Originally Posted by
sweeks
The main artery supplying blood to the thumb ("Princeps Pollicis Artery") passes through the "notch" between the thumb and index finger. If you are riding with pressure in this area from the bars or brake hoods, the thumb may not be getting enough blood to stay warm. I've had good results keeping my thumb and index finger together as much as possible to keep pressure off this artery.
Arterial Supply of the Hand
That’s interesting, and good to know. And you can see in the graphic that the vein is on the palm side of the hand. So yeah…the pressure of leaning on the bars/hoods likely restricts circulation. And FWIW…the same phenomenon happens when I’m using the snow thrower. And of course I’m gripping the handles and clutch levers of it…putting the same pressure on the vein. So I guess that’s why.
Dan