The vessel originates in the lower abdomen, surfaces at the perineum, then rises along the anterior midline of the body. It travels over the pubis, abdomen and chest, passing through the navel and sternum, reaches the throat, curves around the mouth and ends in the mentolabial groove, below the lower lip. An internal branch reaches the eyes. At its origin in the pelvis it shares a common root with the Governing Vessel and the Chong Mai.
The Ren Mai is described as the sea of the Yin meridians: it regulates and nourishes all the Yin energies of the body. It commands the uterus and conception, which makes it a major axis in treating irregular periods, amenorrhoea and infertility. Its abdominal points tonify the Spleen and Kidney and strengthen states of deep fatigue; its chest points act on breathing and oppression. It is also the seat of several Front-Mu points, where the Qi of the organs gathers.