Measurement of the vertebral canal dimensions of the neck of the rat with a comparison to the human.

The aim of this study was to determine the dimensions of the vertebral canal in the neck of the rat, because little is known about the morphology of the rat's cervical spine. A comparison then was made to the vertebral canal in the neck of the human. In part 1 of this study, we determined the precision of three different methods to measure the vertebral canal. The error (coefficient of variation) in these methods was found to range from 1 to 8%. In part 2, we used a computer-based system to measure digital images of the vertebra and determined the anterior to posterior and the transverse vertebral canal dimensions in the neck of 19 young adult Sprague-Dawley rats. The anterior to posterior dimension of the vertebral canal was greatest at the upper cervical (C1-C2) level and progressively decreased in the more caudal segments (C3-T1). The transverse dimension was greatest at the atlas (C1) vertebra and smallest at the axis (C2) vertebra with a steady increase in the transverse dimension with more caudal segments and a maximum transverse dimension at the level of the C6 and C7 vertebra. This study has demonstrated that the vertebral canal in the neck of young adult rats is similar in some regards to that of human. However, there are clear differences between the rat and human. These may be associated with differences in the morphology of the spinal cord or postural differences such as the cervicothoracic lordosis in bipeds compared with that in quadrupeds. (c) 2007 Wiley-Liss, Inc.