I always wondered how common this feature is in men and what is the purpose for it. Does everybody have a ridge? Mine is pretty pronounced and of darker color than the skin of my shaft. It starts at the end of the frenulum and runs all the way down along the back side of my shaft and further around my crotch till it gets lost in my anus. I never dared ask any doctor about it. When I was a boy I thought it was a birth defect. But then my brother had it too. At that time I didn't inspect other dicks closely to make comparisons but I thought nobody else had it. So I was kind of embarassed to have one. Later in life, however, I came to have close encounters with fully erect dicks with ridges, but always less marked than mine. I'd appreciate your opinions or comments about this most curious feature of the penis anatomy. Thanks.