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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 surfaces of the rectum are covered by peritoneum. The rectum is continuous distally with the anal canal at the rectoanal junction (Figure 44.5).

Links and References:
Grant's: 3.42
Netter (1ed.): 369 (2ed.): 365
Rohen/Yokochi: 335