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Medical Dictionary


macrosigmoid (mak-ro-sig′moyd)
Enlargement or dilation of the sigmoid colon. SYN: megasigmoid.

macrosis (ma-kro′sis)
Increase in length or volume. [G.]

macrosmatic (mak′roz-mat′ik)
Denoting an abnormally keen olfactory sense. [macro- + G. osme, smell]

macrosomia (mak-ro-so′me-a)
Abnormally large size of the body. SYN: megasomia. [macro- + G. soma, body]

macrosplanchnic (mak-ro-splangk′nik)
SYN: megalosplanchnic.

macrospore (mak′ro-spor)
The larger of two spore types of certain protozoans or fungi. SYN: megalospore, megaspore. [macro- + G. sporos, seed]

macrostereognosis (mak′ro-ster-e-og-no′sis)
An error of perception in which objects appear larger than they are. [macro- + G. stereos, solid, + gnosis, recognition]

macrostomia (mak-ro-sto′me-a)
Abnormally large size of the mouth resulting from failure of fusion between the maxillary and mandibular processes of the embryonic face. [macro- + G. stoma, mouth]

macrotia (mak-ro′she-a)
Congenital excessive enlargement of the auricle or pinna. [macro- + G. ous, ear]

macrotome (mak′ro-tom)
An instrument for making gross anatomic sections. [macro- + G. tome, cutting]

macula, pl .maculae (mak′u-la, -u-le)
1. [TA] A circumscribed flat area, up to 1.0 cm in diameter, perceptibly different in color from the surrounding tissue. 2. A small, discolored patch or spot on the skin, neither elevated above nor depressed below the skin's surface. SEE ALSO: spot. 3. The neuroepithelial sensory receptors of the utricle and saccule of the vestibular labyrinth collectively. SYN: maculae utriculosaccularis [TA] . SEE ALSO: neuroepithelium of m.. SYN: macule, spot (1) . [L. a spot] maculae acusticae m. of saccule, m. of utricle. m. adherens SYN: desmosome. m. albida, pl .maculae albidae gray-white or white, rounded or irregularly shaped, slightly opaque patches or spots that are sometimes observed postmortem in the epicardium, especially in middle-aged or older persons; they result from fibrous thickening, and sometimes hyalinization, of the epicardium; similar lesions may also occur in the visceral layer of the peritoneum. SYN: m. lactea, m. tendinea, tache blanche, tache laiteuse (2) , tendinous spot, white spot. m. atrophica an atrophic glistening white spot on the skin. m. cerulea a bluish stain on the skin caused by the bites of fleas or lice, especially pediculosis pubis. SYN: blue spot (1) . m. communicans SYN: gap junction. m. communis the thickened area in the medial wall of the auditory vesicle that later subdivides to form the maculae of the sacculus and utriculus as well as the cristae of the ampullae of the semicircular ducts. m. corneae a moderately dense opacity of the cornea. SYN: corneal spot. m. cribrosa, pl .maculae cribrosae [TA] one of three areas on the wall of the vestibule of the labyrinth, marked by numerous foramina giving passage to nerve filaments supplying portions of the membranous labyrinth; m. cribrosa inferior [TA], located in the posterior bony ampulla for passage of posterior ampullary nerve fibers; m. cribrosa media [TA], area near the base of the cochlea through which the saccular nerve fibers pass; m. cribrosa superior [TA], perforated area above the elliptical recess for passage of the utriculoampullary nerve fibers; m. cribrosa quarta, a name sometimes applied to the opening for the cochlear nerve. m. cribrosa quarta a name sometimes applied to the opening for the cochlear nerve. m. densa a closely packed group of densely staining cells in the distal tubular epithelium of a nephron, in direct apposition to the juxtaglomerular cells; they may function as either chemoreceptors or as baroreceptors feeding information to the juxtaglomerular cells. false m. an extrafoveal point of fixation. m. flava a yellowish spot at the anterior extremity of the rima glottidis where the two vocal folds join. m. gonorrhoica a spot of red brighter than the surrounding membrane, at the congested orifice of the duct of Bartholin gland, sometimes seen in gonorrhea. honeycomb m. edema of the macular region of the retina. m. lactea SYN: m. albida. m. lutea [TA] SYN: m. of retina. m. pellucida SYN: follicular stigma. m. of retina [TA] an oval area of the sensory retina, 3 by 5 mm, temporal to the optic disk corresponding to the posterior pole of the eye; at its center is the central fovea, which contains only retinal cones. SYN: m. lutea [TA] , area centralis, m. retinae, macular area, punctum luteum, Soemmerring spot, yellow spot. m. retinae SYN: m. of retina. m. of saccule [TA] the oval neuroepithelial sensory receptor in the anterior wall of the saccule; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibers around their bodies. SYN: m. sacculi [TA] , saccular spot. m. sacculi [TA] SYN: m. of saccule. m. tendinea SYN: m. albida. m. of utricle [TA] the neuroepithelial sensory receptor in the inferolateral wall of the utricle; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibers around their bodies; sensitive to linear acceleration in the longitudinal axis of the body and to gravitational influences. SYN: m. utriculi [TA] , utricular spot. m. utriculi [TA] SYN: m. of utricle. maculae utriculosaccularis [TA] SYN: m. (3) .

macular, maculate (mak′u-lar, -lat)
1. Relating to or marked by macules. 2. Denoting the central retina, especially the macula retinae.

macule (mak′ul)
SYN: macula. [L. macula, spot] ash-leaf m. a hypopigmented, often ash leaf-shaped m. that is present at birth in many patients with tuberous sclerosis.

maculocerebral (mak′u-lo-ser′e-bral)
Relating to the macula lutea and the brain; denoting a type of nervous disease marked by degenerative lesions in both the retina and the brain.

maculoerythematous (mak′u-lo-er-i-the′ma-tus)
Denoting lesions that are erythematous and macular, covering wide areas.

maculopapule (mak′u-lo-pap′ul)
A lesion with a flat base surrounding a papule in the center.

maculopathy (mak-u-lop′a-the)
Any pathological condition of the macula lutea. SYN: macular retinopathy. bull's-eye m. an ocular condition in which edema or degeneration of the sensory retina at the posterior pole of the eye causes alternating areas of light and dark, as in a target; seen in toxic, inflammatory, and hereditary conditions. cystoid m. cystic degeneration of the central retina that may occur after cataract extraction, in senile macular degeneration, and in other retinal abnormalities. familial pseudoinflammatory m. familial macular degeneration resembling inflammatory changes. nicotinic acid m. m. observed in persons taking 3000 mg or more of nicotinic acid daily; normal vision returns after this medication is discontinued. solar m. damage to the fovea centralis of the retina and the adjacent choroid due to the thermal action of infrared rays, consequent to sungazing or watching a solar eclipse without sufficient eye protection. SEE ALSO: photoretinopathy. SYN: eclipse blindness, solar blindness.

A non-medical, pejorative term for: 1. Rabid. 2. Mentally ill; insane. [A.S. gemad]

madarosis (mad-a-ro′sis)
1. SYN: milphosis. 2. SYN: alopecia adnata. [G. a falling off of the eyelashes, fr. madao, to fall off (of hair)]

madder (mad′er)
1. The dried and powdered root of Rubia tinctorum (family Rubiaceae); it contains several glycosides that upon fermentation give the red dyes alizarin and purpurin. When m. (or alizarin) is fed to young animals, the calcium in newly deposited bone salt, hydroxyapatite, is stained red. 2. Any dye obtained from plants of the m. family (Rubiaceae). SYN: turkey red. [A.S. maedere]

Ernest E., English ophthalmologist, 1860–1933. See M. rod.

Otto W., German surgeon, 1846–1926. See M. deformity, M. disease, M. neck.

Max, German surgeon, 1868–1951. See M. operation.

madness (mad′nes)
The state of being mad.

Thorvald J.M., 1870–1957. See Arrhenius-M. theory.

Madurella (mad′u-rel′a)
A genus of fungi including a number of species, such as M. grisea and M. mycetomi, that cause mycetoma. [Madura, India]

maduromycosis (mad′u-ro-mi-ko′sis)
SYN: mycetoma. [Madura, India, + mycosis]

Abbreviation for macrophage-activating factor.

mafenide (ma′fe-nid)
A topical antibacterial agent active against anaerobic pathogens. M. acetate is the preferred salt for ointment; m. hydrochloride is the preferred salt for solution. SYN: 4-homosulfanilamide.

Angelo, Italian physician and anatomic pathologist, 1847–1903. See M. syndrome.

magaldrate (mag′al-drat)
A chemical combination of aluminum hydroxide and magnesium hydroxide, used as an antacid.

François, French physiologist, 1783–1855. See foramen of M., Bell-M. law, M. law, M. spaces, under space, M.-Hertwig sign, M.-Hertwig syndrome.

magenstrasse (mag′en-stras′e)
SYN: gastric canal. [Ger. Magen, stomach, + Strasse, road]

maggot (mag′ot)
A fly larva or grub. cheese m. SYN: Philopia casei. surgical m. a sterilized botfly m. used in an obsolete therapy of wound debridement and removal of necrotic tissues.

Sir Ivan Whiteside, British anesthesiologist, 1888–1975. See M. forceps.

magistral (maj′is-tral)
Denoting a preparation compounded according to a physician's prescription, in contrast to officinal (derived from a pharmacist's stock). [L. magister, master]

magma (mag′ma)
1. A soft mass left after extraction of the active principles. 2. A salve or thick paste. [G. a soft mass or salve, fr. masso, to knead] m. reticulare delicate noncellular strands running between the yolk sac and the outer wall of the blastocyst which is the early chorionic sac.

Valentin J.J., Paris psychiatrist, 1835–1916. See M. trombone movement, M. sign.

magnesia (mag-ne′zhuh)
SYN: magnesium oxide. [see magnesium] calcined m. SYN: magnesium oxide. m. magma SYN: milk of m..

magnesium (Mg) (mag-ne′ze-um)
An alkaline earth element, atomic no. 12, atomic wt. 24.3050, that oxidizes to magnesia; a bioelement, many salts have clinical applications. [Mod. L. fr. G. Magnesia, a region in Thessaly] m. aluminum silicate an antacid. SYN: aluminum m. silicate. m. bacteriopheophytinate bacteriochlorophyll. m. benzoate has been used in gout and rheumatoid arthritis. m. carbonate used in gastric and intestinal acidity and as a laxative. m. chloride has been used as a laxative. m. citrate a laxative; usually administered as an effervescent flavored beverage. effervescent m. citrate m. carbonate, citric acid, sodium bicarbonate, and sugar, moistened with alcohol, passed through a sieve, and dried to a coarse granular powder; used as a laxative. effervescent m. sulfate effervescent Epsom salt; m. sulfate, sodium bicarbonate, tartaric acid, and citric acid, moistened, passed through a sieve, and dried to a coarse granular powder; a purgative. m. hydroxide an antacid and laxative. m. lactate a laxative. m. oxide used as an antacid and laxative. SYN: calcined magnesia, magnesia. m. peroxide decomposes in water to hydrogen peroxide; used as an ingredient in dentifrices and in antiseptic dusting powder. m. phytinates chlorophyll a and b. See entries under chlorophyll. m. salicylate a sodium-free salicylate derivative with anti-inflammatory, analgesic, and antipyretic actions; used for relief of mild to moderate pain. m. stearate a compound of m. with variable proportions of stearic and palmitic acids; used in the preparation of tablets, as a lubricant, and as an ingredient in some baby powders. m. sulfate active ingredient of most natural laxative waters; used as a promptly acting cathartic in certain poisonings, in the treatment of increased intracranial pressure and edema, as an anticonvulsant in eclampsia (when administered intravenously), and as an anti-inflammatory (when applied locally). SYN: Epsom salts. tribasic m. phosphate tertiary m. phosphate, it is used as an antacid but it does not produce systemic alkalization; 1 g is equivalent in neutralizing power to about 0.46 g of sodium bicarbonate. m. trisilicate a compound of m. oxide and silicon dioxide with varying proportions of water; occurs in nature as meerschaum, pararepiolite, and repiolite; a gastric antacid.

1. A body that has the property of attracting particles of iron, cobalt, nickel, or any of various metallic alloys and that when freely suspended tends to assume a definite direction between the magnetic poles of the earth (magnetic polarity). 2. A bar or horseshoe-shaped piece of iron or steel that has been made magnetic by contact with another m. or, as in an electromagnet, by passage of electric current around a metallic (iron) core. 3. An electromagnet built in a cylindrical configuration to accommodate a patient in its core, for magnetic resonance imaging. [G. magnes] superconducting m. a m. whose coils are cooled, usually with liquid helium, to a temperature at which the metal becomes superconducting, effectively removing all electrical resistance.

1. Relating to or characteristic of a magnet. 2. Possessing magnetism.

magnetism (mag′ne-tizm)
The property of mutual attraction or repulsion possessed by magnets. animal m. a psychic force akin to the property of mutual attraction or repulsion possessed by metal magnets and once believed to be the principal factor in hypnosis, which thus was called animal m.. See hypnosis, mesmerism.

magnetocardiography (mag′ne-to-kar-de-og′ra-fe)
Measurement of the magnetic field of the heart, produced by the same ionic currents that generate the electrocardiogram, and showing characteristic P, QRS, T, and U waves.

magnetoencephalogram (MEG) (mag-ne′to-en-sef′a-lo-gram)
A Gauss-time record of the magnetic field of the brain.

magnetoencephalography (mag-ne′to-en-sef-a-log′ra-fe)
The process of recording the brain's magnetic field.

magnetometer (mag-ne-tom′e-ter)
An instrument for detecting and measuring the magnetic field.

magneton (mag′ne-ton)
A unit of measurement of the magnetic moment of a particle ( e.g., atom or subatomic particle). Bohr m. (μB) a constant in the equation relating the difference in energies between parallel and antiparallel spin alignments of electrons in a magnetic field; the net magnetic moment of one unpaired electron; used in electron spin resonance spectrometry for detection and estimation of free radicals; the smallest unit of magnetic moment (approximately 9.274 × 10−24 J T−1). SYN: electron m.. electron m. SYN: Bohr m.. nuclear m. (μN) a constant in the equation relating the difference in energies between parallel and antiparallel spin alignments of atomic nuclei in a magnetic field; used in nuclear magnetic resonance spectrometry; 5.05 × 10−27 J T−1.

magnetotherapy (mag-ne′to-thar′a-pe)
Attempted treatment of disease by application of magnets or induced magnetic fields.

magnification (mag′ni-fi-ka′shun)
1. The seeming increase in size of an object viewed under the microscope; when noted, this increased size is expressed by a figure preceded by ×, indicating the number of times its diameter is enlarged. 2. The increased amplitude of a tracing, as of a muscular contraction, caused by the use of a lever with a long writing arm, i.e., one in which the fulcrum is placed nearer to the muscle than to the writing point. [L. magnifico, pp. -atus, to magnify]

magnitude (mag′ni-tood)
Size or extent. average pulse m. the amplitude of pulse averaged throughout its duration; identical with peak amplitude for a square wave or pulse without droop. peak m. the greatest amplitude.

magnocellular (mag′no-sel′u-lar)
Composed of cells of large size. [L. magnus, large, + cellular]

magnum (mag′num)
SYN: capitate (1) . [L. magnus, large]

Rudolph, German physiologist, 1873–1927. See M. sign.

magnus (mag′nus)
Large; great; denoting a structure of large size. [L.]

Ivan, 20th century cardiologist, 1897–1965. See M. fibers, under fiber.

Ma-huang (mah-hwahng)
Name for Ephedra equisetina. [Chinese]

Abbreviation for Mycobacterium avium-intracellulare. SEE ALSO: Mycobacterium avium-intracellulare complex.

maidenhair tree
SYN: Ginkgo biloba.

maidenhead (ma′den-hed)
Obsolete term for the intact hymen of a virgin.

maidism (ma′dizm)
SYN: pellagra. [Zea mays, maize]

Rudolf, German physician, 1824–1888. See M. sinus.

maim (mam)
To disable or cripple by an injury.


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