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The brain stem is the part of the central nervous system that includes the midbrain, the bridge, and the medulla. This structure plays an extremely important role in the body - it contains, among others, centers governing such processes as heart function or respiration, and for this reason any damage to the brainstem can lead to a threat to the patient's life. But what exactly are the functions of the brain stem and what pathological processes can take place within it?
The brainstem(brainstem) is the part of the brain that includes the midbrain, the pons, and the medulla. Generally, the central nervous system, which is a specific management center for the entire organism, includes the brain and the spinal cord. Within the former, several different parts of it are distinguished, which are the endbrain, the diencephalon, the midbrain, the medulla and the cerebellum. Some of these structures - due to their essentially similar functions - are grouped into one entity - the brainstem.
Brain stem: structure
Typically the brainstem includes:
- midbrain
- most
- core extension
Some authors, however, extend the definition of the brain stem and consider its elements - apart from the structures mentioned above - also certain nuclei of the forebrain and diencephalon. In the most popular approach, however, only three parts of the brain are included in the brainstem.
The midbrain is located anteriorly from the bridge and its primary task is to coordinate the activity of the muscle cells of the eyeballs and to regulate the reflexes related to the organs of hearing and sight.
A bridge is the part of the brain stem that is primarily responsible for transmitting signals between the cerebral cortex and the cerebellum, besides, the bridge also controls the course of various motor activities.
The medulla is a structure in which there are many centers related to the control of basic life processes, such as, for example, respiration and blood circulation.
Brain stem: functions
The primary function of the brain stem is to transmit nerve impulses between the various parts of the central nervous system. It is donemultidirectional, incl. It is through this structure that the signals from the cerebral cortex to the cerebellum and vice versa run.
It is similar with the sensory impulses, for example from touch, pain or temperature receptors, as well as with motor impulses, which are sent from motor neurons located in the structures of the central nervous system and finally reaching the effector organs on the periphery - they all too flow through the brainstem.
The brain stem is also directly related to the cranial nerves - it is within it that the nuclei are located, from which most of the distinguished cranial nerves begin (more precisely, the third to twelfth cranial nerves).
The most important function of the brain stem, however, is to coordinate the course of many different vital processes in human life. The structures belonging to it include such important centers as, first of all:
- breathing control center
- a center that controls heart function and blood pressure
- thermoregulation center
- center that controls the course of metabolic processes
- center responsible for integrating sensory and motor stimuli
- centers regulating reflex activities (such as coughing, sneezing, sweating or swallowing)
It is also important that the brainstem is responsible for keeping us awake - it is the centers located in this part of the central nervous system that decide whether we are currently awake or just asleep.
Brain stem: diseases
Considering the importance of the functions of the brainstem, it is not difficult to conclude that damage to this structure can have dire consequences. They can result, among others, in disturbed functions of the cranial nerves (the symptoms of which depend on which nerve is dysfunctional in the patient - there may be visual disturbances, as well as dizziness or swallowing disorders).
However, the most serious are the conditions in which the dysfunction of any of the previously mentioned important centers located within the brainstem occurs - then there may be severe respiratory disorders or cardiovascular disorders, but also disorders awareness that may eventually develop into a coma.
But in what situations may the brain stem dysfunction occur? First of all, their cause may be head injuries - then it may develop, among others, shock syndromebrain, the dangerous consequence of which may be intussusception of the brain stem. Among other disease problems that may also affect the brain stem, the following are mentioned:
- brainstem tumors (such as e.g. astrocytoma or ependymoma, luckily these changes are not common)
- Duret's hemorrhage (i.e. a hemorrhage to the brainstem, resulting from its wedging into the large opening of the skull)
- brainstem stroke
- demyelinating changes (e.g. related to multiple sclerosis)
Death of the brain stem
The problem that is worth mentioning when discussing the structure and function of the brainstem is brain-stem death. Currently, it is considered the basic criterion of brain death - in this situation, when there is irreversible damage to the structures belonging to the brainstem, it is absolutely impossible for a person to function independently.
Death of the brain stem is diagnosed primarily by assessing whether the subject has the so-called trunk reflexes - they are:
- corneal reflex
- gagging
- coughing reflex
- oculocerebral reflex
Apart from checking the above-mentioned ones, before determining the death of the brain stem, the patient's reaction to the pain stimulus, the spontaneous movement of his eyes and the pupil's reaction to light are also assessed. However, before the aforementioned analyzes can be undertaken, it is first necessary to observe that the subject is in a coma and that he is not experiencing spontaneous respiration - only then can one proceed to activities through which a diagnosis of brain-stem death can be made.
About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.