The medulla oblongata is a bulbous structure in the brain that controls a variety of basic body functions, including digestion, sleep, breathing, and heartbeat. It is one of the parts of the brain responsible for the autonomic nervous system, which regulates such essential activities without our active awareness. Located at the base of the skull, the medulla oblongata is also the connection between the brain and the spinal cord.

Composed of both white matter and gray matter, the medulla oblongata is roughly triangular in shape, tapering from a wider section at the midbrain to a relatively narrow band where it joins the spine. Seven cranial nerves emerge from the medulla oblongata and help control sensory and motor functions, along with arousal and sleep.

The medulla also contains two clumps of motor nerves called pyramids, which control skeletal muscles. The neurons connecting the pyramids to the muscles cross each other in an X-shaped formation, meaning that the right side of the medulla controls the left side of the body. Therefore, injury or disease affecting one side of the medulla may produce paralysis or loss of senses on the other side of the body.

Another part of the medulla, two oval structures called olives, contain cells that are involved in balance, coordination, and the modulation of sound impulses from the inner ear.

Since the medulla oblongata is essential to basic body functions, damage to this part of the brain often causes instant death. In some cases, people with damaged medulla oblongatas can remain alive, but will need to be put on life-support machines to maintain breathing, heartbeat, and other functions.

ADDITIONAL FACTS

  1. Injury to or disease of the medulla may cause vertigo, vomiting, loss of the gag reflex, difficulty in swallowing, loss of the ability to sense pain and temperature, or loss of concentration.
  2. General anesthesia works in part by suppressing wakefulness and arousal in the medulla oblongata—but if too much is administered, autonomic functions, such as heartbeat and breathing, are in danger of stopping.
  3. Studies have shown that autistic children tend to have smaller brain stems and medulla oblongatas.