week 4 lectures (tract tracing)

Question 1

what happens when you cut an axon and how can this be used in tracing?

Answer 1

• the cell will degenerate
• the cell will lose its myelin
• the history of the loss of this myelin can be logged using a myelin stain

Question 2

where do the axons switch to the different side of the brain

Answer 2

between the hindbrain and the spinal chord

Question 3

what happens to the ascending axons when there is myelitis at a section of the spinal chord?

Answer 3

axons that entered the spinal chord below the lesion are severed and so those axons lose their myelin

axons that enter the spinal chord above the lesion have preserved myelin

Question 4

what do the ascending dorsal tracts convey information about and what are the different types?

Answer 4

touch, pressure

cuneate tract is upper body
gracile tract is lower body

Question 5

what are the two types of spinocerebellar tracts and what information do they convey?

Answer 5

dorsal and ventral

they convey information about proprioception

Question 6

what are the two descending corticospinal tracts and what information do they convey?

Answer 6

lateral and ventral

motor information

Question 7

are the lateral and ventral corticospinal tracts crossed or uncrossed pathways?

Answer 7

the lateral is crossed

the ventral is uncrossed

Question 8

what is a key feature of brown sequard syndrome?

Answer 8

limbs below site of lesion are effective

if right leg is losing touch and pressure sensation, the right leg is losing pain and temperature sensation and vice versa