Intermediomedial nucleus

At a glance

English

Intermediomedial nucleus

Latin (TA2)

Nucleus intermediomedialis

System

Brain and spinal cord

Region

Whole body

Side

Single, on the midline

About the intermediomedial nucleus

The intermediomedial nucleus is a slender column of neurons in the grey matter of the spinal cord. It lies in the intermediate zone, the part of the grey matter between the dorsal and ventral horns, close to the central canal and medial to the other cell groups of this zone. In the layered scheme of the spinal grey matter it falls within lamina VII. Unlike the intermediolateral nucleus, which is confined to particular segments, it can be traced through most of the length of the cord.

Its neighbours make its position clear. Lateral to it, in the thoracic and upper lumbar segments, the intermediolateral nucleus forms the lateral horn. Dorsal to it, in the thoracic and upper lumbar cord, lies the thoracic nucleus (Clarke's column) at the base of the dorsal horn. Medially lies the grey commissure around the central canal.

The nucleus is concerned mainly with visceral information. It receives visceral afferent fibres, which enter through the dorsal roots and carry signals from the organs of the chest, abdomen and pelvis, and its cells act as interneurons and relay cells. They pass these signals to the neurons of the autonomic outflow, so taking part in visceral reflexes, and to higher levels of the nervous system.

The nucleus is not usually tested on its own in the clinic, but it belongs to the central grey matter that is damaged early when a cavity forms in the cord, as in syringomyelia, or in central cord injury. The central grey is supplied by branches of the anterior spinal artery.

Function and supply

Function

Receives visceral afferent fibres and relays visceral signals to autonomic neurons and higher centres, taking part in visceral reflexes.

Blood supply

Central (sulcal) branches of the anterior spinal artery.