What is called the fourth finger?

The fourth finger is most commonly called the ring finger. Anatomically, starting from the thumb as the first finger, the order is thumb, index finger, middle finger, ring finger, and little finger or pinky. In medical terminology, it is known as digitus annularis, digitus quartus, or the fourth digit. It is called the ring finger because in many Western cultures it is the traditional finger on which a wedding ring, engagement ring, and wedding band are worn, a custom dating back to ancient Romans who believed the vena amoris, or vein of love, ran directly from this finger to the heart. Interestingly, the ring finger is not the same on every hand or culture. In some Orthodox Christian traditions and in countries like India, Germany, Russia, and Norway, the wedding ring is worn on the ring finger of the right hand instead of the left. Biologically, the ring finger's length relative to the index finger, known as the 2D:4D ratio, is studied in science for correlations with prenatal testosterone exposure.