Human Anatomy Part 2 - K. A. Diubenko, A. K. Kolomiitsev, Yu. B. Chaikovsky 2008

Special Section
Nervous system, systema nervosum - Special Section
Brain - Forebrain - Third ventricle

The Third ventricle, ventriculus tertius, is the cavity of the Diencephalon and is a narrow vertical slit located in the sagittal plane between the medial surfaces of the thalami (Fig. 143 B, 149). The cavity of the third ventricle is lined with ependyma and filled with CEREBROSPINAL FLUID. Its lateral walls are bounded by the medial surfaces of the thalamus and the structures of the Hypothalamus. The anterior wall of the ventricle is formed by the lamina terminalis, the anterior commissure, and the columns of the fornix. Between the curvature of the columns of the fornix and the thalamus are the interventricular foramina (foramina of Monro)*, foramina interventricularia Monro, which connect the third ventricle with the Lateral ventricles of the corresponding side.

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Fig. 149. Choroid tela of the third ventricle (superior view).

The superior wall of the third ventricle, or roof, is formed by the choroid tela of the ventricle, tela choroidea, which resembles a thin plate located beneath the fornix and the corpus callosum.

The posterior wall of the third ventricle is formed by the habenular commissure, the Base of the pineal body, and the posterior epithalamic commissure. Below the commissure is the opening of the cerebral aqueduct, aqueductus cerebri, which connects the third and fourth ventricles. In the region of the base of the pineal body, there is the pineal recess, recessus pinealis.

The inferior wall, or floor, of the third ventricle is formed by: the optic chiasm, the tuber cinereum, the infundibulum, the mammillary bodies, and the posterior perforated substance. In the region of the floor of the third ventricle, There are two recesses: the infundibular recess, recessus infundibuli, and the optic recess, recessus opticus.

* Alexander Monro secundus (1783-1817) was a Scottish anatomist. He studied the Structure AND Functions of the Brain. The interventricular foramen (foramen of Monro) was named after him.



Last update: 08/08/2026

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