FIGS. 18 and 19 illustrate use of instrument 910 to create an operating space at an obstructed site within an anatomical wall, such as wall W of the inguinal region which is obstructed due to the lack of space between adjacent layers of tissue forming wall W. As shown in FIG. 18, a penetrating instrument including a portal or trocar sleeve S and a penetrating member P, such as a trocar, disposed w