Question: Why does some of my fingers on my hand get cold and others don't?

Reka Nagy answered on 10 Nov 2016:

Humans regulate their own body temperature, maintaining it at a toasty 37 degrees Celsius when we are healthy. Your body keeps the tightest control on temperature in your organs, as these are needed to keep you alive – your fingers and toes are not as vital as your heart, for example, which is why they tend to get colder in winter.

Temperature control has a lot to do with blood, circulation and nerves. Some nerves can sense temperature and report back to a part of our brain called the hypothalamus, which is the master temperature regulator. It decides whether we need to get warmer or colder. When we are warm, blood vessels expand, allowing more blood to flow nearer the surface of the skin, so it can get cooled down by air touching the skin. When we are cold, the opposite happens – blood vessels constrict, reducing the amount of blood near the surface of the skin, preventing heat loss.

Each of your fingers has a different network of blood vessels and nerves going through it, and these take different routes to get there, running on both sides of your wrist (see the picture here – ignore the labels! https://goo.gl/tjo1uM ). Your pinky and part of your ring finger are regulated by the nerves and blood vessels travelling on the outside of your wrist, while your middle and index fingers, and part of your thumb are regulated by nerves and blood cells coming from the inside of your wrist. This could be a reason why different fingers are slightly different temperatures.