Vertebral level of the termination of the spinal cord in human fetuses
Vettivel, S.
Journal of Anatomy 179: 149-161
1991
ISSN/ISBN: 0021-8782 PMID: 1817132 Document Number: 372216
Most text books of anatomy and Embryology mention that at birth, the human spinal cord extends upto the level of third lumbar vertebra. But Rao (1949) and Jit and Charnalia (1959) reported a higher level of termination in the case of Indian neonates and even in some fetuses and Barson (1970) in the full term fetuses of England. So there is the possibility of racial differences in the level of termination of spinal cord existing even in the fetuses and neonates. This study was made on 78 formalin-preserved South Indian fetuses (42 male and 36 female) ranging from 40 to 330 mm crown rump length and 9 full term neonates (2 male and 7 female). Laminae of vertebrae were removed and the spinal cord was exposed. The sex was recorded and vertebral level of termination was determined in all the fetuses and neonates. Crown rump length, length of vertebral column and length of spinal cord were determined in all the fetuses. The recession of spinal cord and ascent of conus medullaris were calculated. Vertebral level of termination ranged from 5th sacral to first lumbar vertebra: recession ranged from 3 to 90 mm and ascent ranged from 4 to 13 vertebrae. Even in the fetus of 40 mm crown rump length, the spinal cord was shorter than the vertebral canal and terminated at the level of 5th sacral than the vertebral canal and terminated at the level of 5th sacral vertebra. In some fetuses of 174, 186 and 190 mm crown rump length, the spinal cord terminated at the 2nd lumbar vertebra. There was a rapid ascent of conus medullaris upto 120 mm crown rump length stage, when it reached fourth or even third lumbar vertebra. Beyond that, the ascent was fairly uniformly gradual and the spinal cord terminated mostly opposite first or second lumbar vertebra in the full term neonates. The South Indian female fetuses had cords terminating at the same or often higher level than male fetuses. Spinal cords of South Indian neonates terminated at a higher level than North Indian neonates and a vertebra or more higher than the level quotes by Western text books. The correlation between crown rump length, length of vertebral column, length of spina cord, vertebral level of termination and recession of spinal cord among all male, female and both was highly statistically significant at P < 0.001.