No, it surrounds it.
The third ventricle
Thalamus and hypothalamus respectively which are In the third ventricle
intermediate mass
The thalamus is situated at the top of the brain stem, connecting the brain to the spinal cord and vertebrates. The thalamus wraps around the third ventricle, making up the upper part of the ventricle wall.
The hypothalamus is a small mass below the thalamus and forms floor and part of the lateral walls of the third ventricle.
Thalamus
Right and left masses of the thalamus.
thalamus
third ventricle
The diencephalon consists of thalamus, hypothalamus, and epithalamus.
diencephalon
The 'Thalamus'