Practice question · True or false
A patient whose spinal cord is completely severed above the knee still shows a knee-jerk reflex when the tendon is tapped, even though the brain can no longer feel or move the leg.
Hints
- The knee-jerk is a spinal reflex arc - where is it wired?
- If the arc lives entirely in the cord below the cut, the brain's disconnection need not abolish it.
Show the answer
True
Why
True. The knee-jerk reflex arc is contained in the spinal cord, so it can still fire when tapped even though the severed cord blocks sensation and voluntary movement from reaching or leaving the brain. This is direct evidence that spinal reflexes do not require the brain.
Practise Central Nervous System
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