The part of the stapler that contains the staples and is depressed to make contact with the paper is called the magazine.
The magazine contains staples which are pushed to the front by the follow block. The follow rod is pulled forward by the follow spring.
Along with the magazine the outercase called the metal head comprise the upper assembly.
The lower assembly is often called the foot.
The foot contains the anvil which the upper assembly strikes. The anvil typically has two forms for the staples to take under pressure.
Most staplers contain two leaf springs. One in the base to secure the latch that allows for the release of the upper assemly, called the clearing spring, and one between the magazine and metal head that returns the upper assembly to its original position after use.
Look here for a diagram of a stapler, perhaps you can use www.google.com to search for other stapler diagrams. http://www.emeraldinsight.com/fig/0330260409001.png