The central canal spans the length of the spinal cord from the caudal angle of the fourth ventricle to the conus medullaris. The space almost acts as a central reference point of the axial spinal cord, lying in the midline within the gray commissure. In fact, the dorsal and ventral portions of the gray commissure are named concerning the central canal. The caliber of the canal is small, and its shape is uniformly elliptical.
At the spinomedullary junction, the central canal begins as the caudal continuation of the fourth ventricle and travels down the length of the spinal cord to the conus medullaris where it widens and forms the triangular structure, the ventriculus terminalis.
Along with the other parts of the ventricular system, the canal represents the lumen of the primitive neural tube. With aging, the lumen of the canal can fill with debris from the epithelial lining.
Variable widening of the ventriculus terminalis (of Krause) has been described in the central canal. Furthermore, there have been multiple reported cases of forking or bifurcation in the caudal end of the central canal in embryo or infant studies.