What is a polysynaptic reflex arc?

Polysynaptic reflex arcs contains two synapses one between the motor and relay neurone and one between the relay and sensory neurone. Both off these synapses are in the spinal cord. And allows you to respond to a stimulus for example moving your finger away from a pin after a pin prick.

A Polysnapytic reflex arc, is a reflex arc composed of multiple neurons and thus synapses too (poly). The impulse is carried from the sensory neuron to the interneuron (in the spine) and directly to the motor neuron which can make an action take place. This is an extremely quick impulse and it does not go up to the brain.

When a reflex arc is polysynaptic it means that multiple interneurons ( another name for these are relay neurons) interface between the sensory and motor neurone in the reflex pathway. This produces coordinated patterns of muscle activity to remove a part of the body from a potentially harmful stimulus.