Ventricular System and CSF

Which of the following structures forms the roof of the third ventricle?

A 3-year-old boy from Delhi presents with progressive headache, vomiting, and developmental delay over 2 months. On examination, he has a bulging anterior fontanelle, increased head circumference (crossing percentiles), and bilateral papilloedema. Fundoscopy reveals optic disc swelling. A non-contrast CT head shows dilated lateral and third ventricles with a normal-sized fourth ventricle. The cerebral aqueduct appears narrowed on sagittal imaging. What is the most likely site of CSF obstruction?

The choroid plexus of the lateral ventricles is located in which of the following regions?

A 62-year-old man from Mumbai is admitted with acute-onset severe frontal headache, neck stiffness, and confusion. CSF analysis shows elevated protein (180 mg/dL), normal glucose, and pleocytosis with lymphocytic predominance. MRI brain with contrast reveals communicating hydrocephalus with enhancement of the basal cisterns and sulci. A diagnosis of tuberculous meningitis is made. Which of the following best explains the mechanism of hydrocephalus in this patient?