How many items are there to remove in the game operation?

In the classic game "Operation," there are a total of 13 items that players must remove from the patient's body without touching the sides of the openings. Each item is represented by a specific organ or object, such as the "funny bone" or "breadbasket." The objective is to successfully extract these items using a pair of tweezers while avoiding the buzzer that sounds if the sides are touched.