Hold your arm out, palm up.
Now touch your thumb to your pinky finger.
Do you see a small, raised tendon pop up in the center of your wrist?
If yes—you have the palmaris longus muscle.
If not—you’re part of the 10–15% of people who don’t—and that’s completely normal.
🔬 What Is the Palmaris Longus?
The palmaris longus is a thin, rope-like tendon that runs from your forearm to your wrist. When you pinch thumb to pinky, it becomes visible as a subtle cord in the middle of your inner wrist.
But here’s the fascinating part:
It serves no essential function in modern humans.
You don’t need it for grip strength, wrist movement, or dexterity. People born without it (or who’ve had it removed) show no difference in hand function.
🧬 Why Do We Have It? (A Glimpse into Evolution)
This muscle is a vestigial remnant—a leftover from our primate ancestors.
