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Spinal bulb: anatomical structure and functions

Spinal bulb: anatomical structure and functions

July 19, 2024

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

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


Presenting the structure: medulla oblongata

Also called myelocephalus, the medulla is a subcortical structure located in the lower part of the brainstem. . With a cone-like shape, it is the structure of the nervous system that connects the brain and the spinal cord (hence its other name, medulla oblongata), limiting the decussation of the pyramidal beams and the protuberance .

In the medulla oblongata can be found nerve connections, both motor and sensory , passing through it the different nervous tracts. It is a neurovegetative nucleus, responsible for the maintenance and functioning of the organs in an automated and non-conscious way. It also maintains the vital signs. It is therefore an area of ​​great importance for the survival of the human being.


Anatomical configuration

When talking about the medulla, 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 most known nervous tracts.

It is generally considered that the medulla oblongata is mainly divisible in three parts: pyramids and their pyramidal decussation, lemniscos and lemniscal decussation and lower olive complex . Below we can see some of the most relevant structures of each of these brain nuclei, in addition to other nuclei of interest of the medulla.

1. Bulbar pyramids and pyramidal decussation

Called thus by their form, in the pyramids of the medulla oblongata they are located the bundles of nervous fibers that connect the crust with the bulb and the spine. So that, It is in this area where the brain connects with the rest of the body , sending motor information to muscle fibers spread throughout the body.


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

2. Lemniscos and lemniscal decussation

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

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

3. Olive grove complex

The olive complex is a structure located in the trunk of the brain, being part in the protuberance 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 with the vision.

Other relevant nuclei and tracts

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

Ambiguous nucleus

In this structure the vagus, accessory and glossopharyngeal nerves are initiated. These nerves participate in the control of feeding and digestion, controlling the muscles of the pharynx and larynx. So, they are the ones allow us to swallow and food to move through the digestive tract .

Solitary tract nucleus

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.

Backbone of the bum

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 , framed in part in the peripheral nervous system.

Trigeminal nucleus

In this location we can find the trigeminal nerve, which is of special relevance at the time of transmit 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 is involved? Functions of the medulla

The correct functioning of the medulla oblongata is vital for human beings. Literally, given that the destruction or cessation of the operation of this area causes death. To understand why this is so important, we need to consider some of the main functions of this structure.

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 that of serve as a link between brain and / or cerebellum and marrow . Thus, it is responsible for transmitting the sensory and motor nervous information of the rest of the body.

Control of heart rate and blood pressure

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

Regulation of breathing

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

It is a process that precisely because of its importance can not depend on our ability to manage the focus of attention, which is reflected in the fact that we never forget to breathe, however complex the task we are doing, or even if we sleep. In general, the spinal bulb is useful precisely because of that hierarchy of tasks that allows to establish and thanks to which we make a more optimal use of the resources of the nervous system.

Participate in nutrition and digestion

The control of involuntary muscles, such as those that push food through the digestive tract when we eat, it 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 when regulating it. emission of gastric flows . This means that it is an encephalon structure that contributes to maintaining the ideal chemical equilibria in the body.

Bibliographic references:

  • Carlson, N.R. (2014). Physiology of Behavior (11th Edition). Madrid: Pearson Education.
  • Kandel, E.R .; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.

Central Nervous System: Crash Course A&P #11 (July 2024).


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