TRACTS Flashcards
what can the sensory tracts be split into
Conscious tracts:
-DCML
-anterolateral
Unconscious:
-spinocerebellar tracts
what info does the DCML carry?
-vibration
-proprioception
-fine touch (tactile sensation)
which parts of the spinal cord are used in the DCML and name them
dark blue- fasciculus gracilis
light blue- fasciculus cuneatus
explain the DMCL
-peripheral nerve receptors pick up sensory info regarding fine touch (tactile sensation), vibration + proprioception and pass it onto the first order neurones
-first order neurones carry info from the peripheral nerves to the medulla oblangata
-information regarding T6 and above (upper limbs) gets carried through the fasciculus cuneatus in the spinal cord to the cuneate nucleus and information regarding <T6 is carried through the fasciculus gracilis to the gracilis nucleus in the medulla oblangate
-first order neurones synapse at the medulla oblangate and the second order neurones begin
-second order neurons begin in the gracilis/ cuneatus nucleus in the medulla oblangata where they decussate
-after decussating the second order neurons travel through the contralateral medial lemniscus to the thalamus
-second order neurons synapse in the ventral posterolateral nucleus of the thalamus
-third order neurons ascend from the ventral posterolateral nucleus of the thalamus, travel through the internal capsule and terminate at the sensory cortex
what tracts make up the anterolateral system?
anterior spinothalamic tract and lateral spinothalamic tract
what sensory info does the anterior spinothalamic tract carry?
crude touch (wisps of hair, super light touch)
pressure
what sensory info does the lateral spinothalamic tract carry?
pain + temperature
sPinoThalamic
what parts of the spine are involved in the anterior and lateral spinothalamic tract?
red circle- anterior spinothalamic tract
other red part- lateral spinothalamic tract
what sensations are felt through the anterior spinothalamic tract
ant- aunt- crude and always under pressure
-crude touch (tactile sensation)
-pressure
what sensations are felt through the lateral spinothalamic tract?
pain
temperature
sPinoThalamic
describe the spinothalamic tract
-1st order neurones carry sensory info (crude touch, pressure, temperature, pain) from the peripheral nerves synapse at the dorsal horn of the spinal cord (also known as substantia gelatinosa)
-2nd order neurones decussate in the spinal cord and form 2 tracts to carry info tothe thalamus
-pain and temperature info is carried through the lateral spinothalamic tract and pressure and crude touch is carried through the anterior spinothalamic tract
-second order neurons synapse at the thalamus
-third order neurons ascend from the ventral posterolateral nucleus of the thalamus and carry sensory signals to the ipsilateral primary sensory cortex
what is Brown- Sequard syndrome?
-when there is a hemisection (one sided lesion) of the spinal cord
-this is most often due to traumatic injury
what sensory loss will there be in brown sequard syndrome and why?
ipsilateral loss of touch, vibration and proprioception
-this is due to affecting the DCML pathway, this decussates in the medulla oblangata and so if there is a spinal cord lesion the sensory loss will be ipsilateral
contralateral loss of pain, temperature
-this is due to the anterolateral system being affected, this decussates in the spinal cord and so the sensory loss will be contralateral
what tract carries unconscious proprioception?
Spinocerebellar
How do spinocerebellar lesions present?
as ipsilateral proprioception loss
(usually also a descending pathway damaged, rarely damaged alone)
