Hands and Fingers

The most useful frame of reference for describing position and motion in the context of keyboard use is the hand. The field of anatomy provides useful terminology for discussing directions and axes relative to the hand:

The dorsopalmar axis runs from the back of the hand (dorsal) to the palm (palmar).
- A movement toward the back of the hand is a flexion.
- A movement toward the palm is an extension.
The radioulnar axis runs from the thumb side (radial) to the pinky side (ulnar).
- A movement toward the thumb side is an adduction.
- A movement toward the pinky side is an abduction.
The proximodistal axis runs from the wrist (proximal) to the fingertips (distal).
- A movement toward the fingertips is a protraction.
- A movement toward the wrist is a retraction.

Hand model by Abdur Razzak Sawon (CC-BY-4.0)

When we want to be precise, we use these directions, motions, and axes instead of terms such as left, right, up, down, forward, and backward because they are unambiguous and clearly identify the hand as the frame of reference. Furthermore, this is the standard terminology used in academic and medical literature.

Finger Numbers

In AKLDB, we name and number the fingers as follows:

Hand	Finger	Number	Hand	Finger	Number
Left	Pinky	1	Right	Thumb	6
		Ring		2		Index	7
		Middle		3		Middle	8
		Index		4		Ring	9
		Thumb		5		Pinky	10

Other analyzers use different numbers; for example, Cmini uses 0-indexed finger numbers.