Which of these is a neural tube defect?
**Core Concept**
Neural tube defects (NTDs) are congenital anomalies resulting from the incomplete closure of the neural tube during embryonic development, leading to abnormalities in the brain and spinal cord. These defects can occur in various forms, including anencephaly and spina bifida.
**Why the Correct Answer is Right**
Spina bifida is a type of neural tube defect characterized by the incomplete closure of the posterior neural tube, resulting in a protrusion of the meninges and spinal cord through the defect. This condition can occur in the lumbar, sacral, or thoracic regions of the spine. The exact cause of spina bifida is not fully understood, but it is believed to be related to genetic and environmental factors, including maternal nutritional deficiencies and certain medications.
**Why Each Wrong Option is Incorrect**
**Option A:** Anencephaly is a type of neural tube defect characterized by the absence of a major portion of the brain and skull. While anencephaly is a neural tube defect, it is not the correct answer in this case.
**Option B:** Gastroschisis is a congenital anomaly characterized by a defect in the abdominal wall, allowing the intestines to protrude outside the body. It is not a neural tube defect.
**Option C:** Omphalocele is a congenital anomaly characterized by a defect in the navel area, allowing the intestines and other organs to protrude outside the body. It is not a neural tube defect.
**Clinical Pearl / High-Yield Fact**
Neural tube defects are often associated with maternal nutritional deficiencies, particularly in folic acid. Pregnant women are advised to take folic acid supplements to prevent neural tube defects.
**Correct Answer: C. Spina bifida**