Isthmus of the rhomboid brain
Last reviewed: 23.04.2024
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The Isthmus of the rhomboid brain (istmus rhombencephali - BNA) unites formations formed on the border of the middle and rhomboid brain. These are the upper cerebellar pedunculi (pedunculi cerebellares craniales, s. Superiores), the upper cerebral sail (velum medullare superius) and the triangle of the loop (trigonum linisci - BNA).
The upper cerebral sail is a thin plate of white matter, stretched between the upper cerebellar legs and the cerebellum. Ahead (above) it is attached to the roof of the midbrain, where in the groove between the two lower hills ends the bridle of the upper cerebral sail (frenulum veli medullares superioris). On the sides of the bridle from the brain tissue, the roots of the nerve block out. Together with the upper cerebellar legs, the upper cerebral sail forms the anterior upper wall of the roof of the IV ventricle of the brain. In the lateral sections of the isthmus of the rhomboid brain is a gray formation - the triangle of the loop. Its boundaries are: in front - the handle of the lower mound, behind and above - the upper cerebellar pedicle, on the side - the stem of the brain, which is separated from the isthmus of the rhomboid brain by the lateral groove. In the region of the triangle in its depth, fibers of the lateral (auditory) loop (liniscus lateralis) lie.
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