In the Yungdrung Bön tradition, the soul is known as la.  According to sutra, the soul is defined as the innermost, subtle essence of the five elements of space, air, fire, water and earth. The primary locus of the soul continually moves throughout the body and completes one full cycle each month in accordance with the cycle of the moon.  Within Tibetan medical texts, it is advised to not bleed, damage, or conduct surgery in the area of the body in which the soul is located at any given time.  The exact location of the soul differs slightly between texts.  The translation below is from the medical text, Menbum Karpo.