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1. a narrow slit or cleft, especially one of the deeper or more constant furrows separating the gyri of the brain.
2. a deep cleft in the surface of a tooth, usually due to imperfect fusion of the enamel of the adjoining dental lobes. It can be treated with a dental sealant to decrease risk of caries.
abdominal fissure a congenital cleft in the abdominal wall; see also gastroschisis and thoracoceloschisis. Called also celoschisis.
anal fissure (fissure in ano) a painful lineal ulcer at the margin of the anus.
anterior median fissure a longitudinal furrow along the midline of the ventral surface of the spinal cord and medulla oblongata.
fissure of Bichat transverse fissure (def. 2).
branchial fissure pharyngeal groove.
central fissure fissure of Rolando.
collateral fissure a longitudinal fissure on the inferior surface of the cerebral hemisphere between the fusiform gyrus and the hippocampal gyrus.
Henle's f's spaces filled with connective tissue between the muscular fibers of the heart.
hippocampal fissure one extending from the splenium of the corpus callosum almost to the tip of the temporal lobe; called also hippocampal sulcus.
longitudinal fissure the deep fissure between the two cerebral hemispheres.
palpebral fissure the longitudinal opening between the eyelids.
portal fissure porta hepatis.
posterior median fissure
1. a shallow vertical groove in the closed part of the medulla oblongata, continuous with the posterior median fissure of the spinal cord.
2. a shallow vertical groove dividing the spinal cord throughout its length in the midline posteriorly; called also posterior median sulcus.
presylvian fissure the anterior branch of the fissure of Sylvius.
pudendal fissure rima pudendi.
Rolando's fissure (fissure of Rolando) a groove running obliquely across the superolateral surface of a cerebral hemisphere, separating the frontal lobe from the parietal lobe. Called also central fissure and central sulcus.
fissure of round ligament one on the visceral surface of the liver, lodging the round ligament in the adult.
sylvian fissure (fissure of Sylvius) one extending laterally between the temporal and frontal lobes, and turning posteriorly between the temporal and parietal lobes.
1. porta hepatis.
2. the transverse cerebral fissure between the diencephalon and the cerebral hemispheres; called also fissure of Bichat.
zygal fissure any of the fissures on the cerebral cortex that consist of two branches connected by a stem.
a shallow groove between the dentate gyrus and the parahippocampal gyrus; the remains of a fissure extending deep into the hippocampus between the Ammon horn and the dentate gyrus, which becomes obliterated during fetal development.