Fig. 2

Porcine sacral anatomy as visualized on contrast-enhanced CT images. a) Sagittal section through the median line. Incomplete posterior fusion of the sacral vertebrae are shown with thick arrows. b) Curved planar reformation of the axial images along the curve shown with thick dashed line in a. The four sacral vertebrae are labeled and dashed arrows show three pairs of the posterior sacral foramina apertures. c) Oblique planar reformation images (obtained along the straight thin dashed lines in a) showing the entire sacral foramina (dashed arrows) including the dorsal and ventral sections. Arrowheads indicate the nearly absent spinous process. d) Unformatted axial CT images of the sacral region (more cranial slices are shown first) show the gap between S1 and S2 vertebrae (thick arrow) and S1-S2 sacral foramen (dashed arrows)