The loss of penile sensitivity is due to the following:
1. Loss of the foreskin nerves. The inner foreskin possesses a greater density of nerve endings and is probably more erogenous than even the glans. This tremendous amount of sensitivity is lost completely when the foreskin is amputated. Also, the most sensitive part of the penis, the frenulum of the foreskin, is removed in most infant circumcisions. The frenulum is the continuation of the inner foreskin which attaches to the underside of the glans. Thus, circumcision robs us of a large percentage, if not the majority, of erogenous nerve endings to the penis.
2. Damage to the glans. The erogenous sensitivity that remains after circumcision is primarily in the glans. This is further reduced by the removal of the protective foreskin which leaves the glans permanently exposed. The penis head developed over millions of years of evolution as an internal organ, meant to be safely enclosed by the prepuce. The skin covering of the glans IS the foreskin. The glans becomes artificially keratinized (dry, hardened, discolored, and wrinkled) as a result of permanent exposure, and thus significantly less sensitive.
3. Loss of skin mobility. The nerve endings in the glans are best stimulated by a rolling massage action. Direct friction tends to fire off pain receptors causing irritation and also causes further keratinization of the glans. With the skin system of the penis significantly reduced by circumcision, the mobility is essentially gone and now the penis is a static mass with no dynamic self stimulation mechanism. Direct friction is now the primary form of stimulation. So circumcision further reduces erogenous sensitivity in the penis by reducing skin mobility and thus the ability to use the foreskin to massage the glans.