The flexor digiti minimi brevis is a small muscle in your hand that helps you bend your pinky finger. It sits on the palm side of your hand, along the outer edge below the pinky, in the padded area often called the “pinky side” of the palm. When it contracts, it flexes the pinky mainly at the knuckle where the finger meets the hand, helping you curl the pinky toward your palm.
Even though it’s small, it matters for grip strength, hand control, and stability during many training tasks. Any time you hold a dumbbell, grip a pull-up bar, carry heavy bags, row, or hang from rings, the pinky side of your grip plays a big role in locking in the handle. If that side of the hand is weak or fatigued, you may feel your grip “peel open,” especially during longer sets, high-rep pulling work, or heavy carries. That can limit how hard you can train your back, arms, and core, which indirectly affects your ability to build muscle and keep training consistent while you lean down for visible abs.
You might notice this muscle working when you squeeze something hard, pinch the edge of a plate, or try to hold a thick handle. Mild soreness in the fleshy pad under the pinky after a lot of gripping is often normal, but sharp pain, tingling, or numbness is not and should be checked.
For your six-pack goal, think of it as a support player. Stronger, more durable grip muscles help you train harder in the big movements that burn lots of calories and build a strong midsection, while reducing the chance your grip gives out before your core does.