Final answer:
The knee-jer`k reflex of the quadriceps muscle is a monosynaptic reflex found in the human body, as it involves a direct connection between a sensory neuron and a motor neuron.
Step-by-step explanation:
The monosynaptic reflex commonly found in the human body is the knee-jer`k reflex of the quadriceps. When the patellar tendon is struck with a rubber mallet, it causes a quick stretch of the quadriceps muscle. This stimulates the muscle spindle, sending a signal via the dorsal root into the spinal cord where it synapses directly with the ventral horn motor neuron, without any interneurons, thus causing the muscle to contract.
The knee-jer`k reflex is monosynaptic because it involves a direct connection between a sensory neuron and a motor neuron. This reflex is part of a neurological exam and indicates the lower motor neuron (LMN) system is functioning properly. It is physiologically important for maintaining stability and muscle length.