Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

MD
abbreviation for Latin Medici´nae Doc´tor (Doctor of Medicine).

Md
mendelevium.

MDA
methylenedioxyamphetamine.

MDMA
3,4-methylenedioxymethamphetamine.

meadow dermatitis
meadow grass dermatitis phytophotodermatitis with eruption of vesicles and bullae in streaks or other configurations, caused by exposure to sunlight after contact with meadow grass.

meal
(mēl) a portion of food or foods taken at some particular and usually stated or fixed time. See also test meal. barium meal gastrointestinal series. opaque meal a meal containing some substance opaque to x-rays, permitting visualization of the gastroin...

mean
(mēn) an average; a number that in some sense represents the central value of a set of numbers.

mean airway pressure
the average pressure generated during the respiratory cycle.

mean arterial blood pressure
the average arterial blood pressure in a given artery over a complete cycle of one heartbeat; in the brachial artery it is calculated to be the diastolic blood pressure plus 1/3 of the difference between the systolic and diastolic pressures.

mean arterial pressure
mean arterial blood pressure.

mean circulatory filling pressure
a measure of the average (arterial and venous) pressure necessary to cause filling of the circulation with blood; it varies with blood volume and is directly proportional to the rate of venous return and thus to cardiac output.

mean corpuscular volume
(MCV) the average volume of erythrocytes, conventionally expressed in cubic micrometers or femtoliters (μm3 = fL) per erythrocyte. It is obtained by multiplying the hematocrit (in L/L) by 1000 and dividing by the erythrocyte count (in millions per μL): MCV = Hct/RBC. Automated electronic blood cell counters ge...

mean electrical axis
the average direction of the activation or repolarization process during the cardiac cycle; it may be determined for any deflection (P, QRS, ST-T) and in the frontal, transverse, or sagittal plane.

Mean sign
Kocher sign.

measles
(me´zәlz) a highly contagious illness caused by a virus; it is usually a childhood disease but can be contracted at any age. The incubation period averages about 11 days; a person can transmit the disease for about a week, from 3 or 4 days before the rash appears until it begins to fade. One attack of measle...

measles virus
a virus of the family Paramyxoviridae that causes measles.

measles virus pneumonia
viral pneumonia caused by the measles virus; it ranges from a mild type occurring during a bout of measles to severe, even fatal, giant cell pneumonia.

measles virus vaccine live
a live attenuated virus vaccine used for immunization against measles, although it is usually administered as the combination measles, mumps, and rubella virus vaccine.

measles-like viruses
Morbillivirus.

measure
(mezh´әr) to determine the amount or extent of something. a specific amount or extent of something. a graduated scale by which the size or shape of something can be determined.

measurement error
the difference between what exists in reality and what is measured by a measurement method.

meat poisoning
acute, often severe gastroenteritis, most often caused by meat contaminated with Bacillus cereus, Clostridium perfringens, invasive Escherichia coli, Salmonella, Staphylococcus aureus, or Yersinia enterocolitica.

meat wrapper's lung
a type of hypersensitivity pneumonitis seen in meat wrappers, caused by inhalation of fumes of phthalic anhydride contained in the label or the polyvinylchloride wrapping.

meatoscopy
(me″ә-tos´kә-pe) visual examination of a meatus, especially the urinary meatus or a ureteral orifice.

meatotomy
(me″ә-tot´ә-me) incision of a meatus, such as an acoustic or urinary meatus, in order to enlarge it.

meatus
(me-a´tәs) pl. meat´uses, mea´tus an opening or passage, especially one leading to the body surface. adj., mea´tal., adj.

meatus acusticus
acoustic meatus.

meatus of nose
nasal meatus.

mebendazole
(mә-ben´dә-zōl) an anthelmintic used in the treatment of trichuriasis, enterobiasis, ascariasis, and hookworm disease.

mecamylamine
(mek″ә-mil´ә-mēn) a ganglionic blocking agent administered orally as the hydrochloride salt as an antihypertensive agent.

mechanical acne
aggravation of existing acne lesions by mechanical factors such as friction, rubbing, stretching, pressure, pinching, or pulling, which may be provoked by such factors as chin straps, articles of clothing, orthopedic casts, backpacks, chairs, or car or bus seats.

mechanical dermatitis
mechanical irritant dermatitis irritant dermatitis caused by a mechanical irritant; the most common type is thorns and glochids from cactus plants.

mechanical fragility
unusual susceptibility of certain erythrocytes to hemolysis under mechanical stress.

mechanical ileus
term formerly used for intestinal obstructions from mechanical causes, such as hernias, adhesions, or volvulus.

mechanical jaundice
obstructive jaundice.

mechanical ventilation
ventilation accomplished by extrinsic means, usually distinguished as either negative pressure or positive pressure ventilation. See also spontaneous ventilation.

mechanics
(mә-kan´iks) the science dealing with the motions of material bodies. body mechanics the application of kinesiology to use of the body in daily life activities and to the prevention and correction of problems related to posture.

mechanoreceptor
(mek″ә-no-re-sep´tәr) a sensory receptor consisting of a nerve ending sensitive to mechanical pressures or distortions, such as those responding to touch and muscle contractions.

mechanotherapy
(mek″ә-no-ther´ә-pe) use of mechanical apparatus in treatment of disease or its results, especially in therapeutic exercises.

mechlorethamine
(mek″lor-eth´ә-mēn) an alkylating agent that produces interstrand and intrastrand cross-linkages in DNA to cause miscoding, breakage, and failure of replication. Used primarily for the treatment of disseminated Hodgkin disease, especially in the MOPP treatment regimen, and for other lymphomas, including...

Meckel cartilage
the ventral cartilage of the first branchial arch.

Meckel diverticulum
an occasional sacculation or appendage of the ileum, derived from an unobliterated yolk stalk.

Meckel space
a recess in the dura mater that lodges the trigeminal ganglion.

Meckel syndrome
(mek´el) Meckel-Gruber syndrome.

Meckel-Gruber syndrome
(mek´el groo´ber) a hereditary autosomal recessive syndrome in which infants are usually born with a sloping forehead, posterior meningoencephalocele, polydactyly (extra fingers or toes), and polycystic kidneys; most die soon after birth. Called also Gruber syndrome.

Meclan
(mek´lan) trademark for a preparation of meclocycline sulfosalicylate, a topical antibacterial.

meclizine
(mek´lĭ-zēn) an antihistamine used orally as the hydrochloride salt to counteract the nausea of motion sickness and to treat and prevent vertigo associated with diseases affecting the vestibular system.

meclocycline
(mĕ″klo-si´klēn) a tetracyclineantibiotic used topically as meclocycline sulfosalicylate for treatment of acne vulgaris.

meclofenamate
(mek″lo-fen´ә-māt) a nonsteroidal antiinflammatory drug used as the sodium salt in the treatment of rheumatic and nonrheumatic inflammatory disorders, pain, dysmenorrhea, hypermenorrhea, and vascular headaches; administered orally or rectally.

meconium
(mә-ko´ne-әm) dark green mucilaginous material in the intestine of the full-term fetus; this is the first type of feces passed by the newborn infant.

meconium aspiration syndrome
the respiratory complications resulting from the passage and aspiration of meconium prior to or during delivery. Postterm infants and those who had hypoxia or acidosis in utero are at higher risk.

meconium ileus
ileus in the newborn due to intestinal obstruction by thick meconium, often linked to cystic fibrosis.

meconium peritonitis
peritonitis resulting from perforation of the intestine into the peritoneal cavity while a fetus is in the womb or shortly after a baby is born; this results in escape of meconium into the peritoneal cavity, and occurs most often as a complication of meconium ileus in cystic fibrosis.

meconium plug syndrome
intestinal obstruction in an infant due to unusually thick or hard meconium in which neither enzymatic nor ganglion cell deficiency can be demonstrated, most often sen in premature infants.

meconium-stained fluid
amniotic fluid that is stained green, a symptom of fetal hypoxia; caused by relaxation of the fetus' anal sphincter and escape of meconium.

MED
minimal effective dose; minimal erythema dose.

Medex
(med´eks) a physician assistant program for former military medical corpsmen; also, a graduate of such a program.

media
(me´de-ә) plural of medium. middle. tunica media.

medial
(me´de-әl) pertaining to or situated toward the midline.

medial anterior malleolar artery
origin, anterior tibial artery; branches, none; distribution, ankle joint.

medial calcific sclerosis
Mönckeberg arteriosclerosis.

medial circumflex femoral artery
origin, deep femoral artery; branches, deep, superficial, ascending, transverse, and acetabular branches; distribution, hip joint, thigh muscles.

medial circumflex femoral veins
veins following the course of the medial circumflex femoral artery, emptying into the femoral or the deep femoral vein.

medial cutaneous nerve of arm
origin, medial cord of brachial plexus (T1); distribution, skin on medial and posterior sides of arm; modality, general sensory.

medial cutaneous nerve of forearm
origin, medial cord of brachial plexus (C8, T1); branches, anterior and posterior branches; distribution, skin of front, medial, and posteromedial aspects of forearm; modality, general sensory.

medial cutaneous nerve of thigh
a branch of the anterior cutaneous branch of the femoral nerve; it supplies the skin on the medial side of the thigh and knee and has a branch that forms part of the patellar plexus.

medial frontobasal artery
: origin, anterior cerebral artery; branches, none; distribution, cortex of medioinferior frontal lobe.

medial geniculate body
either of the two metathalamus eminences, one on each side just lateral to the superior colliculi, concerned with hearing.

medial inferior genicular artery
origin, popliteal artery; branches, none; distribution, knee joint.

medial ligament
a large fan-shaped ligament on the medial side of the ankle.

medial marginal vein
a vein running along the medial side of the top of the foot, returning blood from the dorsal venous arch, the dorsal venous network, and superficial veins of the sole and draining into the great saphenous vein.

medial nasal process
medial nasal prominence the more central of the two limbs of a horseshoe-shaped elevation in the future nasal region of the embryo; it joins with the maxillary prominence on the same side in the formation of half of the upper jaw.

medial occipital artery
origin, fourth segment of posterior cerebral artery; branches, parietal, parietooccipital, calcarine, and occipitotemporal branches, and branch to dorsal corpus callosum; distribution, back of corpus callosum, precuneus, cuneus, lingual gyrus, and posterior part of lateral surface of occipital lobe.

medial occipitotemporal gyrus
the medial portion of the fusiform gyrus.

medial palpebral arteries
origin,ophthalmic artery; branches,posterior conjunctival arteries and superior and inferior palpebral arches; distribution, eyelids. There are two (superior and inferior).

medial pectoral nerve
origin, medial cord or lower trunk of brachial plexus (C8, T1); distribution, usually several nerves supplying the pectoralis major and pectoralis minor muscles; modality, motor.

medial plantar artery
origin, posterior tibial artery; branches, deep and superficial branches; distribution, sole of the foot and toes.

medial plantar nerve
origin, the larger of the terminal branches of the tibial nerve; branches, common plantar digital nerves and muscular branches; distribution, abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and first lumbrical muscles, and small cutaneous and articular branches to the medial side of the sole, and to the firs...

medial popliteal nerve
tibial nerve.

medial pterygoid muscle
origin, medial surface of lateral pterygoid plate, tuberosity of maxilla; insertion, medial surface of ramus and angle of mandible; innervation, mandibular nerve; action, closes jaws.

medial pterygoid nerve
nerve to medial pterygoid.

medial rectus muscle of eyeball
origin, common tendinous ring; insertion, medial side of sclera; innervation, oculomotor nerve; action, rolls eyeball inward, or toward the nose.

medial superior genicular artery
origin, popliteal artery; branches, none; distribution, knee joint, femur, patella, contiguous muscles.

medial supraclavicular nerves
origin, cervical plexus (C3–C4); distribution, descend in posterior triangle, cross the clavicle, and supply the skin of medial infraclavicular region; modality, general sensory.

medial sural cutaneous nerve
origin, tibial nerve; usually joins sural communicating branch of common peroneal nerve to form the sural nerve; distribution, may continue as the sural nerve; modality, general sensory.

medial tarsal arteries
origin, dorsalis pedis artery; branches, none; distribution, side of foot.

medial vein of lateral ventricle
a vein passing through the medial wall of the lateral ventricle to drain the parietal and occipital lobes into the internal cerebral or great cerebral vein.

medial zone of hypothalamus
a longitudinal division of the hypothalamus, containing part of the preoptic nuclei as well as the anterior, dorsomedial, and ventromedial hypothalamic nuclei.

medialis
(me″de-a´lis) Latin word meaning medial; a term used in anatomy.

median
(me´de-әn) situated in the median plane or in the midline of a body or structure. any value that divides the probability distribution of a random variable in half; that is, the probability of observing a value above the median and the probability of observing a value below the median are both less th...

median antebrachial vein
a vein that arises from a palmar venous plexus and passes up the forearm between the cephalic and the basilic veins to the elbow, where it either joins one of these, divides in two to join both, or joins the median cubital vein.

median anterior maxillary cyst
one in or near the incisive canal, arising from proliferation of epithelial remnants of the nasopalatine duct.

median artery
origin, anterior interosseous artery; branches, none; distribution, median nerve, muscles of front of forearm.

median basilic vein
a vein sometimes present as the medial branch, ending in the basilic vein, of a bifurcation (division into two branches) of the median antebrachial vein.

median callosal artery
origin, anterior communicating artery; distribution, runs above the terminal lamina of hypothalamus to supply anterior hypothalamic and subcallosal areas and corpus callosum.

median cephalic vein
a vein sometimes present as the lateral branch, ending in the cephalic vein, of a bifurcation (division into two branches) of the median antebrachial vein.

median cleft facial syndrome
a hereditary form of defective midline development of the head and face, including ocular hypertelorism, occult cleft nose and maxilla, and sometimes mental retardation or other defects. Called also frontonasal dysplasia.

median commissural artery
origin, anterior communicating artery; branches, none; distribution, supraoptic commissures and optic chiasm.

median cubital vein
the large connecting branch that arises from the cephalic vein below the elbow and passes obliquely upward over the cubital fossa to join the basilic vein.

median curative dose
(CD50) one that abolishes symptoms in half of test subjects.