Illustrated Encyclopedia of Human Anatomic Variation: Opus III: Nervous System
Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed
Hydromyelia or hydrorrhachis interna is a defective closure or arrangement of the divisions of the primary fetal central canal. Its presence may be indicated by subsequent development of syringomyelia or by its association with spina bifida. Hydrorrhachis externa is the abnormal congenital accumulation of fluid between the meninges of the cord causing a diminution of cord volume.
Heterotopias (misplacement of parts) of the spinal cord include gray matter islands located in the white matter; these may be isolated or partially joined to the gray horns by slender strands of gray matter.
Malposition of bundles of white matter or passage of bundles of white matter (nerve fibers) through unusual sites to reach their destination has been described. Additional variations include: (a) doubling of the spinal cord in some of its parts; (b) the spinal cord (in an adult) extending to the level of the third sacral vertebra; and (c) doubling of the central canal. The denticulate ligaments vary in number between 18 and 22 in normal individuals.
In one study of 129 adults, the point of termination of the spinal cord varied from the lower third of the twelfth thoracic vertebra to the middle third of the third lumbar. In 95% of these 129 cases, the cord terminated at the level of the first and second lumbar vertebra.
Image 08 Image 11 Image 30
Holiday, M. and R.P. Cormack. (1927) Notes on a case of partial duplication of the spinal cord in the lumbar region. Trans R. Soc. Trop. Med. Hygiene 21:215-218.
Jit, I. and V.M. Charnalia. (1959) The vertebral level of the termination of the spinal cord. J. Anat. Soc. India 8:93-101.
Joylet, -. (1867) Sur un cas d'anomalie du canal central de la moelle épinière, observée sur la moelle de Mme. V., agée de 80 ans, morte à la Salpêtière. Soc. Biol. Comptes Rendus des Séances et Mémoires 19:7-8.
Kraus, W. and A. Weil. (1926) Duplicité de la moelle Epinière. Rev. Neurol. 33:317-323.
Lazorthes, G., Poulhès, J. et S. Gaubert. (1952) La significance et la hauteur des arcades du ligament dentelé. Assoc. Anatomistes Comptes Rendus 39:303-311.
Reimann, A.F. and B.J. Anson. (1944) Vertebral level of termination of the spinal cord with report of a case of sacral cord. Anat. Rec. 88:127-138.
Trétiakoff, C. et V. Ramos. (1921) Etude anatomique d'un cas de moelle bifide (double moelle lombaire). Rev. Neurol. 28:768-772.
Van Gieson, I. (1892) A study of the artifacts of the nervous system. N.Y. Med. J. 56:337-447.
Wagner, J. (1861) Notiz über einen teilweise doppelten Centralkanal im Rückenmark des Menschen. Arch. Anat. Physiol. Wissen. Med. 1861:735-747.
Walker, A.E. (1944) Dilatation of the vertebral canal associated with congenital anomalies of the spinal cord. Am. J. Roentgenology 52:571-582.
Weber, F.P. (1928) Duplication of the spinal cord. Br. Med. J. 1:1106.Section Top | Title Page
Please send us comments by filling out our Comment Form.
All contents copyright © 1995-2018 the Author(s) and Michael P. D'Alessandro, M.D. All rights reserved.
"Anatomy Atlases", the Anatomy Atlases logo, and "A digital library of anatomy information" are all Trademarks of Michael P. D'Alessandro, M.D.
Anatomy Atlases is funded in whole by Michael P. D'Alessandro, M.D. Advertising is not accepted.
Your personal information remains confidential and is not sold, leased, or given to any third party be they reliable or not.
The information contained in Anatomy Atlases is not a substitute for the medical care and advice of your physician. There may be variations in treatment that your physician may recommend based on individual facts and circumstances.