ABSTRACT
The intervertebral disk is a fibrocartilaginous structure, biconcave in configuration, and situated between contiguous vertebral bodies. Although there are 24 vertebrae (26 if the sacrum and coccyx are included) and thus 25 intervertebral spaces, there are only 23 intervertebral disks. This discrepancy is due to the fact that there are no intervertebral disks between the occiput (CO) and the atlas (C1) or between the atlas (C1) and the axis (C2). The first disk is therefore located between C2 and C3.
