Spina bifida (Latin: "split spine") is a birth defect where there is incomplete closing of the backbone and membranes around the spinal cord. There are three main types: spina bifida occulta, meningocele, and myelomeningocele. The most common location is the lower back but rarely they may occur in the middle back or neck. Occulta has no or only mild signs. Signs of occulta may include a hairy patch, dimple, dark spot, or swelling on the back at the site of the gap in the spine.