Three separate longitudinal ribbons of smooth muscle on the outer surfaces of the colon are known as

he Taeniae coil

Explanation:

The mesocolic,free and omental taeniae are collectively known as TAENIAE.

They are the 3 ribbon of smooth muscle of the ascending,transverse, descending and the sigmoid  colon. Anatomically their longitudinal   contractions give the natural bulges(HAUSTRAL) in the colon.

The Haustral helps in translocation of chyme to the next haustral, and  aiding the mixing of chyme for water absorption in the colon,  

The coil of these  smooth muscles is under the parasympathetic nervous system through Sacral nerve (of the spinal cord)  innervation.