Meyer's loop is part of the optic radiation that runs in the temporal lobe lateral to the temporal horn of the lateral ventricle. It constitutes the inferior portion of the optic radiation, which extends into the posterior part of the temporal lobe.

Ventricle

The fibers of Meyer's loop cover the roof and the upper half of the lateral tip of the temporal horn of the lateral ventricle and then run posteriorly along the lateral wall of the temporal horn¹.

Clinical Relevance

Damage to Meyer's loop causes a homonymous superior quadrantanopia in the contralateral visual field². The extent of Meyer's loop is subject to considerable anatomical variability³.

Fiber Tracking

Visual representation for surgical planning can be obtained using MRI HDFT sequences⁴. In conventional DTI sequences, Meyer's loop often cannot be adequately visualized because of the pronounced angulation of the fiber bundle from anterior to posterior.

Figure

Meyer's loop MRI — MRI tractography of the optic pathway. Meyer's loop is shown in yellow, the central bundle in green, and the dorsal bundle in blue. Figure adapted from Mandelstam (2012).

References

Raabe, Andreas, ed. The craniotomy atlas. Georg Thieme Verlag, 2019. ↩ ↩
Visual field deficits. In: Greenberg M, ed. Handbook of Neurosurgery. 9th Edition. Thieme; 2019. ↩ ↩
Taoka, T., et al. "Diffusion tensor tractography of the Meyer loop in cases of temporal lobe resection for temporal lobe epilepsy: correlation between postsurgical visual field defect and anterior limit of Meyer loop on tractography." American Journal of Neuroradiology 29.7 (2008): 1329-1334. ↩ ↩
Fernandez-Miranda JC, Pathak S, Engh J, et al. High-Definition Fiber Tractography of the Human Brain. Neurosurgery. 2012;71(2):430-453. ↩ ↩