Some People Are Missing A Wrist Tendon And Live To Tell The Tale
Category: Human Anatomy 6th May 2026
Here is a delightful bit of human cheating: some of us simply do not have the palmaris longus, a thin muscle and tendon that runs from the inside of the forearm to the palm. It is small, mostly useless for modern life, and vanishes entirely in a noticeable slice of the population. Nobody throws a parade when it goes, but anatomists raise a glass.
The absence rate is not uniform. Depending on the population you ask, anywhere from around 1.5 percent to more than 60 percent of people may be missing it, with a global average often quoted near 14 percent. That means roughly one in eight folk could fail the simple wrist test and be none the worse for wear.
The test is charmingly low tech. Touch your thumb to your little finger and flex your wrist toward the ceiling. If a long, central tendon pops up in the middle of your wrist, congratulations: you have a palmaris longus. If not, congratulations anyway: you are anatomically leaner in that specific department.
Why does it exist? It is a classic evolutionary leftover. Our tree-swinging ancestors had a greater need for a strong, flexible palm; in us it has become a cosmetic ribbon. Its real fame comes from modern medicine rather than function. Surgeons love it because it can be harvested as a graft for tendon and ligament repairs with minimal loss of function for the donor. Think of it as the spare key you never knew you had until someone needs to fix a hinge.
I once watched a surgery where the surgeon cheerfully removed the palmaris longus as if it were a good garlic clove. The patient later typed, carried coffee, and lived exactly the same life, which is the point. It is a tiny, amusing reminder that our bodies are patchworks of history: some useful, some obsolete, and some quietly pleasant for surgeons in a pinch.