neuro - basics (NTK!) Flashcards
gracile and cuneate tract separated by ?
post intermediate sulcus
gracile tract starts from ?
sacral and coccygeal input
cuneate tract starts from?
around T6-T5
in the ‘dorsal column tracts’
sacral region is located more _
cervical region is located more_
vs
in the ‘lateral tracts’ (asc. spinothalamic and desc. corticospinal)
cervical region is located more _
sacral region located more _
dorsal column
sacral = medial
cervical = lateral
lateral tracts
cervical = medial
sacral = lateral
BODY - dorsal column medial lemniscus
information for…
pathway..
1st origin.. travel.. travel .. * synapes and terminate..
2nd origin.. decussate.. travel.. synapse and terminate..
3rd
origin..
terminate
Dorsal column medial lemniscus (asending)
- upper limb = fasciculus cuneatus (T6-C2)
- lower limb = fasciculus gracilis (sacral and coccygeal)
- touch
- press
- proprioception
1st
origin = DRG
travel = asc. or desc. - 1 or 2 levels in the lissaur’s tract
travel up *not decuss yet =
dorsal column fasiculus (gracilus or cuteatus)
synapse and terminate =
ipsi. nucleus gracilis or cuneatus - in (closed medulla)
2nd (a "projection neuron") origin = closed medulla decussate = closed medulla travels up = medial lemniscus synapses and terminate = thalamus (VPL)
3rd
origin = thalamus (VPL)
terminate = cortex (on respected homunculus area of somatosensory cortext/ postcentral gyrus)
BODY - anterolateral / spinothalamic
information for..
pathway..
1st
origin =
travels =*
synapse and terminate =
2nd (a "projection neuron") origin = decussates = travels up = synapses and terminate =
3rd origin = terminate = lower limb- upper limb
anterolateral / spinothalamic (ascending)
- pain and temp (lateral)
- crude touch (anterior)
1st
origin = DRG (at level of spinal cord)
travel*= 1 or 2 lvls - lissaur’s tract
synapse and terminate = ipsi. dorsal horn
(rexed lamina lvl 2 = substantia gelatinosa)
2nd (a “projection neuron”)
origin = dorsal horn (at level)
decussates = anterior white commissure (at level)
travels up = spinal lemniscus contralaterlly
(aka sp.thal tract past medulla)
synapses and terminate = thalamus (VPL)
3rd origin = thalamus (VPL) terminate = somatosensory cortex / postcentral gyrus (on respected homunculus area) lower limb - superior cortex upper limb - lateral cortex
descending pathways exit through..
- through vental ROOT
subparts of the anterolateral / spinothalamic system ? * 4
- spino/thalamic
- spino/reticular
- spino/mesencephalic or spino/tectal
- spino/hypothalamic
- spinothalamic (direct, main one, pain/temp/crude touch)
- spinoreticular ( indirect, c. alertness and arousal in response to stim, activation of the noradrenergic system - termiate brainstem norepinephrin NE neurons and reticular formation)
- spinomesencephalic / spinotectal (indirect orients the head and eyes towards stimulus)
- spinohypothalamic (pain evoked endocrine response)
name anterolateral system 1st 2nd 3rd order neurons
1st = sensory neuron 2nd = interneuron 3rd = relay neuron
BODY - corticospinal tract
*** upper motor neurons / lower motor neurons
information for..
pathway..
1st upper motor neuron origin= travel = travel = and become travel = decuss = 85% fibres - travel in= synapse= terminate =
2nd - lower motor neuron
orig =
term=
cont. travel ipsi= 15% continue as decussate = synapse = terminate = 1. 2. 3.
cortico/spinal tract (descending)
- lateral cortico = appendicular mus
- anterior cortico = axial mus
85%
1st upper motor neuron
origin= primary motor cortex (precentral gyrus)
travel = internal capsule
travel = cerebral peduncle (become in medulla)
travel = medulla - ‘pyramidal tracts’
decuss = 85% fibres - medulla pyramids
(junction of medulla and sp. cord)
travel in= lateral corticospinal tract
synapse= contra. ventral horn, syn w lower motor neuron/ terminate = at level sp. cord
2nd - lower motor neuron
orig = ventral horn
term= (appendicular) mus
15%
cont. travel ipsi= 15% continue as anterior corticospinal tract
decussate = anterior white commisure (at level sp. cord)
synapse = contra. ventral horn (at spinal level)
terminate = lower motor neurons (axial mus)
*trunk mus
*posture mus
*subconcious controlled mus
HEAD - spinal trigeminal tracts / trigemino-thalamic system
Sensory
- spinal trigeminal pathway
- chief sensory trigeminal pathway
- mesencephalic
information for .. pathway... 1st -touch, pressure, prop (chief sensory) origin = enter = synapse/term = decuss = mid pons vs - pain and temp (spinal trigeminal) origin = enter = travel= synapse = *for chief some stay ipsilateral for propriocetion - mesencephalic (reflex proprioception)
2nd orig= decuss = ascd = synapse and terminate =
3rd
orig =
term =
spinaltrigeminal tract
Sensory
- pain and temp (HEAD) = spinal trigeminal nucleus
- touch, press, proprio (HEAD) = chief sensory nucleus
- reflex proprioception (HEAD) = mesecephalic
1st -touch, pressure, prop (chief sensory) origin = trigeminal ganglion enter = mid pons (level) synapse/term = - ipsi. mid pons > chief sensory nucleus decuss = mid pons vs - pain and temp (spinal trigeminal) origin = trigeminal ganlion enter = mid pons travel= desc to caudal medulla synapse = ipsi. caudal medulla > spinal trigeminal nucleus
- for chief some stay ipsilateral for propriocetion
- mesencephalic (reflex proprioception)
2nd origin= caudal med (spinal tri nucl) or pons (chief sens nu) decuss = caudal medulla or pons ascd = trigeminal lemniscus synapse and terminate = thalamus (VPM)
3rd
orig = thalamus VPM
term = ipislateral cortical areas (SI and SII)
mechanoreceptors *4
- meissner (corpuscles) = motion detection/grip control
- merkel (cells) = shape/texture
- ruffini (corpuscles) = tangential force, hand shape, motion detection
- pacinian (corpuscles) = distant events thu vibration
Sensory for the HEAD comes mainly from… nerves
but also from…nerves
mainly - cn 5 (trigeminal)
but also
- cn 7 facial
- cn 9 glossopharangeal
- cn 10 vagus
HEAD - corticobulbar pathway
(not tract more just fibres - bulbar means brainstem)
Motor
pathway..
corticobulbar
- motor (HEAD)
1st
origin = primary motor cortex (precentral gyrus)
travel =
-internal capsule
- cerebral peduncles (wh become) corticobulbar fibres
- leave the tract
synapse = cranial nerve nuclei (equiv to ventral horn neurons)
HEAD - corticobulbar pathway
(not tract more just fibres - bulbar means brainstem)
Motor
pathway..
corticobulbar
- Motor pathway (spinal 5)
1st
origin = primary motor cortex (precentral gyrus)
travel =
-internal capsule
- cerebral peduncles (wh become) corticobulbar fibres
- leave the tract
synapse = cranial nerve nuclei (equiv to ventral horn neurons)
A patient has impaired sensation of pressure and vibration in his left leg. Which of the following structures is most likely damaged?
Left fasciculus gracilis
Which of the following statements best describes the anterolateral pathway?
2nd order neurons decussate in the spinal cord 2 levels above or below the level it enters
Which of the following is a possible consequence of a lesion involving the left spinothalamic tract?
Contralateral loss of pain sensation
