ASCENDING TRACTS

Question 1

what are the 2 major Ascending tracts?

Answer 1

Dorsal column tracts/medial lemniscus system
Spinothalamic tract (ant & lateral)

Question 2

sensations controlled by Dorsal column tracts/medial lemniscus system

Answer 2

fine touch
conscious proprioception
vibration

Question 3

Dorsal Column tract pathway

Answer 3

first order neurone in the DRG –> enters SC via dorsal horn and ascends upwards through the Fasiculus gracilis (LL) and Fasciculis cuneatus (UL) –> terminates in the nucleus gracilis and nucleus cuneatus of MO –> 2nd order neurons in the NG and NC –> crosses over to the contralateral side –> ascends together as MEDIAL LEMNISCUS –> passes through the pons and midbrain –> 2nd Order neurone terminates in the Thalamus –> 3rd order neurone in the thalamus –> cortex (according to the homunculus)

Question 4

sensations controlled by spinothalamic tract/spinal lemniscus system

Answer 4

Pain & Temperature (lateral STT)
Deep pressure

Question 5

Spinothalamic tract pathway

Answer 5

first order neurone in the DRG –> enters spinal cord via dorsal horn –> synapse with the second order neurone in the dorsal horn –> SON crosses almost immediately to the contralateral side –> ascend to medulla, pons, midbrain all the way unto the thalamus –> synapse with the third order neurone in the Thalamus –> TON travels to the cortex (according to the homunculus)