Motor neurones originate in the motor cortex of the brain (their cell bodies making up itâs grey matterâŠcell bodies are where the âcomputingâ goes on). These send their axons (their âwiringâ) down through the the body of the brain, through the brainstem and to the spinal cord (theses are called the pyramidal tracts) These are the upper motoneurones. In the spinal cord, they connect (via a âsynapseâ) to a very short interneurone which only traverses the spinal cord and synapses with another motoneurone which leaves the spinal cord (via the ventral root) and goes to the muscle it supplies. This is the lower motoneurone! So upper motoneurone is brain to spinal cord, lower motoneurone is spinal cord to muscle.
This is why the person in the clip, inexplicably dressed as a pig, was wrong with his answer.
Itâs fun to be talking about this stuff again