Red nucleus

Red nucleus
Transverse section through the midbrain showing the location of the red nuclei. The superior colliculi are at the top of image and the cerebral peduncles at the bottom of image – both in section.
Details
Identifiers
Latin	nucleus ruber
MeSH	A08.186.211.132.659.822.642
NeuroNames	hier-496
NeuroLex ID	Red nucleus
Dorlands /Elsevier	n_11/12583247
TA	A14.1.06.323
FMA	62407
Anatomical terms of neuroanatomy

The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. It is pale pink in color; the color is believed to be due to iron, which is present in the red nucleus in at least two different forms: hemoglobin and ferritin.^[1] It comprises a caudal magnocellular and a rostral parvocellular part. It is located in the tegmentum of the midbrain next to the substantia nigra. The red nucleus and substantia nigra are subcortical centers of the extrapyramidal motor system.

Function

In vertebrates without a significant corticospinal tract, gait is mainly controlled by the red nucleus.

However, where the corticospinal tract is dominant (as in primates), the rubrospinal tract may be considered to be vestigial. Therefore, here the red nucleus is less important in motor functions than in many other mammals. However, the crawling of babies is controlled by the red nucleus, as is arm swinging in typical walking.^[2] The red nucleus may play an additional role in controlling muscles of the shoulder and upper arm via projections of its magnocellular part. In humans, the red nucleus also has sparse control over hands, as the rubrospinal tract is more involved in large muscle movement such as that for arms (but not the legs, as the tract terminates in the superior thoracic region of the spinal cord). Fine control of the fingers is not modified by the functioning of the red nucleus (rather it relies on the corticospinal tract). The majority of red nucleus axons do not project to the spinal cord, but instead (via its parvocellular part) relay information from the motor cortex to the cerebellum through the inferior olivary complex, an important relay center in the medulla.

Input and output

The red nucleus receives many inputs from the cerebellum (interposed nucleus and the lateral cerebellar nucleus) of the opposite side and an input from the motor cortex of the same side.

The red nucleus has two sets of efferents:-

• In humans, the majority of the output goes to the bundle of fibers continues through the medial tegmental field toward the inferior olive of the same side, to form part of a pathway that ultimately influence the cerebellum.
• The other output (the rubrospinal projection) goes to the rhombencephalic reticular formation and spinal cord of the opposite side, making up the rubrospinal tract, which runs ventral to the lateral corticospinal tract. As stated earlier, the rubrospinal tract is more important in non-primate species: in primates, because of the well-developed cerebral cortex, the corticospinal tract has taken over the role of the rubrospinal.

See also

• List of regions in the human brain

Additional images

• 
  Schematic representation of the chief ganglionic categories (I to V).
• 
  Deep dissection of brain-stem. Ventral view.
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  Transverse section through mid-brain.
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  Transverse section of mid-brain at level of superior colliculi.
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  Coronal section of brain immediately in front of pons.
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  Human brain frontal (coronal) section
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  Red nucleus
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  Cerebral peduncle, optic chasm, cerebral aqueduct. Inferior view. Deep dissection.
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  Cerebral peduncle, optic chasm, cerebral aqueduct. Inferior view. Deep dissection.
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  Cerebrum. Inferior view.Deep dissection

References

External links

Wikimedia Commons has media related to Red nucleus.

• Stained brain slice images which include the "Red nucleus" at the BrainMaps project
• Diagram at uni-tuebingen.de