Question

Where is the 3rd ventricle of the brain located?
(a) Cerebrum
(b) Cerebellum
(c) Pons Varolii
(d) Diencephalon

Answer 1

Hint: The brain contains a total of four ventricles. The first and second are present in each hemisphere. The third ventricle, although has some similar functions to the other ventricles, is located separately. It is present in a region between the first two ventricles.

Complete step by step answer:
- The third ventricle is a part of the ventricular system of the brain. It is a cavity formed in the diencephalon between the left and right ventricle and between the two thalami.
- It is filled with cerebrospinal fluid (CSF) and is lined by ependyma.
- The structure of the ventricle contains two lateral walls, a roof, a floor, an anterior, and a posterior wall.
- The roof of the ventricle forms the choroid plexus which produces cerebrospinal fluid.
- The hypothalamic sulcus exists on the lateral side of the ventricle.

So, the correct answer is ‘Diencephalon’.

Additional Information:
- The third ventricle communicates with the first and second (lateral) ventricles via the foramen of Monro and communicates with the fourth ventricle via the aqueduct of Sylvius.
- The ependyma lines all the ventricles of the brain. It is a modified epithelium and forms the blood-CSF barrier.
- The diencephalon consists of the third ventricle, thalamus, hypothalamus, epithalamus, and subthalamus.

Note:
- The teal choroidea is present in each of the brain’s ventricles and adheres to the ependyma and is where the choroid plexus is formed.
- A rare tumor of the third ventricle exists which is known as choroid glioma.
- All ventricles develop from the neural canal of the neural tube.