Somatosensory pathways and receptors (Dr. Duas) Flashcards
What are the two types of cutaneous receptors for conscious proprioception
rapidly adapting and the slowly adapting receptors
function of rapidly adapting receptors
respond to application and removal of the stimulus but NOT during maintained stimulation
function of slowly adapting receptors
active as long as the stimulus is present
merkels disk senses
pressure
paccinian corpuscle senses
vibration
meissner’s corpuscle senses
tactile impulse
ruffini’s endings sense
pressure
pathway for conscious proprioception from the limbs and the trunk ?
PCMLS pathway
Pathway for PCMLS pathway
Primary afferent
fasiculus cuneatus/fasciculus gracilis–>fasiculus cuneate nuclei within the medulla–>medial lemniscus–>VPL of thalamus
fasciculus gracillis
sacral, lumbar and lower thoracic levels
fasciculus cuneatus
upper thoracic and cervical levels
in the alternative PCMLS pathway where do the synapses occur
lamina II and IV, as well as the typical cuneatus nuclei and gracillis nuclei
what provides conscious proprioception from the head
anterior and posterior trigeminothalamic tracts
describe the posterior trigeminothalamic tract
synapses in principal nucleus and ascends via the PTTT (does NOT cross the midline) to VPM
describe the anterior tigeminothalamic tract
principal nucleus, crosses midline and ascends via ATT to VPM
where is the primary central cortex located ?
post central gyrus
if you have lesion in area 1 of the PSC what do you lose ?
loss of texture and discrimination
if you have a lesion in area 2 of the PSC what do you lose ?
loss of size and shape discrimination
what is asterogenesis
loss of size and shape
if you have a lesion in area 3b of the PSC what do you lose?
diminished texture discrimination and asterogenesis (loss of size and shape)
cutaneous receptors are found where in PSC
3b and 1
proprioceptive receptors are found where in PSC
3a and 2
where is the second somatosensory cortex found (SII)
inner face of the upper bank of the lateral sulcus
the secondary somatosensory cortex is supplied by
middle cerebral artery
lesion of the posterior spinal artery leads to injury to what
posterior columns (PCML pathway)
lesion of the anterior spinal artery would injury what
medial lemniscus (PCML pathway)
lesion of the thalamogeniculate branches of the posterior cerebral artery would result in injury to
VPL and VPM
injury to the anterior and middle cerebral arteries would injury the
primary sensory cortex
lesion to the basilar and superior cerebellar arteries would result in injury to
basilar and superior cerebellar arteries
what are the two pathways for nonconscious proprioception ?
spinocerebellar pathway
trigeminocerebellar pathway
spinocerebellar pathway functions to
sensory information from the limbs and the trunk
trigeminocerebellar pathway functions to
sensory information from the head
nonconscious proprioception to lower limb
anterior spinocerebellar tract
posterior spinocerebellar tract
nonconsciocus proprioception to the upper limb
rostral spinocerebellar tract
cuneocerebellar tract
which two spinocerebellar pathways are mostly mechanoreceptors
anterior spinocerebellar
rostral spinocerebellar
what is friedrich ataxia
congenital autosomal recessive disease-degeneration of the spinal cord pathways including spinocerebellar tracts leading to lack of coordination during walking and other movements
where do the primary afferent fibers synapse in the spinocerebellar tract
posterior tract-dorsal nucleus of clark (lamina 7-T1-L2)
anterior tract- lamina 5, 8, spinal border cells of L3-L5
which part of the tracts for lower limb of the spinocerebellar tracts are mostly cutaneous mechanoreceptors
anterior spinocerebellar tract
which tract of the spinocerebellar tracts cross the midliine
anterior spinocerebellar tract (anterior commissure)
the spinocerebellar tracts enter the _________before they ascend into the lateral cerebellar vermis
restiform body (the rostral spinocerebellar tract also enters the cerebellar peduncle)
where does the rostral spinocerebellar tract synapse before ascending up the spinal cord
lamina VII (C4-C8)
Describe the Pathway of the cuneocerebellar tract ?
primary afferent fibers ascned via the cuneocerebellar tract and synapse in the lateral cuneate nucleus enter the restiform body and enter the medial cerebellar vermis (does not cross midline)
describe the pathway of the rostral spinocerebellar tract ?
primary afferent fibers synapse in lamina VII to anterior spinocerebellar tract through restiform body and cerebellar peduncle to the LATERAL cerebellar vermis (does NOT cross the midline)
what are the main pathways of protopathic sensibility
anterolateral system (spinothalamic and spinoreticular tract
spinocerbicothalamic tract
anterior trigeminothalamic tract
A-delta mechanical nociceptors
thinly myelinated fibers
C-polmodal nociceptors
nonmyelinated fibers
describe the spinothalamic tract
primary afferent fibers
synapse in lamina 1,5, and 2
cross at each segment at the anterior commissure
ascend via ALS
axon collaterals to the reticular formation
VPL of the thalamus
types of fibers in lamina 1 and 5
a delta fibers
types of fibers in lamina 2
c fibes
describe the spinoreticular tract
parimary afferent fibers in lamina II and III, interneurons 5, 8, cross at anterior commisure and ascend via anterolateral : spinoreticluar fibers and VPL of thalamus
where does the spinocervicothalamic tract synapse
limain III, IV, acsends and then lateral cervical nucleus and then crosses midline
protopathic for the head
ATT tract, synapses in spinal trigeminal nucleus and acsends via ATT and enters VPM
what is wallenberg syndrome
lesion of the posterior inferior cerebellar artery resulting in CONTRALATERAL loss of pain, temperature and crude touch over the body and ipsilateral loss over the face
rupture of arterila vasocorona between the ant. and post. spinal arteries would injur
spinal als
posterior inferior cerebellar artery would injure
medullary ALS and spinal trigeminal nucleus
injury to the thalamogeniculate branches of the posterior cerebral artery would injur
VPL and VPM
injury to the anterior and middle cerebral arteries would injur
primary sensory cortex
syringomyleIA
cystic cavitation of the central regions of the spinal gray matter; destruction of the decussating ALS fibers in the anterior commisure
where is pain perceived
at the subcortical levels
what pathway seems necessary to localize pain
spinothalamic pathway
what pathway is important for suffering component of the pain experience (some drugs like benzodiazepines can disrupt this component)
spinoreticular
VPL injury causes what type of pain
transient release of pain
VPM injury causes what type of pain
long lasting pain relief
function of enkephalingergic neruons
they suppress the activity of pain fibers
