Caudate nucleus

What parts does the caudate nucleus consist of?

The nucleus has a curved shape that mirrors the contour of the lateral ventricle. This is a result of the telencephalon twisting during embryogenesis. On a frontal section, due to its C-shape, the structure is visualized simultaneously in two areas far apart from each other.

Anatomically, three parts are distinguished:

• Head (caput) — the rostral part. It forms the lateral wall of the anterior horn of the lateral ventricle. Externally (rostrally), the head is covered by the putamen (putamen).
• Body (corpus) — runs along the body of the lateral ventricle, participating in the formation of its lateral wall.
• Tail (cauda) — descends into the temporal lobe. It forms the roof arching over the inferior horn of the lateral ventricle, extending anteriorly all the way to the amygdala (corpus amygdaloideum), which lies in the anterior pocket of the inferior horn.

Topography and embryonic development

The caudate nucleus originates in the embryo from the ganglionic eminence, a derivative of the ventral part of the telencephalon. Together with the putamen, it forms a phylogenetically new structure — the neostriatum. With the evolution and development of the cerebral cortex, the neostriatum increased in size, reaching its maximum development in higher mammals and humans.

The caudate nucleus and the globus pallidus (globus pallidus) are connected by numerous delicate "bridges" of gray matter. On an anatomical specimen, they appear as stripes, which is why these nuclei are grouped under the common name corpus striatum (corpus striatum). The striated appearance forms during embryogenesis when the fibers of the internal capsule (capsula interna) grow through the initially homogeneous basal ganglia.

Topographically, the nucleus curves around the thalamus and the lentiform nucleus. In the groove between the thalamus and the caudate nucleus runs the stria terminalis (stria terminalis), which originates from the amygdala and carries its efferent fibers.

Functions and hierarchy of motor centers

The caudate nucleus is part of the motor system of the brain. The basal ganglia form complex regulatory feedback loops with the motor areas of the cortex.

• Movement control: The basal ganglia exert an inhibitory or disinhibitory influence on the thalamus, which serves as a relay between the basal ganglia and the cortex. Thus, they "permit" or "forbid" the initiation of specific motor programs in the cortex.
• Tone regulation: The basal ganglia participate in the initiation and coordination of complex motor patterns and the regulation of baseline muscle tone.
• Protective function: The caudate nucleus, along with the subthalamic nucleus and certain parts of the pons, protects the brain from excessive excitation.

During evolution, the cortex formed a new motor (pyramidal) system that increasingly subordinated the older centers, including the neostriatum. In humans, motor function depends entirely on the integrity of the pyramidal system, and older nerve centers are unable to compensate for the impairment of the new centers.

Blood supply

The striate branches of the middle cerebral artery (a. cerebri media) supply blood to the basal ganglia, including the caudate nucleus. These deep branches ascend vertically and nourish most of the striatum. The anterior parts of the basal ganglia also receive blood supply from the anterior cerebral artery basin.

Clinical significance

Damage to the basal ganglia leads to an excess or deficit of motor impulses, as well as pathological changes in muscle tone.

• Parkinson's disease: The most common cause of basal ganglia damage. It manifests as the clinical triad: rigidity, akinesia, and tremor.
• Syncinesias: With the development of spastic paralysis, involuntary associated movements — syncinesias — may occur in the paralyzed limbs. They are generated by phylogenetically older motor centers.
• Epilepsy: In epilepsy, a weakness of the brain's protective structures, including the caudate nucleus, is hypothesized.

Class and exam questions

What else to study on this topic

• Putamen
• Globus pallidus
• Lateral ventricles of the brain
• Thalamus (Thalamus)
• Extrapyramidal system

Other topics in the "Anatomical Structures" section

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