The USDA created the food pyramid to encourage a healthy diet, but the USDA also has a mission to encourage agricultural products grown in the US. There can be a LOT of conflict between those two goals. So the food pyramid (ahem, I mean MyPlate) is not simply an objective summary of the available evidence.
The stretch reflex (myotatic reflex) is a muscle contraction in response to stretching within the muscle. It is a monosynaptic reflex which provides automatic regulation of skeletal muscle length. When a muscle lengthens, the muscle spindle is stretched and its nerve activity increases.
patellar reflex. a deep tendon reflex, elicited by a sharp tap on the tendon just distal to the patella, normally characterized by contraction of the quadriceps muscle and extension of the leg at the knee. The reflex is hyperactive in disease of the pyramidal tract above the level of the second lumbar vertebra.