Spinal cord: anatomical structure and functions

Spinal cord: anatomical structure and functions

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

Regardless of our will, our body makes the heart beat steadily, maintains respiratory function, follows a long process of desiring, digesting and then excreting food, regulates sexual response or prepares us to react to dangers or desirable stimuli. The regulation of basic body functions is carried out by one of the parts of the brain known as the brain stem. Within this structure, there is another one which is known as the spinal cord and which has a very important role .

Presenting the structure: spinal cord

Also called myelinebrosis, the spinal cord is a subcortical structure located in the lower part of the brain stem . With a cone-like shape, it is the structure of the nervous system that connects the brain and the spinal cord (hence another name, medulla oblongata), bordering on the decusation of the pyramidal beams and the protrusion .

Both motor and sensory nerve connections can be found in the spinal cord, with the various nerve tracts passing through it. It is a neurovegetative nucleus, which is responsible for the maintenance and functioning of the organs in an automated manner, unrelated to consciousness. It also maintains vital signs. It is therefore an area of great importance for the survival of the human being.

Anatomical configuration

When we talk about the spinal bulb 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, starting in them some of the most well-known nerve tracts.

It is generally considered that the spinal cord is mainly divisible into three parts: pyramids and their pyramidal decusation, lemnisks and lemnischal decusation and the lower olive grove complex . Below we can observe some of the most relevant structures of each of these brain nuclei, in addition to other nuclei of interest in the spinal bulb.

1. Bulbar pyramids and pyramid decusation

Named for their shape, the pyramids of the spinal cord contain the bundles of nerve fibers that connect the cortex to the bulb and the spine. Thus, it is in this zone where the brain is connected to the rest of the body , sending motor information to muscle fibres distributed throughout the body.

In pyramidal decusation, the nerve fibres of the pyramids decay, i.e. they mostly change sides, with the fibres of the left pyramid on the right and vice versa. In this area, the motor pathways in particular decline.

2. Lemniscs and lemnisdiction

Lemnisks are bundles of nerve fibers whose function, as in the case of the 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 of a sensory type.

As in the case of the decusation of the pyramids, the fibre bundles of the lemnisks decay , following the same process in this case for the sensory information.

3. Olive grove complex

The olive grove complex is a structure located in the brain stem, being part in the protrusion and part in the spinal bulb . The region present in the bulb connects to the cerebellum, being linked to the control of motor skills. It has also been linked to vision.

Other relevant cores and tracts

These are other structures that are also found within the spinal cord.

Ambiguous core

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

Core of the solitary tract

This is the part of the spinal cord 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.

Bum’s dorsal core

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 by the peripheral nervous system.

Trigeminal core

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

What are you involved in? Spinal cord functions

The correct functioning of the spinal cord is vital for human beings. Literally, since the destruction or cessation of the functioning of this area causes death. To understand why it is so important, we need to consider some of the main functions this structure has.

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

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

Heart rate and blood pressure control

The spinal cord keeps us alive, as it has the important function of controlling vital and unconscious elements such as heartbeat and blood pressure . Thus, it is in charge of maintaining the heart rate and regulating vasoconstriction.

Breathing regulation

Breathing is one of the basic functions that makes life possible, since we need the presence of a constant supply of oxygen for the functioning of the different organs. The spinal bulb manages the control of the 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 carrying out, or even if we sleep. In general, the spinal bulb is useful precisely because of this hierarchy of tasks that it allows us to establish and thanks to which we make a more optimal use of the resources of the nervous system.

Participates in nutrition and digestion

The control of the 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 spinal bulb by regulating the emission of gastric flows . This means that it is a structure in the brain that helps maintain the ideal chemical balance in the body.

Bibliographic references:

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

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