Rachischisis is a birth defect that occurs during the development of the embryo in utero. It occurs when the posterior neuropore of the neural tube of a developing embryo failed to close. There are two main types of rachischisis. These are the rachischisis partialis and the rachischisis totalis. The difference between the two lies on the extent of the occurrence of rachischisis along the spinal cord. In rachischisis partialis, only a part of the spinal cord is affected (thus the name). The condition is also referred to as merorachischisis or mesorachischisis.1
The neural tube of the developing embryo is the structure that which the brain and the spinal cord develop from. Abnormalities during the development of the neural tube can lead to congenital abnormalities. One of which is spina bifida, i.e. a defect characterized by an incomplete closing of the backbone and membranes around the spinal cord. Rachischisis is one form of spina bifida.
Word origin: Greek rachis (spine) + schizein (to split) + partialis (partial)
1 Dorland. (2012). Dorland's illustrated medical dictionary. Philadelphia: Elsevier/Saunders.