Failure of neural tube closure in the sacral region (caudal neuropore, normally closes by day 27) results in:
- A Spina bifida with meningomyelocele at the lumbosacral level ✓
- B Anencephaly
- C Holoprosencephaly
- D Arnold-Chiari malformation
Correct answer: A. Spina bifida with meningomyelocele at the lumbosacral level
Explanation
The caudal neuropore closes on day 26–28. Failure of caudal neuropore closure causes the lower defects: myeloschisis and meningomyelocele at the lumbosacral level. The rostral neuropore closes earlier (day 24–25); its failure leads to anencephaly. Neural tube defects are associated with folic acid deficiency and can be detected prenatally by elevated maternal serum AFP. Holoprosencephaly is a prosencephalic cleavage failure, and Chiari malformation involves posterior fossa and cerebellar tonsillar herniation.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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