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The midbrain is one part of the central nervous system. The midbrain is located between the forebrain and the hindbrain. It primarily influences the course of human movements. In addition, the midbrain is also associated with the sense of sight and the sense of hearing. How is the midbrain built and what can the consequences of damaging this structure be?
Midbrain(Latinmesencephalon , English mesencephalon or midbrain) enters, next to the forebrain, diencephalon, bridge, medulla and medulla spinal cord into the central nervous system.
The midbrain, as the name suggests, is located in the middle of the brain - it connects the forebrain and the hindbrain. Together with the aforementioned bridge and the extended medulla, the midbrain forms the brainstem.
Midbrain: external structure
Within the midbrain, its ventral part is distinguished, which is formed by the branches of the brain, and the dorsal part, which is formed by the covers of the midbrain. The abdominal part is even and there are branches of the brain in it.
There is a depression between the limbs of the brain, known as the intercranial fossa - this is an important location because this is where the fibers of the third cranial nerve, the oculomotor nerve, leave the brainstem.
In the dorsal part of the midbrain there are two pairs of mounds of the midbrain cover.
The upper mounds are related to the sense of sight - the arms of the upper mounds extend from them and connect with the lateral geniculate body.
The lower mounds are also present in this region of the midbrain, which - via the arms of the lower mounds - are connected to the structure related to the sense of hearing, which is the medial geniculate body.
In the dorsal part of the midbrain, the roots of one of the cranial nerves also extend from the brain - in this location, above the hillocks, fibers of the compound nerve are present.
Midbrain: internal structure
In the transverse section of the midbrain, the ventral parts of the branches of the brain (called its branches), their dorsal parts (called the cap) and the cover of the midbrain are distinguished.
In the ventral part of the midbrain, there are also cortico-spinal and cortico-pontic fibers, right behind them there isthe black substance, which consists of two parts: the compact black substance and the black reticular substance.
There is a red nucleus dorsally from the black matter in the midbrain, and laterally from it run the medial and lateral bands (which are the ascending sensory pathways).
Within the discussed part of the brain there is also a structure belonging to the ventricular system - here we are talking about the brain's water supply, which connects the third and fourth ventricles. The central gray matter is located around the water pipe.
The nuclei of several cranial nerves are also located in the midbrain:
- nuclei of the oculomotor nerve (which are the main nucleus of the oculomotor nerve, the middle nucleus of the oculomotor nerve, the middle caudal nucleus of the oculomotor nerve and the additional nucleus of the oculomotor nerve)
- nuclei of the block nerve
- intracerebral nucleus of the trigeminal nerve
Midbrain: Features
Some of the functions performed by the midbrain have already been mentioned earlier - this structure is involved in the perception of sensory experiences on the part of the organ of hearing or sight. In addition, the role of the midbrain is also involved in controlling the rhythm of sleep and wake and thermoregulation.
A very important function of the midbrain is also participation in the course of movements made by people. This task is performed primarily by the black substance - it secretes both the stimulating neurotransmitter (which is dopamine) and the neurotransmitter that inhibits nerve cells (which is GABA).
Due to the presence of the brain's water supply within it, the midbrain is also involved in the circulation of the cerebrospinal fluid.
Midbrain: diseases
Like other parts of the central nervous system, the midbrain can be affected by a variety of pathological processes. It can be damaged by both strokes and head injuries ( although in the case of the latter, it should be emphasized immediately that damage to the midbrain caused by injuries is actually very rare).
Parkinson's disease, in which there is a deficiency of nerve cells belonging to the substantia nigra, is a special entity, the cause of which are abnormalities in the functioning of the midbrain structures.
Symptoms of midbrain diseases can be different - most often, involuntary movements (such as tremors) appear in their course. With damage to specific elements of this structure, visual impairment or hearing impairment are also possible.
Then, when the patency is blockedlocated in the midbrain of the brain's water supply (e.g. due to the compression of this structure by neoplastic changes), patients may develop acquired hydrocephalus.
About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.Read more articles by this author