Medical Dictionary

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claw (klaw)
A sharp, slender, usually curved nail on the paw of an animal. [L. clavus, a nail]

clawfoot (klaw′fut)
A condition of the foot characterized by hyperextension at the metatarsophalangeal joint and flexion at the interphalangeal joints, as a fixed contracture.

clawhand (klaw′hand)
Atrophy of the interosseous muscles of the hand with hyperextension of the metacarpophalangeal joints and flexion of the interphalangeal joints; develops as a result of nerve injury either at the spinal cord or peripheral nerve level.

Claybrook
Edwin B., U.S. surgeon, 1871–1931. See C. sign.

CLB
Abbreviation for cyanobacterialike, coccidialike or Cryptosporidium-like organisms that have now been identified as coccidia in the genus Cyclospora (C. cayetanensis).

cleaning (klen′ing)
In dentistry, a procedure whereby accretions are removed from the teeth or from a dental prosthesis. SEE ALSO: dental prophylaxis. ultrasonic c. in dentistry, the use of a high-frequency vibrating point to remove deposits from tooth structure; also the process of c. dentures by placing them in a special liquid in a container that generates high-frequency vibrations.

clearance (kler′ans)
1. (C with a subscript indicating the substance removed)Removal of a substance from the blood, e.g., by renal excretion, expressed in terms of the volume flow of arterial blood or plasma that would contain the amount of substance removed per unit of time; measured in mL/min. Renal c. of any substance except urea or free water is calculated as the urine flow in mL/min multiplied by the urinary concentration of the substance divided by the arterial plasma concentration of the substance; normal human values are commonly expressed per 1.73 m2 body surface area. 2. A condition in which bodies may pass each other without hindrance, or the distance between bodies. 3. Removal of something from some place; e.g., “esophageal acid c.” refers to removal from the esophagus of some acid that has refluxed into it from the stomach, evaluated by the time taken for restoration of a normal pH in the esophagus. p-aminohippurate c. a good measure of renal plasma flow, which it slightly underestimates; when a low plasma concentration of p-aminohippurate (PAH) is maintained by intravenous infusion, the kidney extracts and excretes almost all of the PAH from the plasma before it reaches the renal vein. creatinine c. measurement of the c. of endogenous creatinine, used for evaluating the glomerular filtration rate (GFR). endogenous creatinine c. a term distinguishing measurements based on the creatinine normally present in plasma; since no infusion is necessary, an average value may be obtained by collecting urine for a long period, e.g., 24 hours. exogenous creatinine c. a term distinguishing measurements based on infusing creatinine intravenously to raise its plasma concentration and facilitate its accurate chemical determination. free water c. the amount of water excreted in the urine beyond that which would accompany the excreted solutes if the urine were isosmotic with plasma; it represents the loss of body water in excess of solute tending to raise body osmolality and making urine hyposmotic. Unlike other clearances, it is calculated by subtracting the osmolal c. from the actual volume of urine excreted per minute. A negative value for free water c. represents the amount of water that the body has reclaimed from isosmotic tubule fluid to make the urine hyperosmotic and to lower body osmolality. interocclusal c. SYN: freeway space. inulin c. an accurate measure of the rate of filtration through the renal glomeruli, because inulin filters freely with water and is neither excreted nor reabsorbed through tubule walls. Inulin is not a normal constituent of plasma and must be infused continously to maintain a steady plasma concentration and a steady rate of urinary excretion during the measurement. Inulin c. in a normal adult person is about 120 mL/min (range 100–150) per 1.73 m2 body surface area. isotope c. the rate at which an isotope is removed (usually by blood flow) from a tissue or organ such as the brain. maximum urea c. the urea c. when the urine flow exceeds 2 ml/min; normal value is about 75 mL blood/min per 1.73 m2 body surface area. mucociliary c. the movement of the mucous covering of the respiratory epithelium by the beating of cilia: rapid, forward (effective) stroke and slow, return (recovery) stroke. occlusal c. a condition in which the opposing occlusal surfaces may glide over one another without any interfering projection. osmolal c. the volume of urine that would be excreted per minute if the urinary solutes were accompanied by just enough water to make the urine isosmotic with plasma, i.e., so that the solute excretion did not change the osmolality of body fluids. To calculate it, the volume of urine excreted per minute is multiplied by the urinary osmolality (usually measured by freezing point depression) and divided by the plasma osmolality. Osmolal c. is less than actual urine flow when urine is hyposmotic and exceeds it when urine is hyperosmotic. standard urea c. the value obtained when the square root of the urine flow (when below 2 mL/min) is multiplied by the urine urea concentration and divided by the whole blood urea concentration; represents an old empirical adjustment for the effect of low urine flow on urea excretion; sometimes corrected for body size by dividing by some function of body weight or surface area. Later, plasma concentration was substituted for blood concentration in the calculation. The normal value is about 54 mL/min per 1.73 m2 in an adult person. SYN: Van Slyke formula. urea c. the volume of plasma (or blood) that would be completely cleared of urea by one minute's excretion of urine; originally calculated as urine flow multiplied by urine urea concentration divided by concentration of urea in whole blood rather than plasma, representing blood urea c. rather than plasma urea c..

clearer (kler′er)
An agent, used in histological preparations, which is miscible in both the dehydrating or fixing fluid and the embedding substance.

cleavage (klev′ij)
1. Series of mitotic cell divisions occurring in the ovum immediately following its fertilization. SYN: segmentation (2) . SEE ALSO: c. division. 2. Splitting of a complex molecule into two or more simpler molecules. SYN: scission (2) . 3. Linear clefts in the skin indicating the direction of the fibers in the dermis. SEE ALSO: tension lines, under line. 4. Midline depression or furrow between mature female breasts (common). abnormal c. of cardiac valve congenital malformation of a valve leaflet with a defect extending from the free margin. adequal c. c. resulting in the formation of blastomeres of approximately equal size. complete c. SYN: holoblastic c.. determinate c. c. resulting in blastomeres each capable of developing only into a particular embryonic structure. discoidal c. meroblastic c. limited to the small cap (animal pole) of protoplasm of large-yolked eggs, such as the telolecithal eggs of birds. enamel c. the splitting of enamel in a plane parallel to the direction of the enamel rods. equal c. c. producing blastomeres of like size. equatorial c. c. in which the plane of cytoplasmic division is at right angles to the axis of the ovum. holoblastic c. c. in which the blastomeres are completely separated; the entire egg participates in cell division. SYN: complete c., total c.. hydrolytic c. SYN: hydrolysis. incomplete c. SYN: meroblastic c.. indeterminate c. c. resulting in blastomeres of similar developmental potencies, each capable, when isolated, of producing an entire embryonic body. meridional c. c. in a plane through the axis of the zygote. meroblastic c. incomplete separation of the blastomeres, with the divisions being limited to the nonyolked portion of the egg. SYN: incomplete c.. phosphoroclastic c. SYN: phosphorolysis. progressive c. in fungi, a type of sporulation in which c. planes in the cytoplasm first produce protospores and then sporangiospores in a sporangium. pudendal c. SYN: pudendal cleft. subdural c. SYN: subdural space. superficial c. meroblastic c. with the divisions limited to the peripheral (surface) cytoplasm of a centrolecithal egg. thioclastic c. the splitting of a bond in fashion analogous to hydrolysis or phosphorolysis except that the elements of a substituted hydrogen sulfide (usually coenzyme A) are added across the break. total c. SYN: holoblastic c.. unequal c. c. producing blastomeres of different sizes at the two poles. yolk c. segmentation of the vitellus.

cleaver (kle′ver)
A heavy knife for cutting or chopping. enamel c. an instrument with a heavy shank and a very short blade at about 90° to the axis of the handle; used with a hoeing motion to strip enamel from the axial surfaces of a tooth in preparation for a crown.

cleft (kleft) [TA]
A fissure. anal c. SYN: intergluteal c.. branchial clefts a bilateral series of slitlike openings into the pharynx through which water is drawn by aquatic animals; in the walls of the clefts are the vascular gill filaments that take up oxygen from the water passing through the clefts; sometimes loosely applied to the branchial ectodermal grooves of mammalian embryos, which are imperforate, rudimentary homologues of complete gill clefts. SYN: gill clefts. cholesterol c. a space caused by the dissolving out of cholesterol crystals in sections of tissue embedded in paraffin. complete posterior laryngeal c. See laryngotracheoesophageal c.. facial c. a c. resulting from incomplete merging or fusion of embryonic processes normally uniting in the formation of the face, e.g., c. lip or c. palate. SYN: prosopoanoschisis. first visceral c. SYN: hyomandibular c.. gill clefts SYN: branchial clefts. gingival c. a fissure associated with pocket formation and lined by mixed gingival and pocket epithelium. gluteal c. SYN: intergluteal c.. hyobranchial c. the c. caudal to the hyoid arch of the embryo. hyomandibular c. the c. between the hyoid and mandibular arches of the embryo; the external auditory meatus is developed from its dorsal portion. SYN: first visceral c.. intergluteal c. [TA] the sulcus between the buttocks (nates). SYN: crena analis [TA] , crena ani&star, crena interglutealis&star, natal c.&star, anal c., crena clunium, gluteal c.. interneuromeric clefts clefts between the neuromeric or segmental elevations in the primitive rhombencephalon. Larrey c. SYN: trigonum sternocostale. laryngotracheoesophageal c. absence of fusion of the musculature or cricoid cartilaginous laminae of varying severity: type 1, submucous c. of the interarytenoid muscles (known also as occult posterior laryngeal c. or submucous laryngeal c.); type 2, partial cricoid c. (known also as partial posterior laryngeal c.); type 3, total cricoid c. (known also as laryngotracheoesophageal c. or total cricoid c.); and type 4, extension of the c. into the esophagus. Maurer clefts SYN: Maurer dots, under dot. median maxillary anterior alveolar c. an asymptomatic midline defect of the maxillary anterior ridge; the result of a failure of fusion or development of the lateral halves of the palate. natal c. intergluteal c.. oblique facial c. SYN: prosoposchisis. occult posterior laryngeal c. See laryngotracheoesophageal c.. partial cricoid c. See laryngotracheoesophageal c.. partial posterior laryngeal c. See laryngotracheoesophageal c.. posterior laryngeal c. laryngotracheoesophageal c. (type 2 or 3). pudendal c. [TA] the c. between the labia majora. SYN: rima pudendi [TA] , fissura pudendi, pudendal cleavage, pudendal slit, rima vulvae, urogenital c., vulvar slit. residual c. the remnants of the pituitary diverticulum that occur between the pars distalis and pars intermedia; a distinct lumen is present in some animals, but, in humans, is present only during prenatal development and sometimes in young children. SYN: residual lumen. Schmidt-Lanterman clefts SYN: Schmidt-Lanterman incisures, under incisure. subdural c. SYN: subdural space. submucous laryngeal c. See laryngotracheoesophageal c.. synaptic c. the space about 20 nm wide between the axolemma and the postsynaptic surface. SEE ALSO: synapse. total cricoid c. See laryngotracheoesophageal c.. urogenital c. SYN: pudendal c.. visceral c. any c. between two branchial (visceral) arches in the embryo.

cleid-
See cleido-.

cleidagra, clidagra (kli-dag′ra)
Rarely used term for a sudden severe pain in the clavicle, resembling gout. [cleid- + G. agra, seizure]

cleidal (kli′dal)
Relating to the clavicle. SYN: clidal.

cleido-, cleid-
The clavicle; also spelled clido-, clid-. [G. kleis, bar, bolt]

cleidocostal (kli-do-kos′tal)
Relating to the clavicle and a rib. SYN: clidocostal. [cleido- + L. costa, rib]

cleidocranial (kli′do-kra′ne-al)
Relating to the clavicle and the cranium. SYN: clidocranial. [G. kleis, clavicle, + kranion, cranium]

cleidotomy (kli-dot′o-me)
Cutting the clavicle of a dead fetus to effect a vaginal delivery. [cleido- + -tomy]

-cleisis
Closure. [G. kleisis, a closing]

cleistothecium (klis-to-the′se-um)
In fungi, an ascocarp that is closed, with randomly dispersed asci. [G. kleistos, enclosed, + theke, box]

Cleland
W. Wallace, U.S. biochemist, *1930. See C. reagent.

clemastine (klem′as-ten)
An H1 antihistaminic. SYN: meclastine.

cleoid (kle′oyd)
A dental instrument with a pointed elliptical cutting end, used in excavating cavities or carving fillings and waxes. [A. S. cle, claw + G. eidos, resemblance]

cleptoparasite (klep-to-par′a-sit)
A parasite that develops on the prey of the parasite's host. [G. klepto, to steal, + parasite]

Cléret
M. Francois, French physician, 1876–1968. See Launois-C. syndrome.

Clevenger
Shobal V., U.S. neurologist, 1843–1920. See C. fissure.

CLIA
Abbreviation for Clinical Laboratory Improvement Amendments.

click (klik)
A slight, sharp sound. ejection c. a clicking ejection sound. See sound. mitral c. the opening snap of the mitral valve. systolic c. a sharp, clicking sound heard during cardiac systole; when heard in early systole it is usually an ejection sound; in late systole the c. usually signifies mitral insufficiency, as in the dysfunction of the mitral valvular apparatus when it prolapses into the left atrium during systole (see Barlow syndrome); rarely may also be due to pleuropericardial adhesions or other extracardiac mechanisms.

clicking (klik′ing)
A snapping, crepitant noise noted on excursions of the temporomandibular articulation, due to an asynchronous movement of the disk and condyle.

clid-
See clido-.

clidal (kli′dal)
SYN: cleidal.

clidinium bromide (kli-din′e-um)
An anticholinergic.

clido-, clid-
The clavicle. SEE ALSO: cleido-. [G. kleis, bar, bolt]

clidocostal (kli-do-kos′tal)
SYN: cleidocostal.

clidocranial (kli-do-kra′ne-al)
SYN: cleidocranial.

climacophobia (kli′ma-ko-fo′be-a)
Morbid fear of stairs or of climbing. [G. klimax, ladder, + phobos, fear]

climacteric (kli-mak′ter-ik, kli-mak-ter′ik)
1. The period of endocrinal, somatic, and transitory psychologic changes occurring in the transition to menopause. 2. A critical period of life. SYN: climacterium. [G. klimakter, the rung of a ladder]

climacterium (kli-mak-ter′e-um)
SYN: climacteric.

climatology (kli-ma-tol′o-je)
The study of climate and its relation to disease.

climatotherapy (kli′ma-to-thar′a-pe)
Treatment of disease by removal of the patient to a region having a climate more favorable for recovery.

climax (kli′maks)
1. The height or acme of a disease; its stage of greatest severity. 2. SYN: orgasm. [G. klimax, staircase]

climograph (kli′mo-graf)
A diagram showing the effect of climate on health. [G. klima, climate, + grapho, to record]

clindamycin (klin-da-mi′sin)
An antibacterial and antibiotic.

cline (klin)
A systematic relation between location and the frequencies of alleles; lines connecting points of equal frequency are termed isoclines, and the direction of the c. at any point is at right angles to an isocline. [G. klino, to slope]

clinic (klin′ik)
1. An institution, building, or part of a building where ambulatory patients are cared for. 2. An institution, building, or part of a building in which medical instruction is given to students by means of demonstrations in the presence of the sick. 3. A lecture or symposium on a subject relating to disease. [G. kline, bed]

clinical (klin′i-kl)
1. Relating to the bedside of a patient or to the course of the disease. 2. Denoting the symptoms and course of a disease, as distinguished from the laboratory findings of anatomical changes. 3. Relating to a clinic. [G. kline, bed, + -al]

Clinical Laboratory Improvement Amendments (CLIA)
Federal legislation, and the personnel and procedures established by it under the aegis of the Health Care Financing Administration (HCFA), for the surveillance and regulation of all clinical laboratory procedures in the U.S.The C. of 1988 (CLIA '88) were passed by Congress in response to public concerns about the quality of laboratory testing, particularly in physician office laboratories and in Pap smear interpretation. This legislation brought all 150,000 U.S. clinical laboratories, including physician office laboratories, under uniform regulations. A clinical laboratory is defined as any facility where materials derived from the human body are examined for the purpose of providing information for the diagnosis, prevention, or treatment of disease or the assessment of health. Standards applied to laboratory personnel and procedures are based on test complexity and potential harm to the patient. The regulations establish application procedures and fees for CLIA registration, enforcement and surveillance methods, and sanctions applicable when laboratories fail to meet standards. CLIA regulations define three categories of testing complexity: waived, moderate, and high. A subcategory for physician-performed microscopy exists at the moderate complexity level. For tests of moderate or high complexity, the laboratory must participate in a continuing program of proficiency testing whereby an independent laboratory periodically submits specimens of known composition for testing. The imposition and enforcement of CLIA regulations have elicited opposition, particularly from private physicians performing office testing. Opponents of the legislation claim that, while there is little, if any, demonstrable evidence that the CLIA rules have resulted in an improvement in patient care, regulation of office laboratories impedes the ability of physicians to serve their patients' needs. Patients and third-party payers have had to absorb increases in the cost of laboratory testing due to compliance with CLIA regulations. In addition, about one-third of physicians have discontinued some or all office testing as a result of CLIA. This has led to added inconvenience and expense for both patients and physicians. Particularly for children, the poor, and the elderly, the difficulty of arranging repeated visits and of complying with monitoring schedules decreases the quality of overall patient care. Delayed receipt by physicians of laboratory test results diminishes patient compliance, leads to delays or errors in diagnosis, and requires the use of anticipatory treatment, which leads to unnecessary expense and in some cases avoidable hospitalization.

clinician (klin-ish′un)
A health professional engaged in the care of patients, as distinguished from one working in other areas.

clinicopathologic (klin′i-ko-path-o-loj′ik)
Pertaining to the signs and symptoms manifested by a patient, and also the results of laboratory studies, as they relate to the findings in the gross and histologic examination of tissue by means of biopsy or autopsy, or both.

clino-
A slope (inclination or declination) or bend. [G. klino, to slope, incline, or bend]

clinocephalic, clinocephalous (kli-no-se-fal′ik, -sef′a-lus)
Relating to clinocephaly.

clinocephaly (kli′no-sef′a-le)
Craniosynostosis in which the upper surface of the skull is concave, presenting a saddle-shaped appearance in profile. SYN: saddle head. [clino- + G. kephale, head]

clinodactyly (kli′no-dak′ti-le)
Permanent deflection of one or more fingers. [clino- + G. daktylos, finger]

clinography (klin-og′ra-fe)
Graphic representation of the signs and symptoms exhibited by a patient. [G. kline, bed, + grapho, to write]

clinoid (kli′noyd)
1. Resembling a four-poster bed. 2. SYN: c. process. [G. kline, bed, + eidos, resemblance]

clioquinol (kli-o-kwin′ol)
SYN: iodochlorhydroxyquin.

clioxanide (kli-ok′sa-nid)
An anthelmintic.

clip (klip′)
1. A fastener used to hold a part or thing together with another. 2. A fastener used to close off a small vessel. wound c. a metal clasp or device for surgical approximation of skin incisions.

clithrophobia (klith-ro-fo′be-a)
Morbid fear of being locked in. [G. kleithron, a bolt, + phobos, fear]

clition (klit′e-on)
A craniometric point in the middle of the highest part of the clivus on the sphenoid bone. [G. klitos, a declivity]

clitoridean (klit′o-ri-de′an)
Relating to the clitoris.

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