The point on the midline of the dorsal surface of the medulla oblongata that marks the caudal angle of the rhomboid fossa or fourth ventricle. It corresponds to a small, transverse medullary fold overhanging the calamus scriptorius. [L. barrier]
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obex 'ō-.beks n a thin triangular lamina of gray matter in the roof of the fourth ventricle of the brain
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n.
the curved lower margin of the fourth ventricle of the brain, between the medulla oblongata and the cerebellum.
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(oґbeks) [L. “barrierâ€] [TA] the ependyma-lined junction of the taeniae of the fourth ventricle of the brain at the inferior angle.Medical dictionary. 2011.