The student nurse is explaining myelomeningocele to a family. Which description of myelomeningocele by the student does not require intervention by the nurse?

It is a fusion failure of the vertebral arches without herniation of the cord or meninges.

There is a defect in the base of the skull through which the brain and meninges have herniated.

A membrane-covered sac of meninges, filled with spinal fluid, is protruding through a defect in the spine.

A sac-like cyst of meninges, containing a portion of the spinal cord and fluid, is protruding through a defect in the spine.