The third and fourth ventricles of the brain are linked by a slender canal designated as the:

• A. cerebral aqueduct
• B. lateral aperture
• C. interventricular foramen
• D. central canal

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the anatomy of the brain's ventricular system, which consists of interconnected cavities filled with cerebrospinal fluid (CSF). These ventricles include the lateral ventricles, third ventricle, fourth ventricle, and the connecting structures between them.
2. Step 2: Recall the specific connections between the ventricles. The lateral ventricles connect to the third ventricle via the interventricular foramen (also known as the foramen of Monro). The third ventricle connects to the fourth ventricle through a slender canal.
3. Step 3: Identify the name of the slender canal that links the third and fourth ventricles. This structure is called the cerebral aqueduct (also known as the aqueduct of Sylvius). It is a narrow channel located in the midbrain.
4. Step 4: Eliminate the other options provided in the question: 'lateral aperture' refers to openings in the fourth ventricle that allow CSF to flow into the subarachnoid space, 'interventricular foramen' connects the lateral ventricles to the third ventricle, and 'central canal' is a structure in the spinal cord that carries CSF.
5. Step 5: Conclude that the correct answer is 'cerebral aqueduct,' as it is the specific structure linking the third and fourth ventricles in the brain.