Central somatosensory pathways Flashcards
Are the dorsal columns grey matter or white matter?
White matter
What sort of information travels in the dorsal columns?
Ascending sensory information from the tactile receptors
How are the dorsal columns organised?
Segregated into topographic regions
How many neurons are involved in the tactile mechanoreceptive pathway?
Three neurons
Where does decussation occur in the tactile mechanoreceptive pathway?
Caudal medulla
Where does information from the tactile mechanoreceptive pathway travel to in the brain?
Somatosensory cortex
How far up does the first axon in the tactile mechanoreceptor pathway travel?
To medulla
Then meets next neuron
What are the dorsal column nuclei called?
Gracile nucleus and Cuneate nucleus
What areas of the body do the gracile and cuneate nuclei transmit information about?
Gracile: lower limb
Cuneate: thoracic and cervical regions
What are the internal arcuate fibres?
Internal arcuate fibers are the axons of neurons within the gracile and cuneate nuclei of the medulla oblongata.
These fibres cross from one side of the medulla to the other to form the medial lemniscus.
Where are the gracile and cuneate nuclei located?
Medulla
What happens to the axons in the tactile mechanoreceptor pathway once they leave the dorsal column nuclei?
Enter medial lemniscus
Twisting: dorsal goes to ventral
‘Bundle of fibres that form a ribbon’
What happens to the axons in the tactile mechanoreceptor pathway when they leave the medial lemniscus?
More twisting > orgnaising topography for somatosensory cortex
Go to thalamus > terminate in ventral posterolateral nucleus
Where in the thalamus do axons in the tactile mechanoreceptor pathway terminate?
Ventral posterolateral nucleus
Where does the ventral posterolateral nucleus project to?
Cerebral cortex (somatosensory cortex)