LECTURE 8: ascending and decending pathways Flashcards
what kind of pathways are ascending pathways
sensory pathways
what is the function of the somatosensation
need to distinguish between sensory information from sensation
what interprets sensation giving us perception as active process between us and environment
thalamus and cortex
what neurons are ones with long axons that carry info long ways
projection neurons
_ neurons pathways include ___ projection neurons that may also have ____
3 and 3 and interneurons
what does the 1st order neuron do
bring into from periphery to CNS ( SC or BS)
what neuron bring in for from SC or brainstem to thalamus
2nd neuron
what does the 3rd neuron do
thalamus to somatosensory cortex
what are teh 3 types of somatosensory pathways to the brain
conscious relay
divergent
non conscious relay
what pathways is detailed and discriminative sensation are conveyed
conscious
what pathway is in for transmitted to may location in the brainstem and cerebrum with different #’s of neurons
divergent
how many projection neurons do conscious replay pathways have
3
what is the conscious relay pathway responsible for
light touch, proprio , noncicpetion , temp
what are the 2 ways the conscious relay pathways travel up. the SC to the brain
dorsal columns an anterolateral columns
what is the dorsal columns responsible for
conscious proprioception , light touch
what is the anterolateral columns responsible for
pain and temp
where does crude awareness have to go
to the thalamus
for detailed awareness where does sensory information has to go
somatosensory cortex and be processed there
what is stereognosis
being able to identify an object with tactile manipulation with eyes closed
where is the 1st order neurons for the dorsal column medial lemnicus pathways
dorsal root ganglion and then enter gray matter of dorsal horn
where is the second order neuron in the DCML
medulla and then goes up to the thalamus
where does the axons cross in DCLM
2nd order neuron in the medulla , cross at the midline as internal accurate fibers and then ascen to DCLM pathway
when does the 1st synapse happen in the DCML
in the nucleus gracilis or cuneatus depending where it is coming from
where is the 3rd order neuron in the DCML
in thamlus and then going to the pormary somatosensory cortex ( post central gyrus)
what is the secondary somatosensory gyrus
immediately post to primary , processes info from primary somatosensory gyrus and thalamus from sterognosis and sensory
what is the anterolateral pathways responsible for
crude touch , pain , temp
what pathways does the anterolateral pathways have
conscious and divergent
what is the lateral spinothalamic tract responsible for
fast nociception and temp
what is the anterior spinothalamic tract responsible for
crude tube
what do C fibers transmit
crude touch
what do A- delta and C fibers transmits
temp
what fo A- delta fibers with free nerve ending transmit
fast nociception ( mechanical)
where does the lateral spinothalamic tract cross at
anterior commissure in the SC
where does the 3rd order neuron go in teh lateral spinothalamic tract
synapses in the thalamus and goes thru the internal capsule and goes to primary and secondary association of somatosensory cortices
slow nociception that reach conscious awareness go thru what
spino emotional pathway
what are the 1st order neurons for slow - medial nociception ( c fibers)
c fibers with free nerve endings that synapse in the dorsal horn
what are the 2nd order neurons of the slow - medial nociception
projection neurons ascend to reach midbrain , reticular formation (pons) and emotion areas thru sc in 3 tracts
what are the 3 tracts that the 2nd order neurons go thru for slow - medial nociception
spinomesencephalic
spinoreticular
spino-emotional
what is the spiniomescencephalic
it is the superior colloculus and periaqueductal gray matter in the midbrain
what is the spinoreticualr
reticular formation
what is the spino - emotional
thalamus then going to anterior cingulate gyrus , insula , amygdala, dorsolateral prefrontal cortex
wher does subconscious temperature transmit to
reticular formation , thalamus l subcortical nuclei , and hypothalamus
what are spinocerebellar tracts
non conscious relay tracts that are very important for unconscious postural and movement adjustments
where does the posterior/ dorsal spinocerebellar tract come from and does it cross
form LE and lower body and doesn’t cross
where is the 1st order neuron for the posterior spinocerebellar
cell body at the dorsal root ganglion and then synapses at the clark’s nucleus in the dorsal gray matter
where is the 2nd order neuron posteior spinocerebellar tract
forms the post. spinocerebellar tract within the fasciculus gracilis and then goes thru the inferior cerebellar peduncle to cerebellar cortex
so if there is a problem in the right side of the cerebellum what side of the ebody will be affected
right side
where does the cuneocerebellar comes form
face , neck , UEs, and upper body
in the cuneocerebellar tract where does the 1st and 2nd order neuron synapse
lateral cuneate nucleus in medulla and then enters thru inferior cerebellar peduncle
what are examples of the internal feedback tract
anterior spinocerebellar and rostrospinocerebellar tract
what is the path for the anterior spinocerebellar tract
cell bolts in the spinal throacolumbar gray matter in ventral horns and then axons cross the midline of the SC and ascend to the midbrain and then fibers go thru the superior peduncles and most of them cross a 2nd time to go to the cerebellum while other stay contractleral
during the anterior spinocerebellar tract each cerebellar hemisphere receives input from
B sides of body
where do the internal feedback tract start
inside of the spinal cord
what is the path for rostrospinocerebellar tract
get info from cervical sc and T1 to ipsilateral cerebellum thru inferior and superior cerebellar peduncles
when we use sensory information to anticipate needs for movement we use
feedforward mechanisms
when we use sensory information during or after the movement we are using
feedback mechanisms
is the gray matter or white matter filled with cell bodies
gray
what cells are the primary output cells in the cerebrum
pyramidal cells
what is the white matter filled with
axons
what fibers extend from the sub cortical to cerebral cortex or from cortex to SC brainstem , basal ganglia ,and thalamus
projection fibers
what connects homologous areas of hemispheres
comissural fibers
what fibers connect cortical regions within 1 hemispheres can be long or short
association fibers
what are the internal capsule do
project fibers either to the brian or from the brain to the sc
where do descending motor tracts originate form
in the cerebral cortex ( pyramidal) or brainstem (extrapyramidal)
where do descending motor tracts descend to
descend to down to synapse with alpha or gamma MNs and/or interneurons in the brainstem or SC
what adjusts the motor tract activity of the descending motor tracts
cerebellum and motor aspects of basal ganglia
where do postural/gross movement synapse at in the motor tract
mediakky
where do fine movement synapse at in the motor tract
laterally
what are the 2 pyramidal tracts
corticospinal and corticobulbar tract
what is the function of the lateral corticospinal tract
voluntary limb and fractionates movement
what is the function for the medial corticospinal tract
automatic trunk and proximal movements
what is the function for the corticobulbar tract
face
the pyramidal tracts come from where
the primary motor cortex and premotor cortex
whar are the 2 extrapyramidal tracts
reticuolospinal and vestibulospinal tract
what does the reticulospinal tract facilitate
postural and gross llimb movements , coordinates trunk and prox muscles of 4 limbs of walking and anticipatory postural changes for reaching
there are abnormal synergies post BI due to ______ writhing adjustments from ____
reticulospinal tract
what is the function of the medial vestibulospinal tract
takes informatiom about head movement and position form vestibular apparatus and affects activity of neck and upper back
what is the function of the lateral vestibulospinal tracts
info about gravity from vestibular apparatus facilitating MNs to extensors when head is upright
what is the path for the reticulospinal tract and vestibulospinal tract
Originate in the BS and then comes down to the ventral horn of their tract and and then leave
in the corticospinal tract what is the flexor - extensor rule for LMNs in the SC
MNs that innervate flexor mm are located more posteriorly to MNs that innervate extensors
talking about thru the tract on the SC
in the corticospinal tract what is the proximal - distal rule for LMNs in the SC
MNs that inn distal mm are located lateral to MNs that innervate proximal mm
talking about the tract on the SC
where does the lateral corticospinal tract cross
decussates at pyramidal decussation of medulla
where does the medial CST cross
it doesn’t cross
where does the lateral CST originate from
primary motor cortex
where does the medial CST originate from
promoter cortex
where does the lateral CST descends thru
laterla funiculus of sc
where does the medial CST descend thru
medial / ventral funicuclus of SC ( anterior white matter)
what is the difference between the pathway for the lateral and medial CST
the lateral CST comes from the primary motor cortex and the medial CST comes from the promotor cortex they both travel down but the lateral crosses at the pyramidial decussation at the medulla and the medial CST does not cross and the lateral CST descends in the lateral funiculus of SC and the medial CST descends in medial funiculus of SC and they both synapses on interneurons or Mns in ventral horn
what do nonspecific motor tracts facilitate
activity of interneurons and MNs in SC
when are nonspecific motor tracts active
during intense emotions
what are examples of the nonspecific motor tracts
ceruleospinal tract and raphespinal tract
where does the ceruleopspinal tract originate and release
originates from locus coeruleus at junction between midbrain and pons and releases norepinephrine for tonic facilitation of spinal MNs
where does the raphespinal tract originate and release
originates from raphe nuclei of upper medulla and release serotonin to modulate spinal MNs
what does the corticobrainstem tracts provide
voluntary control of many mm of head and head
what is the path of the corticobrainstem tracts
originate in the cerebral cortex’s motor areas and reach CN nuclei in brainstem to activate MNs that innervate mm of face , tongue , pharynx , larynx and traps and scm
where is the primary motor cortex
precentral gyrus
where is the premotor cortex
immediately anterior to primary motor cortex , lateral surface
what is the function of the premotor cortex
prepares for movement esp those that invovled serval joints
where is the supplementary motor cortex
immediately anterior to primary motor cortex, superior and medial surface
what is the function of the supplementary motor cortex
replanning movements
what are signs or motor tract lesions
paresis
abnormal reflexes
myoplasticity
abnormal muscle tone e
loss of fractioned mvmt
abnormal cocontraction
what kind of fibers is the corpus callosum and anterior commisure
commissural fibers
cingulum , short associayion fibers , superior longitudinal fasciculus and inferior longitudinal fasciculus are exmaples of what type of fibers
association fibers
what is an example of projection fibers
internal capsule
