The obex is the most caudal point in the fourth ventricle and is therefore considered as part of the ventricular system in the brain. It is the point in the medulla where ventricle narrows to become the central canal of the spinal cord.

It occurs at the level of the foramen magnum and is therefore considered the point where the medulla becomes the spinal cord.

History and etymology

"Obex" is Latin for "barrier".

Anatomy: Brain
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Article information

rID: 5851
Section: Anatomy
Synonyms or Alternate Spellings:

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