Anterior fasciculus proprius

At a glance

English

Anterior fasciculus proprius

Latin (TA2)

Fasciculus proprius anterior

System

Nerve

Region

Whole body

Side

Single, on the midline

About the anterior fasciculus proprius

The anterior fasciculus proprius is one of three proper (propriospinal or spinospinal) bundles of the spinal cord, alongside a lateral and a posterior one. Together they form a thin rim of white matter that hugs the grey matter on every side. Unlike the long tracts, which join the cord to the brain, these bundles begin and end within the cord itself. Their fibres may climb or descend, and some stay on one side while others cross.

In the anterior funiculus the bundle wraps around the front and medial aspect of the anterior horn, deep to the long descending tracts such as the anterior corticospinal and vestibulospinal fibres. Most of its axons come from neurons in the grey matter, chiefly from the medial cell group of the anterior horn and nearby interneurons. Each axon runs up or down over a short or moderate distance and then turns back into the grey matter to end. Another set of fibres reaches it from the opposite grey matter, crossing over in the anterior white commissure. In front it is continuous with the lateral fasciculus proprius.

Functionally these short links act as the wiring between segments. They let reflex activity entering at one level spread to motor neurons several levels away, and they help coordinate the muscles of the neck and trunk that are served by the medial motor columns. Many descending commands from the brainstem are relayed through propriospinal neurons before they reach motor cells, which makes the system a working part of posture and locomotion rather than a mere bystander.

Because the propriospinal pathways lie deep and close to the grey matter, they are usually affected together with the grey matter in central cord lesions. In partial cord injury they are thought to offer alternative routes that can support some recovery of movement.

Course and supply

Supplies

Links neighbouring segments of the spinal cord, spreading reflexes over several levels and helping to coordinate the axial muscles of the neck and trunk.

Blood supply

Lies close to the anterior horn, supplied mainly by the sulcal branches of the anterior spinal artery.