Fig. 5.

The coronal image shows the anatomical structures of the anal canal: Levators (orange) continue to the external sphincter (red arrow), and muscularis propria layer of the rectal wall (yellow arrows) continues as the internal sphincter (green arrow). The tiny hyperintense line between the internal and external sphincters indicates an intersphincteric plane (purple line) and the purple arrow indicates the interspnincteric groove which corresponds to the dentate line not visible on magnetic resonance imaging. The blue oval demonstrates the level of puborectalis sling.