Abbreviation: DTR
A reflex to test the integrity of a sensory and motor neuron circuit. Upon tapping of the reflex hammer, activation of the dorsal root ganglion causes firing of the lower motor neuron for the agonist muscle and relaxation of the antagonist muscle, resulting in automatic movement. An increased DTR indicates an upper motor neuron issue, whereas decreased DTR indicates a LMN, neuromuscular junction, or muscle issue.