afferent from face-> synapse at principal (chief sensory) trigeminal nucleus-> decussation and joins medial leminiscus-> VPM nucleus of thalamus-> P. limb of internal capsule-> sensory cortex
What happens if you get a stroke in anterior cerebral artery?
lose TVP in trunk, leg, foot etc
What happens if you get a stroke in the medial cerebral artery?
lose TVP in arms, face, etc.
Describe the Trigeminal T and P pathway
pain/temp afferents on CNS-> travel down to nucleus of spinal 5 and synapse-> (2nd order) decussation-> spinothalmic tract-> synapse at VPM of thalamus -> (3rd) P. limb of Internal capsule-> sensory cortex
What are the 2 descending tracts?
lateral corticospinal tract
anterior corticospinal tract
Describe the lateral corticospinal tract pathway
primary motor cortex (pyramidal cells)-> corona radiata-> P. limb of internal capsule-> cerebral peduncle-> pyramids of medulla-> decussation-> lateral corticospinal tract-> synapses in ventral horn->(3rd) goes to either lower motor neurons, upper motor neurons, or interneurons
Where does the lateral corticospinal tract pathway typically lead?
to alpha motor neurons of distal muscles
Describe the Anterior (ventral) corticospinal tract
Primary motor cortex-> corona radiata-> posterior limb of internal capsule-> cerebral peduncles-> pyramids of medulla-> ventral corticospinal tract-> entral horns where they innervate muscles of the trunk
What are the 2 posterior spinal tracts and what do they have in common?
what are the 2 lateral spinal tracts and what do they have in common and what do they have in common?what are the 2 anterior spinal tracts?
lateral corticospinal and dorsal columns (gracile and cuneate) -> cross over at medulla
dorsal spinocerebellar and ventral spinocerebellar-> ipsilateral
ventral corticospinal and spinothalamic-> cross at the spinal level
What happens if you get a lesion on the midline/top of gyrus?
mess up legs/feet
What happens if you get a lesion at the lateral gyrus?
mess up hands/face
Which would be more affected by stroke, the midline or lateral gyrus?
lateral gyrus because it is larger
what will happen if you get a stroke in internal capsule?
Can paralyze entire side of body
What happens if you get a stroke in pyramids?
paralysis of affected side and other symptoms due to lots of other structures being found here
What happens if you get unilateral damage of a nerve that innervates a trunk muscle?
it probably wont be damaged much because they are often bilaterally innervated
Does the forehead have bilateral innervation?
yes
What happens if you get a cerebral stroke??
lower half of 1 side will be affected
What happens if you get CN 7 damage?
whole side of face will be affected
Describe the direct pathway
cortex excites striatum which inhibits the globus pallidus (which is an inhibitor) so now we get activation of the motor thalamus and thus activation of the motor cortex and activation of upper motor neurons and activation of the lower motor neurons :)
Describe the indirect pathway
cortex excites striatum which inhibits the inhibitor names ext. GP which excites the subthalamic nucleus and this excites the int. GP which means it excited the inhibitor and thus we get inhibition of motor thalamus and inhibition of motor cortex and inhibition of UMN and inhibition of lower motor neurons
What happens if you have a lesion at the sub. nigra or pars compacta?
parkinsons disease
What happens if you have lesion at the subthalamic nucleus?
hemiballismus
What happens if you have issues with your cholinergic neurons or GPE of your indirect pathway ?
huntingtons :(
What are the 2 spinocerebellar tracts and what do they give us?
posterior spinocerebellar and anterior spinocerebellar
Proprioception :)
Describe the posterior spinocerebellar tract
DRG axons (1st)-> synapse in gray horn and enter posterior spinocerebellar tract on SAME side (2nd)-> cerebellar cortex on same side
Describe the anterior spinocerebellar tracts
DRG-> synapse and enter anterioe spinalcerebellar tract on same or opposite side->cerebellar cortex on same side typically
