Meyer’s Loop

Synonyms

Temporal optic radiations

Definition

The anterior, ventral portion of the optic radiations. Nerve fibers which exit the lateral geniculate nuclei project caudally to the primary visual cortex in the mesial portion of the occipital lobe. These fibers form a relatively broad band of white matter pathways known as the optic radiations. The ventral-most of this band of fibers loops slightly forward deep in the temporal lobe before continuing back to the lingual gyrus of the occipital cortex. This temporal deviation of the optic radiations is referred to as Meyer’s loop (see Fig. 1). Because these fibers essentially carry information originally derived from the ventral portion of the retina, lesions to this pathway will result in a contralateral superior quadrantanopsia.

Fig. 1

Schematic drawing of axial section of brain at the level of the midbrain showing the optic radiations and their temporal extensions (Meyer’s loop) from the lateral geniculate bodies to the visual cortex....