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

trigeminal nerve
the fifth cranial nerve, which arises in the pons and is composed of both sensory and motor fibers. It has three divisions: the ophthalmic division carries sensory impulses from the skin of the upper eyelid, side of the nose, forehead, and front part of the scalp. The maxillary division carries sensory impulses from the mucous ...

trigeminal paralysis
paralysis due to a lesion of the trigeminal nerve, marked by sensory loss in the face and weakness of the muscles of mastication.

trigeminal pulse
one with a pause after every third beat.

trigeminus reflex
oculopupillary reflex.

trigeminy
(tri-jem´ĭ-ne) the condition of occurring in threes, especially the occurrence of three pulse beats in rapid succession.

trigger
(trig´er) an event that stimulates initiation of a subsequent event or process. flow trigger a trigger for initiating assisted ventilation, consisting of a mechanism for measuring the patient's inspiratory effort and starting assisted ventilation when flow reaches a given level. ...

trigger point
a spot on the body at which pressure or other stimulus gives rise to specific sensations or symptoms.

trigger zone
an area to which stimulation may cause physiological or pathological changes. See also dolorogenic zone and trigger point.

triggered
(trig´әrd) having an output that is set in motion by a smaller input.

triggered activity
activity in which nondriven action potentials arise from afterpotentials that were caused by the previous action potential.

triggered mode
a pacing mode in which the stimulus is emitted in response to a sensed event.

triglyceride
(tri-glis´әr-īd) a compound consisting of three molecules of fatty acids bound with one molecule of glycerol; it is a neutral fat that is the usual storage form of lipids in animals. Elevated serum triglycerides are now considered as important as high cholesterol levels in the development of ischemic heart di...

trigonal muscles
a submucous sheet of smooth muscle at the bladder trigone, continuous with ureteral muscles above and with those of the proximal urethra below; divided into morphologically distinct superficial and deep layers.

trigone
(tri´gōn) triangle. the first three cusps of an upper molar tooth. adj., trigo´nal., adj. trigone of bladder a triangular region of the wall of the urinary bladder, an area in which the muscle fibers are closely adherent to the mucosa; its three angles correspo...

trigonitis
(trig″o-ni´tis) inflammation or localized hyperemia of the vesical trigone.

trigonocephalus
(trig″o-no-sef´ә-lәs) an individual exhibiting trigonocephaly.

trigonocephaly
(trig″o-no-sef´ә-le) triangular shape of the head due to sharp forward angulation at the midline of the frontal bone. adj., trigonocephal´ic., adj.

trigonum
(tri-go´nәm) triangle.

trihexyphenidyl
(tri-hek″se-fen´ĭ-dil) an antidyskinetic used as the hydrochloride salt in the treatment of parkinsonism and for the control of drug-induced extrapyramidal reactions (except tardive dyskinesia); administered orally.

triiodothyronine
(tri-i″o-do-thi´ro-nēn) a thyroid hormone that contains iodine and is liberated from thyroglobulin by hydrolysis. It has several times the biologic activity of thyroxine. free triiodothyronine the fraction of triiodothyronine in the serum that is not bound to a binding protein.

triiodothyronine resin uptake test
a thyroid function test, measuring how many sites on thyroxine-binding globulin (TBG) are occupied by endogenous triiodothyronine (T3) and how many sites remain available. An excess of radioactive exogenous triiodothyronine is added to the sample, followed by the addition of a resin that also binds T3. A portion of the radioact...

trikates
(tri´kāts) a solution of potassium acetate, potassium bicarbonate, and potassium citrate used as a potassium supplement in the treatment and prevention of hypokalemia, administered orally.

triketohydrindene hydrate test
(for free carboxyl or alpha-amino groups) to a solution of aminoacetic acid and water, a solution of sodium acid is added, followed by a solution of triketohydrindene hydrate. The suspected matter is then added and the mixture is boiled. A violet color indicates a free carboxyl and alpha-amino group from a protein, pepton...

trilabe
(tri´lāb) a three-pronged lithotrite.

Trilafon
(tri´lә-fon) trademark for preparations of perphenazine, an antiemetic and antipsychotic agent.

trilaminar
(tri-lam´ĭ-nәr) three-layered.

trilobate
(tri-lo´bāt) having three lobes.

trilocular
(tri-lok´u-lәr) having three loculi or cells.

trilogy
(tril´ә-je) a group or series of three. trilogy of Fallot a term sometimes applied to concurrent pulmonic stenosis, atrial septal defect, and right ventricular hypertrophy.

trimalleolar fracture
fracture of the medial and lateral malleoli and the posterior tip of the tibia.

trimensual
(tri-men´su-әl) occurring every three months.

trimeprazine
(tri-mep´rә-zēn) a phenothiazine derivative with powerful antihistaminic action; used as the tartrate salt to relieve itching.

trimester
(tri-mes´tәr) a period of 3 months.

trimethadione
(tri″meth-ә-di´ōn) an anticonvulsant with analgesic properties, administered orally for treatment of petit mal epilepsy.

trimethaphan
(tri-meth´ә-fan) a short-acting ganglionic blocking agent, used as trimethaphan camsylate as an antihypertensive to produce controlled hypotension during surgery and for the emergency treatment of hypertensive crises and pulmonary edema due to hypertension; administered intravenously.

trimethobenzamide
(tri-meth″o-ben´zah-mīd) an antiemetic administered orally, intramuscularly, or rectally as the hydrochloride salt.

trimethoprim
(tri-meth´o-prim) an oral antibacterial closely related to pyrimethamine; it is almost always administered in combination with a sulfonamide because the two potentiate each other. Used primarily for treatment of urinary tract infections and pneumocystis pneumonia. The sulfate salt is applied topically to the conjunctiva, in c...

trimetrexate
(tri″mә-trek´sāt) a folic acid antagonist structurally related to methotrexate, used as the glucuronate salt, in combination with leucovorin, to treat pneumocystis pneumonia in acquired immunodeficiency syndrome, administered intravenously.

trimipramine
(tri-mip´rә-mēn) a tricyclic antidepressant of the dibenzazepine group, administered orally as the maleate salt for treatment of depression, peptic ulcers, and certain types of severe chronic pain.

trimorphous
(tri-mor´fәs) existing in three different forms.

trinitrophenol
(tri″ni-tro-fe´nol) a substance used as dye, tissue fixative, antiseptic, astringent, and stimulant of epithelialization; its toxic effects are similar to those of dinitrophenol. It can be detonated on percussion or by heating above 300° C. Called also picric acid.

trinitrotoluene
(tri″ni-tro-tol´u-ēn) TNT: a high explosive derived from toluene; it sometimes causes poisoning in those who work with it, marked by dermatitis, gastritis, abdominal pain, vomiting, constipation, and flatulence.

trinitrotoluene poisoning
a form of poisoning in munition workers that work with trinitrotoluene, characterized by dermatitis, gastritis with abdominal pain, vomiting, constipation, flatulence, and blood changes. Called also TNT poisoning.

trinucleotide repeat
triplet repeat.

triocephalus
(tri″o-sef´ә-lәs) a malformed fetus with no organs of sight, hearing, or smell, the head being a nearly shapeless mass.

triol
(tri´ol) an organic compound containing three hydroxy groups; a trihydric alcohol, such as glycerol.

triolein breath test
a breath test for pancreatic function; the fasting patient is administered triolein labeled with either carbon 13 or carbon 14 and levels of labeled carbon dioxide in the exhaled breath are subsequently measured at regular time intervals; low levels of carbon dioxide indicate inadequate levels of the enzyme pancreatic lip...

triorchidism
(tri-or´ki-diz-әm) the presence of three testes.

triose
(tri´ōs) a monosaccharide containing three carbon atoms in a molecule.

trioxsalen
(tri-ok´sә-lәn) a psoralen used in conjunction with ultraviolet radiation exposure in treatment of vitiligo and psoriasis.

tripara
(trip´ә-rә) tertipara.

triparanol syndrome
alopecia, poliosis, ichthyosis, irreversible cataracts, and impotence, due to the use of triparanol, a drug formerly used to depress the synthesis of cholesterol.

tripelennamine
(tri″pә-len´ә-min) an antihistamine used orally as the citrate and hydrochloride salts in the symptomatic treatment of various allergic disorders.

tripeptide
(tri-pep´tid) a peptide formed from three amino acids.

triphalangism
(tri-fal´әn-jiz-әm) three phalanges in a digit normally having only two.

triphasic
(tri-fa´zik) having three phases.

triphenylmethane
(tri-fen″әl-meth´ān) a substance from coal tar, the basis of various dyes and stains, including rosaniline, basic fuchsin, and gentian violet.

Tripier amputation
amputation of the foot through the calcaneus.

triplane fracture
fracture of the distal lateral tibia occurring in three planes: sagittally through the epiphysis, horizontally through the physis, and coronally through the metaphysis.

triple blind
(trip´әl blīnd) pertaining to a clinical trial or other experiment in which neither the subject, the person administering treatment, nor the person evaluating the response to treatment knows which subjects are receiving a particular treatment or lack of treatment; see also placebo.

triple bond
a covalent bond in which two atoms share three pairs of electrons.

triple point
the temperature and pressure at which the solid, liquid, and gas phases of a substance are in equilibrium.

triple response
a physiologic reaction of the skin to stroking with a blunt instrument: first a red line develops at the site of stroking, owing to the release of histamine or a histamine-like substance, then a flare develops around the red line, and lastly a wheal is formed as a result of local edema.

triple test
(for evaluation of breast masses) the use of physical examination, mammography, and fine needle aspiration to evaluate palpable breast masses. Results of each method are given point values of 1 (benign), 2 (suspicious), or 3 (malignant) and the points are totaled; a total score of 4 or less indicates a probably benign les...

triple-A syndrome
[alacrima-achalasia-addisonian] Allgrove syndrome.

triplegia
(tri-ple´jә) paralysis of three extremities.

triplet
(trip´lәt) one of three offspring produced at one birth. a combination of three objects or entities acting together, as three lenses. codon.

triplet code
the form taken by the genetic code, in which each amino acid or start or stop signal is encoded by a group of three nucleotides (codon).

triplet repeat
an unstable DNA sequence of three nucleotides, occurring in some human genes and normally repeated in tandem 5 to 50 times; expansion above that number has been linked to certain genetic disorders. The triplet sequences always begin with C and end with G (see genetic code. See also triplet repeat disorders.

triplet repeat disorders
disorders caused by unstable, dynamic mutations that result in expansion of triplet repeats within the affected gene, leading to abnormalities in gene expression and function. The group includes Huntington disease, myotonic dystrophy, Friedreich ataxia, and fragile X syndrome.

triplex
(tri´pleks) (trip´leks) triple or threefold.

triploid
(trip´loid) having triple the haploid number of chromosomes (3n).

triplokoria
(trip″lo-kor´e-ә) the presence of three pupils in an eye.

triplopia
(trip-lo´pe-ә) defective vision, objects being seen as threefold; usually a hysterical symptom.

tripod position
a position assumed by the patient with abdominal weakness or meningeal irritation while sitting in bed, supporting the body with the hands in a plane posterior to the pelvis. a sitting position assumed by the patient with respiratory insufficiency, with the hands anterior to the frontal plane. See also tripo...

tripoding
(tri´pod-ing) the use of three points of support, as adopted by paralyzed patients when changing from a sitting or standing position.

triprolidine
(tri-pro´lĭ-dēn) an antihistamine with sedative and anticholinergic effects; used as the hydrochloride salt in the treatment of nasal, eye, and skin manifestations of allergic reactions, including allergic rhinitis, conjunctivitis, and itching, and also as an ingredient in some cough and cold preparations, adm...

triptorelin
(trip″to-rel´in) a synthetic analogue of gonadorelin that on prolonged administration suppresses gonadotropin release; used as triptorelin pamoate as an antineoplastic in the palliative treatment of prostatic carcinoma, administered intramuscularly.

tripus
(tri´pәs) a conjoined twin fetus having three feet.

triquetral bone
the carpal bone lying between the lunate and pisiform bones in the row of carpal bones that is closer to the wrist and farther from the fingers.

trisaccharide
(tri-sak´ә-rīd) a sugar in which each molecule yields three molecules of monosaccharides on hydrolysis.

trisalicylate
(tri″sal-ĭ-sil´āt) (tri″sә-lis´ә-lāt) a compound containing three salicylate ions. choline magnesium trisalicylate a combination of choline and magnesium salicylates, used as an analgesic, antipyretic, antiinflammatory, and antirheum...

trismus
(triz´mәs) motor disturbance of the trigeminal nerve, especially spasm of the masticatory muscles, with difficulty in opening the mouth (lockjaw); a characteristic early symptom of tetanus.

trisomy
(tri´so-me) the presence of an additional (third) chromosome of one type in an otherwise diploid cell (2n + 1). adj., triso´mic., adj.

trisomy 11q syndrome
a rare syndrome resulting from the presence of an extra long arm of chromosome 11; because different segments may be involved, the associated anomalies are highly variable and include preauricular fistulas, hypoplasia of the gallbladder, micropenis, bicornuate uterus, microphthalmos, malformations of the heart, lung, and ...

trisomy 13 syndrome
holoprosencephaly due to an extra chromosome 13, in which central nervous system defects are associated with mental retardation, cleft lip and palate, polydactyly (extra fingers or toes), and dermal pattern anomalies, as well as abnormalities of the heart, abdominal organs, and genital organs. Called also Patau syndrome.

trisomy 18 syndrome
a condition due to the presence of an extra chromosome 18, characterized by neonatal hepatitis, mental retardation, scaphocephaly or other skull abnormalities, small receding mandible, drooping of the eyelids, low-set ears, corneal opacities, deafness, webbed neck, short digits, ventricular septal defects, Meckel diverticulum, and ot...

trisomy 21 syndrome
Down syndrome.

trisomy 22 syndrome
a rare syndrome due to an extra chromosome 22, characterized typically by mental and growth retardation, microcephaly, low-set or malformed ears, micrognathia, long philtrum, preauricular skin tag or sinus, and congenital heart disease. In males, there is often a small penis or undescended testes.

trisomy 8 syndrome
a syndrome associated with an extra chromosome 8, usually mosaic (trisomy 8/normal), characterized by mild to severe mental retardation, prominent forehead, deep-set eyes, thick lips, prominent ears, and camptodactyly (abnormally flexed fingers).

trisomy C syndrome
trisomy 8 syndrome.

trisomy D syndrome
trisomy 13 syndrome.

trisomy E syndrome
trisomy 18 syndrome.

trisplanchnic
(tri-splangk´nik) pertaining to the three great visceral cavities, the skull, thorax, and abdomen.

tristichia
(tri-stik´e-ә) the presence of three rows of eyelashes.

trisulcate
(tri-sul´kāt) having three furrows.

trisulfide
(tri-sul´fīd) a sulfur compound containing three atoms of sulfur.

tritanomaly
(tri″tә-nom´ә-le) a rare type of anomalous trichromatic vision in which the third, blue-sensitive, cones have decreased sensitivity.

tritanope
(tri´tә-nōp″) a person exhibiting tritanopia.

tritanopia
(tri″tә-no´pe-ә) color vision deficiency in which the blue-sensitive pigment of the retinal cones is absent. adj., tritanop´ic., adj.