Medulla Oblongata: Anatomical Structure And Functions

We examine one of the most relevant and vital parts of the brainstem (and brain).

In his daily life, the human being performs a large number of behaviors and actions. We shower, go to work, talk and interact with others, walk, eat or go to bed. Most of these actions are carried out consciously and voluntarily. However, our body does much more than that.

Regardless of our will, our body makes the heart beat constantly, maintains respiratory function, follows a long process to desire, digest and subsequently excrete food after digestion, regulate sexual response or prepare us to react to dangers or stimuli appetizing. The regulation of basic bodily functions is carried out by one of the parts of the brain known as the brainstem. Within this structure, there is another that is known as the medulla oblongata and that has a very important role.

What is the medulla oblongata?

Also called the myelencephalon, the medulla oblongata is a subcortical structure located in the lower part of the brain stem. With a shape similar to a cone, it is the structure of the nervous system that connects the brain and the spinal cord (hence another of its names, medulla oblongata), limiting with the decussation of the pyramidal bundles and the pons.

Both motor and sensory nerve connections can be found in the medulla oblongata , passing through it the different nerve tracts. It is a neurovegetative nucleus, taking care of the maintenance and functioning of the organs in an automated way and oblivious to consciousness. It also maintains vital signs, so problems that compromise its functioning lead to brain death. It is therefore an area of ​​great importance for the survival of human beings.

Parts and anatomical configuration

When we talk about the medulla oblongata, we are talking about a structure that is not homogeneous in its composition and function. On the contrary, this structure is made up of different nuclei, beginning in them some of the best known nervous tracts, and these parts of the medulla oblongata have different functions.

The medulla oblongata is generally considered to be mainly divisible into three parts: pyramids and their pyramidal decussation, lemniscus and lemniscal decussation, and inferior olive grove complex. Below we can observe some of the most relevant structures of each of these brain nuclei, as well as other nuclei of interest in the medulla oblongata.

1. Bulbar pyramids and pyramidal decussation

Named for their shape, bundles of nerve fibers are located in the pyramids of the medulla oblongata that connect the cortex with the medulla and the spinal cord. Thus, it is in this area where the brain connects with the rest of the body, sending motor information to muscle fibers distributed throughout the body.

In pyramidal decussation, the nerve fibers of the pyramids decay, that is, they mostly change sides, the fibers of the left pyramid being on the right and vice versa. Specifically, in this area motor pathways especially decline.

2. Lemnisci and lemniscal decussation

Lemnisci are bundles of nerve fibers whose function, as in the case of pyramids, is to transmit information between the brain, specifically the thalamus, and the spinal cord. In this case, however, the information they carry is mainly sensory.

As in the case of the decussation of the pyramids, the fiber bundles of the lemnisci decuse, following the same process in this case for sensory information.

3. Olive complex

The olive complex is a structure located in the brain stem, being part in the pons and part in the medulla oblongata. The region present in the bulb connects with the cerebellum, being linked to motor control. It has also been linked to vision.

Other relevant nuclei and tracts

These are other structures that are also found within the medulla oblongata.

Ambiguous core

The vagus, accessory, and glossopharyngeal nerves begin in this structure. These nerves participate in the control of food and digestion, controlling the muscles of the pharynx and larynx. Thus, they are what allow us to swallow and the food to move through the digestive tract.

Nucleus of the solitary tract

It is the part of the medulla oblongata that regulates the sensitivity of the viscera, intervening in the same way in cardiorespiratory function. Likewise, the face-lateral part also participates in the perception of taste, a process that takes place exclusively inside the skull.

Dorsal nucleus of vagus

This nucleus, through which the vagus nerve passes, is linked to digestion, controlling the production and emission of gastric flows. It is, therefore, part of a network of neural networks involved in the enteric nervous system, partly framed in the peripheral nervous system.

Trigeminal nucleus

In this location we can find the trigeminal nerve, which is of special relevance when transmitting information about pain, temperature and touch. It is an area in which neuronal cells accumulate to process information at a very basic level; Other brain structures will be responsible for continuing to work from this information when nerve cells transmit the signal to the upper area.

What do you participate in? Functions of the medulla oblongata

The proper functioning of the medulla oblongata is vital for humans. Literally, since the destruction or cessation of the operation of this area causes death.

To understand why it is so important, it is necessary to consider some of the main functions this structure has, as well as to take into account that, since it is located at the base of the brain, a large part of the vertically arranged neural networks pass through this structure of the system. central nervous.

Transmits information from the spinal cord to the brain and vice versa

Being the part of the nervous system that connects the brain and spinal cord, one of the main functions of the medulla oblongata is to serve as a link between the brain and / or cerebellum and the medulla. Thus, it is responsible for transmitting both sensory and motor nervous information from the rest of the body.

Control of heart rate and blood pressure

The medulla oblongata keeps us alive, as it has the important function of controlling vital and unconscious elements such as the heartbeat and blood pressure. Thus, it is responsible for maintaining the heart rate and regulating vasoconstriction.

Regulation of respiration

Breathing is one of the basic functions that life allows, since we need the presence of a constant supply of oxygen for the functioning of the different organs. The medulla oblongata manages the control of respiratory function, maintaining it at all times.

It is a process that precisely because of its importance cannot depend on our ability to manage the focus of attention, which is reflected, for example, in the fact that we never forget to breathe, no matter how complex the task we are doing, or even if we sleep. In general, the medulla oblongata is useful precisely because of that hierarchy of tasks that it allows to establish and thanks to which we make more optimal use of the resources of the nervous system.

Participate in nutrition and digestion

Control of involuntary muscles, such as those that push food through the digestive tract when we eat, depends on a part of the bulbar complex. In addition to muscle control, the functioning of the digestive system is also linked to the medulla oblongata by regulating the emission of gastric flows. This means that it is a structure of the brain that helps to maintain the ideal chemical balances in the body.

Bibliographic references:

  • Carlson, NR (2014). Physiology of Behavior (11 Edition). Madrid: Pearson Education.
  • Hughes, T. (2003). Neurology of swallowing and oral feeding disorders: Assessment and management. Journal of Neurology, Neurosurgery & Psychiatry. 74 (90003): 48iii.
  • Kandel, ER; Schwartz, JH & Jessell, TM (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.
  • Kolb, B. & Whishaw, IQ (2009). Fundamentals of human neuropsychology: Sixth edition. New York, NY: Worth Publishers.
  • Vilensky, J .; Robertson, W .; Suarez-Quian, C. (2015). The Clinical Anatomy of the Cranial Nerves: The Nerves of “On Olympus Towering Top”. Ames, Iowa: Wiley-Blackwell.

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