A patient with a right temporal lobe lesion extending into the deep white matter shows a visual field defect. Which field defect is most characteristic?
- A Left upper quadrantanopia ('pie in the sky') ✓
- B Left lower quadrantanopia ('pie on the floor')
- C Left homonymous hemianopia with macular sparing
- D Right homonymous hemianopia without macular sparing
Correct answer: A. Left upper quadrantanopia ('pie in the sky')
Explanation
The inferior fibers of the optic radiation (Meyer's loop) sweep forward into the temporal lobe before arching posteriorly to the visual cortex. These fibers carry impulses from the upper half of the contralateral visual field. A right temporal lobe lesion affecting Meyer's loop produces a left upper quadrantanopia. Parietal lobe lesions affect superior optic radiation fibers and produce lower quadrantanopia (option B). Complete hemianopia with macular sparing (option C) results from occipital lobe lesions.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.