A 28-year-old woman, complaining of frequent

headaches, is examined by a neurologist. During clinical examination, he notes

that the patient presents with visual field defects that follow the

pattern of bitemporal hemianopia. He decides to send the patient for a brain

MRI scan, the image of which is shown in Figure 1.

A tumour in which of the labelled structures on the MRI

image in Figure 1 would most likely lead to this patient’s clinical

presentation?

Figure

1: Brain MRI