Any measurable or observable characteristic related to the physical magnitude of the narrow cleft inferior to the corpus callosum, within the diencephalon, between the paired thalami; its floor is formed by the hypothalamus, its anterior wall by the lamina terminalis, and its roof by ependyma; it communicates with the fourth ventricle by the cerebral aqueduct, and with the lateral ventricles by the interventricular foramina.
Synonyms:
exact_synonym:
ventricle of diencephalon size trait; ventriculus tertius size trait