anatomy and physiology mcqs

Question #366

Which of the below is the most suitable combination of electrodes for recording a nerve action potential?

The region under the stimulating anode will become hyperpolarised, potentially resulting in conduction block ('anode block') if this electrode is placed in the path of the advancing action potential wave. 1 should therefore be the stimulating anode. The stimulating cathode (2) is place next to 1.

It is conventional to place the recording anode (4) downstream of the recording cathode (5): inverting these electrodes will invert the waveform recorded.

The earth electrode (3) is placed between the stimulating and recording electrode pairs in order to minimise stimulus artefact.

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