Anal wink

The anal wink, anal reflex, perineal reflex, or anocutaneous reflex is the reflexive contraction of the external anal sphincter upon stroking of the skin around the anus.

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A noxious or tactile stimuli will cause a wink contraction of the anal sphincter muscles and also flexion. The stimuli is detected by the nociceptors in the perineal skin to the pudendal nerve, where a response is integrated by the spinal cord sacral segments S1-S3.

The absence of this reflex indicates that there is an interruption of the reflex arc, which may be in the sensory afferent limb or the motor efferent limb. The synapse between the afferent and efferent limbs occurs in the lowest sacral segments of the spinal cord.

Child abuse controversy

Dr. Bruce Woodling developed the anal wink test which he alleged was an indisputable diagnostic indicator that a child had been sodomised. In a clinical setting, he would spread a child’s buttocks and touch the anus with a cotton swab. If the anus "winked", Woodling testified, this was "proof of sodomy". His testimony was prominent in the McMartin preschool child abuse case.

It has since been established that Woodling never made any effort to validate his test, and it has been utterly discredited.

Woodling's pseudoscientific testimony contributed to Ray Buckey spending five years in prison without bail, during his trial. Buckey was later released without conviction.

See also

• Reflex anal dilatation