It starts in the red nucleus of the midbrain, crosses the midline at once and runs down through the pons and medulla into the spinal cord, ending mostly in its neck and upper-back segments. It is an extrapyramidal motor tract that favours the flexor muscles of the arm. [1][2]
A tract has no shape of its own in this atlas; lit: the parts it runs through, in order.
The 3D brain needs JavaScript. The steps below still say where the rubrospinal tract runs, in order.
The brain starts seen from the left, a little from the front and below, where the brainstem runs down to the spinal cord. Step through lights one step at a time, about 1.2 s each, top to bottom; tap a step below to light it. The lit step is in the bright highlight colour, the steps before it stay lit in a paler tint of it and the steps still ahead are grey. Drag to turn, pinch or scroll to zoom. Step through is off because your device asks for reduced motion; tap each step instead.
The tract and the red nucleus are not drawn: the first step lights the whole midbrain that holds the nucleus, and each later step the whole part the tract runs through. The atlas has only the top of the spinal cord, drawn as its thin central canal. [3][1]
The route, in 4 steps
The tract starts in the magnocellular (large-celled) part of the red nucleus, a pale pink nucleus in the tegmentum of the upper midbrain, next to the substantia nigra. Not a separate shape in this atlas; lit: the part that holds it, the midbrain. [1][2]Where is the red nucleus (midbrain)?
Anterior (ventral) tegmental decussation: straight after leaving the red nucleus the fibres cross the midline in the midbrain, so each red nucleus reaches the opposite side of the spinal cord. The atlas has no shape for the crossing, so it is not marked. [1][2]
Now on the opposite side, the fibres run down the back part of the pons, set towards the middle of its upper tegmentum, behind the corticospinal fibres in the basilar part in front. [1][4]Where is the pons?
In the medulla they descend in its lateral tegmentum, medial to the spinocerebellar tract and behind the spinothalamic tract: in the back half of the medulla, not in the pyramids at its front. [1][5]Where is the medulla oblongata?
In the spinal cord the fibres run in the lateral funiculus, just in front of the lateral corticospinal tract, and end mainly in the cervical and thoracic segments, so they act on the arms rather than the legs; they generally excite flexor motor neurons and inhibit extensor ones. [1][2]Where is the spinal cord?
More about the rubrospinal tract
Other names: rubrospinal pathway, rubrospinal fibres [1]
In humans it is small, with fewer axons than the corticospinal tract, which has taken over most of its role; in many other mammals the red nucleus and this tract matter much more for walking. [1][2]
The red nucleus takes input from the cerebellum of the opposite side and from the motor cortex of the same side. When the commands sent by the cerebrum and the position of the body reported by the proprioceptors do not match, the cerebellum drives the red nucleus to send corrections down this tract. [2][6]
Most of the red nucleus's output does not go to the spinal cord at all: its small-celled (parvocellular) part sends fibres to the inferior olive in the medulla, a loop that reaches back to the cerebellum. [2][1]
It is one of the extrapyramidal tracts, which do not pass through the pyramids of the medulla, along with the vestibulospinal, reticulospinal and tectospinal tracts. [7][1]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); it has no shape for tracts, so a pathway is shown by the parts it runs through.