| ape fissure | A small, inconstant semilunar groove on the cortical convexity near the occipital pole, marking the anterior border of the striate cortex (area 17) and considered homologous with the major sulcus of the same name that is a more constant feature of the cerebral cortex in monkeys and apes. Synonym: sulcus lunatus cerebri, ape fissure, lunate fissure, lunate sulcus, simian fissure. (05 Mar 2000) |
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| auricular fissure | A fissure separating the tympanic portion from the mastoid portion of the temporal bone; it transmits the auricular branch of the vagus nerve. Synonym: fissura tympanomastoidea, auricular fissure, tympanomastoid suture. (05 Mar 2000) |
| azygos fissure | The four-layered pleural fold that separates the lobus azygos from the rest of the right upper lobe of the lung, seen as an oblique line pointing downward toward the mediastinal shadow in the upper right lung field on a chest radiograph. (05 Mar 2000) |
| Bichat's fissure | The nearly circular fissure corresponding to the medial margin of the cerebral (pallial) mantle, marking the hilus of the cerebral hemisphere, consisting of the callosomarginal fissure and choroidal fissure along the hippocampus, both of which are continuous with the stem of the fissure of Sylvius at the anterior extremity of the temporal lobe. (05 Mar 2000) |
| branchial fissure | A persistent branchial cleft. (05 Mar 2000) |
| Broca's fissure | The fissure surrounding Broca's convolution. (05 Mar 2000) |
| calcarine 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) |
| callosomarginal fissure | A fissure on the mesial surface of the cerebral hemisphere, bounding the upper surface of the cingulate gyrus (callosal convolution); the anterior portion is called the pars subfrontalis; the posterior portion which curves up to the superomedial margin of the hemisphere and borders the paracentral lobule posteriorly, the pars marginalis. Synonym: sulcus cinguli, callosomarginal fissure, callosomarginal sulcus, sulcus callosomarginalis, sulcus of cingulum. (05 Mar 2000) |
| major fissure | The deep fissure in each lung that runs obliquely downward and forward. It divides the upper and lower lobes of the left lung and separates the upper and middle lobes from the lower lobe of the right lung. Synonym: fissura obliqua pulmonis, major fissure, oblique fissure. (05 Mar 2000) |
| palpebral fissure | The opening for the eyes between the eyelids. (12 Dec 1998) |
| Pansch's fissure | A cerebral fissure (sulcus) running from the lower extremity of the central fissure (sulcus) nearly to the end of the occipital lobe. (05 Mar 2000) |
| paracentral fissure | A curved fissure (sulcus) on the medial surface of the cerebral hemisphere, bounding the paracentral gyrus and separating it from the precuneus and the cingulate gyrus. (05 Mar 2000) |
| parieto-occipital fissure | A very deep, almost vertically oriented fissure on the medial surface of the cerebral cortex, marking the border between the parietal lobe and the cuneus of the occipital lobe; its lower part curves forward and fuses with the anterior extent of the calcarine fissure (sulcus calcarinus); the great depth of this combined fissure causes a bulge in the medial wall of the occipital horn of the lateral ventricle, the calcar avis. Synonym: sulcus parieto-occipitalis, fissura parietooccipitalis, parieto-occipital fissure. (05 Mar 2000) |
| vestibular fissure of cochlea | A fine fissure in the lower part of the first turn of the cochlea, formed by a spiral lamina which projects from the outer wall of the cochlea but does not quite reach the osseous spiral lamina, thus leaving a narrow gap. (05 Mar 2000) |
| caudal transverse fissure | A transverse fissure on the visceral surface of the liver between the caudate and quadrate lobes, lodging the portal vein, hepatic artery, hepatic nerve plexus, hepatic ducts, and lymphatic vessels. Synonym: caudal transverse fissure, portal fissure. (05 Mar 2000) |