How can you determine function of a muscle simply by looking at the anatomy?

Yes, you could. Smooth muscles are spindle-shaped and have one nucleus per cell. Skeletal muscles are cylindrical - shaped, are striated, and have several nuclei per cell. Cardiac muscle is similar to skeletal muscle but is branched (bifurcated). In the anatomy, smooth muscles are used for involuntary movements (such as peristalsis) while skeletal muscles for voluntary movements