Smooth muscle

-Nonstriated, uninucleated and spindle-shaped fibers -Involuntary control -occur inside the body in places where structures need to be constricted or dilated to function. This includes the muscles that regulate the size of the pupil of the eye, constrict arteries when you are cold or dilate them when you have been running, and the muscles around the gut tube which enable it to pass contents all the way through