Human Anatomy - Kotsan I. Ya. 2009

Brain
Third ventricle

The third ventricle (ventriculus tertius) occupies a central position within the Diencephalon. It is a slit-like cavity located in the median sagittal plane between the right and left thalami, filled with CEREBROSPINAL FLUID. The walls of the ventricle are lined with ependyma. The third ventricle features 6 walls: two lateral, anterior, posterior, inferior, and superior.

The lateral walls of the third ventricle are formed by the facing medial surfaces of the thalami, as well as the medial PARTS OF THE subthalamic region located below the hypothalamic sulcus.

The anterior wall of the third ventricle is formed by the lamina terminalis, the columns of the fornix, and the anterior commissure. On each side, the Column of the fornix and the adjacent anterior part of the thalamus bound the interventricular foramen, which connects the cavity of the third ventricle with the lateral ventricle of the corresponding side.

The posterior wall of the third ventricle is formed by the epithalamic commissure, beneath which lies the opening leading into the cerebral aqueduct, connecting the cavities of the third and fourth ventricles.

The inferior wall, or floor, of the third ventricle is formed by the Hypothalamus, specifically its posterior surface facing the ventricular cavity. Two recesses of the third ventricle cavity are distinguished in the inferior wall: the infundibular recess (recessus infundibulli) and the optic recess (recessus opticus), which are located anterior to the optic chiasm, between its anterior surface and the lamina terminalis.

The superior wall, or roof, of the third ventricle is formed by the tela choroidea, which consists of two layers of the pia mater. From the side of the ventricular cavity, the tela choroidea of the third ventricle is covered by an epithelial lamina—the remnant of the posterior wall of the secondary Brain vesicle. The outgrowths (villi) of the inferior layer of the tela choroidea, together with the covering epithelial lamina suspended in the cavity of the third ventricle, form the choroid plexus of the third ventricle (plexus choroideus ventriculi tertii). In the region of the interventricular foramen, the choroid plexus of the third ventricle is continuous with the choroid plexus of the lateral ventricle.



Last update: 08/08/2026

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