fissure (fish´ur)

1. A deep furrow, cleft, or slit.(For most of the brain fissures, see entries under sulcus) 2. In dentistry, a developmental break or fault in the tooth enamel.fissura (1) [NA] ; [L. fissura]
abdominal f. congenital failure of the ventral body wall to close. See also celosomia, gastroschisis.
Ammon's f. a pearl-shaped opening in the sclera during early embryogenesis.
anal f. a crack or slit in the mucous membrane of the anus, very painful and difficult to heal.
anterior median f. of medulla oblongata the longitudinal groove in the midline of the anterior aspect of the medulla oblongata; it is the medullary equivalent of the anterior median f. of the spinal cord and ends at the foramen cecum posterius; its caudal part is obliterated by the decussation of the pyramids.fissura mediana anterior medullae oblongatae [NA], anteromedian groove (1) ;
anterior median f. of spinal cord a deep median f. on the anterior surface of the spinal cord.fissura mediana anterior medullae spinalis [NA], anteromedian groove (2), sulcus ventralis;
antitragohelicine f. a fissure in the auricular cartilage between the cauda helicis and the antitragus.fissura antitragohelicina [NA] ;
ape f. lunate cerebral sulcus
auricular f. tympanomastoid f
azygos f. 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.
Bichat's f. the nearly circular f. corresponding to the medial margin of the cerebral (pallial) mantle, marking the hilus of the cerebral hemisphere, consisting of the callosomarginal f. and choroidal f. along the hippocampus, both of which are continuous with the stem of the f. of Sylvius at the anterior extremity of the temporal lobe.
branchial f. a persistent branchial cleft.
Broca's f. the f. surrounding Broca's convolution.
calcarine f. calcarine sulcus
callosomarginal f. cingulate sulcus
caudal transverse f. porta hepatis
cerebellar f.'s the deep furrows which divide the lobules of the cerebellum. See also postcentral f., primary f. of cerebellum, secondary f. of cerebellum.fissurae cerebelli [NA] ;
cerebral f.'s the variously named fissures of the cerebral hemispheres. See also sulci cerebri, under sulcus.
choroid f. 1. optic f 2. optic f
choroidal f. 1. optic f 2. 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;fissura choroidea (1) ;
Clevenger's f. inferior temporal sulcus
collateral f. collateral sulcus
decidual f. a cleft in the decidua basalis or placenta.
dentate f. hippocampal sulcus
Duverney's f.'s notches in cartilage of external acoustic meatus, under notch
Ecker's f. petro-occipital f
enamel f. a deep cleft between adjoining cusps affording retention to caries-producing agents.
glaserian f. petrotympanic f
great horizontal f. horizontal f. of cerebellum
great longitudinal f. longitudinal f. of cerebrum
Henle's f.'s minute spaces filled with connective tissue between the muscular fasciculi of the heart.
hippocampal f. hippocampal sulcus
horizontal f. of cerebellum horizontal f. that divides the ansiform lobule into its major parts, crus I (superior semilunar lobule) and crus II (inferior semilunar lobule).fissura horizontalis cerebelli [NA], great horizontal f;
horizontal f. of right lung transverse f. of the lung
inferior accessory f. the f. that commonly separates the medial basal segment of the right lower lobe of the lung from the other basal segments, seen as an oblique line near the right heart border on chest radiographs.
inferior orbital f. a cleft between the greater wing of the sphenoid and the orbital plate of the maxilla, through which pass the maxillary division and the orbital branch of the trigeminal nerve, fibers from the pterygopalatine (Meckel's) ganglion, and the infraorbital vessels.fissura orbitalis inferior [NA], sphenomaxillary f;
lateral cerebral f. lateral cerebral sulcus
left sagittal f. a sagittal groove on the undersurface of the liver formed by the fissura ligamenti teretis anteriorly and the fissura ligamenti venosi posteriorly.
f. for ligamentum teres f. of round ligament of liver
f. of ligamentum venosum a deep cleft extending from the porta hepatis and the inferior vena cava between the left lobe and the caudate lobe; it lodges the ligamentum venosum and is thus a vestige of the fossa of the ductus venosus.fissura ligamenti venosi [NA], f. of venous ligament;
linguogingival f. a f. sometimes occurring on the lingual surface of one of the upper incisors and extending into the cementum.
f.'s of liver See left sagittal f., right sagittal f., porta hepatis, f. of round ligament of liver, f. of ligamentum venosum.
longitudinal f. of cerebrum the deep cleft separating the two hemispheres of the cerebrum.fissura longitudinalis cerebri [NA], great longitudinal f;
lunate f. lunate cerebral sulcus
f.'s of lung See transverse f. of the lung, oblique f. of lung.
major f. oblique f. of lung
minor f. transverse f. of the lung
oblique f. oblique f. of lung
oblique f. of lung 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.fissura obliqua pulmonis [NA], major f., oblique f;
optic f. in the embryo, the temporary gap in the ventral margin of the developing optic cup.choroid f. (1), choroid f. (2), choroidal f. (1) ;
oral f. rima oris
palpebral f. rima palpebrarum
Pansch's f. a cerebral f. (sulcus) running from the lower extremity of the central f. (sulcus) nearly to the end of the occipital lobe.
paracentral f. a curved f. (sulcus) on the medial surface of the cerebral hemisphere, bounding the paracentral gyrus and separating it from the precuneus and the cingulate gyrus.
parieto-occipital f. parieto-occipital sulcus
petro-occipital f. 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).fissura petro-occipitalis [NA], Ecker's f;
petrosquamous f. a shallow fissure indicating externally the line of fusion of the petrous and squamous portions of the temporal bone.fissura petrosquamosa [NA] ;
petrotympanic f. 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.fissura petrotympanica [NA], glaserian f;
portal f. porta hepatis
postcentral f. a f. on the superior surface of the cerebellum separating the culmen from the central lobule.
posterior median f. of the medulla oblongata posterior median sulcus of medulla oblongata
posterior median f. of spinal cord posterior median sulcus of spinal cord
posterolateral f. the earliest f. to appear in the development of the cerebellum; it separates the flocculus and nodulus from the uvula and tonsil.fissura posterolateralis [NA], prenodular f;
posthippocampal f. calcarine sulcus
postlingual f. a transverse f. on the superior vermis of the cerebellum separating the lingula from the central lobule.
postlunate f. a transverse f. on the superior vermis of the cerebellum separating the posterior lunate lobule in front from the ansiform lobule behind.
postpyramidal f. a f. that separates the pyramid of the cerebellum from the tuber.
postrhinal f. a f. separating the hippocampal from the collateral gyrus.
prenodular f. posterolateral f
primary f. of cerebellum the deepest f. of the cerebellum; demarcates the division of anterior and posterior lobes of the cerebellum; second to appear embryologically.fissura prima cerebelli [NA] ;
pterygoid f. 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.incisura pterygoidea [NA], fissura pterygoidea, pterygoid notch;
pterygomaxillary f. 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.fissura pterygomaxillaris [NA], fissura pterygopalatina;
rhinal f. rhinal sulcus
right sagittal f. a sagittal groove on the undersurface of the liver formed by the fossa vesicae felleae anteriorly and the sulcus venae cavae posteriorly.
f. of Rolando central sulcus
f. of round ligament of liver a cleft on the inferior surface of the liver, running from the inferior border to the left extremity of the porta hepatis; it lodges the round ligament of the liver.fissura ligamenti teretis [NA], f. for ligamentum teres, fossa venae umbilicalis, umbilical f., umbilical fossa;
Santorini's f.'s notches in cartilage of external acoustic meatus, under notch
secondary f. of cerebellum a f. that separates the uvula of the inferior vermis of the cerebellum from the pyramid.fissura secunda cerebelli [NA] ;
simian f. lunate cerebral sulcus
sphenoidal f. superior orbital f
sphenomaxillary f. inferior orbital f
sphenopetrosal f. a narrow fissure between the undersurface of the greater wing of the sphenoid and the petrous portion of the temporal bone.fissura sphenopetrosa [NA] ;
squamotympanic f. the f. separating the tympanic part of the temporal bone from the squamous part; it is continuous medially with the petrotympanic f. and the petrosquamous f.fissura tympanosquamosa [NA], tympanosquamous f;
superior orbital f. a cleft between the greater and the lesser wings of the sphenoid establishing a channel of communication between the middle cranial fossa and the orbit, through which pass the oculomotor and trochlear nerves, the ophthalmic division of the trigeminal nerve, the abducens nerve, and the ophthalmic veins.fissura orbitalis superior [NA], foramen lacerum anterius, sphenoidal f;
superior temporal f. superior temporal sulcus
sylvian f. , f. of Sylvius lateral cerebral sulcus
transverse f. of cerebellum the cleft caused by the protrusion of the anterior lobe of the cerebellum over the superior and middle cerebellar peduncles.fissura transversa cerebelli;
transverse f. of cerebrum the triangular space between the corpus callosum and fornix above and the dorsal surface of the thalamus below, which is bounded laterally by the choroid f. of the lateral ventricle, lined by pia mater, and opens caudally into the cistern of the great cerebral vein of the subarachnoid space.fissura transversa cerebri [NA] ;
transverse f. of the lung the deep fissure that separates the upper and middle lobes of the right lung.fissura horizontalis pulmonis dextri [NA], horizontal f. of right lung, minor f;
tympanomastoid f. a fissure separating the tympanic portion from the mastoid portion of the temporal bone; it transmits the auricular branch of the vagus nerve.fissura tympanomastoidea [NA], auricular f., tympanomastoid suture;
tympanosquamous f. squamotympanic f
umbilical f. f. of round ligament of liver
f. of venous ligament f. of ligamentum venosum
vestibular f. of cochlea a fine f. 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.
zygal f. a figure formed by two nearly parallel cerebral f.'s connected by a short f. at right angles, forming an H.


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