The corrugator cutis ani is a thin smooth and striated muscle layer in the perianal skin, producing the radial puckering pattern of the anus at rest. Its integrity is a clinical indicator of pudendal nerve function. Loss of the corrugator pattern is an early sign of pudendal neuropathy or lower motor neuron sacral injury.
| Origin | Subcutaneous fibromuscular tissue surrounding the external anal sphincter |
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| Insertion | Perianal skin, producing the radial wrinkling pattern visible around the anus |
| Nerve Supply | Inferior rectal nerve (branch of pudendal nerve, S2-S4) |
| Blood Supply | Inferior rectal artery branches |
| Actions | Produces the characteristic corrugated or wrinkled appearance of the perianal skin; contributes to anal continence by maintaining skin apposition around the anus |
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The corrugator ani wink reflex (visible anal pucker on stroking the perianal skin) tests the integrity of the S2-S4 reflex arc through the inferior rectal nerve and the pudendal nerve. Loss of the anal wink indicates sacral nerve root lesion, cauda equina injury, or pudendal nerve damage. It is routinely tested in spinal trauma assessment. Perianal haematoma and hemorrhoidal surgery risks the integrity of the corrugator cutis ani, contributing to anal skin retraction.
Cauda equina syndrome from central lumbar disc herniation or spinal stenosis compresses S2-S4 nerve roots, abolishing the corrugator ani reflex and producing saddle anaesthesia, urinary retention, and faecal incontinence; emergency decompressive surgery within 48 hours maximises neurological recovery.
