Ventriculus terminalis

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.

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.

Anatomy: Spine
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Article information

rID: 12435
Section: Anatomy
Synonyms or Alternate Spellings:
  • 7th ventricle
  • Seventh ventricle
  • Terminal ventricle of Krause
  • Terminal ventricle
  • Ventriculus terminalis of Krause
  • 5th ventricle
  • Ventriculus terminale

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