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Medical Dictionary


scotograph (sko′to-graf)
An appliance for aiding one to write in straight lines in the dark or for aiding the blind to write, as used by the historian W.H. Prescott. SYN: noctograph. [scoto- + G. grapho, to write]

scotoma, pl .scotomata (sko-to′ma, sko-to′ma-ta)
1. An isolated area of varying size and shape, within the visual field, in which vision is absent or depressed. 2. A blind spot in psychological awareness. [G. skotoma, vertigo, fr. skotos, darkness] absolute s. a s. in which there is no perception of light. anular s. a circular s. surrounding the center of the field of vision. See ring s.. arcuate s. a s. extending from the blind spot and arching into the nasal field following the lines of retinal nerve fibers. Bjerrum s. a comet-shaped s., occurring in glaucoma, attached at the temporal end to the blind spot or separated from it by a narrow gap; the defect widens as it extends above and nasally curves around the fixation spot, and then extends downward to end exactly at the nasal horizontal meridian. SYN: Bjerrum sign, sickle s.. cecocentral s. a s. involving the optic disk area (blind spot) and the papillomacular fibers; there are three forms: 1) the cecocentral defect, which extends from the blind spot toward or into the fixation area; 2) angioscotoma; 3) glaucomatous nerve-fiber bundle s., due to involvement of nerve-fiber bundles at the edge of the optic disk. SEE ALSO: Bjerrum s., R&slash;onne nasal step. central s. a s. involving the fixation point. color s. an area of depressed color vision in the visual field. flittering s. SYN: scintillating s.. glaucomatous nerve-fiber bundle s. cecocentral s.. hemianopic s. a s. involving half of the central field. mental s. absence of insight into, or inability to comprehend, items relative to a subject whose content is highly emotional to the individual. SYN: blind spot (2) . negative s. a s. that is not ordinarily perceived, but is detected only on examination of the visual field. paracentral s. a s. adjacent to the fixation point. pericentral s. a s. that surrounds the fixation point more or less symmetrically. peripheral s. a s. outside of the central 30 degrees of the visual field. physiologic s. the negative s. in the visual field, corresponding to the optic disk. SYN: blind spot (1) . positive s. a s. that is perceived as a black spot within the field of vision. quadrantic s. a s. involving a quarter segment of the central visual field. relative s. a s. in which there is visual depression but not complete loss of light perception. ring s. an annular area of blindness in the visual field surrounding the fixation point in pigmentary degeneration of the retina and in glaucoma. scintillating s. a localized area of blindness edged by brilliantly colored shimmering lights (teichopsia); usually a prodromal symptom of migraine. SEE ALSO: fortification spectrum. SYN: flittering s.. Seidel s. a form of Bjerrum s.. SEE ALSO: Seidel sign. sickle s. SYN: Bjerrum s.. zonular s. a curved s. not corresponding to the path of retinal nerve fibers.

scotomata (sko-to′ma-ta)
Plural of scotoma.

scotomatous (sko-to′ma-tus)
Relating to scotoma.

scotometer (sko-tom′e-ter)
An instrument for determining the size, shape, and intensity of a scotoma.

scotometry (sko-tom′e-tre)
The plotting and measuring of a scotoma. [scoto- + G. metron, measure]

scotophilia (sko-to-fil′e-a)
SYN: nyctophilia. [scoto- + G. philos, fond]

scotophobia (sko-to-fo′be-a)
SYN: nyctophobia. [scoto- + G. phobos, fear]

scotopia (sko-to′pe-a)
SYN: scotopic vision. [scoto- + G. opsis, vision]

scotopic (sko-to′pik, -top′ik)
Referring to low illumination to which the eye is dark-adapted. See s. vision.

scotopsin (sko-top′sin)
The protein moiety of the pigment in the rods of the retina.

scotoscopy (sko-tos′ko-pe)
SYN: retinoscopy. [scoto- + G. skopeo, to view]

Charles I., Jr., U.S. pediatrician, *1934. See Aarskog-S. syndrome.

Henry William Jr., U.S. surgeon, *1916. See S. operation.

H., English scientist. See Scott-Wilson reagent.

scotty dog (scot′te dawg)
The fancied appearance of the articular facets on oblique radiographs of the lumbar spine; the neck of the s. is the pars interarticularis, site of the most common defect in spondylolysis.

SYN: scraping.

scrapie (skrap′e, skra′pe)
A communicable spongiform encephalopathy of the central nervous system of sheep and goats caused by a prion and characterized by a very long incubation period followed by pruritus, abnormalities of gait, and invariably death; it resembles Creutzfeldt-Jakob disease and kuru in humans. [from scraping by affected animals against objects to relieve itching]

scraping (skrap′ing)
A specimen scraped from a lesion or specific site, for cytologic examination. SEE ALSO: smear. SYN: scrape.

screen (skren)
1. A sheet of any substance used to shield an object from any influence, such as heat, light, x-rays, etc. 2. A sheet upon which an image is projected. 3. Formerly, to make a fluoroscopic examination. 4. In psychoanalysis, concealment, as one image or memory concealing another. SEE ALSO: s. memory. 5. To examine, evaluate; to process a group to select or separate certain individuals from it. 6. A thin layer of crystals that converts x-rays to light photons to expose film; used in a cassette to produce radiographic images on film. [Fr. écran] Bjerrum s. SYN: tangent s.. s.-film contact the closeness and uniformity with which the x-ray film in a cassette lies against the s. (6). Image resolution is dependent on this property. fluorescent s. a s. coated with fluorescent crystals such as the calcium tungstate used in the fluoroscope. Hess s. a s. used in the measurement of ocular deviation. intensifying s. a s. (6) used in radiography. multiple marker s. use of two or more markers in the maternal serum to determine the relative risk of an abnormal fetus. SEE ALSO: triple s.. rare-earth s. an intensifying s. (6) made of a rare-earth oxide phosphor, more efficient than calcium tungstate, especially at the higher kilovoltages used in modern radiography. tangent s. a flat, usually black surface used to measure the central 30 degrees of the field of vision. SYN: Bjerrum s.. triple s. test of maternal serum α-fetoprotein, chorionic gonadotropin, and unconjugated estrogen for indications of increased risk of fetal abnormality, especially trisomy 21. vestibular s. a s. made of acrylic resin that covers the labial or buccal surfaces of one or both dental arches; used to treat oral habits and to stimulate tooth movement by using perioral muscle force.

screening (skren′ing)
1. To screen (5). 2. Examination of a group of usually asymptomatic individuals to detect those with a high probability of having a given disease, typically by means of an inexpensive diagnostic test. 3. In the mental health professions, initial patient evaluation that includes medical and psychiatric history, mental status evaluation, and diagnostic formulation to determine the patient's suitability for a particular treatment modality. carrier s. indiscriminate examination of members of a population to detect heterozygotes for serious disorders and counsel about the risks of marriages with other carriers, and by antenatal diagnosis where a married couple are both carriers; often sacrifices specificity to sensitivity and is most effectively applied to populations known to be at high risk. cytologic s. a s. for the detection of early disease, usually cancer, through microscopic examination of a cellular specimen by inspecting each cell and structure present, usually at ×100 magnification with a mechanical stage, so that all areas are screened; the findings are evaluated and significant abnormalities are flagged ( e.g., by dotting the cover slip) for further evaluation by a cytopathologist. This s. is usually performed by a cytotechnologist, but at times is done by automated machine prescreening. familial s. s. directed at close relatives of probands with diseases that may lie latent, as in age-dependent dominant traits, or that may involve risk to progeny, as X-linked traits. mass s. examination of a large population to detect the manifestation of a disease in order to initiate treatment or prevent spread, as part of a public health campaign. multiphasic s. the routine use of multiple tests, usually biochemical, for the purpose of detecting disease at a preventable or curable stage. neonatal s. testing of newborns for the detection of preventable or curable disease or for diagnosis of genetic disease. prenatal s. s. for the detection of fetal disease, usually by ultrasound examination or by testing amnionic fluid obtained by amniocentesis. Other s. techniques include testing maternal serum and placental biopsy.

screw (skroo)
A helically grooved cylinder for fastening two objects together or for adjusting the position of an object resting on one end of the s.. afterloading s. a device for setting the length at which a contracting muscle encounters an afterload.

screw-worm (skroo′werm)
The larva of the botfly, Cochliomyia hominivorax, and other similar forms that cause human and animal myiasis. primary screw-worm an obligatory s. that can penetrate normal tissues and feed as a primary invader. The important myiasis flies of humans that serve as p. screw-worms are Cochliomyia hominivorax, Chrysomyia bezziana, and Wohlfahrtia magnifica. secondary screw-worm an accidental or facultative s. that enters a prior wound or suppurated condition and feeds on infected rather than intact tissues. Many blowflies are included, such as Calliphora vicina, Phaenicia sericata, Phormia regina, Cochliomyia macellaria, Chrysomyia species, and other fleshflies.

scribe (skrib)
1. To write, trace, or mark by making a line with a marker or pointed instrument, as in surveying a dental cast for a removable prosthesis. 2. To form, by instrumentation, negative areas within a master cast to provide a positive beading in the framework of a removable partial denture, or the posterior palatal seal area for a complete denture. [L. scribo, pp. scripto, to write]

Belding H., U.S. nephrologist, *1921. See S. shunt.

scrobiculate (skro-bik′u-lat)
Pitted; marked with minute depressions. [L. scrobiculus; dim. of scrobis, a trench]

scrobiculus cordis (skro-bik′u-lus kor′dis)
SYN: epigastric fossa. [L. pit or fossa of the heart]

scrofula (skrof′u-la)
Historic term for cervical tuberculous lymphadenitis. [L. scrofulae (pl. only), a glandular swelling, s., fr. scrofa, a breeding sow]

scrofuloderma (skrof′u-lo-der′ma)
Tuberculosis resulting from extension into the skin from underlying atypical mycobacterial infection, most commonly of cervical lymph nodes in children with tonsillar infection by bovine tubercle bacillus. [scrofula + G. derma, skin]

scrofulous (skrof′u-lus)
Relating to or suffering from scrofula.

scrotal (skro′tal)
Relating to the scrotum. SYN: oscheal.

scrotectomy (skro-tek′to-me)
Removal of all or part of the scrotum. [scrotum, + G. ektome, excision]

scrotiform (skro′ti-form)
Having the shape or form of a scrotum.

scrotitis (skro-ti′tis)
Inflammation of the scrotum.

scrotoplasty (skro′to-plas-te)
Surgical reconstruction of the scrotum. SYN: oscheoplasty. [scrotum + G. plastos, formed]

scrotum, pl .scrotascrotums (skro′tum, -ta, -tumz) [TA]
A musculocutaneous sac containing the testes; it is formed of skin, containing a network of nonstriated muscular fibers (the dartos or dartus fascia), which also forms the scrotal septum internally. SYN: marsupium (1) . [L.] lymph s. SYN: elephantiasis scroti. watering-can s. urinary fistulas in s. and perineum, resulting from disease of the perineal urethra. SEE ALSO: watering-can perineum.

scruple (skroo′pl)
An apothecaries' weight of 20 grains or one-third of a dram. [L. scrupulus, a small sharp stone, a weight, the 24th part of an ounce, a s., dim. of scrupus, a sharp stone]

Acronym for self-contained underwater breathing apparatus.

Scultetus, Scultet
Originally Schultes, Johann, German surgeon, 1595–1645. See S. bandage, S. position.

scum (skum)
A film of insoluble material that rises to the surface of a liquid, as in epistasis. [M.E.]

scurf (skerf)
SYN: dandruff. [A.S.]

scurvy (sker′ve)
A disease marked by inanition, debility, anemia, and edema of the dependent parts; a spongy condition sometimes with ulceration of the gums and loss of teeth, hemorrhages into the skin from the mucous membranes and internal organs, and poor wound healing; due to a diet lacking vitamin C. SYN: scorbutus, sea s.. [fr. A.S. scurf] Alpine s. SYN: pellagra. hemorrhagic s. s. with extensive hemorrhages in gums, skin, and other tissues, typical of severe stage of the disease. infantile s. osteopathia hemorrhagia infantum;a cachectic condition in infants, resulting from malnutrition and marked by pallor, fetid breath, coated tongue, diarrhea, and subperiosteal hemorrhages; probably a combination of s. and rickets due to combined deficiency of vitamins C and D. SYN: Barlow disease, Cheadle disease, osteopathia hemorrhagica infantum, s. rickets. land s. formerly, s. occurring in people who had not been to sea. sea s. SYN: s..

scutate (skoo′tat)
SYN: scutiform.

scute (skoot)
A thin lamina or plate. SYN: scutum (1) . [L. scutum, shield] tympanic s. the thin bony plate separating the epitympanic recess from the mastoid cells.

scutiform (skoo′ti-form)
Shield-shaped. SYN: scutate. [L. scutum, shield, + forma, form]

Scutigera (skoo-tij′er-a)
A genus of centipedes commonly found in the eastern U.S.; the Eastern house centipede is a member of the species S. cleopatra. [L. scutum, an oblong shield]

scutulum, pl .scutula (skoo′tu-lum, -la; skoo′choo-loom)
A yellow, saucer-shaped crust, the characteristic lesion of favus, consisting of a mass of hyphae, pus, and scales. [L. dim. of scutum, shield]

scutum, pl .scuta (skoo′tum, -ta)
1. SYN: scute. 2. In ixodid (hard) ticks, a plate that largely or entirely covers the dorsum of the male and forms an anterior shield behind the capitulum of the female or immature ticks. [L. shield]

scybala (sib′a-la)
Plural of scybalum.

scybalous (sib′a-lus)
Relating to scybala.

scybalum, pl .scybala (sib′a-lum, -la)
A hard, round mass of inspissated feces. [G. skybalon, excrement]

scyphiform (si′fi-form)
SYN: scyphoid. [G. skyphos, goblet, cup, + L. forma, form]

scyphoid (si′foyd)
Cup-shaped. SYN: scyphiform. [G. skyphos, cup, + eidos, resemblance]

Abbreviation for streptodornase; standard deviation.

Abbreviation for specific dynamic action.

Abbreviation for sodium dodecyl sulfate.

Symbol for selenium.

seal (sel)
1. A tight closure. 2. To effect a tight closure. border s. the contact of the denture border with the underlying or adjacent tissues to prevent the passage of air or other substances. SYN: peripheral s.. palatal s. SYN: posterior palatal s.. peripheral s. SYN: border s.. posterior palatal s. the s. at the posterior border of a denture. SEE ALSO: posterior palatal s. area. SYN: palatal s., post dam, postdam, postpalatal s.. postpalatal s. SYN: posterior palatal s.. velopharyngeal s. closure between the oral and nasopharyngeal cavities.

sealant (se′lant)
A material used to effect an airtight closure. dental s. SYN: fissure s.. fissure s. a dental material usually made from interaction between bisphenol A and glycidyl methacrylate; such sealants are used to seal nonfused, noncarious pits and fissures on surfaces of teeth. SYN: dental s..

sea nettle (se net′il)
SYN: Chrysaora quinquecirrha.

searcher (ser′cher)
A form of sound used to determine the presence of a calculus in the bladder.

Carl E., U.S. psychologist, 1866–1949. See S. test.

seasickness (se′sik-nes)
A form of motion sickness caused by the motion of a floating platform, such as a ship, boat, or raft. SYN: mal de mer, naupathia, vomitus marinus.

season (se′zon)
A particular phase of some slow cyclic phenomenon, especially the annual weather cycle.


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