Navel

The navel (clinically known as the umbilicus; : umbilici or umbilicuses; commonly known as the belly button or tummy button) is a protruding, flat, or hollowed area on the abdomen at the attachment site of the umbilical cord. All placental mammals have a navel, although it is generally more conspicuous in humans. Umbilical vein and Umbilical artery The umbilicus is used to visually separate the abdomen into quadrants. The umbilicus is a prominent scar on the abdomen, with its position being 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 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. Parts of the adult navel include the "umbilical cord remnant" or "umbilical tip", which is the often protruding scar left by the detachment of the umbilical cord. This is located in the center of the navel, sometimes described as the belly button. Around the cord remnant, is the "umbilical collar", formed by the dense fibrous umbilical ring. Surrounding the umbilical collar is the periumbilical skin. Directly behind the navel is a thick fibrous cord formed from the umbilical cord, called the urachus, which originates from the bladder. The navel is unique to each individual due to it being a scar, and various general forms have been classified by medical practitioners. Outie: A navel consisting of the umbilical tip protruding past the periumbilical skin is an outie. Essentially any navel which is not concave. Swirly/spiral: A rare form in which the umbilical cord scar forms a swirl shape. Split: The protruding umbilical cord scar extends outwards, but is cleft in two by a fissure which extends part or all the way through the umbilical cord scar. This form is similar in appearance to a coffee bean. Protrusion: The umbilical cord remnant is completely divulged, exposing the full umbilical scar.