The Vital Role of the Medulla Oblongata in Brain Function

When we contemplate the brain, thoughts often gravitate towards higher-level functions like reasoning, emotions, and thinking. However, at a more fundamental level, crucial functions essential for survival are orchestrated by the medulla oblongata, possibly one of the earliest-evolved parts of the brain. Some experts even argue that the medulla holds the utmost importance among all brain components.

Around 555–558 million years ago, bilaterians, the ancestors of all vertebrates, made their appearance. They possessed a bilaterally symmetrical body plan and a hollow gut tube extending from mouth to anus, housing a nerve cord that foreshadowed the spinal cord. Over 500 million years ago, the first vertebrates, thought to resemble modern hagfish, emerged, featuring three enlargements at the front end of their nerve cord: the forebrain, midbrain, and hindbrain.

The medulla, situated within the hindbrain, evolved from the upper part of the spinal cord. It stands as the lowest and most primitive region of the vertebrate brain. The medulla governs vital, involuntary functions upon which life hinges: control of breathing, heart rate, and blood pressure. Within the medulla, chemoreceptors monitor blood oxygen and carbon dioxide levels, coordinating changes in breathing rate accordingly. Its destruction leads to instant death due to respiratory failure. Baroreceptors, situated in the aorta and carotid artery, detect shifts in arterial blood pressure and transmit messages to the cardiovascular center within the medulla. This center, in response, instigates adjustments to restore blood pressure and heart rate to their normal ranges.

The medulla further houses reflex centers that prompt immediate responses, independent of cognitive processing, initiating actions like vomiting, coughing, and swallowing when needed. Additionally, it serves as a conduit for nerves entering and exiting the brain, facilitating communication between the brain and spinal cord.

At the core of our brain's functions lies the medulla, the most ancient brain structure, overseeing vital processes like respiration, heart rate, and blood pressure, as well as automatic reactions such as coughing and sneezing. During World War II, the Office of War Information issued this poster to caution U.S. soldiers about covering their coughs and sneezes to curtail the spread of germs.