The red nucleus is a structure in the rostral (upper) midbrain, in the midbrain tegmentum next to the substantia nigra. It is involved in motor coordination. [1]
Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole midbrain. The red nucleus lies within the tegmentum of the upper midbrain; it has no shape of its own in the BodyParts3D model, so nothing is drawn at a guessed point. [1][2]
The 3D brain needs JavaScript. The text below still says where the red nucleus is and what it does.
Slice
Opens cut by a side (sagittal) slice through the midbrain, which holds the red nucleus. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Lit here: the midbrain, the part that holds the red nucleus — see it on its own page.
It sits in the rostral midbrain, in the tegmentum, next to the substantia nigra. [1]
It has two parts: a caudal (lower) magnocellular part and a rostral (upper) parvocellular part. [1]
With the substantia nigra it is one of the subcortical centres of the extrapyramidal motor system. [1][3]
What it does
It is involved in motor coordination. In vertebrates without a large corticospinal tract, gait is mainly controlled by the red nucleus. [1]
In humans the corticospinal tract dominates, so the red nucleus matters less than in many other mammals; it still controls the crawling of babies and the arm swing of ordinary walking. [1]
Its magnocellular part may help control the muscles of the shoulder and upper arm; fine control of the fingers relies on the corticospinal tract instead. [1]
Connections
Inputs: many from the cerebellum of the opposite side (the interposed and lateral cerebellar nuclei) and one from the motor cortex of the same side. [1]
In humans most of its output runs to the inferior olive of the same side, part of a pathway that ultimately feeds the cerebellum: through its parvocellular part it relays information from the motor cortex to the cerebellum. [1]
A smaller output, the rubrospinal tract, goes to the reticular formation and spinal cord of the opposite side; it ends in the upper thoracic spinal cord, so it reaches the arm muscles but not the legs. [1]
Other names
Also called the nucleus ruber. The name comes from its pale pink colour, thought to be due to the iron it holds in at least two forms, haemoglobin and ferritin. [1]
Size
The model has no shape for the red nucleus itself, so it is not measured here. The midbrain that holds it measures about 29 mm front to back, 17 mm top to bottom and 29 mm side to side on this model (the box it fits in, not its volume). [4]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.