The little finger.
For most people, the fifth finger--the gripping finger--is probably second in importance only to the thumb. Emergency room personnel should not be too ready to sacrifice this finger to satisfy the needs of other damaged digits.
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D005385:Fingers / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged