The human hand has four fingers and a thumb. Each finger has three segments connected by a movable joint that allows extension and flexion. The thumb only has two segments; however, the joint that connects the hand to the thumb provides the thumb with a larger range of motion than the fingers.
Fingers provide sensory feedback about objects that we touch, enabling people to detect heat, cold, pain, and surface texture. The finger tips are especially sensitive, having a higher density of touch and thermoreceptors than any other part of the skin. These sensors permit people to detect small objects that are close together. Control of the fingers is precise, enabling sophisticated motions such as accurate hand writing, typing, and the playing of musical instruments. This control also allows people to grasp fragile objects without breaking them and also to hold them securely.
Fingers are strong. Most people can hold a significant portion of their body weight supported by only the fingers of one hand. Fingers can also achieve a tight grasp on objects. An example of this is gripping a baseball bat while hitting.
The sensory feedback, precision of movement, and strength found in fingers is something that we have not been able to reproduce artificially. Prosthetic fingers have some capacity for these skills, but lack most of the capability associated with natural fingers. Researchers continue to develop new devices to improve utility.
