Metencephalon
The rear brain is part of the central nervous system.
It belongs to the brain and is here used by the hindbrain (Rhombencephalon), which also includes the medulla oblongata (elongated marrow).
The pons belong to the hindbrain (bridge) and the cerebellum (Cerebellum).
The cerebellum plays a big role in coordinating movements.
The pons is traversed by numerous nerve fibers that run from the brain to the periphery or from the periphery to the brain. In addition, some cranial nerves have their exit point here.
Cerebrum (1st - 6th) = endbrain -
Telencephalon (Cerembrum)
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You can find an overview of all Dr-Gumpert images at: medical illustrations
$config[ads_text2] not foundPons
The pons borders downward (caudal) to the Medulla oblongata and counts to Brain stem.
He goes cranially into that Midbrain (Mesencephalon) above.
The bridge can be folded in two sections divide the front (ventral) located Base (Pars basilaris pontis) and the posterior (dorsal) Hood (Tegmentum).
Towards the rear, the pons and the medulla oblongata form the Bottom of the lozenge pit.
Here is the one fourth ventricle, one of several with Cerebral water (Liquor) filled cavities in the area of the brain.
The ventral portion the pons is clearly distinguishable from the rest of the brain stem, because here Nerve fibers run across and thus present on both sides Form transverse ridgeswhich are separated from one another by a notch in the middle.
An important artery supplying the back of the brain, the artery, runs in this notch basilaristhat from the confluence the both vertebral arteries emerges.
There are many in the Pons Nerve fiber tracts. Those that run from the cerebral cortex to the periphery, such as the Pyramidal track, one of the most important neural pathways for the Arbitrary movement, and nerve tracts that run from the periphery into the cerebral cortex, for example the Lateral spinothalamic tract.
He counts to Front strand and above all forwards information about Pain and temperature (summarized as protopathic information) from peripheral to central.
In the pons there are also numerous nerve cell nuclei that Nuclei pontes. In them will be among other things Fibers of the pyramidal tract (corticopontine fibers) that come from the cerebral cortex, switched and then as a kind of copy into the cerebellum forwarded (pontocerebellar fibers).
This is to help the cerebellum know which ones Movement information sent to the muscles of the face, torso, arms and legs.
The cerebellum then plays a crucial role for that precise coordination and fine motor skills.
So a large part of the bridge's work revolves around that Motor skills.
Further back (dorsal) in the bridge are parts of the Formatio reticularis. This is a network of nerve cell nuclei and fibers that runs through the entire brain stem and plays a central role in the regulation of Cycle and breathing plays.
4 of the 12th Cranial nerves have their exit point in the area of the bridge. The 5th cranial nerve, the Trigeminal nerve, exits on both sides of the bridge. He is responsible for the innervation of the Masticatory muscles and the sensitivity in the Facial area. Also the Cornea (Cornea) is sensitively innervated by the trigeminal nerve, so it is part of the reflex arc in the Lid closing reflex (Corneal reflex).
The sixth cranial nerve, the Abducens nerve, is the only cranial nerve that emerges from the back of the brain stem. He is responsible for the care of one of the six Eye muscles.
The seventh nerve, the Facial nerve, occurs in Cerebellar bridge angle off, i.e. in the area between the cerebellum and the bridge. Among other things, he plays an essential role for the facial expressions and the taste.
Also the eighth cranial nerve, the Vestibulocochlear nerve, emerges at the cerebellopontine angle, it is for Listen and Sense of balance indispensable.
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The Pons is at the so-called Locked-in Syndrome damaged.
The cause for this is usually one thrombosis, a blood clot, in the basilar artery.
This leads to one Infarct in the bridge, The oxygen supply in one part of the Pons is permanently interrupted, so this part has no function. Affected Patients are awake and perceive their surroundings undisturbed, but they are unable to move or speak, because the nerve fibers that make this possible run through the pons, which are no longer functional due to the thrombosis.
The affected patient's only ability to communicate with the outside world is vertical eye movements.
Cerebellum
The Cerebellum lies in the posterior fossa below the Occipital lobe and attaches to the brain stem from behind.
It is in two hemispheres and a middle part, the Cerebellar worm (Vermis cerebelli) structured.
You can also do it in Cerebellar medulla (Inside) and Cerebellar cortex (Outside) subdivide.
The cerebellar cortex contains three cell layers: The Molecular layer, the Purkinje cell layer and the Granule cell layer (from the outside to the inside).
The cerebellum is with the brain stem about three each so-called Cerebellar stalks connected, the upper, middle and lower (Pedunculus cerebelli superior, medius and inferior).
Between the front part of the cerebellum and the rear part of the pons and medulla oblongata lies the with Cerebral water (Liquor) filled fourth ventricle.
In the cerebellar medulla lie on both sides four nerve cell nuclei. The nucleus fastigii, nucleus globosus, nucleus dentatus and nucleus emboliformis.
Be in these cores Information about nerve cells received, switched and forwarded.
So the cerebellum plays a central role in the Fine-tune movements. It turns the “gross motor skills” that the motocortex initiates in the cerebral cortex into one, so to speak Fine motor skills.
It receives a lot of information about this. Among other things, nerve fibers run for this from the spinal cord, the cerebral cortex, the brain stem and the Equilibrium organs into the cerebellum.
These nerve fibers run in the three cerebellar stalks mentioned above. After processing and coordinating the information, the cerebellum sends its "revised version" to the Thalamus, the Formatio reticularis, the Nucleus ruber in the midbrain and nerve cell nuclei that are responsible for this balance (Vestibular nuclei).
In addition to controlling and fine-tuning motor skills, the cerebellum also seems to play an important role for that storage once learned and more automated over time Movement pattern to have.
It is also discussed whether the cerebellum also has a meaning cognitive processes like behavior and affect.
In terms of function, the cerebellum can be divided into three different sections. That's how it is Vestibulocerebellum especially for Balance, standing up and Coordination of eye movements responsible. The Spinocerebellum draws for Standing and walking responsible. The Pontocerebellum is the Fine regulator for the entire motor skills. Regardless of whether it is about reaching for a coffee cup, using the tweezers or playing the piano.
Lesions in the cerebellum sometimes result in relatively characteristic findings.
The most typical symptom is that Cerebellar ataxia. This can be the Sitting, standing or walking demonstrate.
It is no longer possible to sit or stand upright safely without a support Gait pattern is legs apart (broad-based) and chopped off, it works gross motor skills and awkward.
Other neurological symptoms are relatively characteristic of a cerebellar lesion and can be detected by simple clinical examinations:
A Intention tremor is a tremor (Tremble), which gets stronger the closer the pointing finger gets to the target.
It can be tested by the patient Index finger to your own nose leads. Swings the finger more and more rhythmically, the closer it gets to the nose, this is an indication of an intention tremor.
Another test for diagnosing a cerebellar problem is a rapid alternation of opposing movementsFor example, turning the hand so that the palm of the hand and then the back of the hand are on top. Is this not possible or clearly faltering and difficult, this is known as Dysdiadochokinesis, i.e. the inability to rapidly alternate opposing (antagonistic) Perform movements.
Another sign of cerebellar damage is the so-called Rebound phenomenon. Here, the doctor grabs the patient's forearm, which is bent at the elbow joint, and pulls it towards him while he asks the patient to hold against it. If the doctor suddenly lets go, the patient cannot react quickly enough in a coordinated manner and would hit his forearm in the face. This is prevented by the doctor using a safety handle. Damage to the cerebellum therefore shows quite typical symptoms that can initially be uncovered in everyday clinical and neurological life without great effort.
For more information, see: Cerebellum
