Medical Dictionary banner
Medical Dictionary - Dictionary of Medicine and Human Biology

Medical Dictionary


extern (eks′tern)
An advanced student or recent graduate who assists in the medical or surgical care of hospital patients; formerly, one who lived outside of the institution. [F. externe, outside, a day scholar]

external (eks-ter′nal) [TA]
On the outside or farther from the center; often incorrectly used to mean lateral. SYN: externus [TA] . [L. externus]

externus (eks-ter′nus) [TA]
SYN: external.

exteroceptive (eks′ter-o-sep′tiv)
Relating to the exteroceptors; denoting the surface of the body containing the end organs adapted to receive impressions or stimuli from without. [L. exterus, outside, + capio, to take]

exteroceptor (eks′ter-o-sep′ter, -tor)
One of the peripheral end organs of the afferent nerves in the skin or mucous membrane, which respond to stimulation by external agents. [L. exterus, external, + receptor, receiver]

extinction (eks-tingk′shun)
1. In behavior modification or classical or operant conditioning, a progressive decrease in the frequency of a response that is not positively reinforced; the withdrawal of reinforcers known to maintain an undesirable behavior. See conditioning. 2. SYN: absorbance. [L. extinguo, to quench] specific e. SYN: specific absorption coefficient. visual e. SYN: pseudo-hemianopia.

extinguish (eks-ting′gwish)
1. To abolish; to quench, as a flame; to cause loss of identity; to destroy. 2. In psychology, to progressively abolish a previously conditioned response. See conditioning. [L. extinguo, to quench]

extirpation (eks-tir-pa′shun)
Partial or complete removal of an organ or diseased tissue. [L. extirpo, to root out, fr. stirps, a stalk, root]

William G., U.S. physician, 1876–1943. See E. reagent.

extorsion (eks-tor′shun)
1. Conjugate rotation of the upper poles of each cornea outward. SYN: excyclotorsion. 2. Outward rotation of a limb or of an organ. [L. extorsio, fr. ex- torqueo, to twist out]

extortor (eks-tor′ter, -tor)
An outward rotator.

Without, outside of. [L.]

extra-articular (eks-tra-ar-tik′u-lar)
Outside of a joint.

extraaxial (eks-tra-aks′e-al)
Off the axis; applied to intracranial lesions that do not arise from the brain itself.

extrabuccal (eks-tra-buk′al)
Outside or not part of the cheek.

extrabulbar (eks-tra-bul′bar)
Outside of or unrelated to any bulb, such as the bulb of the urethra, or the medulla oblongata.

extracaliceal (eks′tra-ka-lis′e-al)
Outside of a calix.

extracapsular (eks′tra-kap′soo-lar)
Outside of the capsule of a joint.

extracarpal (eks-tra-kar′pal)
1. Outside of, having no relation to, the carpus. 2. On the outer side of the carpus.

extracellular (eks-tra-sel′u-lar)
Outside the cells.

extrachromosomal (eks′tra-kro-mo-som′al)
Outside or separated from, a chromosome.

extracorporeal (eks′tra-kor-po′re-al)
Outside of, or unrelated to, the body or any anatomic “corpus.”

extracorpuscular (eks′tra-kor-pus′ku-lar)
Outside the corpuscles, especially the blood corpuscles.

extracranial (eks-tra-kra′ne-al)
Outside of the cranial cavity.

1. (ek′strakt)A concentrated preparation of a drug obtained by removing the active constituents of the drug with suitable solvents, evaporating all or nearly all of the solvent, and adjusting the residual mass or powder to the prescribed standard. 2. (ek-strakt′)To remove part of a mixture with a solvent. 3. To perform extraction. [L. ex-traho, pp. -tractus, to draw out] alcoholic e. a solid e. obtained by extracting the alcohol-soluble principles of a drug, followed by the evaporation of the alcohol. allergenic e. e. (usually containing protein) from various sources, e.g., food, bacteria, pollen, and the like, suspected of specific action in stimulating manifestations of allergy; may be used for skin testing or desensitization. SYN: allergic e.. allergic e. SYN: allergenic e.. belladonna e. a powdered e. from the leaves and/or roots of Atropa belladonna; used to formulate various pharmaceutical dosage forms. Contains the alkaloids of belladonna (atropine and scopolamine) and has been used in the treatment of ulcers, diarrhea, and parkinsonism. Büchner e. a cell-free e. of yeast, such as was prepared by Eduard and Hans Büchner and observed to catalyze alcoholic fermentation; this observation essentially eliminated “vitalism” as being responsible for biologic chemical reactions and initiated the beginnings of modern biochemistry (enzymology). equivalent e. a fluidextract of the same strength, weight for weight, as the original drug. SYN: valoid. fluid e. fluidextract. hydroalcoholic e. a solid e. obtained by extracting the soluble principles of the drug with alcohol and water, followed by evaporation of the solution. liquid e. SYN: fluidextract. pollen e. liquid obtained by extracting the protein from the pollen of plants used for diagnostic testing or treatment.

extractant (ek-strak′tant)
An agent used to isolate or extract a substance from a mixture or combination of substances, from the tissues, or from a crude drug.

extraction (ek-strak′shun)
1. Luxation and removal of a tooth from its alveolus. 2. Partitioning of material (solute) into a solvent. 3. The active portion of a drug; the making of an extract. 4. Surgical removal by pulling out. 5. Removal of the fetus from the uterus or vagina at or near the end of pregnancy, either manually or with instruments. 6. Removal by suction of the product of conception before a menstrual period has been missed. [L. extraho, pp. -tractus, to draw out] Baker pyridine e. hot pyridine treatment of tissues fixed in dilute Bouin fixative, used to extract phospholipids from tissues as a control in the histochemical staining of this material. breech e. obstetrical e. of the baby by the buttocks. partial breech e. assisted breech delivery by the obstetrician with spontaneous delivery of the fetus to the level of the umbilicus. podalic e. obstetrical e. of the baby by the feet. serial e. the selective e. of certain deciduous or permanent teeth, or both, during the early years of dental development, usually with the eventual e. of the first, or occasionally the second, premolars, to encourage autonomous adjustment of moderate to severe crowding of anterior teeth; it may or may not require subsequent orthodontic treatment. spontaneous breech e. delivery of a fetus in the breech presentation without e. by the obstetrician. total breech e. delivery of a fetus in breech presentation with complete e. of the entire fetal body from the uterus.

extractives (ek-strak′tivs)
Substances present in vegetable or animal tissue that can be separated by successive treatment with solvents and recovered by evaporation of the solution.

extractor (ek-strak′ter, tor)
Instrument for use in drawing or pulling out any natural part, as a tooth, or a foreign body. vacuum e. device for producing traction upon the head of a fetus by means of a soft cup held by a vacuum.

extracystic (eks-tra-sis′tik)
Outside of, or unrelated to, the gallbladder or urinary bladder or any cystic tumor.

extradural (eks-tra-doo′ral)
1. On the outer side of the dura mater. 2. Unconnected with the dura mater.

extraembryonic (eks′tra-em-bre-on′ik)
Outside the embryonic body; e.g., those membranes involved with the embryo's protection and nutrition which are discarded at birth without being incorporated in its body.

extraepiphysial (eks′tra-ep-i-fiz′e-al)
Not relating to, or connected with, an epiphysis.

extragenital (eks′tra-jen′i-tal)
Outside of, away from, or unrelated to, the genital organs.

extrahepatic (eks-tra-he-pat′ik)
Outside of, or unrelated to, the liver.

extraligamentous (eks-tra-lig-a-men′tus)
Outside of, or unconnected with, a ligament.

extramalleolus (eks-tra-mal-e′o-lus)
SYN: lateral malleolus.

extramedullary (eks-tra-med′u-lar-e)
Outside of, or unrelated to, any medulla, especially the medulla oblongata.

extramitochondrial (eks-tra-mi-to-kon′dre-al)
Outside of the mitochondria.

extramural (eks-tra-mu′ral)
Outside, not in the substance of, the wall of a part. [extra- + L. murus, wall]

extraneous (eks-tra′ne-us)
Outside of the organism and not belonging to it. [L. extraneus]

extranuclear (eks-tra-noo′kle-er)
Located outside, or not involving, a cell nucleus.

extraocular (eks-tra-ok′u-lar)
Adjacent to but outside the eyeball.

extraoral (eks-tra-o′ral)
Outside of the oral cavity; external to the oral cavity. In its usual use it also includes anything external to the lips and cheeks.

extraovular (eks′tra-ov′u-lar, -ov′u-lar)
Outside the egg;existence after hatching from the egg, as in reptiles and birds.

extrapapillary (eks-tra-pap′i-la-re)
Unconnected with any papillary structure.

extraparenchymal (eks′tra-pa-reng′ki-mal)
Unrelated to the parenchyma of an organ.

extraperineal (eks-tra-per-i-ne′al)
Not connected with the perineum.

extraperiosteal (eks-tra-per-e-os′te-al)
Not connected with, or unrelated to, the periosteum.

extraperitoneal (eks-tra-per-i-to-ne′al)
Outside of the peritoneal cavity.

extraphysiologic (eks′tra-fiz-e-o-loj′ik)
Outside of the domain of physiology; more than physiologic, therefore pathologic.

extraplacental (eks-tra-pla-sen′tal)
Unrelated to the placenta.

extraprostatic (eks-tra-pros-tat′ik)
Outside of, or independent of, the prostate.

extrapsychic (eks-tra-fiz′ik)
Denoting the psychological dynamics that occur in the mind in association with the individual's exchanges with other persons or events. Cf.:intrapsychic.

extrapulmonary (eks-tra-pul′mo-nar-e)
Outside of, or having no relation to, the lungs.

extrapyramidal (eks-tra-pi-ram′i-dal)
Other than the pyramidal tract. See e. motor system.

extrasensory (eks-tra-sen′sor-e)
Outside or beyond the ordinary senses; not limited to the senses, as in e. perception.

extraserous (eks-tra-se′rus)
Outside a serous cavity.

extrasomatic (eks-tra-so-mat′ik)
Outside of, or unrelated to, the body.

extrasystole (eks′tra-sis′to-le)
A nonspecific word for an ectopic beat from any source in the heart. SYN: premature beat, premature systole. atrial e. premature complex of the heart arising from an ectopic atrial focus. SYN: auricular e.. atrioventricular e. SYN: junctional e.. auricular e. SYN: atrial e.. interpolated e. a ventricular or atrial e. which, instead of being followed by a compensatory or noncompensatory pause, is sandwiched between two consecutive sinus cycles. junctional e. a premature beat arising from the AV junction and leading to a simultaneous or almost simultaneous contraction of atria and ventricles. SYN: atrioventricular e.. return e. a form of reciprocal rhythm in which the impulse having arisen in the ventricle ascends toward the atria, but before reaching the atria is reflected back to the ventricles to produce a second ventricular contraction. supraventricular e. an e. arising from a center above the ventricle, i.e., arising from the atrium or AV junction. ventricular e. a premature ventricular complex.

extratarsal (eks-tra-tar′sal)
1. Outside, having no relation to, the tarsus. 2. On the outer side of the tarsus.

extratracheal (eks-tra-tra′ke-al)
Outside of the trachea.

extratubal (eks-tra-too′bal)
Outside of any tube; specifically, not in the auditory (eustachian) or uterine (fallopian) tubes.

extrauterine (eks-tra-u′ter-in)
Outside of the uterus.

extravaginal (eks-tra-vaj′i-nal)
Outside of the vagina.

extravasate (eks-trav′a-sat)
1. To exude from or pass out of a vessel into the tissues, said of blood, lymph, or urine. 2. The substance thus exuded. SYN: extravasation (2) , suffusion (4) . [L. extra, out of, + vas, vessel]

extravasation (eks-trav′a-sa′shun)
1. The act of extravasating. 2. SYN: extravasate (2) . [extra- + L. vas, vessel]

extravascular (eks-tra-vas′ku-lar)
Outside of the blood vessels or lymphatics or of any special blood vessel.


. . . Feedback