The ventriculus terminalis or terminal ventricle of Krause, also known as the 5th ventricle, is an ependymal-lined fusiform dilatation of the terminal central canal of the spinal cord, positioned at the transition from the tip of the conus medullaris to the origin of the filum terminale. This differs from a filar cyst which is located within the filum terminale.
It represents the canalization and retrogressive differentiation of the caudal end of the developing spinal cord and regresses in size during the first weeks after birth.
Irrespective of the modality used to image the spine, a ventriculus terminalis in newborns appears as a cystic structure at the tip of the conus medullaris, extending over 8-10 mm with a transverse diameter of 2-4 mm. Later in childhood it often remains visible as a tiny cystic structure but is rarely identifiable in adults.
History and etymology
In 1859 the German anatomist Benedikt Stilling (1810-1879) 5, wrote that the ventriculus terminalis was an expanded CSF-space in the distal spinal cord with an ependymal lining; interestingly at that time it was called the seventh ventricle! Another German anatomist, Wilhelm Krause, determined that this was a true ventricle and named it the fifth ventricle 4.
Abnormal persistence or cystic dilatation of the ventriculus terminalis (cyst of the medullary conus) can occur and may present symptomatically in adulthood with bladder or bowel sphincter disturbance.
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- 2. Coleman LT, Zimmerman RA, Rorke LB. Ventriculus terminalis of the conus medullaris: MR findings in children. AJNR Am J Neuroradiol. 1995;16 (7): 1421-6. Pubmed citation
- 3. Susan Standring. Gray's Anatomy. (2015) ISBN: 9780702052309
- 4. Duque, Jorge, Ríos, John & Fernando García-Aguirre, Johnny. (2017). A historical approach to the ventricular system of the brain. Revista de la Facultad de Medicina. 65. 473-477. 10.15446/revfacmed.v65n3.57884.
- 5. Koehler PJ. Isaäc Van Deen and Benedikt Stilling: a controversy on the function of the spinal cord in the 19th century. (1992) Journal of the history of the neurosciences. 1 (3): 189-200. doi:10.1080/09647049209525532 - Pubmed
- 6. Irani N, Goud AR, Lowe LH. Isolated filar cyst on lumbar spine sonography in infants: a case-control study. (2006) Pediatric radiology. 36 (12): 1283-8. doi:10.1007/s00247-006-0317-9 - Pubmed
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