The document describes the anatomy and clinical features of the anal canal. It notes that the anal canal is approximately 4 cm long, with 2/3 above the dentate line and 1/3 below. It discusses the layers of the anal canal including the internal and external sphincters. Clinical features of various anal abnormalities are summarized such as hemorrhoids, fissures, fistulae and abscesses. Treatment approaches for these conditions include conservative measures, injections, banding and surgery.