A complex system of intermediate neurons. found mostly in the brain. join the afferent with the efferent pathways. 

He believes that every instinctive process consists of an afferent part or message. a central part. and an efferent part or discharge. 

In some cases ligation of the afferent vessels has been successful. 

The respiratory center is also connected by afferent nerves with the mucous membrane of the air passages. 

There are two sets of nerve-fibers. those which transmit sensory impulses. called afferent or sensory nerves. and those which transmit motor impulses. called efferent or motor nerves.