Autonomic nerves are concerned with muscular functions which are reflexive, such as breathing, heartbeats and peristalsis (rhythmic movements of the intestines. Update Date: 09/25/2008Daniel B. Hoch, MD, PhD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.