Spinal tracts Flashcards
what is the VPMn
ventral posterior medial nucleus
- in thalamus
- carries somatosensory info from the head, face, and neck
what is the VPLn
ventral posterior lateral nucleus
- in the thalamus
- carries somatosensory info from everything below the neck
what is the DCML
dorsal column medial lemniscus tract
- pathway from periphery through the dorsal column of the spine to the medial lemniscus to S1
- carries cutaneous info
where do the dorsal and anterior spinocerebellar pathways travel
lower limbs to the cerebellum
what is the dorsal spinocerebellar pathway
- somatosensory info from GTO and muscle spindle axons enters the dorsal horn of the spinal cord
- travels up the ipsilateral side of the dorsal horn
- synapses at clarkes nucleus
- travels up DSCT until it reaches junction of medulla and pons
- info enters cerebellum via inferior cerebellar peduncle
- some info decussates and continues to the contralateral S1 via the thalamus through DCML
no decussation in main pathway
where are the decussation points in the dorsal spinocerebellar pathway
there are none
- info from right side of body enters right cerebellum
where are the synapse(s) in the dorsal spinocerebellar pathway
clarkes nucleus
how many orders of neurons are there in the dorsal spinocerebellar pathway and where do they travel
1st order
- from info to clarkes nucleus
2nd order
- from clarkes nuclues to the cerebellum
what is clarkes nucleus
major spinal relay centre
- composed of neurons in the dorsal horn of the spinal cord
- only interacts with the dorsal spinocerebellar pathway
what is the anterior spinocerebellar pathway
- somatosensory info from GTOs enters the dorsal horn of the spinal cord
- decussates into spinal cerebellar tract (same info in DSCT)
- travels up ASCT until juntion of medulla and pons
- decussates at the caudal medulla
- enters cerebellum vai superior cerebellar peduncle
where are the decussation points in the anterior spinocerebellar pathway
- at the level of the spine where info enters
- caudal medulla
- info from right side of body enters the right side cerebellum (double cross)
where are the synapse(s) in the anterior spinocerebellar pathway
1st synapse = at the level of entry into the spine
2nd synapse = cerebellum
how many orders of neurons are there in the anterior spinocerebellar pathway and where do they travel
1st order
- from info to the entry into the dorsal horn
2nd order
- from level of entry into the spine to the cerebellum
what is the reason for the double cross in the anterior spinocerebellar pathway
help survive certain spinal cord injuries
another afferent copy of the same info is travelling on the other side of the spine
what are the equivalent pathways for the upper limbs compared to the ASCT and DSCT
ASCT (lower limbs) = rostral spinocerebellar tract (upper limbs)
DSCT (lower limbs) = cuneocerebellar tract (upper limbs)
where does info go after being processsed by the cerebellum
contralateral sensory and motor areas via the thalamus
why are DSCT and ASCT important
important for unconsicous proprioception
- increased force to counteract a force
- motor commands are generated without “permission” from M1 and then we feel it afer
explain the pathway of DCML
- sensory neurons travel to the dorsal horn
- info travels up the dorsal columns in the gracile or cuneate fascicle
- decussates in the medulla
- info travels up medial lemniscus through brainstem to the thalamus
- synapses at the thalamus onto internal capsule
- info travels in internal capsule from the thalamus to S1
where are the decussation points in DCML
only at the caudal medulla
- info innervates contralateral side of brain
where are the synapse(s) in DCML
- caudal medulla (decussation pt)
- thalamus
- S1 - to integrate with more neurons
how many orders of neurons are involved in DCML and where do they travel
1st order
- info from sensroy to teh medulla (through spinal cord)
2nd order
- info from medulla to thalamus
3rd order
- info from thalamus to S1 (through internal capsule)
is there a difference in the info carried by DSCT and ASCT
no - copies of the same info, just travel on different sides of the spine
where are the VPMn and VPLn located
thalamus
what is the somatotropic organisation of the dorsal column of the spinal cord
organised by bodoy part
- distal body parts = medial
- proximal body parts = lateral
which spinal tract(s) are used in the descending pathway from S1
ventral/anterior corticospinal tract (10%)
lateral corticospinal tract (90%)
what info does the lateral CST carry
all periphery (not trunk and core)
what info does the ventral CST carry
trunk and core (innervates bilaterally)
what percent of CST neurons come from S1
~30%
what side of the body is affected by damage to descending neuron ABOVE the pyramidal decussation
contralateral side of the body
what side of the body is affected by damage to descending neuron BELOW the pyramidal decussation
ipsilateral side
what are the pyramids
protuberance of descending neurosn arising from different areas of cerebral cortex
- lateral CST decussation point
what type of info is carried in the DCML
proprioceptive info
