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Basal Nuclei

Nuclei basales

For medical students2 min readUpdated 2026-10-10

Basal nuclei are large masses of gray matter located deep within the white matter at the base of the cerebral hemispheres. They serve as critical subcortical centers of the telencephalon, closely associated with the surrounding white matter and the ventricular system.

LocalizationBase of the cerebral hemispheres
Corpus striatumCaudate nucleus, lentiform nucleus, and claustrum
ClaustrumSeparated from the lentiform nucleus by the external capsule
AmygdalaLocated in the temporal lobe anterior to the inferior horn of the ventricle

General Classification of Basal Nuclei

The subcortical nuclei of the telencephalon form a complex gray matter network. Anatomists group a significant portion of these structures into a single entity known as the corpus striatum (corpus striatum).

Traditionally, the corpus striatum comprises three main anatomical structures:

In addition to the corpus striatum, the basal nuclei include the amygdaloid body (corpus amygdaloideum), which is situated separately within the temporal lobe structures.

Structure of the Caudate Nucleus

The caudate nucleus (nucleus caudatus) is elongated and topographically closely related to the lateral ventricle system. Its structure is divided into three consecutive parts, each adjacent to a specific region of the ventricle:

  1. Head (caput) — the most massive anterior region. It directly contributes to forming the lateral wall of the anterior horn of the lateral ventricle.
  2. Body (corpus) — the middle portion of the nucleus. Topographically, the body runs parallel to the central part (body) of the lateral ventricle.
  3. Tail (cauda) — the tapering posterior region. The tail curves inferiorly into the temporal lobe, where it helps form the wall of the inferior horn of the lateral ventricle.

Lentiform Nucleus and Claustrum

The lentiform nucleus (nucleus lentiformis) lies lateral to the caudate nucleus. Its long axis is oriented sagittally (anterior to posterior). Thin sheets of white matter divide the mass of the nucleus into segments.

These white matter laminae are termed the medial and lateral medullary laminae (laminae medullares). They divide the nucleus into:

Lateral to the lentiform nucleus lies the claustrum (claustrum), a very thin sheet of gray matter. The claustrum is separated from the putamen (the lateral part of the lentiform nucleus) by a layer of white matter known as the external capsule (capsula externa).

Anatomy of the Amygdala

The amygdaloid body (corpus amygdaloideum) is located deep within the temporal lobe, situated directly anterior to the inferior horn of the lateral ventricle. In some anatomical classifications, this structure is viewed not as an isolated nucleus, but as a local thickening of the temporal cortex.

The amygdala comprises several functional and anatomical zones:

Mnemonic

The parts of the caudate nucleus correspond to the horns of the lateral ventricle: Head — Anterior horn, Body — Central part (body), Tail — Inferior horn.

Frequently asked questions

Which nuclei form the striopallidal system and how are they classified phylogenetically?

The striopallidal system is formed by the caudate nucleus, putamen, and globus pallidus. Phylogenetically, these structures are divided into older and newer components:

  • Globus pallidus (globus pallidus) — belongs to the paleostriatum (paleostriatum), a phylogenetically older structure.
  • Caudate nucleus (nucleus caudatus) and putamen (putamen) — form the neostriatum, which developed later and expanded alongside the cerebral cortex.
Which white matter structure separates the caudate and lentiform nuclei?

The internal capsule (capsula interna) separates the caudate and lentiform nuclei. This white matter structure is the primary highway for all projection fibers. On axial brain slices, it has a characteristic V-shape and additionally separates the lentiform nucleus from the thalamus.

Which specific white matter lamina separates the putamen from the globus pallidus?

The medial medullary lamina (lamina medullaris medialis) separates the putamen and globus pallidus. It is a thin strip of white matter running between these structures, while the putamen itself lies laterally and partially wraps around the globus pallidus.

What functions do the basal nuclei perform within the extrapyramidal system?

Within the extrapyramidal system, the basal nuclei act as control centers for involuntary movements and muscle tone regulation. Their main functions include:

  • initiation and cessation of movements;
  • control of amplitude, velocity, and complex motor patterns;
  • suppression of extraneous, involuntary movements;
  • provision of cognitive control over motor activity.
What anatomical structures lie lateral to the claustrum?

The extreme capsule (extreme capsule) and the insular cortex (insula cortex) lie lateral to the claustrum (claustrum). The claustrum separates the medially located external capsule from the laterally located extreme capsule, which sits between the claustrum and the insular cortex.

Where are the basal nuclei located?

They lie within the white matter at the base of the cerebral hemispheres.

What structures form the lentiform nucleus?

It consists of the laterally positioned putamen and the medially positioned globus pallidus.

What separates the claustrum from the lentiform nucleus?

The external capsule (capsula externa), a layer of white matter, runs between the claustrum and the lentiform nucleus (specifically its putamen).

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