Practice question · Multiple choice
A patient with a complete spinal transection at the neck still shows a knee-jerk reflex when tapped, despite feeling nothing below the injury. What does the surviving reflex reveal?
Hints
- Trace the arc: receptor, spinal cord, muscle. Which of those is above the cut?
- The patient feels nothing, so awareness and the reflex are running on different wiring.
Show the answer
D. That the circuit is complete within the spinal cord
Why
The arc is entirely below the injury: sensory neuron in, motor neuron out, no brain required. Feeling the tap needs an ascending pathway that has been cut, so the leg moves and the patient never knows. The spinal cord is a processor in its own right, not a cable to the brain.
Practise Central Nervous System
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