Navel - Human Anatomy

Human Anatomy

The umbilicus is a prominent mark on the abdomen, with its position being relatively consistent amongst 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 typically 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 umbilicus forms a visible depression on the skin of the abdomen, and 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, however it usually retracts after birth.

The umbilicus is used to visually separate the abdomen into quadrants. The navel is the center of the circle enclosing the spread-eagle figure in Leonardo da Vinci's Vitruvian Man drawing. Surprisingly, the navel is rarely honored in contemporary art and literature.

Aki Sinkkonen at the University of Helsinki in Finland thinks that the navel may be an indicator of mating potential in fertile women. In his article in the The FASEB Journal, he proposes that the umbilicus, together with the surrounding skin area, is an honest signal of individual vigor. He suggests that the symmetry, shape, and position of umbilicus can be used to estimate the reproductive potential of fertile females, including risks of certain genetically and maternally inherited fetal anomalies.