Frenar band and frenulum, both of which have been shown to be erogenously sensitive in many men. Also about 1/3 or more of the shaft skin.Modern "medical" infant circ's were started by the Victorians in the late 1800s. They were neurotic about youth masturbation and were certain R.I.C. would throttle it. They later realized it was having little effect. From then on, infant circumcision has been a "treatment" in search of a malady. After more than a century of searching, no bulletproof "medical" rationalization was found. The search continues to this day.