Upper Motor Neurons Keep the Brake On

Upper motor neurons regulate lower motor neurons by inhibiting their activity. When upper motor neurons malfunction, lower motor neurons become overactive, leading to clinical signs such as hyperreflexia, increased muscle tone, and an up-going Babinski sign. Recognizing these manifestations is crucial in neurological examinations, where hyperreflexia serves as a key indicator of upper motor neuron issues, encapsulated in the mnemonic 'up, up, up signs' for upper motor neuron effects and 'down, down, down signs' for lower motor neuron effects.