Parts of the Human Brain (and Functions)

The human brain has been described as the most complex system in the known universe and not without reason.

It is made up of a network of glia, neurons and nerve pathways and is the most important part of the Central Nervous System, but its intricate structure and functioning does not mean that we cannot make a classification of the main parts of the brain.

Table of Contents

The main parts of the brain

In humans, The brain or cerebrum 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 thanks to which we can carry out the most complex mental operations and have consciousness, that is, a sense of self. Precisely for this 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 make it up can be classified. A good way to classify the different parts of the brain above may be by considering the different formations that form inside the head of a human embryo. There are a total of three structures

1.1. Hindbrain

This is the upper part of the spinal cord and Throughout the development of the fetus, it will be transformed into the structures in charge of carrying out tasks essential for survival, such as controlling heart rate and breathing. It will end up becoming the cerebellum, the brain stem bridge and the medulla oblongata, as we will see.

1.2. Midbrain

In human embryos it appears just above the hindbrain, and will gradually transform into the medial part of the brain, also responsible for carrying out a good part of the basic survival functions but that also acts as a bridge between the other two structures.

1.3. Prosencephalon

Located at the farthest 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 most 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 hindbrain gives way are the diencephalon and the telencephalon.

The parts of the adult brain

Going into more 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, the parts of the brain that are generated from the forebrain, and then move on to the midbrain area and the hindbrain, in that order.

2.1. Telencephalon

The telencephalon is the part of the brain that is easiest 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

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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 structures of the brain. 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.

Besides, Each hemisphere is made up of several lobes of the brain, each of which is more involved in certain mental processes. The lobes of the brain are these:

2.1.2. basal ganglia

The second component of the telencephalon is the group formed by the basal ganglia These are a group of structures located below the cerebral cortex and distributed symmetrically under each of the hemispheres. The basal ganglia are the globus pallidus, the putamen and the caudate nucleus, which are complemented by a region known as the substantia nigra.

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

2.1.3. Limbic system

The limbic system is a set of brain structures whose boundaries are quite diffuse, as it mixes with many different parts of the brain. Its functions are related to the appearance and regulation of emotions and the bodily responses beyond the head that accompany them. That is why it is sometimes considered “the emotional brain” as opposed to the “rational brain” which 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 zones is very artificial, and even more so considering that we are not as rational as it might seem.

If you are interested in knowing more about this part of the brain, you can access this article about the limbic system.

2.1.4. Hippocampus

He hippocampus It 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 forms of mammals. Its function is related to the storage and retrieval of memories, learning and spatial navigation.

2.1.5. Amygdala

The brain amygdala It is a set of neurons that are grouped on the inner side of the temporal lobe of each of the hemispheres. That is, like what happens 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 amygdala is part of the limbic system, and it is one of the brain structures that are most important when it comes to relating emotional states with situations we experience; That is why it plays a key role in the mental processes related to emotional memory and the learning linked to it, which are very important. Ultimately, knowing what emotions each type of stimulus or experience is paired with makes us adopt an attitude towards them and opt for some possible reactions and not others.

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2.2. diencephalon

The diencephalon is the second large 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 cerebral hemisphere). The thalamus sends this information to higher areas of the brain, so that the information that has begun to be synthesized in it continues to be processed there, and is also capable of making it possible for the Autonomous Nervous System to react quickly to stimuli that may mean the presence of a danger.

2.2.2. hypothalamus

The hypothalamus is located just below the thalamus, and is mainly responsible for ensuring that the entire organism is constantly in a state of homeostasis that is, in balance in all senses: body temperature, hormone levels in the blood, breathing rate, etc.

Furthermore, 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.

You can read more about the hypothalamus in this article

23. Brain stem

The brainstem, or brainstem, is the part of the brain that is most directly connected to the spinal cord, and is also responsible for carrying out the basic tasks of maintaining vital functions such as involuntary breathing or heart rate. It is made up of the parts that evolve from the midbrain and hindbrain. Its parts are the following.

2.3.1. Midbrain

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

2.3.2. Boss

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

2.3.3. medulla oblongata

It is the lower part of the brain stem, and its functions are very similar to those of the other two structures in this part of the brain. Additionally, it is the link between the brain and the spinal cord. In the medulla oblongata there is a part known as the decussation of the pyramids, which is where the bundles of nerve fibers from the two hemifields (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 in charge of processing information from the left hand while the left is in charge of the other, for example.

If you are interested in reading more about the brainstem, you can read this article

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2.4. Cerebellum

Along with the medulla oblongata and the pons, the cerebellum is the third major structure that evolves from the hindbrain Additionally, the cerebellum and pons are part of a region called the metencephalon.

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

If you are interested in knowing more about the cerebellum, you can visit this article

Other related structures of the nervous system

The different parts of the brain not only work by coordinating with each other but they require the participation of other circuits of the neuroendorine system.

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

cranial pairs

The cranial nerves are bundles of axons that emerge from different points in the lower part of the brain and They 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 come from the different parts of the brain but from various sections of the spinal cord.

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

You can read more about these nerves in the brain in this article.

Autonomic nervous system

The Autonomous Nervous System is a network of axons, ganglia and organs that It is responsible for regulating 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 they are completely automated.

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

Through these communication pathways, parts of the body are controlled that, being the basis for the survival of the tissues and cells that make up the body, cannot depend on voluntary decisions or attention management, which means that they also If they are automated processes, even if a person wants to, they cannot be intervened on or made to stop, since this could lead to immediate death. You can read more about him in this article.