Originally posted by: teh g00g13
The rectus abdominis muscles run lengthwise down the front of your abdomen on the right and left sides. At birth the umbilical cord exits through an opening between these two muscle walls, and then after birth the muscles usually fuse or join together. At that time the belly button (the skin over the opening where the umbilical cord was cut) sinks in and becomes an ?innie.?
But sometimes the muscle walls don?t fuse completely in that area. Then the overlying skin and underlying tissue will pooch out a little and form an ?outie? bellybutton. There are no exercises that will make the necessary muscle fibers join together. Although usually closure has occurred during childhood, sometimes the umbilical muscle area will still fuse together during the teen years. Don?t push and poke at your bellybutton. You can?t make in stay inward