Have a look here.Each movement is controlled by a servo, and the servos in turn are controlled by an Arduino. So two servos in the base turn it and move the bottom limb. Another servo in the base moves the "elbow" by a lever (rather than having the heavy servo in the elbow itself). A small servo in the wrist handles the end effector.EDIT.... Having said that, remember that the Arduino "components" are only the processor side of things, along with a few shields. Motors, sensors and so on are not Arduino parts. Have a look around sites like Pololu, Sparkfun and adafruit.