| posterior median fissure of spinal cord | A shallow furrow in the median line of the posterior surface of the spinal cord. Synonym: sulcus medianus posterior medullae spinalis, posterior median fissure of spinal cord. (05 Mar 2000) |
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| posterior median fissure of the medulla oblongata | The longitudinal groove marking the posterior midline of the medulla oblongata; continuous below with the posterior median sulcus of the spinal cord. Synonym: sulcus medianus posterior medullae oblongatae, posterior median fissure of the medulla oblongata. (05 Mar 2000) |
| posterolateral fissure | The earliest fissure to appear in the development of the cerebellum; it separates the flocculus and nodulus from the uvula and tonsil. Synonym: fissura posterolateralis, prenodular fissure. (05 Mar 2000) |
| posthippocampal fissure | A deep fissure on the medial aspect of the cerebral cortex, extending on an arched line from the isthmus of the fornicate gyrus back to the occipital pole, marking the border between the lingual gyrus below and the cuneus above it. The cortex in the depth of the sulcus corresponds to the horizontal meridian of the contralateral half of the visual field. Synonym: sulcus calcarinus, calcarine fissure, fissura calcarina, posthippocampal fissure. (05 Mar 2000) |
| postlingual fissure | A transverse fissure on the superior vermis of the cerebellum separating the lingula from the central lobule. (05 Mar 2000) |
| postlunate fissure | A transverse fissure on the superior vermis of the cerebellum separating the posterior lunate lobule in front from the ansiform lobule behind. (05 Mar 2000) |
| postpyramidal fissure | A fissure that separates the pyramid of the cerebellum from the tuber. (05 Mar 2000) |
| postrhinal fissure | A fissure separating the hippocampal from the collateral gyrus. (05 Mar 2000) |
| prenodular fissure | The earliest fissure to appear in the development of the cerebellum; it separates the flocculus and nodulus from the uvula and tonsil. Synonym: fissura posterolateralis, prenodular fissure. (05 Mar 2000) |
| primary fissure of cerebellum | The deepest fissure of the cerebellum; demarcates the division of anterior and posterior lobes of the cerebellum; second to appear embryologically. Synonym: fissura prima cerebelli. (05 Mar 2000) |
| hippocampal fissure | A shallow groove between the dentate gyrus and the parahippocampal gyrus; the remains of a fissure extending deep into the hippocampus between Ammon's horn and the dentate gyrus which becomes obliterated during foetal development. Synonym: sulcus hippocampi, dentate fissure, fissura dentata, fissura hippocampi, hippocampal fissure. (05 Mar 2000) |
| secondary fissure of cerebellum | A fissure that separates the uvula of the inferior vermis of the cerebellum from the pyramid. Synonym: fissura secunda cerebelli. (05 Mar 2000) |
| pterygoid fissure | The cleft between the medial and lateral laminae of the pterygoid process of the sphenoid bone into which the pyramidal process of the palatine bone is fitted. Synonym: incisura pterygoidea, fissura pterygoidea, pterygoid notch. (05 Mar 2000) |
| pterygomaxillary fissure | The narrow gap between the lateral pterygoid plate and the infratemporal surface of the maxilla through which the infratemporal fossa communicates with the pterygopalatine fossa; gives passage to the third part of the maxillary artery and the posterior superior alveolar arteries, veins and nerves. Synonym: fissura pterygomaxillaris, fissura pterygopalatina. (05 Mar 2000) |
| horizontal fissure of cerebellum | Horizontal fissure that divides the ansiform lobule into its major parts, crus I (superior semilunar lobule) and crus II (inferior semilunar lobule). Synonym: fissura horizontalis cerebelli, great horizontal fissure. (05 Mar 2000) |