Not sure Poll’s faith in me is justified!
I think that the first three scores out of five are a measure of spasticity (i.e. tight muscles). The higher the number, the worse the flexibility of the muscle / action. Dorsiflexion & plantarflexion bending your foot at the ankle (dorsi is toes up, plantar is toes down). Had to google extensor hallus longus. The extensor hallucis longus is a muscle that moves the big toe. So it seems that your foot movements are quite stiff; your big toe slightly less so. Spasticity is a sign of a problem with the upper motor neuron (the pathway between the brain and the nerves to the muscles that tells the muscle to relax).
Brisk reflex can be normal, but I don’t know why they would note it like this is if it was, so I guess it was abnormally brisk.
Myoclonus is jerks / spasms in which bits of the body move involuntarily - the sort of thing that anyone can get when falling asleep. Clonus is also a muscle contraction thing but with repeats, like a regular beat. I’m wondering whether the person writing the report meant myoclonus or clonus? A reflex test that elicits lots of beats of clonus is the highest end of the scale (no response is the lowest).
Downgoing/upgoing plantars refers to when the neuro scrapes the sole of your foot. Downgoing (when your sole arches away from the scrape and your big toe goes down) is normal. Upgoing or an extensor movement (big toe going up, sole pushing into the scrape) is abnormal. From this and your reflex result, it’s your right side that’s got the problem.
All of these things are related to the upper motor neuron I think.