Meyer's loop (temporal optic radiation)
Radiation & CN III · Superior quadrantanopia
The inferior fibres of the optic radiation, carrying the inferior retina and therefore the superior contralateral visual quadrant. They sweep forward around the temporal horn of the lateral ventricle into the temporal lobe before turning back to the lower bank of the calcarine sulcus (lingual gyrus).
Traced from the start
- Temporal hemiretinaNasal hemiretinaMacula and papillomacular bundle
- Optic nerve (CN II)
- Optic tract
- Lateral geniculate nucleus
- Meyer's loop (temporal optic radiation)
Detail
- Carries
- Inferior retinal quadrants, i.e. the superior contralateral visual field
- Course
- Anteriorly into the temporal lobe to within a few centimetres of the temporal pole, round the temporal horn, then posteriorly
- Terminates
- Lingual gyrus, below the calcarine sulcus
- Blood supply
- Inferior division of the middle cerebral artery and the anterior choroidal artery
When it goes wrong
Temporal lobe lesion: tumour, inferior-division MCA infarct, anterior temporal lobectomy for epilepsy
Contralateral superior homonymous quadrantanopia ('pie in the sky'), with receptive dysphasia if the dominant lobe is involved or memory impairment and focal impaired-awareness seizures
Practise this structure
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