The substantia innominata, also innominate substance or substantia innominata of Meynert (Latin for unnamed substance), is a series of layers in the human brain consisting partly of gray and partly of white matter, which lies below the anterior part of the thalamus and lentiform nucleus.

It is part of the basal forebrain structures and includes the nucleus basalis.

A portion of the substantia innominata, below the globus pallidus is considered as part of the extended amygdala.

In the late 20th century following improved imaging by staining it was reclassified as part of the striatopallidal system, which is made up of the dorsal striatum and dorsal pallidum, and the ventral striatum and ventral pallidum.

[2][3] This article incorporates text in the public domain from page 837 of the 20th edition of Gray's Anatomy (1918)