effector

One who or that which brings about an event or result, accomplishes a purpose, etc.

• Yea; and I devised Numbers—high art!—and letters’ composition, / And memory, effector of all things, / And mother of the Muses: […]

Any muscle, organ etc. that can respond to a stimulus from a nerve.

The part of a nerve that carries a stimulus to a muscle etc.

Any small molecule that effects the function of an enzyme by binding to an allosteric site.

An actuator.