Nervous system

A nervous system was a being's network of nerves and axons that enable control of the body.

The Third Doctor speculated that the Nestene creature in Channing's tank was a kind of brain or nervous system, humanly speaking. (TV: Spearhead from Space)

Sutekh said he could shred the Fourth Doctor's nervous system into fibres and draw the pain out for centuries. (TV: Pyramids of Mars)

Mehendri Solon required the head from a species with a central nervous system to complete Morbius' body. (TV: The Brain of Morbius)

The Hoothi infected other creatures, usually having better control over ones with more complex nervous systems. (PROSE: Love and War)