Psycholinguistics & Neurolinguistics

Parts of the human brain

Parts of the human brain and what function does each of them have?

Parts of the human brain

1. Main parts of the brain

In humans, the brain or brain is the part of the Central Nervous System that is located at the end of the  spinal cord , inside the skull. It is, in short, the organ through which we can perform the most complex mental operations and be aware, that is, sense of self. Precisely for that reason within the brain there are a large number of structures working together at great speed, a fact that makes the functioning of the brain, even today, a mystery in many of its aspects.

To begin to understand what we know about this complex machinery, it is essential to know the parts of the brain, that is, the way in which the structures that compose it can be classified. A good way to classify the different parts of the brain above can be attending to the different formations that are formed inside the head of a human embryo. They are a total of three structures .

1.1. Rhombencephalon

It is the upper part of the spinal cord and throughout the development of the fetus will be transformed into the structures responsible for performing tasks essential for survival , such as the control of heart rate and breathing. It will end up transforming into the cerebellum, the brainstem bridge and the medulla, as we will see.

1.2. Midbrain

In human embryos, it appears just above the rhombencephalon, and will be transformed into the medial part of the brain,  also responsible for performing a good part of the basic survival functions but also acts as a bridge between the other two structures.

1.3. Forebrain

Located at the far end of the spinal cord and on the side closest to the face of the embryo, the forebrain is the formation that will be transformed into the parts of the brain that have appeared more recently in our evolutionary line and that, therefore,   they have to do with the use of language, planning and the search for creative solutions to new problems . As we will see, the two main structures to which the development of the rhombencephalon gives way are the diencephalon and the telencephalon.

2. The parts of the adult brain

Going more in detail, we can stop to see the different components of the brain in fully developed human beings. It is in this set of organs where we find all those parts of the brain that define the way our mind works. 

Here we will see, first of all, the parts of the brain that are generated from the forebrain, and then move on to the midbrain area and the rhombencephalon, in that order.

2.1. Tele Cephalus

The telencephalon is the part of the brain that is easier to see with the naked eye, since it occupies most of the surface of the brain. Its components are the cerebral cortex, the basal ganglia and the limbic system .

2.1.1. Cerebral cortex

The cerebral cortex (or cortex) is the part of the brain that is rough and full of folds . It covers the rest of the brain above, and is the area in which the information necessary to carry out the most complex mental processes is integrated, since the information that reaches this region has already been partially processed by other brain structures. The cortex is divided into two cerebral hemispheres that are almost symmetrical to the naked eye, although on a microscopic scale they are very different.

In addition, each hemisphere is composed of several lobes of the brain , each of which is more involved in certain mental processes. The lobes of the brain are these:

  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
  • Insula

2.1.2. Basal ganglia

The second component of the telencephalon is the set formed by the basal ganglia . These are a group of structures located below the cerebral cortex and distributed symmetrically under each hemisphere. The basal ganglia are the pale globe, the putamen and the caudate nucleus, which are complemented by a region known as the black substance.

The basal ganglia are the parts of the brain that allow us to perform relatively complex and precise movements easily and almost automatically: writing, speaking, modifying our facial expressions voluntarily , etc. Therefore, they monitor in a semi-automatic way the way in which we carry out chains of movements that we have already practiced many times before to dominate them, and at the same time allow us to learn them well, among other functions.

2.1.3. Limbic system

The limbic system is a set of brain structures whose limits are quite diffuse , since it mixes with many different parts of the brain. Their functions are related to the appearance and regulation of emotions and bodily responses beyond the head that accompany them. That is why it is sometimes considered “the emotional brain” as opposed to the “rational brain” that would correspond to the areas occupied by the cerebral cortex (and especially the frontal lobe).

However, neither the limbic system nor the cortex can function well independently , and therefore this distinction between rational and emotional areas is very artificial, and more so considering that we are not as rational as it might seem.

2.1.4. Hippocampus

The hippocampus is an elongated structure located in the inner part of the temporal lobes, one of the oldest regions of the cerebral cortex, present in the oldest mammalian forms. Its function is related to the storage and recovery of memories, learning and space navigation. 

2.1.5. Amygdala

The cerebral tonsil is a set of neurons that cluster in the inner face of the temporal lobe of each hemisphere. That is, as with the hippocampus, it is one of those parts of the brain that are found in duplicate in each human brain, with one in each half (left and right) of the brain. 

The cerebral tonsil is part of the limbic system , and is one of the brain structures that are most important when it comes to relating emotional states to situations we live; That is why it plays a key role in the mental processes related to emotional memory and the learning related to it, which are very important. After all, knowing what emotions are paired with each type of stimulus or experience makes us adopt an attitude towards them and opt for possible reactions and not others.

2.2. Diencephalon

The diencephalon is the second great structure that forms the forebrain, and is located just below the telencephalon , in the depths of the Central Nervous System. The parts of the brain that make up the diencephalon are basically the thalamus and the hypothalamus.

2.2.1. Thalamus

It is the largest part of the diencephalon, and it is the nucleus in which all the information that comes to us through the senses is integrated for the first time (except for smell, which reaches the brain directly through the olfactory bulb of each hemisphere cerebral). The thalamus sends this information to higher areas of the brain, so that the information that has begun to be synthesized there is further processed, and it is also capable of making it possible for the Autonomous Nervous System to react quickly to stimuli that can mean the presence of a danger.

2.2.2. Hypothalamus

The hypothalamus is located just below the thalamus, and is primarily responsible for making the entire organism constantly in a state of homeostasis , that is, in equilibrium in every way: body temperature, blood hormone levels, rhythm of the breathing, etc.

In addition, thanks to its ability to make different glands in the body secrete hormones, it induces us to more or less high states of stress and general activation depending on what is happening in other parts of the brain. It is also the structure responsible for the appearance of the state of thirst and hunger.

2.3. Brain stem

The brain stem, or brain stem, is the part of the brain that is most directly connected to the spinal cord , and is also responsible for performing basic maintenance tasks of vital functions such as involuntary breathing or heart rhythm. It is formed by the parts that evolve from the midbrain and the rhombencephalon. Its parts are as follows.

2.3.1. Midbrain

The midbrain is the part of the brain stem that is just below the diencephalon . It is responsible for communicating the brain stem with the superior structures and vice versa, and also intervenes in the maintenance of automatic processes that allow us to survive. It is divided into tectum and tegmentum.

2.3.2. Boss

This structure is also known as the Varolio bridge or brainstem bridge . It is located just below the midbrain.

2.3.3. Spinal bulb

It is the lower part of the brainstem , and its functions are very similar to those of the other two structures of this part of the brain. In addition, it is the link between the brain and the spinal cord. In the medulla oblongata is a part known as the decussation of the pyramids , which is where the bundles of nerve fibers of the two hemicampos (the left and right halves of the human body) intersect to pass from one side to the other; This explains why the right hemisphere is responsible for processing information on the left hand while the left is responsible for the other, for example.

2.4. Cerebellum

Next to the medulla and the bulge, the cerebellum is the third great structure that evolves from the rhombencephalon . In addition, the cerebellum and the bump are part of a region called metencephalon.

The cerebellum is one of the parts of the brain with a higher concentration of neurons and among its many functions the most studied is the regulation and monitoring of complex movements that require some coordination. It also has a role in maintaining balance when standing and walking.

Other related nervous system structures

The different parts of the brain not only work in coordination with each other , but they also need the participation of other neuroendocrine system surgeons. 

These structures and systems, which do not belong to the brain itself, are the cerebral nerves (or cranial nerves) and the Autonomous Nervous System (SNA).

Cranial nerves

The cranial nerves are bundles of axons that leave different points of the lower area of ​​the brain and go to other parts of the body without passing through the spinal cord . This is what distinguishes them from the rest of the nerves, which do not leave the different parts of the brain but from several sections of the cord.

Examples of the cranial nerves are the trigeminal nerve, the vagus nerve or the olfactory; All of them are of great importance, and in the case of the trigeminal, their incorrect functioning can generate a lot of pain. 

Autonomic nervous system

The Autonomous Nervous System is a network of axons, ganglia and organs that regulates the functions that keep us alive , such as digestion, involuntary breathing or heartbeat. That is why these functions cannot be controlled voluntarily; They are too important, and fully automated. 

This network of neurons interacts especially with the parts of the brain that are lower (those of the brain stem), and is divided into a sympathetic system, parasympathetic system and enteric system. 

Through these communication channels, parts of the body are controlled that, being at the base of the survival of the tissues and cells that make up the body, cannot depend on voluntary decisions or the management of care, which means that in addition If they are automated processes, even if a person wants to, they cannot intervene on them or cause them to stop, since this could lead to immediate death.

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