The indusium griseum, (supracallosal gyrus, gyrus epicallosus, dorsal hippocampal continuation) consists of a thin membranous layer of

grey matter Grey matter, or gray matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil ( dendrites and unmyelinated axons), glial cells ( astrocytes and oligodendrocytes), synapses, ...

in contact with the upper surface of the

corpus callosum The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental ...

and continuous laterally with the grey matter of the

cingulate cortex The cingulate cortex is a part of the brain situated in the medial aspect of the cerebral cortex. The cingulate cortex includes the entire cingulate gyrus, which lies immediately above the corpus callosum, and the continuation of this in the cin ...

and inferiorly with the

hippocampus The hippocampus (: hippocampi; via Latin from Ancient Greek, Greek , 'seahorse'), also hippocampus proper, is a major component of the brain of humans and many other vertebrates. In the human brain the hippocampus, the dentate gyrus, and the ...

. It is vestigial in humans and is a remnant of the former position of the hippocampus in lower animals. On either side of the midline of the indusium griseum are two ridges formed by bands of longitudinally directed fibers known as the medial and lateral longitudinal striae. The indusium griseum is prolonged around the

splenium The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental m ...

of the corpus callosum as a delicate layer, the fasciolar gyrus, (also gyrus fasciolaris) which is continuous below with the surface of the

dentate gyrus The dentate gyrus (DG) is one of the subfields of the hippocampus, in the hippocampal formation. The hippocampal formation is located in the temporal lobe of the brain, and includes the hippocampus (including CA1 to CA4) subfields, and other su ...

. The indusium griseum and fasciolar gyrus are very small components of the

limbic lobe The limbic lobe is an arc-shaped cortical region of the limbic system, on the medial surface of each cerebral hemisphere of the mammalian brain, consisting of parts of the frontal, parietal and temporal lobes. The term is ambiguous, with some au ...

, and are continuations of the hippocampal formation, forming an unremarkable thin continuous ring of grey matter at the edge of the cortex. Toward the genu of the corpus callosum it curves down along the rostrum to form the subcallosal gyrus.

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* {{Authority control Gyri