Central canal

The central canal represents the adult remainder of the central cavity of the neural tube. It generally occludes (closes off) with age.

Structure

The central canal below at the ventricular system of the brain, beginning at a region called the obex where the fourth ventricle, a cavity present in the brainstem, narrows.

The central canal is located in the anterior third of the spinal cord in the cervical and thoracic regions. In the lumbar spine it enlarges and is located more centrally. At the conus medullaris, where the spinal cord tapers, it is located more posteriorly.

Terminal ventricle

The terminal ventricle (ventriculus terminalis, fifth ventricle or ampulla caudalis) is the widest part of the central canal of the spinal cord that is located at or near the conus medullaris. It was described by Stilling in 1859 and Krause in 1875. Krause introduced the term fifth ventricle after observation of normal ependymal cells. The central canal expands as a fusiform terminal ventricle, and approximately 8–10 mm in length in the conus medullaris (or conus terminalis). Although the terminal ventricle is visible in the fetus and children, it is usually absent in adults.

Sometimes, the terminal ventricle is observed by MRI or ultrasound in children less than 5 years old.

Microanatomy

The central canal shares the same ependymal lining as the ventricular system of the brain.

The canal is lined by ciliated, column-shaped cells, outside of which is a band of gelatinous substance, called the substantia gelatinosa of Rolando also substantia gelatinosa centralis or central gelatinous substance of spinal cord. This gelatinous substance consists mainly of neuroglia, but contains a few nerve cells and fibers; it is traversed by processes from the deep ends of the columnar ciliated cells which line the central canal.

Development

The central canal represents the adult remainder of the central cavity of the neural tube. It generally occludes (closes off) with age.