Tweezers are small hand tools used for grasping objects too small to be easily handled with the human fingers. Tweezers are thumb-driven forceps most likely derived from tongs used to grab or hold hot objects since the dawn of recorded history. In a scientific or medical context, they are normally referred to as just "forceps", a name that is used together with other grasping surgical instruments that resemble pliers, pincers and scissors-like clamps.
Tweezers make use of two third-class levers connected at one fixed end (the fulcrum point of each lever), with the pincers at the others. When used, they are commonly held with one hand in a pen grip between the thumb and index finger (sometimes also the middle finger), with the top end resting on the first dorsal interosseous muscle at the webspace between the thumb and index finger. Spring tension holds the grasping ends apart until finger pressure is applied. This provides an extended pinch and allows the user to easily grasp, manipulate and quickly release small or delicate objects with readily variable pressure.
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