The midbrain is one of the most important parts of the brain, in many ways. On the one hand, it is located almost in the center of the brain, occupying a part of its deepest area, and therefore establishes direct communication with many of the main structures of the central nervous system.
On the other hand, it is the area that joins the brainstem to the diencephalon and parts of the cerebral cortex. Without the midbrain we could not survive.
Below we will see what the characteristics of this region of the brain are, we will review its main functions and its different anatomical components, and we will see what happens when certain injuries or diseases alter its functioning.
The midbrain is one of the parts of the brain stem It is located in its upper area, above the pons (or pons), and just below the diencephalon, composed mainly of the thalamus and hypothalamus. It is the part of the brain stem closest to the center of the brain, while the pons and medulla oblongata are more oriented toward the spinal cord.
Furthermore, the midbrain It is crossed by a narrow canal called the Silvio aqueduct, through which cerebrospinal fluid flows from the third ventricle to the fourth. This liquid has the function of isolating and protecting various structures of the nervous system.
Your anatomy
The shape of the midbrain is that of a trapezium, with a narrower base than its upper part, and with the Sylvian aqueduct (a small canal through which cerebrospinal fluid circulates) crossing it from top to bottom.
The border between the midbrain and the diencephalon is marked by the optic tracts (the continuation of the nerve fibers of the optic nerves), while its lower limit, which separates it from the pons, is marked by the pontomesencephalic sulcus
Furthermore, on its anterior surface (close to the face) you can distinguish a vertical slit called the interpeduncular fossa which divides two bodies of nerve fibers that go up to the brain, called cerebral peduncles.
Parts of the midbrain
The two fundamental structures that make up the midbrain They are the tectum and the tegmentum
tectum
It is located in the dorsal area of the midbrain, facing the back of the neck, and etymologically means “roof.” Its functions are related to automatic reactions to auditory and sound stimuli.
It is made up of two pairs of lumps, one located on top of the other. These lumps are called colliculi, or colliculi and the upper ones play a role in vision and in directing the eyes towards visual stimuli, while the lower ones are involved in involuntary reactions to sounds.
Tegmentum
In the ventral area of the midbrain is the tegmentum. It contains three main regions, each associated with a color: the substantia nigra, the periaqueductal gray matter, and the red nucleus
The black substance
The substantia nigra is located in the upper area of the midbrain, and is distributed on both sides of this structure, following the division of the cerebral hemispheres. It has many associated functions, especially linked to movements and muscle tone
It is another of the important elements of the motor system. Its function It is related to the coordination of movements
Periaqueductal gray matter
The periaqueductal gray matter, which as its name indicates is located around the Sylvian aqueduct, intervenes in habituation to pain and in analgesic processes in general.
Functions of the midbrain
The location of the midbrain means that the main functions of this structure have to do with the integration between different types of information On the one hand, it collects nervous impulses linked to motor commands that have to be executed by muscles, and on the other it receives sensory data.
In the same way, the quadrigeminal tubercles located in the tectum are responsible for coordinating this type of information among themselves so that they can give rise to action sequences adjusted to what the senses are registering in real time.
On the other hand, certain regions of the midbrain are associated with processes of regulation of consciousness and sleep, as they are crossed by the reticular formation. The midbrain also intervenes in homeostatic functions aimed at keeping the body in good balance, and therefore, for example, it has a role in regulating body temperature.
Thus, the midbrain is responsible for carrying out processes of vital importance for the organism to continue functioning, to the point that the activity in this structure of the nervous system is what signals more clearly whether there is brain death or not. .
Associated diseases and injuries
Any injury that affects the lower areas of the brain can reach the midbrain. The consequences of this type of accident are almost always very serious, producing coma or death
The reason is that the midbrain is a section of the nervous system whose importance is crucial for coordinating basic physiological functions of the organism, and also serves for various types of nervous impulses to reach the groups of higher neurons. Like the midbrain acts as a link between many areas the presence of anomalies in this area affects many others.
Regarding diseases that affect these structures of the brain, the most common are Alzheimer’s disease and Parkinson’s disease. Both are neurological disorders that interfere with the functioning of large areas of the nervous system, including the midbrain, and can lead to mobility and cognition problems.
