As their name suggests, the interneurones are found between two other neurones. Functionally their role is to provide the axon link and to transmit information.
They are often found in the bone marrow where they transmit movement instructions: while a single afferent neurone leaves the brain to give an instruction to move, two interneurones record the information. An interneurone activates the flexor muscle whereas the second interneurone inhibits the extensor muscle via transmission of two signals to the motor neurones.
The interneurones form a link between the afferent and motor neurones. DR Credits