Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 27 On the Digits of the Hand

The thumb is handsomely situated

For while the thumb is opposed to the other digits in function, it was also necessary for it to be opposed to them in location. But if it were placed quite out of opposition and took for itself the middle of the carpus, it would impede the hand in a great number of uses, particularly interfering with those which we perform with the palm of either hand separately, or with both palms at the same time. It was therefore necessary for it to be placed at the side and to be very much separated from the other fingers and linked to them. And while the transverse region of the hand extends equally to the index finger and the little finger, it was better that the thumb be placed next to the index finger, and (as has been stated above) to be loosely articulated to the lower row of carpal bones. 53 For it was fitting that the hands be turned toward each other by the index fingers but turned away at the little fingers. Indeed, in extreme flexions of the fingers the little finger leaves no place empty while the index finger leaves an area of some magnitude which can be closed or blocked by the thumb in the manner of a lid.



Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 27 On the Digits of the Hand