The tendon you’re likely referring to is the palmaris longus tendon , a small, vestigial tendon located in the forearm. It’s considered a remnant of our evolutionary past and is absent in about 10–30% of the human population, depending on genetic and geographic factors. While it was more functional in our ancestors (likely aiding in climbing and gripping), it has become largely unnecessary for modern humans.
Here’s how you can check if you have the palmaris longus tendon:
How to Test for the Palmaris Longus Tendon
- Position Your Hand :
Place your arm flat on a table or hold it out in front of you with the palm facing upward. - Make a Fist and Flex Your Wrist :
Make a tight fist while simultaneously flexing your wrist downward (as if trying to touch your knuckles to your forearm). - Look for a Tendon Protrusion :
Look at the middle of your inner wrist, between your two large wrist bones (the radial and ulnar styloid processes). If you have the palmaris longus tendon, you should see or feel a thin cord-like structure protruding from your skin as you perform this movement. - Check Both Arms :
Repeat the test on both arms, as some people may have the tendon on one arm but not the other.
What Does It Mean If You Don’t Have It?
- Nothing Significant : The absence of the palmaris longus tendon is completely normal and doesn’t affect hand function or strength in any noticeable way.
- Evolutionary Adaptation : Its disappearance is an example of natural selection over time, where traits that are no longer useful gradually diminish in a population.
- Medical Use : Interestingly, when present, the palmaris longus tendon is sometimes harvested by surgeons for reconstructive procedures, such as repairing damaged tendons elsewhere in the body.
Did you have the tendon? Let us know in the comments, and share this article on Facebook so that your friends and family can get in on the fun.