ABSTRACT
Concepts concerning the anatomy of the anorectum are constantly changing in light of new scientific methodology. In addition, the anatomy of this region is so intrinsically related to its physiology that many aspects are appreciated only in the living. The anal canal has a peculiar anatomy and a complex physiology, which accounts for its vital role in continence and its susceptibility to a variety of diseases. The anal canal has a peculiar anatomy and a complex physiology, which accounts for its vital role in continence and its susceptibility to a variety of diseases. The lining of the anal canal consists of an upper mucosal and a lower cutaneous segment. The pectinate or dentate line corresponds to a line of anal valves, which represent remnants of the proctodeal membrane. The anus or anal orifice is an anteroposterior cutaneous slit which, the anal canal, is kept virtually closed due to both tonic circumferential contraction of the sphincters and the anal cushions.
