Question

Third and fourth ventricles of brain are connected by
A. Aqueduct of Sylvius
B. Foramen of Monro
C. Foramen of Magnum
D. Corpus callosum

Answer 1

Hint: Brain has a set of four ventricles that are interconnected to each other. This is known as the ventricular system. The ventricles are- lateral ventricles i.e. right and left ventricles, third ventricle and fourth ventricle.

Complete answer:
Option A- Aqueduct of Sylvius
Also known as cerebral aqueduct/ aqueductus mesencephali/ mesencephalic duct/ Sylvian aqueduct is a structure within the brainstem that contains cerebrospinal fluid and connects the third and fourth ventricles. It is 1 to 3 mm in diameter, located in the midbrain.

Option B- Foramen of Monro
Also known as interventricular foramen is a paired foramina that contains cerebrospinal fluid and connects the lateral and third ventricle.

Option C- Foramen of Magnum
It is the largest foramen of the skull, which is oval in shape with a large anteroposterior diameter present on occipital bone. It forms a connection between the brain and the spinal cord.

Option D- Corpus callosum
It is a nerve tract composed of a bundle of nerve fibres beneath the cerebral cortex in the brain which connects the left and right cerebral hemispheres. It is only found in placental mammals.

Thus, the correct option is option A- Aqueduct of Sylvius.

Note: Cerebrospinal fluid is produced by choroid plexus present in each ventricle. The ventricular system allows the cerebrospinal fluid to circulate the flow from the ventricles to the spinal cord. The cerebral aqueduct is surrounded by gray matter that contains small neurons.