Cambridge O Level Biology · Syllabus 5090 · Coordination and Control
Motor Neurone
What is Motor Neurone?
A neurone that carries electrical impulses from the central nervous system to an effector, which is a muscle or a gland. In a simplified diagram it is recognised by a cell body at one end, carrying many dendrites, with a long fibre leading away to the effector.
This definition is part of the Coordination and Control chapter in Cambridge O Level Biology.
Common mistakes with Motor Neurone
- A wiring point students invent. Not every pathway contains all three neurones, and the syllabus does not claim it does. What you must be able to describe is the reflex arc, which does contain all three. Do not write that a sensory neurone connects directly to a muscle: sensory neurones end in the CNS, and the instruction to a muscle always leaves along a motor neurone.
Questions students ask about Motor Neurone
What is the order of a reflex arc?
Stimulus, receptor, sensory neurone, relay neurone in the central nervous system, motor neurone, effector, response. The effector is a muscle or a gland, and the impulse never travels backwards along this pathway.
Last reviewed Syllabus 2026-2028