What does the narrator do to free himself from the frame to which he is attached in "The Pit and the Pendulum"?summarize

In the "Pit and the Pendulum" the narrator is secured to a wooden frame by a long strap that encircles almost his entire body, with the exception of his head and his left arm, which he uses to reach the food that is left nearby for him to eat.  As he lay upon this contraption contemplating his dilemma, he observes an army of rats drawn to the smell of the meat that is on a plate in close proximity to the narrator.  He reaches out to the small portion of meat that the rats have left uneaten, places it in his left hand with the hope of enticing the rats to navigate towards him and the bandages that looped around his arm from his elbow to his hand.  Ultimately, the rats surged upon his body and in their frenzy to devour the last morsel of meat, they inadvertantly chewed through the binds that tethered the narrator to his lamented area of repose.