The pattern of nerve supply differentiates smooth muscles into two different categories. It is better to explain these classes to understand the nerve supply of smooth muscles.
Single-Unit type smooth muscles:
These muscles are seen in the intestine. The nerve impulses reach one muscle cell and are transmitted to neighboring cells by mechanical pull through the fused cell membrane. Thus the nerve supply is sparse. This type of smooth muscle is know as single-unit type because when an impulse arrives, the whole mass contracts simultaneously as one single unit.
Multi-Unit type smooth muscles:
They are seen in the muscles of ductus deferens. Each muscle cell receives a separate nerve fiber. Because of separate innervation of muscle fibers, these muscles allow fine control over their contraction, much similar to the case of skeletal muscles. Their nerve supply is very rich.