W5- Sensory system of the brain

what is the dorsal column medial lemniscus system responsible for?

-fine touch

-pressure

-vibration

-conscious proprioception

where do the primary sensory neurons of the dorsal column pathway synapse in the spinal cord?

dorsal root ganglion

where are the fasciculi involved in the dorsal column pathway?

-cuneate fasciculus- lateral, receives info from T5 and above

-gracile fasciculus- medial, receives info from T6 and below

where does the dorsal column pathway decussate?

medulla

(travels ipsilaterally up the spinal cord)

where do the neurons of the dorsal column pathway and spinothalamic tract synapse?

primary= dorsal root ganglion

secondary= medulla

tertiary= thalamus

(then travel to primary sensory cortex through internal capsule)

what is the primary sensory cortex?

postcentral gyrus

what is the spinothalamic tract responsible for?

-pain

-temperature

-crude touch

-two point discrimination

where does the spinothalamic tract decussate?

in the spinal cord 2-3 levels above point of entry

(travels contralaterally in the spinal cord)

what is the function of the spinocerebellar tract?

responsible for proprioception to the cerebellum

what is the pathway of the spinocerebellar tract?

-primary neuron synapses in Clarke's nucleus (dorsal root ganglion)

-anterior spinocerebellar tract decussates twice- at anterior white commissure and superior cerebellar peduncle

-posterior spinocerebellar tract remains ipsilateral

-travels to cerebellum

what is the clinical presentation of a lesion in the parietal cortex, internal capsule or thalamus?

contralateral sensory deficit

(lesion occurs after decussation of dorsal column pathway and spinothalamic tract)

what is the clinical presentation of a lesion in the spinal cord?

-contralateral spinothalamic loss (due to decussation occurring 2-3 spinal segments above point of entry)

-ipsilateral dorsal column loss (due to decussation having not yet occurred as not yet reached medulla)