The brain is almost always associated with a kind of oval with a rough surface full of folds, but below this cerebral cortex there are a multitude of very important structures.
In fact, if we were to consider the importance of each of the parts of the brain by judging them according to how relevant they are to our survival, we would conclude that the most fundamental structure is one that neither has the folded shape of the cortex nor has oval Yese is the brainstem, or encephalic stem, located in the lowest part of the brain and in direct contact with the spinal cord.
The brainstem, sometimes called brain stemis a part of the brain shaped like an elongated cylinder or cone and that It is located between the rest of the brain and the spinal cord That means that the brain stem is aligned with the neuronal fibers that run through the spinal cord down the spine; specifically, it passes in front of the cerebellum.
Therefore, it is the part of the brain that is anatomically lower and closer to the neck. Additionally, most of the cranial nerves (or cranial nerves) leave the brain stem.
The brainstem is made up of both parts of white matter and some areas where gray matter predominates, which means that They run through both connection areas and areas in which the neuron bodies are concentrated forming control nuclei.
Although the brainstem is attached to the spinal cord and due to its shape it can be confused with an extension of it, its main function It is not acting as a simple bridge between the brain and the nerves that run through the human body
The brain stem is the part of the human brain that houses the most primitive and ancestral functions, and it appeared in our evolutionary line in species that were nothing like human beings. It is part of what, according to Paul MacLean’s 3 brain theory, It has been called the “reptilian brain” precisely because it has been associated with ancestral physiological processes (although MacLean’s ideas are not considered valid, among other things, because they are based on a very simplified view of the evolution of the human brain.
Thus, the brain stem is responsible for carrying out the most basic nervous system tasks for our survival, those which we can barely influence voluntarily and which have been automated from millions of years of evolution precisely so that our poor decisions or our distractions do not cost us our lives.
Maintaining vital signs
Among the functions in which the brain stem plays a fundamental role are regulation and maintenance of heart rate and automatic control of breathing That is why the brain stem is made up of vital centers that, when damaged, can cause immediate death.
Other functions of the brain stem that are somewhat less important but practically as primitive are the control of hiccups, sneezing and coughing, sucking, swallowing, vomiting and sensitivity to pain. It also has a very important role in regulating arousal levels Specifically, a network of neurons distributed in part throughout the brain stem called the reticular formation is involved in both the regulation of the circadian cycle (sleep-wake) and the maintenance of consciousness.
In addition to all these functions, of course, The brain stem serves to communicate the cranial nerves and spinal cord with the brain, thus being the communication route between the brain and the rest of the body both in afferents and efferents. This is a more passive role than the previous ones, but equally essential for the survival of the brain and the entire organism in general.
Parts of the brain stem
The brain stem is made up of three main structures: the midbrain, pons, and medulla oblongata
1. Midbrain
He midbrain It is the structure of the brain stem located in a higher position and, therefore, closer to structures located higher up, such as the thalamus. Like other parts of the brain stem, it is involved in such primitive functions as regulating the sleep-wake cycle and body temperature, but it also plays a role in reacting quickly to visual and auditory stimuli reflexively, as well as in the control of certain movements.
The two basic components of the midbrain are structures called tectum and tegmentum.
2. Brain stem bridge
He brainstem bridge either pons, is located just below the midbrain and above the medulla oblongata. On its posterior surface (closest to the nape of the neck) is the cerebellum. This structure is the most bulging part of the brainstem, and its anterior surface sags outward as if it were half an egg.
This part of the brain stem intervenes in the control of breathing, in the transition between sleep phases and in the regulation of the level of consciousness among other basic survival processes.
He medulla oblongata (either medulla oblongata) is located in the lowest part of the brain stem. It controls all types of automatic processes totally necessary for survival, such as cardiac control or secretion of gastric substances In addition, it is the part that communicates directly with the spinal cord.
Furthermore, it is in this part of the brainstem where the decussation of the pyramids is located that is, the point at which nerve fibers change hemibody to go from right to left and vice versa (which explains that one half of the body is controlled by the opposite half of the brain).
