The corrugator cutis ani is a layer of smooth muscle fibres in the perianal subcutaneous fat that radiates from the anal verge to produce the corrugated, puckered appearance of the perianal skin. Unlike most other sphincter components, it is a smooth muscle and therefore operates involuntarily. It contributes to the fine-grained sealing of the anal verge at the distal end of the continence mechanism.
| Origin | Subcutaneous fibres of the perianal skin surrounding the anus |
|---|---|
| Insertion | Perianal skin in a radiating pattern around the anal verge |
| Nerve Supply | Inferior rectal nerve (from pudendal nerve, S2-S4) |
| Blood Supply | Inferior rectal artery |
| Actions | Produces the characteristic radial wrinkling of the perianal skin, assisting anal closure |
|---|
Assessment of the corrugator cutis ani reflex, observed as the characteristic wrinkling of the perianal skin in response to gentle pin-prick of the perianal skin, tests the integrity of the S2-S4 reflex arc (the anocutaneous reflex). Loss of this reflex indicates lower sacral cord or pudendal nerve dysfunction. Surgical procedures in the perianal region, including haemorrhoidectomy and fistulotomy, may damage the fine dermal fibres producing a smooth rather than corrugated anal appearance.
Assessed visually as the radiating skin wrinkles around the anal verge at rest, and dynamically by the anocutaneous reflex produced by gentle stroking of the perianal skin.
Absence of the corrugator ani reflex wrinkling response to perianal skin stimulation indicates impaired S2-S4 afferent or efferent arc integrity, seen in cauda equina syndrome, pelvic floor denervation, and sacral nerve injuries, providing a quick bedside test of lower sacral function.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
