Question

the sensory neurons send impulses from the receptors to the brain nd spinal cord nd the motor neuron sends back the messages from the spinal cord nd brain to the effectors that results in a reflex action than what is the use of relay nerves there?

Answer 1

Relay neurons are the neurons which act as the link between the sensory neurons and motor neurons. During a reflex action our brain is not consulted. Relay neuron which is present inside the spinal cord transfers the signal from sensory neurons to motor neurons for immediate activity.