The primary function of the brainstem is ensuring basic vital life functions such as heartbeat, blood pressure and breathing. It also plays a role in arousal and consciousness. Every piece of information that enters or leaves the brain has to pass through this structure. The brainstem is made up of the midbrain, the pons, and the medulla oblongata, each playing a different role in maintaining human life.
The midbrain deals with vision, hearing, eye movement, and body movement. It contains a large bundle of axons, or long, threadlike nerve cells responsible for conducting impulses in the cell body. These axons are vital to voluntary motor function, or the movements that are made on purpose, such as walking, picking up objects, or throwing a ball. It also contains the nerves that control the eyes. The degeneration of the neurons in this part of the brain is associated with Parkinson’s disease.
The pons helps regulate motor control and sensory analysis, as all information that enters through the senses passes through the pons on the way to the parts of the brain involved in further processing. Another pons function of the brainstem is to help determine a person’s level of sleep or consciousness. Part of the structure is attached to the cerebellum, which is involved in controlling movement and posture. Damage to the pons often results in lack of coordination and difficulty processing new sensory data.
The medulla oblongata is located between the pons and the spinal cord. It maintains all the vital body functions, including breathing, digestion, and blood pressure and triggers several different reflexes, including those that cause vomiting, coughing and sneezing. The medulla oblongata also acts as a messenger, passing messages from the brain to the spinal cord.
The location of the structures makes it susceptible to injury that affects the function of the brainstem, because it is surrounded by body protuberances. Severe trauma, such as that from a car accident or fall, can cause an interruption in the function of the brain stem. Depending on which part is affected, this can lead to complications ranging from short-term memory loss to paralysis or death.
The function of the brainstem can also be interrupted by a stroke that affects that region. Depending on the affected area, patients may be paralyzed and unable to speak, but may still be able to communicate by blinking. This condition is referred to as “locked-in” syndrome. If the stroke affects the area responsible for involuntary body functions, such as breathing, death can occur quickly without proper medical intervention.