The internal anal sphincter is a continuation of the smooth muscle of the rectum and is under sympathetic control. It provides approximately 80% of normal resting anal tone. The external anal sphincter and pelvic floor muscles are striated muscles, innervated, respectively, by sacral roots 3 Cited by: 1.
The internal anal sphincter, IAS, (or sphincter ani internus) is a ring of smooth muscle that surrounds about 2.5–4.0 cm of the anal canal; its inferior border is in contact with, but quite separate from, the external anal sphincter.Actions: Keeps the anal canal and orifice closed, aids .
May 01, 2015 · Overall, abnormal anorectal manometry studies revealed that internal anal sphincter dysfunction is the most common finding, alone or in combination with external anal sphincter dysfunction. We suggest that anorectal manometry may be important to delineate anal sphincter function prior to using newer therapeutic mechanical devices.
Sep 01, 1999 · Two types of internal anal sphincter dysfunction have been described in patients with idiopathic incontinence: (a) decreased resting pressure in the internal anal sphincter and (b) increased frequency of spontaneous internal anal sphincter relaxation (sampling reflex).7.Cited by: 361.