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[[Marilyn Milos]], {{RN}}, former executive director and founder of NOCIRC, discusses normal sexual function of the [[penis ]] and [[foreskin ]] and its loss due to [[circumcision]].

Structurally, the [[penis ]] is highly integrated. The [[glans]], [[foreskin]] and [[skin]] of the penile shaft function as a single unit, not as a collection of separate parts with entirely different functions. The functions of the [[glans]] and [[foreskin]] are similar, and overlapping, but come fully into their own at different times during intercourse.

The outer surface of the [[foreskin ]] is specialized to detect feather-light touch and other sensations, including painful ones. The infamous zipper injury is an extreme example of the sort of damage the outer [[skin]] was designed to detect and prevent, long before the zipper posed a threat to the uninitiated.

Compared with the true (outer) [[skin]] of the [[foreskin]], the [[glans ]] is only feebly sensitive to light touch, pain, heat and cold. This is part of the reason we call the foreskin the primary sensory tissue of the [[penis]]. Without the [[foreskin]], the end of the [[penis ]] is numb to a host of sensations that tell the owner whether one of his most prized organs is in good company, or should move to safety.

Electrical stimulation of the [[glans ]] triggers nerve impulses that pass to the spinal cord and then to the muscle of ejaculation. Clearly the glans has much in common with the foreskin. Where [[foreskin ]] and glans part company, functionally as well as physically, is in their sensitivity to light touch, pain and heat and cold. Contrary to common opinion, the [[glans ]] is not highly sensitive to a broad range of stimuli.

It is unclear whether the [[ridged band ]] simply plays backup for the [[glans]], or whether the two have different functions. The location of the retracted [[ridged band ]] on the erect penile shaft suggests that the difference is one of timing. Possibly, the [[foreskin ]] and its [[ridged band ]] are designed to ensure that sexual reflexes are triggered when, and only when, these structures are stretched during intercourse. The biological importance of the [[ridged band ]] to conception is self-evident, but there is still a major gap in our understanding of the relation between form and function of the [[penis]].

[[Penile skin]] has two important characteristics, apparent only on [[erection]]. Firstly [[penile skin]] tenses, stiffens and shortens, firming up the connection between [[shaft skin]] and ridged band. This change allows for the transmission of movement from the base of the erect [[penis ]] to the [[ridged band]].

The changes in [[penile skin]] are brought about by contraction of the [[Dartos]] muscle. Between them, stiffening and frictionality ensure that the [[ridged band ]] is instantly alerted to changes in position of the [[penis ]] within the [[vagina]].

The double-layering of the [[foreskin ]] allows the delicate [[ridged band]], which normally is safely hidden from view, to be deployed on the upper surface of the penile shaft during [[erection]]. There it stands a better chance of being activated. Double-layering also eases vaginal entry by offsetting the frictional resistance of erect [[shaft skin]].

The various parts of the [[penis]], including the foreskin, form a functional whole. The [[foreskin ]] is the primary sensory tissue of the [[penis]]. The [[ridged band]] of the [[foreskin]] is built to trigger orgasm and [[ejaculation]].