The rubrospinal tract is a part of the nervous system

Nervous system

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...

. It is a part of the lateral indirect extra-pyramidal tract.

Function

In humans, the rubrospinal tract is one of several major motor control pathways. It is smaller and has fewer axons than the corticospinal tract

Corticospinal tract

The corticospinal or pyramidal tract is a collection of axons that travel between the cerebral cortex of the brain and the spinal cord....

, suggesting that it is less important in motor control. It is one of the pathways for the mediation of voluntary movement. The tract is responsible for large muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 movement as well as fine motor control, and it terminates primarily in the cervical spinal cord, suggesting that it functions in upper limb but not in lower limb control. It primarily facilitates Flexion

Flexion

In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...

 in the upper extremities (see decorticate posture).

It is small and rudimentary in humans. In some other primates, however, experiments have shown that over time, the rubrospinal tract can assume almost all the duties of the corticospinal tract

Corticospinal tract

The corticospinal or pyramidal tract is a collection of axons that travel between the cerebral cortex of the brain and the spinal cord....

 when the corticospinal tract is lesioned.

Path

In the midbrain, it originates in the magnocellular red nucleus

Magnocellular red nucleus

The magnocellular red nucleus is located in the rostral midbrain and is involved in motor coordination. Together with the parvocellular red nucleus, it makes up the red nucleus....

, crosses to the other side of the midbrain, and descends in the lateral part of the brainstem tegmentum

Tegmentum

The tegmentum is a general area within the brainstem. It is located between the ventricular system and distinctive basal or ventral structures at each level...

.

In the spinal cord

Spinal cord

The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...

, it travels through the lateral funiculus

Lateral funiculus

The most lateral of the bundles of the anterior nerve roots is generally taken as a dividing line that separates the antero-lateral region into two parts, viz., an anterior funiculus, between the anterior median fissure and the most lateral of the anterior nerve roots; and a lateral funiculus,...

 of the spinal cord in the company of the lateral corticospinal tract

Lateral corticospinal tract

The lateral corticospinal tract is the largest part of the corticospinal tract...

.