In Norse Mythology the bridge leading from the realm of the mortals Midgård to the realm of the gods Asgård. The bridge itself is the rainbow and its guardian is the god Heimdall. The bridge is destroyed at the end of the world, Ragnarok. It as built by the Aesir.
... external urethral sphincter is the skeletal muscle that allows voluntary control over urination.
In the human female, the urethra is about 1-1.5 inches (25-38 mm) long ...