The third (brain) ventricle is a cerebrospinal cavity located in the midline of the midbrain (diencephalon) and sandwiched between the right and left pile of vision (thalamus). Usually, the two visual mounds, within a limited area, are intertwined with each other across the mean line: the mounds of vision (adhetio interthalamica).
The 3rd ventricle passes anteriorly into the right and left lateral ventricles located in the respective cerebrum hemispheres. The transition takes place through the right and left ventricular intermediate holes (foramen interventriculare or foramen Monro). Backwards, the 3rd ventricle passes into the brain's water pipe. In the roof of the 3rd ventricle there are two cerebrospinal fluid (choroidal) braids. The lower/lower part of the third ventricle is surrounded by the hypothalamus.