A guiding apparatus comprises a plurality of support members. Each of the plurality of support members has a curved profile to resist bending in at least one direction. The guiding apparatus also comprises a retraction system coupled to the plurality of support members. The plurality of support members has an extended configuration in which the plurality of support members is positioned in an arrangement to form a channel sized to receive an instrument. The plurality of support members has a retracted configuration in which each of the plurality of support members is retracted within the retraction system as the instrument is advanced along a longitudinal axis.
