Getting a Pulse on the Workings of the Thumb

What is opposable, sometimes green, necessary for hitchhiking--and now the object of a research grant worth more than a quarter of a million dollars?

Try the human thumb, for which a Cornell University engineer just received $239,992 to study. The Whitaker Foundation, which funds research in bioengineering and rehabilitation, hopes that the money will allow Francisco Valero-Cuevas to better understand how nerves and muscles in the hand, wrist and forearm work together to control this humble, and most essential, digit.

Despite some 8 million injuries a year to hands and wrists--and half a million surgeries on hands a year--doctors still don’t have a complete understanding of hand mechanics and function. For example, nerve damage in the wrist can paralyze muscles at the base of the thumb, making it more a hook than a supple finger. In some cases, surgeons can perform a tendon transfer, rerouting the sinew from another part of the hand to the base of the thumb, restoring some strength and mobility. The more they learn about the thumb, the better able doctors will be to treat all hand injuries.

Valero-Cuevas will use cadaver hands for his research; attaching the thumb tips to a device carefully tracks every movement as it pushes and pulls on the digit. It’s one project where it pays to be all thumbs.