Cerebellum

Histology

The crust and the Central nucleus of a cerebellum are formed gray matter, the rest mass of white. On cross sections of the cerebellar cortex (Fig. 6) there are superficial, or molecular, the stratum moleculare) and deep, or grainy, the stratum granulosum), between them is a narrow retinal layer (stratum gangliosum), formed by one line of Purkinje cells of very large size. From the Foundation of the Purkinje cells departs severinenko process, penetrating through a layer of beans in the white matter. Almost from the initial part of the process, depart collaterals, partially ending in a layer of beans, partially about neighboring Purkinje cells. From the upper end of Purkinje cells in molecular layer depart branching dendrites always located in the same plane perpendicular to the length of the brains. In addition to these branches, in a molecular layer are small multipolar cells with short branching axonom and large, "pocket", cells with long axonom, the ramifications of which end in the form plexus ("baskets") about many of the Purkinje cells. In a granular bed are very small cells of grain, dendrites, which are surrounded by neighboring cells and in contact with various nerve fibers, and severinenko the processes going in the ascending direction in molecular layer, and the ramifications of their end buttons on the branching dendrites many of Purkinje cells and the "pocket" of cells. Among cells-grains in granular layer occur in small numbers stellate cells (cells correlates), dendrites, which fan out in granular and molecular layers and layer Purkinje cells, short axons branch into a layer of beans, and long axons go into the white substance.

Fig. 6. Microscopic structure of the cerebellar cortex. 1 - molecular layer; II - granular layer III - medullary layer; 1 - "baskets" about Purkinje cells; 2 - fine surface cells molecular layer; 3 - "pocket" cells; 4 - large stellate cells; 5 - mossy fibers; in - glioznogo cells, astrocytes granular layer; 7 - fiber Bergmann; 8 - ccllules empanachees; on - cell-grain; 10 - creeping fiber; 11 - Purkinje cells.

Afferent system cerebellum formed mossy and creeping fibers heading of the legs of the cerebellum through the white material in the cerebellar cortex. Purkinje cells receive impulses directly through mossy and creeping fiber or by cell-grains. Cell-grain receive impulses from mossy fibers and pass them through their axons in a molecular layer on the dendrites "pocket" and stellate cells, and stellate cells through their axons send impulses to the Purkinje cells. In addition, the system has many branches mossy fibers, cell-grains and stellate cells are closed circles actions.
Neuroglia cerebellum consists of various macroglossia, mikroklizmy and oligodendroglialnah cells.
Central four cores M. are located on both sides; in the worm Meters, directly in the middle, " roofing kernel (nuclei fastigii); lateral - spherical nucleus globosus); more lies lateral, in the white matter hemisphere M,- cork nucleus emboliformis), the largest - dentate nucleus dentatus).
In the white matter in the Central part of each plate of the cerebellum, distinguish the fibre: associative linking gyrus and share the same name hemisphere; comisarului linking the opposite hemisphere; projection, divided into centripetal and centrifugal that are directed from the bark (from the Purkinje cells) and end at the Central subcortical nuclei of the cerebellum. Except for some fibers heading to the vestibular nuclei, all efferent fibres coming from the bark M (axons of Purkinje cells), end, apparently, in vnutriposelkovykh nuclei. From the nuclei of centrifugal fiber through the legs M heading to other parts of the brain (printing. table. senior 65, rice, 3).
The connection of the cerebellum with other parts of the brain are three pairs of legs; lower and middle consist mainly of afferent fibers, and the top - of efferent. Lower leg M, or verevchataya body [pedunculus cerebellaris inferior, s. corpus restiforme (BNA)]connects M. from the spinal, oblong, medium and interstitial the brain and contains the outer core verevchataya body (nucleus lateralis funiculi cuneati, s. nucleus corporis restiformis) and fiber, posterior spinal-cerebellar tract (tractus spinocerebellaris post.), originating in the spinal cord, a small number of fibres from the anterior spinal-cerebellar tract (tractus spinocerebellaris ant.), fiber cores gentle and wedge cord (funiculi gracilis et cuneati), from nuclei reticular substance to the cerebellum, and the fiber that connects M with olive trees.
Middle leg of the cerebellum [pedunculus cerebellaris medius, s. bracliium pontis (BNA)]running from the bridge, formed fibers originating in the nuclei of its Foundation. In the gray matter of the bridge over collaterals pyramid fibers running from the bark of a large brain of the same side; then the fibers, beginning in the nuclei of the bridge, form the intersection and go to the opposite side, forming a middle leg M Over medium legs in the cerebral hemispheres M Only a small number of fibers goes in the opposite direction, starting in the cortex, M. and ending in the nuclei of the bridge. Thus, through the kernel bridge frontal-bridge, the bridge, the occipital-pavement and mostomozzhechkovogo systems out of the bark of a large brain cortex opposite side of the cerebellum.
On the bottom IV heart are fiber beginning in nuclei reticular substances (substantia reticularis) and ending in the cortex of the piece. Top leg cerebellum [pedunculus cerebellaris sup., 's. brachium conjunctivum cerebelli (BNA)], consisting of efferent fibres, beginning in nuclei M, goes up and forward, forming a wall of the fourth ventricle, penetrates into the lid of the bridge, the brain stem and after intersection of shares on the descending branch ending in reticular stem cores, and the ascending branch, the fibers of which end up in the red nucleus and nuclei visual occiput. Efferent fibres, originating from the core of the tire, pass through the inner part of the lower leg M and ends in nuclei reticular and vestibular systems located in the barrel; part fibers running from the kernel tires is part of hooked beam around the outside of the upper leg to the cerebellum. Communication Meters with cells of the front horns spinal cord through reticulospinal, rubrospinal and vestibulospinal paths.
By M. coordinates various extrapyramidal centres with each other, with reticular formation, with cortical and spinal motor systems. Some efferent system cerebellum reach reticular formation, others pass through the jagged kernel and go to the optic hill and motor departments of a bark of the big hemispheres. From here on cerebrospinal fibers impulses are passed down. In addition, for the implementation of complex motor act of various nuclear groups are linked in a continuous stream of pulses. It is established that these impulses are guided by certain neuronin circles. One of the most difficult neironnykh circles is the way: between the visual hump - a bark of the big hemispheres - bridge - cerebellar - visual mound.
The blood supply. The cerebellum is supplied with blood out of a three pair of branches and spinal main arteries (AA. vertebralis et basilaris): both the front and rear of the lower and upper arteries M (AA. cerebelli posterior inferior, cerebelli anterior inferior et cerebelli superior). Fourth - middle lower artery M (a. cerebelli inferior media) is a rare, often unmatched. A. cerebelli superior supplies blood to the upper dorsal surface of the cerebellum and the upper worm; a. cerebelli posterior inferior - bottom ventral surface M, the lower the worm and choroid plexus of the fourth ventricle; a. cerebelli anterior inferior - anterolateral surface M. and "piece". There is a large variability in the location and division vessels. Between the main branches of cerebellar arteries and between secondary and tertiary branches exist anastomoses.