This is a T2 MRI L spine demonstrating a sacral myelomeningocele. Meningoceles are congenital cystic dilations of the meninges that herniate through posterior column defects. They are due to a failure of disjunction in which a midline cutaneous defect forms over the neural placode during embryological development, connecting neuroectoderm with ectoderm. Myelomeningoceles involve herniation of neural tissue in addition to herniation of the meninges. 90% of patients presenting with myelomeningoceles also have hydrocephalus. Chiari II malformations, trisomy 18, trisomy 13, diastematomyelia, syringomyelia, arachnoid cysts and tethered spinal cord are also commonly associated. Myelomeningoceles should be repaired immediately after birth to reduce life-threatening risks of infection and meningitis.