Medical Dictionary

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circulatory (ser′ku-la-to-re)
1. Relating to the circulation. 2. SYN: sanguiferous.

circulus, gen. and pl. circuli (ser′ku-lus, -li) [TA]
SYN: circle. 2. A circle formed by connecting arteries, veins, or nerves. [L. dim. of circus, circle] c. arteriosus cerebri [TA] SYN: cerebral arterial circle. c. arteriosus halleri SYN: vascular circle of optic nerve. c. arteriosus iridis major [TA] SYN: major arterial circle of iris. c. arteriosus iridis minor [TA] SYN: minor arterial circle of iris. c. articularis vasculosus SYN: articular vascular plexus. major c. arteriosus of iris [TA] SYN: major arterial circle of iris. minor c. arteriosus of iris [TA] SYN: minor arterial circle of iris. c. vasculosus nervi optici [TA] SYN: vascular circle of optic nerve. c. venosus halleri SYN: areolar venous plexus. c. venosus ridleyi SYN: circular sinus (1) . c. zinnii SYN: vascular circle of optic nerve.

circum-
A circular movement, or a position surrounding the part indicated by the word to which it is joined. SEE ALSO: peri-. [L. around]

circumanal (ser-kum-a′nal)
Surrounding the anus. SYN: perianal, periproctic.

circumarticular (ser′kum-ar-tik′u-lar)
Surrounding a joint. SYN: periarthric, periarticular. [circum- + L. articulus, joint]

circumaxillary (ser-kum-ak′si-lar-e)
Around the axilla. SYN: periaxillary.

circumbulbar (ser-kum-bul′bar)
SYN: peribulbar.

circumcise (ser′kum-siz)
To remove the prepuce or other tissue by circumferential incision (circumcision).

circumcision (ser-kum-sizh′un)
1. Operation to remove part or all of the prepuce. 2. Cutting around an anatomic part ( e.g., the areola of the breast). SYN: peritectomy (2) . [L. circumcido, to cut around, fr. circum, around, + caedo, to cut] female c. a broad term referring to many forms of female genital cutting, ranging from removal of the clitoral prepuce to the removal of the q.v., clitoris, labia minora and parts of the labia majora, and infibulation; done for cultural, not medical, reasons.

circumcorneal (ser-kum-kor′ne-al)
SYN: pericorneal.

circumductio [TA]
SYN: circumduction.

circumduction (ser-kum-duk′shun) [TA]
1. Movement of a part, e.g., an extremity, in a circular direction. 2. SYN: cycloduction. SYN: circumductio [TA] . [circum- + L. duco, pp. ductus, to draw]

circumference (c) (ser-kum′fer-ens) [TA]
The outer boundary, especially of a circular area. SYN: circumferentia [TA] . [L. circumferentia, a bearing around] articular c. of head of radius [TA] the portion of the head of the radius that articulates with the radial notch of the ulna. SYN: circumferentia articularis capitis radii [TA] . articular c. of head of ulna [TA] the portion of the head of the ulna that articulates with the ulnar notch of the radius. SYN: circumferentia articularis capitis ulnae [TA] .

circumferentia (ser-kum-fer-en′she-a) [TA]
SYN: circumference. [L. a bearing around] c. articularis capitis radii [TA] SYN: articular circumference of head of radius. c. articularis capitis ulnae [TA] SYN: articular circumference of head of ulna.

circumflex (ser′kum-fleks)
Describing an arc of a circle or that which winds around something; denotes several anatomic structures: arteries, veins, nerves, and muscles. [circum- + L. flexus, to bend]

circumgemmal (ser-kum-jem′al)
Surrounding a budlike or bulblike body; denoting a mode of nerve termination by fibrils surrounding an end bulb. SYN: perigemmal. [circum- + L. gemma, a bud]

circumintestinal (ser′kum-in-tes′ti-nal)
SYN: perienteric.

circumlental (ser-kum-len′tal)
SYN: perilenticular.

circummandibular (ser′kum-man-dib′u-lar)
Around or about the mandible.

circumnuclear (ser-kum-noo′kle-ar)
SYN: perinuclear.

circumocular (ser-kum-ok′u-lar)
Around the eye. SYN: periocular, periophthalmic. [circum- + L. oculus, eye]

circumoral (ser-kum-or′al)
SYN: perioral. [circum- + L. os (oris), mouth]

circumorbital (ser-kum-or′bi-tal)
Around the orbit. SYN: periorbital (2) .

circumrenal (ser-kum-re′nal)
SYN: perinephric. [circum- + L. ren, kidney]

circumscribed (ser′kum-skribd)
Bounded by a line; limited or confined. SYN: circumscriptus. [circum- + L. scribo, to write]

circumscriptus (ser-kum-skrip′tus)
SYN: circumscribed. [L.]

circumstantiality (ser′kum-stan-she-al′i-te)
A disturbance in the thought process, either voluntary or involuntary, in which one gives an excessive amount of detail (circumstances) that is often tangential, elaborate, and irrelevant, to avoid making a direct statement or answer to a question; observed in schizophrenia and in obsessional disorders. Cf.:tangentiality. [L. circum-sto, pr. p. -stans, to stand around]

circumvallate (ser-kum-val′at)
Denoting a structure surrounded by a wall, as the c. (vallate) papillae of the tongue. [circum- + L. vallum, wall]

circumvascular (ser-kum-vas′ku-lar)
SYN: perivascular. [circum- + L. vasculum, vessel]

circumventricular (ser′kum-ven-trik′u-lar)
Around or in the area of a ventricle, as are the c. organs.

circumvolute (ser-kum-vol′oot)
Twisted around; rolled about. [L. circum-volvo, pp. -volutus, to roll around]

cirrhogenous, cirrhogenic (sir-roj′e-nus, -ro-jen′ik)
Rarely used term for tending to the development of cirrhosis. [G. kirrhos, yellow (liver), + -gen, producing]

cirrhonosus (sir-ron′o-sus)
A disease of the fetus marked anatomically by a yellow staining of the peritoneum and pleura. [G. kirrhos, yellow (liver), + nosos, disease]

cirrhosis (sir-ro′sis)
Endstage liver disease characterized by diffuse damage to hepatic parenchymal cells, with nodular regeneration, fibrosis, and disturbance of normal architecture; associated with failure in the function of hepatic cells and interference with blood flow in the liver, frequently resulting in jaundice, portal hypertension, ascites, and ultimately biochemical and functional signs of hepatic failure. [G. kirrhos, yellow (liver), + -osis, condition] alcoholic c. c. that frequently develops in chronic alcoholism, characterized in an early stage by enlargement of the liver due to fatty change with mild fibrosis, and later by Laënnec c. with contraction of the liver. biliary c. c. due to biliary obstruction, which may be a primary intrahepatic disease or secondary to obstruction of extrahepatic bile ducts; the latter may lead to cholestasis and proliferation in small bile ducts with fibrosis, but marked disturbance of the lobular pattern is infrequent. SEE ALSO: primary biliary c.. capsular c. of liver SYN: Glisson c.. cardiac c. an extensive fibrotic reaction within the liver as a result of chronic constrictive pericarditis or prolonged congestive heart failure; true c. with fibrous bridging of lobules is unusual. SYN: cardiac liver, congestive c., pseudocirrhosis, stasis c.. congestive c. SYN: cardiac c.. cryptogenic c. c. of unknown etiology, with no history of alcoholism or previous acute hepatitis. fatty c. early nutritional c., especially in alcoholics, in which the liver is enlarged by fatty change, with mild fibrosis. Glisson c. chronic perihepatitis with thickening and subsequent contraction, resulting in atrophy and deformity of the liver. SYN: capsular c. of liver. Hanot c. SYN: primary biliary c.. juvenile c. SYN: chronic active hepatitis. Laënnec c. c. in which normal liver lobules are replaced by small regeneration nodules, sometimes containing fat, separated by a fairly regular framework of fine fibrous tissue strands (hob-nail liver); usually due to chronic alcoholism. Can cause severe impairment of liver function, portal hypertension with ascites and esophageal varices, and life-threatening complications. SYN: portal c.. necrotic c. SYN: postnecrotic c.. nutritional c. c. occurring in persons or animals with general or specific dietary deficiencies; methionine and cystine deficiency may produce changes of c. in animals, but it is uncertain whether malnutrition in humans leads to c. or only to reversible fatty infiltration of the liver. periportal c. c. of the liver with wide bands of fibrosis surrounding large segments of liver, with regenerative nodules. pigment c. c. of the liver associated with dark brown discoloration seen in hemochromatosis. pigmentary c. c. resulting from excessive deposits of iron in the liver, usually seen in hemochromatosis. pipe stem c. c. of the liver with fingerlike fibrosis predominantly around portal tracts, seen in schistosomiasis. Leads to portal hypertension but rarely to functional failure of the liver. portal c. SYN: Laënnec c.. posthepatitic c. SYN: chronic active hepatitis. postnecrotic c. c. characterized by necrosis involving whole hepatic lobules, with collapse of the reticular framework to form large scars; regeneration nodules are also large; may follow viral or toxic necrosis, or develop as a result of ischemic necrosis. SYN: necrotic c.. primary biliary c. a condition occurring mainly in middle-aged women, characterized by obstructive jaundice with hyperlipemia, pruritis, and hyperpigmentation of the skin; no obstruction of large bile ducts or proliferation of small bile ducts is found; the liver shows c. with marked portal infiltration by lymphocytes and plasma cells, and frequently by epithelioid cell granulomas; serum antimitochondrial antibodies are present in 85–90% of patients. SYN: Hanot c.. pulmonary c. fibrosis of the lungs; usually interstitial pulmonary fibrosis. stasis c. SYN: cardiac c.. syphilitic c. c. of the liver occurring as a result of tertiary or congenital syphilis. toxic c. c. of the liver resulting from chronic poisoning, as by lead or carbon tetrachloride.

cirrhotic (sir-rot′ik)
Relating to or affected with cirrhosis or advanced fibrosis.

cirri (sir′i)
Plural of cirrus.

cirrose, cirrous (sir′os, sir′us)
Relating to or having cirri.

cirrus, pl .cirri (sir′rus, -ri)
A structure formed from a cluster or tuft of fused cilia, constituting one of the sensory or locomotor organs of certain ciliate protozoa. [L. a curl]

cirsoid (ser′soyd)
SYN: variciform. [G. kirsos, varix, + eidos, appearance]

cirsomphalos (ser-som′fa-los)
Rarely used term for caput medusae [G. kirsos, varix, + omphalos, umbilicus]

cirsophthalmia (ser-sof-thal′me-a)
Varicose dilation of the conjunctival blood vessels. [G. kirsos, varix, + ophthalmos, eye]

CIS
Abbreviation for carcinoma in situ.

cis-
1. Prefix (in italics) meaning on this side, on the near side; opposite of trans-. 2. In genetics, a prefix denoting the location of two or more genes on the same chromosome of a homologous pair, in coupling. 3. In organic chemistry (in italics), a form of geometric isomerism in which similar functional groups are attached on the same side of the plane that includes two adjacent, fixed carbon atoms ( e.g., the 2- and 3-OH groups of ribofuranose) in a ring structure. See entgegen. 4. In organic chemistry, a form of geometric isomerism with regard to carbon-carbon double bonds. Identical functional groups on the same side of the double bond are c.. When the four moieties attached to the carbons of the double bond are all different, then the E/Z nomenclature has to be followed. SYN: zusammen (1) . See entgegen, zusammen. [L.]

cis-aconitic acid (ak-o-nit′ik)
Dehydration product of citric acid; an enzyme-bound intermediate in the tricarboxylic acid cycle.

cisplatin (sis′pla-tin)
A chemotherapeutic agent with antitumor activity; c. binds DNA and interferes with DNA synthesis; strongly emetogenic.

cistern (sis′tern) [TA]
1. [TA] Any cavity or enclosed space serving as a reservoir, especially for chyle, lymph, or cerebrospinal fluid. 2. An ultramicroscopic space occurring between the membranes of the flattened sacs of the endoplasmic reticulum, the Golgi complex, or the two membranes of the nuclear envelope. SYN: cisterna [TA] . [L. cisterna] ambient c. [TA] a c. located on the lateral aspect of the midbrain and dorsally continuous with the quadrigeminal c.; the ambient c. is sometimes defined as including the quadrigeminal c.. SYN: cisterna ambiens [TA] . basal c. SYN: interpeduncular c.. cerebellomedullary c. the largest of the subarachnoid cisterns between the cerebellum and the medulla oblongata; it is divided into a posterior cerebellomedullary c. [TA] located between the cerebellum and the dorsal surface of the medulla (also called cisterna magna), and a lateral cerebellomedullary c. [TA] located between the cerebellum and the lateral aspect of the medulla. c. of chiasm SYN: chiasmatic c.. chiasmatic c. [TA] a dilation of the subarachnoid space below and anterior to the optic chiasm. SYN: cisterna chiasmatis [TA] , c. of chiasm. chyle c. cisterna chyli. c. of cytoplasmic reticulum cisterna. c. of great cerebral vein quadrigeminal c.. interpeduncular c. [TA] a dilation of the subarachnoid space rostral to the basilar pons and ventral and caudal to the mammillary bodies where the arachnoid membrane stretches across between the two temporal lobes over the base of the diencephalon. See interpeduncular fossa. SYN: cisterna interpeduncularis [TA] , basal c., cisterna basalis, cisterna cruralis, Tarin space. c. of lamina terminalis [TA] located immediately rostral to the lamina terminalis. SYN: cisterna laminae terminalis [TA] . lateral cerebellomedullary c. [TA] See cerebellomedullary c.. SYN: cisterna cerebellomedullaris lateralis [TA] . c. of lateral cerebral fossa an elongated expansion of the subarachnoid space where the arachnoid bridges over the opening of the Sylvian fissure. SYN: cisterna fossae lateralis cerebri [TA] . lumbar c. [TA] enlargement of the subarachnoid space between the conus medullaris of spinal cord (about vertebral level L2) and inferior end of subarachnoid space and dura mater (about vertebral level S2); occupied by the dorsal and ventral roots constituting the cauda equina, the terminal filum, and cerebrospinal fluid. Site for lumbar puncture and spinal anesthesia. c. of nuclear envelope SYN: cisterna caryothecae. Pecquet c. SYN: cisterna chyli. pericallosal c. [TA] located immediately adjacent to the full length of the corpus callosum, contains portions of pericallosal artery, a branch of the anterior cerebral artery. SYN: cisterna pericallosa [TA] . pontine c. SYN: pontocerebellar c.. pontocerebellar c. [TA] located on lateral aspects of the pons at its junction with the cerebellum, may be divided into superior and inferior portions. SYN: cisterna pontocerebellaris [TA] , cisterna pontis, pontine c., prepontine c.. posterior cerebellomedullary c. [TA] See cerebellomedullary c.. SYN: cisterna cerebellomedullaris posterior [TA] , cisterna magna&star. prepontine c. SYN: pontocerebellar c.. quadrigeminal c. [TA] an expansion of the subarachnoid space extending forward between the corpus callosum and the thalamus; it encloses the internal cerebral veins which caudally join to form the vena magna cerebri (Galen vein). SYN: cisterna quadrigeminalis [TA] , c. of great cerebral vein&star, cisterna venae magnae cerebri&star, Bichat canal, superior c.. quadrigeminal c. [TA] slightly enlarged portion of the subarachnoid space located immediately dorsal to the tectum of the mesencephalon; contains parts of the great cerebral vein and of the medial posterior choroidal arteries. subarachnoid cisterns [TA] widening portions of the subarachnoid space within the cranium where the arachnoid bridges over a depression on the surface of the brain. SYN: cisternae subarachnoideae [TA] . superior c. SYN: quadrigeminal c.. Sylvian c. the subarachnoid space associated with the lateral cerebral sulcus (Sylvian fissure); contains the M1 segment of the middle cerebral artery and the origin of lenticulostriate arteries, and proximal parts of the middle cerebral artery.

cisterna, gen. and pl. cisternae (sis-ter′na, -ter′ne) [TA]
SYN: cistern. [L. an underground cistern for water, fr. cista, a box] c. ambiens [TA] SYN: ambient cistern. c. basalis SYN: interpeduncular cistern. c. caryothecae the space between the internal and external membranes of the nuclear envelope; may be continuous in places with cisterns of the endoplasmic reticulum. SYN: cistern of nuclear envelope, perinuclear space. c. cerebellomedullaris lateralis [TA] SYN: lateral cerebellomedullary cistern. c. cerebellomedullaris posterior [TA] SYN: posterior cerebellomedullary cistern. See cerebellomedullary cistern. c. chiasmatica [TA] c. chiasmatis [TA] SYN: chiasmatic cistern. c. chyli [TA] a dilated sac at the lower end of the thoracic duct into which the intestinal trunk and two lumbar lymphatic trunks open; it occurs inconsistently and when present is located posterior to the aorta on the anterior aspect of the bodies of the first and second lumbar vertebrae. SYN: chyle cistern&star, ampulla chyli, chylocyst, Pecquet cistern, Pecquet reservoir, receptaculum chyli, receptaculum pecqueti. c. cruralis SYN: interpeduncular cistern. c. fossae lateralis cerebri [TA] SYN: cistern of lateral cerebral fossa. c. interpeduncularis [TA] SYN: interpeduncular cistern. c. laminae terminalis [TA] SYN: cistern of lamina terminalis. c. lumbalis [TA] SYN: LUMBAR CISTERN51. c. magna posterior cerebellomedullary cistern. c. pericallosa [TA] SYN: pericallosal cistern. c. perilymphatica SYN: perilymphatic space. c. pontis SYN: pontocerebellar cistern. c. pontocerebellaris [TA] SYN: pontocerebellar cistern. c. quadrigeminalis [TA] SYN: quadrigeminal cistern. See cistern of great cerebral vein. cisternae subarachnoideae [TA] SYN: subarachnoid cisterns, under cistern. subsurface c. a cistern of the endoplasmic reticulum that lies close to the plasma membrane; such cisternae occur especially in the cell bodies of neurons. terminal cisternae pairs of transversely oriented tubules of the sarcoplasmic reticulum occurring at regular intervals in skeletal muscle fibers; together with an intermediate T tubule they make up a triad. c. venae magnae cerebri quadrigeminal cistern.

cisternal (sis-ter′nal)
Relating to a cisterna.

cisternography (sis′tern-og′ra-fe)
The radiographic study of the basal cisterns of the brain after the subarachnoid introduction of an opaque or other contrast medium, or a radiopharmaceutical with a suitable detector. [cisterna + G. grapho, to write] cerebellopontine c. the radiographic study of the cerebellopontine angle and contiguous structures after the introduction of a radiopaque contrast medium into the subarachnoid space. radionuclide c. scintigraphic imaging of the cisterns at the base of the brain following subarachnoid injection of a gamma-emitting radiopharmaceutical.

cistron (sis′tron)
1. The smallest functional unit of heritability; a length of chromosomal DNA associated with a single biochemical function. Under classical concepts, a gene might consist of more than one c.; in modern molecular biology, the c. is essentially equivalent to the structural gene. 2. The genetic unit defined by the cis/trans test. [cis tr-ans + -on]

cisvestism, cisvestitism (sis-ves′tizm, -ves′ti-tizm)
The practice of dressing in clothes inappropriate to one's position or status. Cf.:transvestism. [L. cis, on the near side of, + vestio, to dress]

Citellus (si-tel′us)
Former name for genus Spermophilus. [Mod. L.]

cito disp.
Abbreviation for L. cito dispensetur, let it be dispensed quickly.

citral (sit′ral)
A monoterpene aldehyde consisting of both geometric isomers found in oils from lemon, orange, verbena, and lemon grass; c.-A is the trans-isomer and c.-B is the cis-isomer (neral).

citrase, citratase (sit′ras, -ra-tas)
SYN: citrate lyase.

citrate (sit′rat, si′trat)
A salt or ester of citric acid; used as anticoagulants because they bind calcium ions. c. aldolase SYN: c. lyase. ATP c. (pro-3S)-lyase an enzyme that catalyzes the reaction of ATP, c., and coenzyme A to form ADP, orthophosphate, oxaloacetate, and acetyl-CoA. An important step in fatty acid biosynthesis. SYN: c.-cleavage enzyme. c. lyase c. (pro-3S)-lyase;an enzyme that catalyzes the cleavage of c. to oxaloacetate and acetate, in the absence of coenzyme A. SYN: citrase, citratase, c. aldolase. c. synthase c. (si)-synthase;an enzyme catalyzing the condensation of oxaloacetate, water, and acetyl-CoA, forming c. and coenzyme A; an important step in the tricarboxylic acid cycle. SYN: condensing enzyme, oxaloacetate transacetase.

citrated (sit′ra-ted)
Containing a citrate; specifically denoting blood serum or milk to which has been added a solution of potassium or sodium citrate, or both.

citric acid (sit′rik)
2-Hydroxypropane-1,2,3-tricarboxylic acid;the acid of citrus fruits, widely distributed in nature and a key intermediate in intermediary metabolism.

citrin (sit′rin)
SYN: vitamin P.

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