Which form involves nerve tissue fully exposed?

• A. Meningocele
• B. Myelomeningocele
• C. Myeloschisis
• D. Occulta

Answer: (C)

The form with nerve tissue fully exposed is myeloschisis. This condition occurs when the neural tube fails to close completely, leaving the spinal cord as an open, bare surface without a protective sac or skin covering. It’s the most severe end of the spina bifida spectrum, so the neural tissue is directly exposed to the environment, which raises the risk of infection and ongoing neurological injury.

By comparison, occulta is a hidden defect with skin intact and no exposed neural tissue. Meningocele involves the meninges and cerebrospinal fluid protruding through a vertebral defect in a sac, but neural tissue is not part of that protruding sac. Myelomeningocele also features a sac protruding through a vertebral defect, containing meninges and neural tissue, but there is typically some covering and the neural tissue is not completely exposed as in myeloschisis.