Medical Dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

fissiparous (fi-sip′a-rus)
Reproducing or propagating by fission. [L. findo, pp. fissus, split, + pario, to produce]

fissula (fiz-u-la)
Diminutive of fissure; a small fissure or cleft. f. ante fenestram [TA] minute, slitlike passage in the labyrinthine wall of the tympanic cavity, extending obliquely from the region of the cochleaform process to the vestibule of the bony labyrinth, anterior to the oval window; it is considered to be an extension of the perilymphatic space, but is occupied by a small band of connective tissue that is continuous with the mucosa of the tympanic cavity.

fissura, pl .fissurae (fi-soo′ra, -soo′re) [TA]
1. SYN: fissure. 2. In neuroanatomy, a particularly deep sulcus of the surface of the brain or spinal cord. [L. fr. findo, to cleave] f. antitragohelicina [TA] a fissure in the auricular cartilage between the cauda helicis and the antitragus. SYN: antitragohelicine fissure. f. calcarina SYN: calcarine sulcus. fissurae cerebelli [TA] SYN: cerebellar fissures, under fissure. f. cerebri lateralis SYN: lateral sulcus. f. choroidea [TA] SYN: optic fissure. f. collateralis SYN: collateral sulcus. f. dentata SYN: hippocampal sulcus. f. hippocampi SYN: hippocampal sulcus. f. horizontalis [TA] SYN: horizontal fissure [TA] of cerebellum. f. horizontalis pulmonis dextri [TA] SYN: transverse fissure of the right lung. f. intersemilunaris [TA] SYN: ansoparamedian fissure. f. intraculminalis [TA] SYN: intraculminate fissure. f. ligamenti teretis hepatis [TA] SYN: fissure for ligamentum teres. f. ligamenti venosi [TA] SYN: fissure for ligamentum venosum. f. longitudinalis cerebri [TA] SYN: longitudinal cerebral fissure. f. mediana anterior medullae oblongatae [TA] SYN: anterior median fissure of medulla oblongata. f. mediana anterior medullae spinalis [TA] SYN: anterior median fissure of spinal cord. f. obliqua pulmonis [TA] SYN: oblique fissure of lung. f. orbitalis inferior [TA] SYN: inferior orbital fissure. f. orbitalis superior [TA] SYN: superior orbital fissure. f. parietooccipitalis SYN: parietooccipital sulcus. f. petro-occipitalis [TA] SYN: petrooccipital fissure. f. petrosquamosa [TA] SYN: petrosquamous fissure. f. petrotympanica [TA] SYN: petrotympanic fissure. f. posterior superior [TA] SYN: posterior superior fissure. f. posterolateralis [TA] SYN: posterolateral fissure. f. precentralis [TA] SYN: precentral fissure. f. preculminalis [TA] SYN: preculminate fissure. f. prepyramidalis [TA] SYN: prepyramidal fissure. f. prima cerebelli [TA] SYN: primary fissure of cerebellum. f. pterygoidea SYN: pterygoid notch. f. pterygomaxillaris [TA] SYN: pterygomaxillary fissure. f. pterygopalatina SYN: pterygomaxillary fissure. f. pudendi SYN: pudendal cleft. f. secunda cerebelli [TA] SYN: secondary fissure [TA] of cerebellum. f. sphenopetrosa [TA] SYN: petrosphenoidal fissure. f. transversa cerebelli SYN: transverse fissure of cerebellum. f. transversa cerebri [TA] SYN: transverse cerebral fissure. f. tympanomastoidea [TA] SYN: tympanomastoid fissure. f. tympanosquamosa [TA] SYN: tympanosquamous fissure.

fissural (fish′u-ral)
Relating to a fissure.

fissuration (fish′u-ra′shun)
State of being fissured.

fissure (fish′ur) [TA]
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. SYN: fissura (1) [TA] . [L. fissura] abdominal f. congenital failure of the ventral body wall to close. SEE ALSO: celosomia, gastroschisis. Ammon f. a round 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. ansoparamedian f. [TA] the f. separating lobule HVIIA, crus II of the ansiform lobule, from lobule HVIIB, the paramedian lobule, of the posterior lobe of the cerebellum. SYN: fissura intersemilunaris [TA] , intersemilunar f.. anterior median f. of medulla oblongata [TA] 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. SYN: fissura mediana anterior medullae oblongatae [TA] , anteromedian groove (1) . anterior median f. of spinal cord [TA] a deep median f. on the anterior surface of the spinal cord. SYN: fissura mediana anterior medullae spinalis [TA] , anteromedian groove (2) , sulcus ventralis. antitragohelicine f. SYN: fissura antitragohelicina. ape f. obsolete term for lunate sulcus [TA] of occipital lobe. auricular f. SYN: tympanomastoid f.. azygos f. the four-layered pleural fold that separates an azygos lobe from the rest of the right upper lobe of the lung, seen as an oblique line curving down from the right apex toward the mediastinal shadow on a chest radiograph. The azygos vein is projected as a teardrop shadow at the inferior end of the azygos f.. Bichat 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 f. the f. surrounding Broca convolution. calcarine f. SYN: calcarine sulcus. callosomarginal f. SYN: cingulate sulcus. caudal transverse f. SYN: porta hepatis. cerebellar fissures the deep furrows which divide the lobules of the cerebellum. SEE ALSO: postcentral f., primary f. of cerebellum, secondary f. [TA] of cerebellum. SYN: fissurae cerebelli [TA] . cerebral fissures the variously named fissures of the cerebral hemispheres. SEE ALSO: sulci cerebri, under sulcus. choroid f. SYN: optic f.. choroidal f. [TA] 1. SYN: 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; Clevenger f. SYN: inferior temporal sulcus. collateral f. SYN: collateral sulcus. decidual f. a cleft in the decidua basalis or placenta. dentate f. SYN: hippocampal sulcus. Duverney fissures SYN: notch in cartilage of acoustic meatus. Ecker f. SYN: petrooccipital f.. enamel f. a deep cleft between adjoining cusps affording retention to caries-producing agents. glaserian f. SYN: petrotympanic f.. great horizontal f. SYN: horizontal f. [TA] of cerebellum. great longitudinal f. SYN: longitudinal cerebral f.. Henle fissures minute spaces filled with connective tissue between the muscular fasciculi of the heart. hippocampal f. SYN: hippocampal sulcus. horizontal f. of right lung SYN: transverse f. of the right lung. horizontal f. [TA] of cerebellum horizontal f. that divides the ansiform lobule into its major parts, crus I (superior semilunar lobule) and crus II (inferior semilunar lobule). SYN: fissura horizontalis [TA] , great horizontal f.. 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, occasionally seen as an oblique line near the right heart border on chest radiographs. inferior orbital f. [TA] 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) ganglion, and the infraorbital vessels. SYN: fissura orbitalis inferior [TA] , sphenomaxillary f.. intersemilunar f. [offalt TA] SYN: ansoparamedian f.. intraculminate f. [TA] the f. located within the culminate lobule separating lobule IV from lobule V in the anterior lobe of the cerebellum and extending to the lateral margin of the cerebellum. SYN: fissura intraculminalis [TA] . lateral cerebral f. SYN: lateral sulcus. left sagittal f. a sagittal groove on the undersurface of the liver formed by the f. for round ligament anteriorly and the f. for ligamentum venosum posteriorly. f. for ligamentum teres [TA] 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. SYN: fissura ligamenti teretis hepatis [TA] , f. for round ligament of liver&star, fossa venae umbilicalis, umbilical f., umbilical fossa. f. for ligamentum venosum [TA] 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. SYN: fissura ligamenti venosi [TA] , 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. fissures of liver left sagittal f., right sagittal f., porta hepatis, f. for ligamentum teres, f. for ligamentum venosum. longitudinal cerebral f. [TA] the deep cleft separating the two hemispheres of the cerebrum. SYN: fissura longitudinalis cerebri [TA] , great longitudinal f.. lunate f. [TA] SYN: lunate sulcus. fissures of lung transverse f. of the right lung, oblique f. of lung. major f. SYN: oblique f. of lung. minor f. SYN: transverse f. of the right lung. oblique f. SYN: oblique f. of lung. oblique f. of lung [TA] the deep f. 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. SYN: fissura obliqua pulmonis [TA] , major f., oblique f.. optic f. in the embryo, the temporary gap in the ventral margin of the developing optic cup. SYN: choroidal f. (1) [TA] , fissura choroidea [TA] , choroid f.. oral f. [TA] the mouth slit; the aperture of the mouth. SYN: rima oris [TA] , oral opening&star. palpebral f. [TA] the lid slit, or f. between the eyelids. SYN: rima palpebrarum [TA] . Pansch 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. See paracentral sulcus. parietooccipital f. SYN: parietooccipital sulcus. petrooccipital f. [TA] a f. 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 foramen (at its posterior end). SYN: fissura petro-occipitalis [TA] , Ecker f.. petrosphenoidal f. [TA] highly variable opening between the medial portion of the posterior border of the greater wing of the sphenoid bone (posterior to foramen ovale) and the medial portion of the anterior border of the petrous part of the temporal bone; it may be seen as a wide, lateral extension of the foramen lacerum in the dry skull, or it may be closed, especially laterally, taking the form of a petrosphenoidal suture rather than a f.. SYN: fissura sphenopetrosa [TA] , sphenopetrosal f.. petrosquamous f. [TA] a shallow f. indicating externally the line of fusion of the petrous and squamous portions of the temporal bone. SYN: fissura petrosquamosa [TA] . petrotympanic f. [TA] a f. 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. SYN: fissura petrotympanica [TA] , glaserian f.. portal f. SYN: 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 SYN: posterior median sulcus of medulla oblongata. posterior median f. of spinal cord SYN: posterior median sulcus of spinal cord. posterior superior f. [TA] the f. located between lobules VI and VII of the posterior lobe of the cerebellum and extending to the lateral margin of the cerebellum. SYN: fissura posterior superior [TA] . posterolateral f. [TA] the earliest f. to appear in the development of the cerebellum; it separates the flocculus and nodulus from the uvula and tonsil. SYN: fissura posterolateralis [TA] , prenodular f.. posthippocampal f. SYN: 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. precentral f. [TA] the f. located between the anterior and posterior parts (lobules II and III) of the central lobule of the anterior lobe of the cerebellum; extends from the vermis to the cerebellar margin; precentral f. a is found between lobule I and lobule II, the latter of which forms the anterior part of the central lobule. SYN: fissura precentralis [TA] . preculminate f. [TA] the f. located between lobules III and IV of the anterior lobe of the cerebellum, representing the f. between the central lobule and culmen; extends from the vermis to the cerebellar margin. SYN: fissura preculminalis [TA] . prenodular f. SYN: posterolateral f.. prepyramidal f. [TA] the f. located between lobules VIIB and VIII of the posterior lobe of the cerebellum; continues from the vermis into the hemisphere where it separates lobule HVIIB from HVIIIA. SYN: fissura prepyramidalis [TA] . primary f. of cerebellum [TA] the deepest f. of the cerebellum; demarcates the division of anterior and posterior lobes of the cerebellum; second to appear embryologically. SYN: fissura prima cerebelli [TA] . pterygoid f. SYN: pterygoid notch. pterygomaxillary f. [TA] 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. SYN: fissura pterygomaxillaris [TA] , fissura pterygopalatina. rhinal f. SYN: rhinal sulcus. right sagittal f. a sagittal groove on the undersurface of the liver formed by the fossa for gallbladder anteriorly and the groove for vena cava posteriorly. f. of Rolando SYN: central sulcus. f. for round ligament of liver f. for ligamentum teres. Santorini fissures SYN: notch in cartilage of acoustic meatus. secondary f. [TA] of cerebellum a f. that separates the uvula of the inferior vermis of the cerebellum from the pyramid. SYN: fissura secunda cerebelli [TA] . simian f. SYN: lunate sulcus. sphenoidal f. SYN: superior orbital f.. sphenomaxillary f. SYN: inferior orbital f.. sphenopetrosal f. SYN: petrosphenoidal f.. squamotympanic f. SYN: tympanosquamous f.. superior orbital f. [TA] 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. SYN: fissura orbitalis superior [TA] , foramen lacerum anterius, sphenoidal f.. superior temporal f. SYN: superior temporal sulcus. sylvian f., f. of Sylvius SYN: lateral 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. SYN: fissura transversa cerebelli. transverse cerebral f. [TA] 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. SYN: fissura transversa cerebri [TA] . transverse f. of the right lung [TA] the deep f. that separates the upper and middle lobes of the right lung. SYN: fissura horizontalis pulmonis dextri [TA] , horizontal f. of right lung, minor f.. tympanomastoid f. [TA] a f. separating the tympanic portion from the mastoid portion of the temporal bone; it transmits the auricular branch of the vagus nerve. SYN: fissura tympanomastoidea [TA] , auricular f., tympanomastoid suture. tympanosquamous f. [TA] 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.. SYN: fissura tympanosquamosa [TA] , squamotympanic f.. umbilical f. SYN: f. for ligamentum teres. f. of venous ligament SYN: f. for 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 fissures connected by a short f. at right angles, forming an H.

fistula, pl .fistulaefistulas (fis′tu-la, -tu-le, -tu-las)
An abnormal passage from one epithelial surface to another epithelial surface. [L. a pipe, a tube] abdominal f. a fistulous passage connecting one of the abdominal viscera to the external surface. amphibolic f., amphibolous f. a complete anal f. opening both externally and internally. anal f. a f. opening at or near the anus; usually, but not always, opening into the rectum above the internal sphincter. arteriovenous f. an abnormal connection, either spontaneous or surgically created, between an artery and a vein. f. auris congenita a congenital f. anterior to the root of the helix resulting from a defect in the formation of the auricle of the ear. biliary f. a f. leading to some portion of the biliary tract. f. bimucosa a complete f., both ends of which open on the mucous surface. blind f. a f. that ends in a cul-de-sac, being open at one extremity only. SYN: incomplete f.. BP f. SYN: bronchopleural f.. branchial f. a congenital f. in the neck resulting from incomplete closure of a branchial cleft or pouch. Brescia-Cimino f. a direct, surgically created, arteriovenous f.; used to facilitate chronic hemodialysis. bronchobiliary f. communication between a bronchus and the biliary system, e.g., after a ruptured hepatic abscess. bronchocavitary f. a communication between the bronchus and a lung abscess cavity. bronchoesophageal f. communication between a bronchus and the esophagus; may occur in association with either infection or tumors involving a bronchus or the esophagus. bronchopleural f. communication between a bronchus and the pleural cavity; usually caused by necrotizing pneumonia or empyema; also may follow pulmonary surgery or irradiation. SYN: BP f.. bronchopleural-cutaneous f. a communication between the tracheobronchial tree and the skin that traverses the pleural space. carotid-cavernous f. a fistulous communication, of spontaneous or traumatic origin, between the cavernous sinus and the traversing internal carotid artery; a pulsating unilateral exophthalmos and a detectable cranial bruit are common manifestations. cholecystoduodenal f. an abnormal communication between gallbladder and duodenum, often secondary to severe cholecystitis with perforation and abscess formation; when stones are present in the gallbladder they may erode through the adjacent duodenal wall; if large stones pass into the duodenum, they may cause gallstone ileus. chyle f. a leak of chyle from a lymph vessel to the skin surface; a complication of radical neck dissection when the thoracic duct is injured. coccygeal f. a fistulous opening of a dermoid cyst in the coccygeal region. colocutaneous f. a fistulous passage connecting the colon and the skin. coloileal f. a fistulous passage connecting the colon and the ileum. colonic f. 1. internal, a fistulous passage connecting the colon and a hollow viscus; 2. external, a fistulous passage connecting the colon and the skin. colovaginal f. a fistulous passage connecting the colon and vagina. colovesical f. a fistulous passage connecting the colon and urinary bladder. SYN: vesicocolic f.. complete f. a f. that is open at both ends. congenital pulmonary arteriovenous f. abnormal congenital communication between pulmonary arteries and veins usually found in the lung parenchyma. dental f. SYN: gingival f.. duodenal f. an opening through the duodenal wall and into another epithelial lined organ or through the abdominal wall. dural cavernous sinus f. a vascular shunt between the meningeal branches of the internal or external carotid arteries, under artery and the cavernous sinus. Eck f. transposition of the portal circulation to the systemic by making an anastomosis between the vena cava and portal vein and then ligating the latter close to the liver. enterocutaneous f. a fistulous passage connecting the intestine and skin of the abdomen. enterovaginal f. a fistulous passage connecting the intestine and the vagina. enterovesical f. a fistulous passage connecting the intestine and the bladder. ethmoidal-lacrimal f. a fistulous communication between the lacrimal sac and the ethmoidal sinus. SYN: internal lacrimal f.. external f. a fistulous pasage connecting a hollow viscus and the skin. fecal f. SYN: intestinal f.. gastric f. a fistulous passage connecting the stomach to the abdominal wall. gastrocolic f. a fistulous passage connecting the stomach and the colon. gastrocutaneous f. a fistulous passage connecting the stomach and the skin. gastroduodenal f. a fistulous passage connecting the stomach to the duodenum. gastrointestinal f. a fistulous passage connecting the stomach with the intestine. genitourinary f. a fistulous opening into the urogenital tract. SYN: urogenital f.. gingival f. a sinus tract originating in a peripheral abscess and opening into the oral cavity on the gingiva. SYN: dental f.. hepatic f. a fistulous passage leading to the liver. hepatopleural f. a fistulous passage connecting the liver and the pleural space. horseshoe f. an anal f. partially encircling the anus and opening at both extremities on the cutaneous surface. H-type f. a rare form of congenital tracheoesophageal f. in which there is no esophageal atresia, manifest as aspiration pneumonias. SYN: H-type tracheoesophageal f.. H-type tracheoesophageal f. SYN: H-type f.. incomplete f. SYN: blind f.. internal f. a fistulous passage connecting hollow viscera. internal lacrimal f. SYN: ethmoidal-lacrimal f.. intestinal f. a tract leading from the lumen of the intestine to the exterior. SYN: fecal f.. labyrinthine f. a f. between a fluid-filled compartment of the inner ear and another fluid-filled compartment in the inner ear (internal) or a space external to the inner ear as the middle ear or mastoid air cells or subarachnoid space (external); it may result in auditory and vestibular disturbances, depending on its location. lacrimal f., f. lacrimalis an abnormal opening into a tear duct or the lacrimal sac. lacteal f. a fistulous opening into one of the lactiferous ducts. SYN: mammary f.. lymphatic f. a congenital f. in the neck connecting with a lymphatic vessel and giving exit to lymph. mammary f. SYN: lacteal f.. Mann-Bollman f. a f. used in experimental investigations; a loop of ileum is isolated, the distal (aboral) end is anastomosed laterally to the duodenum or the small intestine, and the open proximal (oral) end is sutured to the abdominal wall; peristaltic waves travel from oral to aboral end, with leakage to the exterior thus reduced to a minimum. metroperitoneal f. SYN: uteroperitoneal f.. oroantral f. a pathologic communication between the oral cavity and the maxillary sinus, most commonly a complication of maxillary or molar tooth extraction. orofacial f. a pathologic communication between the oral cavity and the face. oronasal f. a pathologic communication between the oral cavity and the nasal cavity. parietal f. a f., either blind or complete, opening on the wall of the thorax or abdomen. SYN: thoracic f.. perilymphatic f. a f. between the vestibule of the inner ear and the middle ear through which perilymph can leak, resulting in auditory and vestibular disturbances; common sites for perilymphatic f. are the oval window through or around the footplate of the stapes or the round window through the round window membrane. perineovaginal f. a fistulous passage connecting the perineum and the vagina. pilonidal f. SYN: pilonidal sinus. pulmonary f. a parietal f. communicating with the lung. rectolabial f. a fistulous passage connecting the rectum to the surface of a labium majus. SYN: rectovulvar f.. rectourethral f. a fistulous passage connecting the rectum and the urethra. rectovaginal f. a fistulous passage connecting the rectum and the vagina. rectovesical f. a fistulous passage connecting the rectum and the bladder. rectovestibular f. a fistulous passage connecting the rectum and the vestibule of the vagina. rectovulvar f. SYN: rectolabial f.. reverse Eck f. side-to-side anastomosis of the portal vein with the inferior vena cava and ligation of the latter above the anastomosis but below the hepatic veins; the blood from the lower part of the body is thus directed through the hepatic circulation. salivary f. a pathologic communication between a salivary duct or gland and the cutaneous surface. sigmoidovesical f. a fistulous passage connecting the sigmoid colon and urinary bladder. spermatic f. a f. communicating with the testis or any of the seminal passages. T-E f. SYN: tracheoesophageal f.. Thiry f. an artificial f. for collecting the intestinal secretions of an animal for experimental purposes; a loop of intestine is isolated, its vascular and nervous connections are preserved, after the continuity of the intestinal tract is restored by an end-to-end anastomosis; one end of the isolated segment is closed, the other attached to the skin of the abdomen. Thiry-Vella f. experimental isolation of a segment of intestine in an animal; a loop of intestine is isolated, its vascular and nervous connections are preserved, and continuity of the intestinal tract is restored by an end-to-end anastomosis, each end of the isolated segment is connected to an independent opening in the abdominal wall. SYN: Vella f.. thoracic f. SYN: parietal f.. tracheobiliary f. a rare congenital anastomosis between an accessory bronchus and aberrant biliary duct system. tracheoesophageal f. fistulous passage connecting the trachea and esophagus; often associated with esophageal atresia; may also be acquired; in the adult, etiology is similar to that of bronchoesophageal f.. SYN: T-E f.. umbilical f. a fistulous passage connecting the intestine or urachus at the umbilicus. urachal f. a fistulous passage connecting the urachus with a hollow organ. ureterocutaneous f. a f. between the ureter and the skin. ureterovaginal f. a f. between the lower ureter and vagina. urethrocutaneous f. f. between urethra and penile skin; most likely a complication of hypospadias repair. urethrovaginal f. a f. between the urethra and the vagina. urinary f. a f. resulting in abnormal drainage of urine to the skin or into another organ. urogenital f. SYN: genitourinary f.. uteroperitoneal f. a fistulous passage connecting the cavity of the uterus with the peritoneal cavity. SYN: metroperitoneal f.. Vella f. SYN: Thiry-Vella f.. vesical f. a fistulous passage from the urinary bladder. vesicocolic f. SYN: colovesical f.. vesicocutaneous f. a f. between the bladder and the skin. vesicointestinal f. a fistulous passage connecting the urinary bladder and the small intestine. vesicouterine f. a f. between the bladder and the uterus. vesicovaginal f. f. between the bladder and the vagina. vesicovaginorectal f. a fistulous passage connecting the vagina, the bladder, and rectum. vitelline f. a f. between the umbilicus and the terminal ileum along the course of a persistent vitelline cord. See Meckel diverticulum.

fistulation, fistulization (fis-tu-la′shun, -tu-li-za′shun)
Formation of a fistula in a part; becoming fistulous.

fistulatome (fis′tu-la-tom)
A long, thin-bladed, probe-pointed knife for slitting open a fistula. SYN: fistula knife, syringotome. [fistula + G. tome, a cutting]

fistulectomy (fis-tu-lek′to-me)
Excision of a fistula. SYN: syringectomy. [fistula + G. ektome, excision]

fistuloenterostomy (fis′tu-lo-en-ter-os′to-me)
An operation connecting a fistula with the intestine. [fistula + G. enteron, intestine, + stoma, mouth]

fistulotomy (fis-tu-lot′o-me)
Incision or surgical enlargement of a fistula. SYN: syringotomy. [fistula + G. tome, incision]

fistulous (fis′tu-lus)
Relating to or containing a fistula.

fit
1. An attack of an acute disease or the sudden appearance of some symptom, such as coughing. 2. A convulsion. 3. (plural) epilepsy 4. In dentistry, the adaptation of any dental restoration, e.g., of an inlay to the cavity preparation in a tooth, or of a denture to its basal seat. [A.S. fitt] induced f. a conformational change in a macromolecule ( E.G., protein) as a result of multiple weak interactions with a ligand or substrate. uncinate f. SYN: temporal lobe epilepsy.

FITC
Abbreviation for fluorescein isothiocyanate.

fitness (fit′nes)
1. Well-being. 2. Suitability. 3. In population genetics, a measure of the relative survival and reproductive success of a given individual or phenotype, or of a population subgroup. 4. A set of attributes, primarily respiratory and cardiovascular, relating to ability to perform tasks requiring expenditure of energy. clinical f. absence of frank disease or of subclinical precursors. evolutionary f. the probability that the line of descent from an individual with a specific trait will not eventually die out. genetic f. in a phenotype, the mean number of surviving offspring that it generates in its lifetime, usually expressed as a fraction or percentage of the average genetic f. of the population. physical f. a state of well-being in which performance is optimal.

Fitz-Hugh
T., Jr., U.S. physician, 1894–1963. See Fitz-Hugh and Curtis syndrome.

fixation (fik-sa′shun)
1. The condition of being firmly attached or set. 2. In histology, the rapid killing of tissue elements and their preservation and hardening to retain as nearly as possible the same relations they had in the living body. SYN: fixing. 3. In chemistry, the conversion of a gas into solid or liquid form by chemical reactions, with or without the help of living tissue. 4. In psychoanalysis, the quality of being firmly attached to a particular person or object or period in one's development. 5. In physiologic optics, the coordinated positioning and accommodation of both eyes that results in bringing or maintaining a sharp image of a stationary or moving object on the fovea of each eye. [L. figo, pp. fixus, to fix, fasten] ammonia f. SYN: ammonia assimilation. bifoveal f. SYN: binocular f.. binocular f. a condition in which both eyes are simultaneously directed to the same target. SYN: bifoveal f.. circumalveolar f. stabilization of a fracture segment or surgical splint by wire passed through and around the dental alveolar process. circummandibular f. stabilization of a fracture segment or surgical splint by wire passed around the mandible. circumzygomatic f. stabilization of a fracture segment or surgical splint by wire passed around the zygomatic arch. complement f. f. of complement in a serum by an antigen-antibody combination whereby it is rendered unavailable to complete a reaction in a second antigen-antibody combination for which complement is necessary; the second system usually serves as an indicator (red blood cells plus specific hemolysin); if complement is fixed with the first antigen-antibody union, hemolysis does not occur, but, if complement is not so removed, it causes hemolysis in the second system; this technique is the basis for complement f. tests, which are widely used in laboratories for the detection of antigens or antibodies. SEE ALSO: Bordet-Gengou phenomenon, Wassermann test. SYN: CF test, complement binding assay. craniofacial f. stabilization of facial fractures to the cranial base by direct wiring or by external skeletal pin f.. crossed f. in convergent strabismus, the use of the right inturned eye to look at objects to the left and the left inturned eye to look at objects to the right, in order to avoid ocular rotation. eccentric f. a monocular condition in which the line of sight connects the object and an extrafoveal retinal area. elastic band f. the stabilization of fractured segments of the jaws by means of intermaxillary elastics applied to splints or appliances. external f. f. of fractured bones by splints, plastic dressings, or transfixion pins. external pin f. in oral surgery, stabilization of fractures of the mandible, maxilla, or zygoma by pins or screws drilled into the bony part through the overlying skin and connected by a metal bar. external pin f., biphase pin f. by replacing the rigid metal bar connector with an acrylic bar adapted at the time of reduction of the fracture. freudian f. f. (4) . genetic f. the increase of the frequency of a gene by genetic drift until no other allele is preserved in a specific finite population. intermaxillary f. f. of fractures of the mandible or maxilla by applying elastic bands or stainless steel wire between the maxillary and mandibular arch bars or other types of splint. SYN: mandibulomaxillary f., maxillomandibular f.. internal f. stabilization of fractured bony parts by direct f. to one another with surgical wires, screws, pins, rods, or plates. SYN: intraosseous f.. intraosseous f. SYN: internal f.. mandibulomaxillary f. SYN: intermaxillary f.. maxillomandibular f. SYN: intermaxillary f.. nasomandibular f. mandibular immobilization, especially for edentulous jaws, with maxillomandibular splints, attached by connecting a circum-mandibular wire with an intraoral interosseous wire passed through a hole drilled into the anterior nasal spine of the maxillae. nitrogen f. process in which atmospheric nitrogen is converted to ammonia.

fixative (fik′sa-tiv)
1. Serving to fix, bind, or make firm or stable. 2. A substance used for the preservation of gross and histologic specimens of tissue, or individual cells, usually by denaturing and precipitating or cross-linking the protein constituents. SEE ALSO: fluid, solution. acetone f. acetone used at low temperatures to fix enzymes, particularly phosphatases; it removes fat and glycogen. AFA f. a combination of alcohol, formalin, and acetic acid used for the fixation of nematodes, trematodes, and cestodes. alcohol-glycerin f. alcohol (70%) with 5% glycerin; suitable for most nematodes. Altmann f. a bichromate-osmic acid f.. Bouin f. a solution of glacial acetic acid, formalin, and picric acid, useful for soft and delicate tissues (as those of embryos) and small pieces of tissues; it preserves glycogen and nuclei and permits brilliant staining, but penetrates slowly, distorts kidney tissue and mitochondria, and does not permit Feulgen stain for DNA. Carnoy f. ethanol, chloroform, and acetic acid (6:3:1) or ethanol and acetic acid (3:1), an extremely rapid f. used for glycogen preservation and as a nuclear f.. Champy f. a mixture of potassium bichromate, chromic acid, and osmic acid, considered an excellent cytologic f. with advantages and disadvantages similar to those of Flemming's f.; it differs from Flemming f. in substituting bichromate for acetic acid. Flemming f. a mixture of chromic acid, osmic acid, and acetic acid that makes an excellent cytoplasmic and chromosomal f., especially when acetic acid is omitted; disadvantages are that it penetrates poorly, requires lengthy washing, and deterioriates rapidly. formaldehyde f. a widely used fixing agent for pathologic histology; the commercial solution is 37–40% formaldehyde and is known as 100% formalin or formol; a common impurity is formic acid, which must be neutralized or the f. made in buffer solution; tissues fixed may have a pigment artifact precipitated. formol-calcium f. a f. for preservation of lipids. formol-Müller f. Müller f. containing 2% commercial formalin. formol-saline f. a general f. for histologic and histochemical preparations. formol-Zenker f. Zenker f. in which glacial acetic acid has been replaced by formalin. glutaraldehyde f. a f. used in phosphate or cacodylate buffer for electron microscopy, and as a chromatin and enzyme f.; may be used preceding osmic acid as a second f. to add membrane preservation for electron microscopy. Golgi osmiobichromate f. an osmic-bichromate mixture used to demonstrate nerve cells and their processes. Helly f. a combination of potassium dichromate, mercuric chloride, formaldehyde, and distilled water, used as a microanatomic f. for cytoplasmic granules and nuclear staining; has the same disadvantages as Zenker f.. Hermann f. a hardening f. of glacial acetic acid, osmic acid, and platinum chloride. Kaiserling f. a method of preserving histologic and pathologic specimens without altering the color, by immersing them in an aqueous solution of potassium nitrate, potassium acetate, and formalin. Luft potassium permanganate f. a f. useful in electron microscopy for cytologic preservation of lipoprotein complexes in membranes and myelin, because of its oxidative properties. Marchi f. a mixture of Müller f. with osmium tetroxide, with potassium chlorate substituted for the potassium dichromate of Müller f. for better results; used to demonstrate degenerating myelin. SEE ALSO: Marchi stain. methanol f. a f. used with dry blood films, and often incorporated into the stain used. Müller f. a hardening f. composed of potassium dichromate, sodium sulfate, and distilled water, similar to Regaud f.. neutral buffered formalin f. a general histologic f. less likely to leave formalin deposits in tissue than formol-saline f.. Newcomer f. a f. containing isopropanol, propionic acid, and dioxane, recommended as a substitute for Carnoy f. in preservation of chromatin; also useful for fixing polysaccharides; small pieces of tissue must be used, although excessive shrinkage may still occur. Orth f. formalin added to Müller f., used for bringing out chromaffin, studying early degenerative processes and necrosis, and for demonstrating rickettsiae and bacteria. osmic acid f. a f. used alone in buffer or as a postfixative after a glutaraldehyde f. in electron microscopy; an excellent membrane f. but a poor preservative of chromatin. Park-Williams f. a f. for spirochetes, comprised of a 2% solution of osmic acid to the fumes of which the bacteria are exposed for a few seconds. picroformol f. a f. containing formalin and picric acid. PVA f. schaudinn f. using either a mercuric chloride, zinc sulfate, or copper sulfate base; contains polyvinyl alcohol plastic powder that is used as an adhesive for fecal specimens in the preparation of permanent smears for subsequent staining. Regaud f. a f. containing formaldehyde and sodium dichromate, used to preserve mitochondria but not fat; requires afterchroming and extensive washing. SAF f. sodium acetate-acetic acid-formalin mixture used to fix fecal specimens for subsequent concentration and staining of smears. Schaudinn f. a solution of mercuric chloride, sodium chloride, alcohol, and glacial acetic acid, used on wet smears for cytologic fixation. single vial fixatives proprietary and commercially available solutions used for stool fixation; from the single vial, a concentration, permanent stain, and some immunoassay procedures can be performed. Thoma f. nitric acid in 95% alcohol, used for decalcifying bone in the preparation of histologic specimens. Zenker f. a rapid f. consisting of mercuric chloride, potassium dichromate, sodium sulfate, glacial acetic acid, and water, useful for trichrome stains; must be washed to remove potassium dichromate and treated with iodine solution to remove mercuric chloride; tissues tend to become brittle if left in the f. for more than 24 hours.

fixator (fik-sa′ter)
A device providing rigid immobilization through external skeletal fixation by means of rods (f.'s) attached to pins which are placed in or through the bone.

fixing (fik′sing)
SYN: fixation (2) .

flaccid (flak′sid, flas′id)
Relaxed, flabby, or without tone. [L. flaccidus]

flaccidity (fla-sid′i-te)
The condition or state of being flaccid.

Flack
Martin W., British physiologist, 1882–1931. See F. node, Keith and F. node.

flagella (fla-jel′a)
Plural of flagellum.

flagellar (fla-jel′ar)
Relating to a flagellum or to the extremity of a protozoan.

Flagellata (flaj′e-la′ta)
Former name for Mastigophora.

flagellate (flaj′e-lat)
1. Possessing one or more flagella. 2. Common name for a member of the class Mastigophora. collared f. SYN: choanomastigote.

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