Somatosensory system 2 Flashcards
Where does the dorsal column medial lemniscal pathway decussate?
All fibres decussate together in the brain stem
Medulla
Which senses is the DCML responsible for?
Discriminatory touch
Pressure
Vibration
Concious proprioception
Which type of fibres does the DCML carry information through?
A alpha and A beta
Where does decussation occur in the Spinothalmic tract?
At all levels of the cord, they do not decussate together
Which senses is the STT responsible for?
Pain Thermosensation Crude touch Itch Tickle
Which fibres carry signals in the STT?
A delta and C fibres
What is brown sequard syndrome?
Severance of half the spinal cord
Pain lost on contrlateral side
Touch and proprioception lost on ipsilateral side
Which tracts make up the DCML?
Medial fasciculus gracilis and fasciculus cuneatus
The fasciculus gracilis provides sensory input where?
Below level T6 ie legs and lower trunk
The fasciculus cuneatus provides sensory input where?
Above T6 ie arms and upper trunk
Describe the path of the DCML from first order neurone to Somatosensory cortex?
Primary afferent enters dorsal horn Ascends via cuneate and gracilis tracts Second order neurones decussate Ascend into medial lemniscus VPL nucleus of thalamus Third order project to SS cortex via posterior internal capsule
How is information conveyed from anterior head?
Trigeminal system
Path of trigeminal system?
Vi-Viii
Soma locted in trigeminal sensory ganglion
Synapse on second order neurones in chief sensory nucleus or spinal nucleus
Decussate and project to VPM nucleus of thalamus
Third order to cortex via thalamocortical neurones
Where is the somatosensory cortex and what does it consist of?
Post central gyrus
Brodmann areas 1, 2, 3a and 3b
What happens to the area of somatosensory cortex when eg when a finger is amputated?
It is utilised by other sensory inputs
