The medulla is part of one of the most important parts of the brain, which is the brainstem. Just as this structure in the past was considered simply an extension of the spinal cord, it has been known since the beginning of the 19th century that it performs distinctly different, very important functions. So how is the elongated core built and for what reasons this organ is so important for human functioning?
Medulla oblongata(Latinmedulla oblongata ) belongs to the brainstem and belongs to those brain centers without which human life is impossible . In the past, it was believed that an extension was nothing more than a continuation of the spinal cord. The truth, however, turned out to be somewhat different when J. Legallois conducted his research in the early nineteenth century. The scientist observed that after the cortex and the cerebellum were removed from the rabbits he studied, these animals were still able to breathe. The situation was different, however, when the researcher resected a specific fragment of the medulla - in such a situation, respiratory activity in rabbits was immediately stopped. The described conclusions were the first observations about the functions of the extended core - over time, the researchers managed to determine what the tasks of this structure are, and the external and internal structure of the extended core became known.
Core extension: external structure
The medulla begins at the point where the spinal cord passes through the foramen in the skull. From the rear, it is largely covered by the cerebellar hemispheres.
The extended core has two surfaces: ventral and dorsal. There are pyramids on the ventral surface that contain the pyramidal pathways of the nervous system - they are separated from each other by the anterior median fissure. At the very end of the core - in its lower part - there is a crossroads of the pyramids, where the fibers of the above-mentioned pyramid paths cross.
An important element belonging to the medulla is the olive - it is located laterally from the pyramids and is limited by two furrows: anterolateral and posterolateral. Nerve fibers emerge from these furrows: from the anterolateral sulcus of the sublingual nerve fibers, and from the posterolateral sulcus, fibers of the glossopharyngeal, vagus and accessory nerves emerge.
Coreextended, as already mentioned, also has a dorsal surface. In its midline there is a posterior median furrow, on both sides of which there are nerve pathways in the form of a slender bundle and a wedge-shaped bundle run from the spinal cord. They end with protrusions, which are called nodules: they are called slender and wedge-shaped nodules and contain slender and wedge-shaped nuclei.
An important structure of the medulla is also the triangular space located above the cusps, the boundaries of which are marked by the lower limbs of the cerebellum - it is the lower part of the bottom of the fourth ventricle of the brain.
Core extension: internal structure
The medulla is a structure involved in the flow of the cerebrospinal fluid: it runs through the medial canal, which widens at the top of the spine and eventually forms part of the fourth ventricle.
The internal organization of the extended core is quite interesting. As in other regions of the central nervous system, gray matter and white matter are evenly distributed, in the case of the medulla, a very uneven distribution of gray matter within it is noticeable. As in the case of the external structure, the ventral and dorsal parts of the core are also distinguished in the internal structure of the core. In the first of these, there are mainly nerve pathways originating in the cortex of the brain. In the ventral part of the medulla there is a reticular formation.
The inside of the medulla is also the site of numerous nerve nuclei. Among them, it is worth mentioning:
- motor nuclei of the cranial nerves (motor nuclei of the glossopharyngeal and vagus nerves, which is called the ambiguous nucleus or the motor nucleus of the sublingual nerve)
- sensory nuclei of the cranial nerves (such as the trigeminal nucleus, the nucleus of the vestibulocochlear nerve or the solitary nucleus, which is the sensory nucleus of the facial, glossopharyngeal and vagus nerves)
- autonomic nuclei (inferior salivary nucleus, which is the nucleus of the glossopharyngeal nerve and the dorsal nucleus of the vagus nerve)
Core extended: features
In the extended core - apart from the elements already mentioned - there are also numerous centers whose task is to control the course of basic life processes. I am talking about such centers as:
- breathing center
- cardiovascular system
- centers responsible for reflex activities (e.g. swallowing center, sneezing center, coughing center orvomiting)
The activity of the extended core is quite complicated - to prove it, it is enough to describe how the extended core controls the course of gas exchange. This structure is connected with many different elements of the nervous system scattered throughout the body - the chemoreceptors located within the blood vessels are one of the most important in this case when it comes to controlling breathing. The task of these receptors is to monitor the acidity of the blood - when it becomes too high, the chemoreceptors send appropriate signals to the medulla. This results in signals from the core to respiratory structures - such as the intercostal muscles or the diaphragm - that mobilize them to contract at an increased rate. Ultimately, then, there is an increase in respiratory function, increased oxygen supply to the body and a decrease in blood acidity.
In addition to controlling the course of basic life processes, the spine is also elongated and the structure through which nerve impulses run from the higher levels of the central nervous system to the spinal cord and vice versa run.
Core extended: effects of damage
The extension core may be damaged due to e.g. injury or insufficient blood supply (i.e. stroke). The effects of such events are usually deplorable - due to the fact that the medulla are centers that control the course of basic life processes, its damage usually results in the patient's death.
Bow. 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.