The medulla is the lowest part of the brainstem, continuous with the spinal cord. It controls the most basic life-support functions: heartbeat, breathing, and blood pressure.

Clusters of neurons in the medulla generate the rhythm of respiration and adjust heart rate and vessel tone in response to the body’s needs. Sensory and motor pathways between the brain and the rest of the body pass through it, many of them crossing to the opposite side. Damage to the medulla is often fatal because the automatic control of breathing and circulation is interrupted.

The medulla also houses nuclei involved in swallowing, coughing, sneezing, and vomiting. It receives input from higher centers that can modulate these automatic processes, yet it can sustain basic vital functions even when higher brain regions are inactive. In that sense it is one of the most ancient and indispensable parts of the nervous system.

Every automatic breath and heartbeat depends on the continuous activity of the medulla.