1. Full penis length and circumference. The "prepuce" (foreskin) constitutes 50% or more of the skin system of the penis [1]. If unfolded and spread flat, the average adult foreskin measures 60-90 square centimeters (10-14 square inches) [2], or about the size of an index card [see illustration]. The foreskin creates a visibly longer penis, especially when the foreskin extends beyond the head of the penis. Also, the double-layered tissue of the foreskin engorges with blood during erection and creates a visibly and sensually thicker shaft and glans.When the engorged foreskin retracts behind the coronal ridge of the glans, it often creates a wider and more pronounced "ridge" that many partners find especially stimulating during penetrative intercourse. The circumcised penis appears truncated and thinner than a full-sized intact penis.
2. Protection. The sleeve of tissue known as the foreskin normally covers the glans and protects it from abrasion, drying, callusing (keratinization), and environmental contaminants. The glans is intended by nature to be a protected internal organ, like the female clitoris [see illustration]. The effect of an exposed glans and resulting keratinization on human sexual response has never been studied. Increasing reports by circumcised men indicate that keratinization causes a loss of sexual sensation, pleasure and fulfillment [3, 4].
3. Ridged bands. The inner foreskin contains bands of densely innervated, sexually responsive tissue [1]. They constitute a primary erogenous zone of the human penis and are important for realizing the fullness and intensity of sexual response [5].
4. Gliding action. The foreskin is the only moving part of the penis. During any sexual activity, the foreskin and glans work in unison; their mutual interaction creates a complete sexual response. In heterosexual intercourse, the non-abrasive gliding of the penis in and out of itself within the vagina facilitates smooth and pleasurable intercourse for both partners [see illustration]. Without this gliding action, the corona of the circumcised penis can function as a one-way valve, dragging vaginal lubricants out into the drying air and making artificial lubricants essential for non-painful intercourse [6].
5. Specialized sensory tissue. In addition to the "ridged bands" mentioned above, thousands of coiled fine-touch receptors (Meissner’s corpuscles) constitute the most important sensory component of the penis [1]. The foreskin contains branches of the dorsal nerve and between 10,000 and 20,000 specialized erotogenic nerve endings of several types, which are capable of sensing slight motion and stretch, subtle changes in temperature, and fine gradations in texture [7, 8, 9, 10, 11, 12].
6. The frenulum. This is a highly nerve-laden web of tissue that tethers the inner foreskin to the underside of the glans [see photo]. It is similar to the frenula found under the tongue, the upper lip and the clitoral hood (female foreskin). For many intact men, the penile frenulum is a male "G-spot" that is highly pleasurable when repeatedly stretched and relaxed during sexual activity [13]. Depending on the surgical method used, the frenulum is partially to completely destroyed by circumcision.
7. Proper blood flow. The foreskin contains several feet of blood vessels, including the frenular artery and branches of the dorsal artery. The loss of this rich vascularization interrupts normal blood flow to the shaft and glans of the penis, damaging the natural function of the penis and altering its development [1].
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