The substantia innominata also innominate substance, or substantia innominata of Meynert (Latin for unnamed substance) is a series of layers in the

human brain The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the act ...

consisting partly of

gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed ...

and partly of

white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distributi ...

, which lies below the anterior part of the

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all direction ...

and

lentiform nucleus The lentiform nucleus, or lenticular nucleus, comprises the putamen and the globus pallidus within the basal ganglia. With the caudate nucleus, it forms the dorsal striatum. It is a large, lens-shaped mass of gray matter just lateral to the inte ...

. It is included as part of the anterior perforated substance (as it appears to be perforated by many holes which are actually blood vessels). It is part of the

basal forebrain Part of the human brain, the basal forebrain structures are located in the forebrain to the front of and below the striatum. They include the ventral basal ganglia (including nucleus accumbens and ventral pallidum), nucleus basalis, diagonal ba ...

structures and includes the nucleus basalis. A portion of the substantia innominata, below the

globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It consists of two adjacent segments, one external, known in rodents simply as the globus pallidus, and one internal, known in rode ...

is considered as part of the extended amygdala.

Layers

Nucleus basalis of Meynert -l- very low mag

It consists of three layers, superior, middle, and inferior. * The ''superior layer'' is named the ansa lenticularis, and its fibers, derived from the medullary lamina of the lentiform nucleus, pass medially to end in the thalamus and subthalamic region, while others are said to end in the

tegmentum The tegmentum (from Latin for "covering") is a general area within the brainstem. The tegmentum is the ventral part of the midbrain and the tectum is the dorsal part of the midbrain. It is located between the ventricular system and distinctive ba ...

and

red nucleus The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. ...

. * The ''middle layer'' consists of nerve cells and nerve fibers; fibers enter it from the parietal lobe through the

external capsule The external capsule is a series of white matter fiber tracts in the brain. These fibers run between the most lateral (toward the side of the head) segment of the lentiform nucleus (more specifically the putamen) and the claustrum. The white matte ...

, while others are said to connect it with the

medial longitudinal fasciculus The medial longitudinal fasciculus (MLF) is an area of crossed over tracts, on each side of the brainstem. These bundles of axons are situated near the midline of the brainstem. They are made up of both ascending and descending fibers that ar ...

. * The ''inferior layer'' forms the main part of the inferior stalk of the thalamus, and connects this body with the

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in proc ...

and the insula.

Striatopallidal system

In the late 20th century following improved imaging by

staining Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in ...

it was reclassified as part of the

striatopallidal system The striatopallidal fibres, also Wilson's pencils, pencil fibres of Wilson, and pencils of Wilson, are prominent myelinated fibres that connect the striatum to the globus pallidus. Their distinctive appearance allows the putamen to be identified o ...

, which is made up of the dorsal striatum and dorsal pallidum, and the ventral striatum and ventral pallidum.

References

External links

Diagram at biocfarm.unibo.it
{{Authority control Rostral basal ganglia and associated structures