The brainstem is the structure located at the base of the brain that puts it in direct continuity with the spinal cord, it connects the cerebrum with the spinal cord. Inside are concentrated many important nerve structures, nerve cells and fibers, which are located deep in the upper parts of the brainstem. Injuries, even those that are small, can have a very serious consequences as this system controls the levels of consciousness and alertness of the body. Patients can suffer from trauma, cancer, strokes, infections and demyelination and some experience complete loss of functionality, which is equivalent to brain damage and henceforth leading to death, however if the brainstem remains intact, the body could remain alive, even when there is severe damage to the cerebrum, which makes thought and movement impossible.
What is the brainstem?
The brainstem, is a sort of station from which messages pass to and from the brain, it is the structure that connects the latter directly to the spinal cord and automatically regulates critical body functions. It is divided into three main parts, the midbrain, pons, and medulla oblongata, which together allow you to control the vital functions of the body, such as breathing, swallowing, vasomotor functions blood pressure, heartbeat rhythm and it helps to adjust body posture.
All the nerve pathways from the brain pass in the brainstem, in many cases intersecting inside of the brainstem. The 10 of the 12 pairs of cranial nerves also originate from the brainstem, however this excludes only those associated to the sense of smell and sight. Others provide motility and sensory abilities to the structures of the skull, including the facial muscles, tongue, pharynx and larynx. They are also responsible for the sense of taste and the balance of hearing.
Brainstem nuclei are also important for the sympathetic and parasympathetic autonomic functions of the body.
What functions does the brainstem serve?
There are three main functions of the brainstem, the first is that the brainstem plays a role in conduction. This means that all information that is being relayed from the body to the cerebrum and cerebellum (as well as vice versa) must traverse through the brainstem. The rising pathways coming from the body to the brain are the sensory pathways. These include the spinothalamic tract (responsible for pain and temperature sensation), the dorsal column, fasciculus gracilis, pressure sensation, cuneatus for touch and proprioception.
The brainstem is responsible for the functions of attention, alertness, excitement, breathing, heartbeat, blood pressure as well as the regulation of these functions. With the ability to convey information in the brain and shared signals from the peripheral nerves and the spinal cord, this also controls other involuntary functions in the human body such as digestion, salivation, sweating, dilation or constriction of the pupils and urination.
The lower part of the brainstem is responsible for the regulation of the vital autonomic functions, while the top part of the brain controls the senses of sight and hearing, alertness, consciousness and sleep. In particular, the midbrain controls the movements of the eyes, and the bridge coordinates the movements of the eyes and face, and controls the sensations perceived by the face, hearing and balance. The medulla oblongata controls the functions of breathing, blood pressure, the pace of the heart and swallowing.
