The passenger flight was descending into the airport terminal area from 34,000 feet mean sea level (msl), with the seat belt sign on. While the flight attendants were securing the galley, the airplane encountered turbulence. The pilot stated that the airplane encountered the turbulence somewhere between 10,000 and 18,000 feet msl. One of the flight attendants fell into another, causing the second flight attendant to hit her head and fracture a rib. The flight landed without further incident. After landing the airplane was met by paramedics at the gate, and the flight attendant was carried off the airplane. There was no significant meteorological information (SIGMET) issued prior to the event, and there was no damage to the airplane.