US Patent 9566052 Tissue retractor apparatus and methods

A delicate tissue retraction system having a hollow tubular retractor, a hollow tubular introducer that is removably installed within the retractor, and a navigation module that is removably installed within the introducer. The navigation module has a shaft with a proximal shaft end and a distal shaft end, and a navigation unit mounted to the proximal shaft end. When assembled, the distal shaft end is contained generally within the introducer and the navigation module outside the introducer. The navigation module indicates the location of one or more points on at least one of the retractor and the introducer to a navigation system.