Anterior corticospinal tract
Encyclopedia
The anterior corticospinal tract (also called the ventral corticospinal tract, medial corticospinal tract, direct pyramidal tract, or anterior cerebrospinal fasciculus) is a small bundle of descending fibers that connect the cerebral cortex
to the spinal cord
. It is usually small, varying inversely in size with the lateral corticospinal tract
, which is the main part of the corticospinal tract
.
It lies close to the anterior median fissure
, and is present only in the upper part of the medulla spinalis; gradually diminishing in size as it descends, it ends about the middle of the thoracic region.
It consists of descending fibers which arise from cells in the motor area of the ipsilateral cerebral hemisphere, and which, as they run downward in the medulla spinalis, cross in succession through the anterior white commissure
to the opposite side, where they end, either directly or indirectly, by arborizing around the motor neuron
s in the anterior column.
A few of its fibers pass to the lateral column of the same side and to the gray matter at the base of the posterior column
.
They conduct voluntary motor impulses from the precentral gyrus to the motor centers of the cord.
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
to 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 is usually small, varying inversely in size with the lateral corticospinal tract
Lateral corticospinal tract
The lateral corticospinal tract is the largest part of the corticospinal tract...
, which is the main part 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....
.
It lies close to the anterior median fissure
Anterior median fissure
Anterior median fissure can refer to:* Anterior median fissure of the spinal cord* Anterior median fissure of the medulla oblongata...
, and is present only in the upper part of the medulla spinalis; gradually diminishing in size as it descends, it ends about the middle of the thoracic region.
It consists of descending fibers which arise from cells in the motor area of the ipsilateral cerebral hemisphere, and which, as they run downward in the medulla spinalis, cross in succession through the anterior white commissure
Anterior white commissure
The anterior white commissure, also known as the alba anterior medullae spinalis, is a bundle of nerve fibers which cross the midline of the spinal cord just anterior to the gray commissure...
to the opposite side, where they end, either directly or indirectly, by arborizing around the motor neuron
Motor neuron
In vertebrates, the term motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles...
s in the anterior column.
A few of its fibers pass to the lateral column of the same side and to the gray matter at the base of the posterior column
Posterior column
thumb | right | Cross-section of the spinal cord Posterior column or dorsal column refers to the area of white matter in the dorsomedial side of the spinal cord. It is made up of the fasciculus gracilis and fasciculus cuneatus and itself is part of the dorsal funiculus...
.
They conduct voluntary motor impulses from the precentral gyrus to the motor centers of the cord.