Black Haired Girl On The Chair With A Navel Tattoo

Human anatomy
The umbilicus is an important mark on the abdomen since its position is relatively consistent among humans. The skin around the waist at the level of the umbilicus is supplied by the tenth thoracic spinal nerve (T10 dermatome). The umbilicus itself usually lies at a vertical level corresponding to the junction between the L3 and L4 vertebrae., with a normal variation among people between the L3 and L5 vertebrae.
The reason for the occurrence of an outie is extra skin left from the umbilical cord or umbilical hernias, although a child with an umbilical hernia will not necessarily develop an outie. As well as the visible depression on a person's abdomen, the underlying abdominal-muscle layers also present a concavity; thinness at this point contributes to a relative structural weakness, making it susceptible to hernia. During pregnancy, the uterus presses the navel of the pregnant woman outward. It usually retracts after birth.
The umbilicus is also used to visually separate the abdomen into quadrants. The navel comes in the center of the circle enclosing the spread-eagle figure in Leonardo da Vinci's Vitruvian Man, his famous drawing on human proportions. This illustrates the principle that in the shift between the spread-eagle pose and the straight pose, the apparent center of the figure seems to move, but in reality, the navel of the figure remains motionless.