| petro-occipital fissure | A fissure between the petrous part of the temporal bone and the basilar part of the occipital bone that extends anteromedially from the jugular foramen; includes the jugular foramem (at its posterior end). Synonym: fissura petro-occipitalis, Ecker's fissure. (05 Mar 2000) |
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| petrosquamous fissure | A shallow fissure indicating externally the line of fusion of the petrous and squamous portions of the temporal bone. Synonym: fissura petrosquamosa. (05 Mar 2000) |
| petrotympanic fissure | A fissure between the tympanic and petrous portions of the temporal bone; it transmits the chorda tympani nerve through a small patent portion, the anterior canaliculus of the chorda tympani. Synonym: fissura petrotympanica, glaserian fissure. (05 Mar 2000) |
| choroidal fissure | The narrow cleft along the medial wall of the lateral ventricle along the margins of which the choroid plexus is attached; it lies between the upper surface of the thalamus and lateral edge of the fornix in the central part of the ventricle and between the terminal stria and fimbria hippocampi in the inferior horn. Synonym: fissura choroidea. (05 Mar 2000) |
| choroid fissure | In the embryo, the temporary gap in the ventral margin of the developing optic cup. Synonym: choroid fissure, choroid fissure, choroidal fissure. (05 Mar 2000) |
| Clevenger's fissure | The sulcus on the basal aspect of the temporal lobe that separates the fusiform gyrus from the inferior temporal gyrus on its lateral side. Synonym: sulcus temporalis inferior, Clevenger's fissure. (05 Mar 2000) |
| minor fissure | The deep fissure that separates the upper and middle lobes of the right lung. Synonym: fissura horizontalis pulmonis dextri, horizontal fissure of right lung, minor fissure. (05 Mar 2000) |
| collateral fissure | A long, deep sagittal fissure on the undersurface of the temporal lobe, marking the border between the fusiform gyrus laterally and the hippocampal and lingual gyri medially; the great depth of the collateral sulcus results in a bulging of the floor of the occipital and temporal horn of the lateral ventricle, the collateral eminence. Synonym: sulcus collateralis, sulcus occipitotemporalis, collateral fissure, fissura collateralis, occipitotemporal sulcus. (05 Mar 2000) |
| pit and fissure caries | Caries initiated in the areas where developmental pits and fissures are located on the tooth surface. (05 Mar 2000) |
| pit and fissure sealants | Agents used to occlude dental enamel pits and fissures in the prevention of dental caries. (12 Dec 1998) |
| portal 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) |
| postcentral fissure | A fissure on the superior surface of the cerebellum separating the culmen from the central lobule. (05 Mar 2000) |
| 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) |
| 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) |