Torque-transmitting, variably flexible insertion device and method for transmitting torque and variably flexing an insertion device

A method for transmitting torque and variably flexing an insertion device for receiving an instrument, the method comprising the following steps:

• providing a hollow body having a given length and a proximal end with an entrance for receiving an instrument and a distal end with a tip for protrusion of the instrument;
• providing tendons within said hollow body;
• transmitting torque along the hollow body from said proximal end toward said distal end with a torque braid;
• applying suction to create a vacuum in the hollow body to thereby frictionally lock said tendons in place selectively to maintain the hollow body in a relatively stiff condition;
• and relieving the vacuum to place the hollow body in a relatively flexible condition, wherein said tendons are not under tension in both said relatively stiff and relatively flexible conditions.