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Examine the rectum, the rectum curves to the right and passes out of the median plane of section which lies within the concavity of the pelvic surface of the sacrum and the coccyx. Confirm that only the anterior and lateral surface of the rectum is covered by peritoneum. The rectum is continuous distally with the anal canal at the rectoanal junction (Figure 43.6).
Clean the internal aspect of the rectum and anal canal, and attempt to identify three transverse rectal folds (of Houston), which project into its lumen. On the internal wall of the anal canal, identify the vertical anal columns
and anal sinuses . At the distal end of the anal columns, identify anal valves,which are semilunar-shaped folds of mucous membrane that span between adjacent columns (Figure 43.6).
Links and References:
Grant's: 3.42
Netter (1ed.): 369 (2ed.): 365
Rohen/Yokochi: 335