室间孔

[ noun ]
the small opening (on both the right and left sides) that connects the third ventricle in the diencephalon with the lateral ventricle in the cerebral hemisphere
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Foramen \Fo*ra"men\, n.; pl. L. {Foramina}, E. {Foramines}. [L.,
fr. forare to bore, pierce.]
A small opening, perforation, or orifice; a fenestra.

{Foramen of Monro} (Anat.), the opening from each lateral
into the third ventricle of the brain.

{Foramen of Winslow} (Anat.), the opening connecting the sac
of the omentum with the general cavity of the peritoneum.