Place your thumb and little finger together. In some people a tendon will be clearly visible, and in others it won't be visible.


Lay your forearm on the table with your palm facing up. Place your thumb and little finger together and lift your hand slightly. In some people a tendon will be clearly visible, and in others it won't be visible.



The reason behind this tendon is the palmaris longus muscle. This muscle is located between the upper arm and wrist. Although the muscle is used for wrist movement, it is not required in the modern person any more, and therefore it is no longer visible in 13% of today's society.

Interestingly, not having this muscle does not effect strength and has no (negative) side effects - except visually.