Copy of `Dorland's Medical Dictionary`

The wordlist doesn't exist anymore, or, the website doesn't exist anymore. On this page you can find a copy of the original information. The information may have been taken offline because it is outdated.

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

open drainage
drainage of a cavity through an opening in the chest wall into which one or more drainage tubes are inserted, the opening not being sealed against the entrance of outside air.

open fracture
one in which a wound through the adjacent or overlying soft tissue communicates with the outside of the body; this must be considered a surgical emergency. The skin penetration may come from within (by a bone protruding through the skin) or from without (such as by a bullet wound that communicates with the bone). Called a...

open heart surgery
surgery that involves incision into one or more chambers of the heart, such as for repair or palliation of congenital heart defects, repair or replacement of defective heart valves, or coronary artery bypass.

open loop
a system in which an input alters the output, but the output has no effect on the input.

open loop reflex
a reflex, such as a flexion reflex, in which the stimulus causes activity that it does not further control and that does not give it feedback.

open operation
an operation in which the tissues and organs are exposed to view through a surgical incision.

open tuberculosis
a type in which lesions discharge tubercle bacilli from the body. tuberculosis of the lungs with cavitation.

open wound
one that communicates directly with the atmosphere.

open-angle glaucoma
a type of glaucoma seen in adults, with the angle of the anterior chamber remaining open but filtration becoming more and more impaired by tissues in the area. Called also simple. See illustration at angle-closure glaucoma.

opening
(o´pәn-ing) a gap or open space; anatomic nomenclature for various types of openings includes aditus, aperture, foramen, fossa, hiatus, inlet, meatus, orifice, ostium, and outlet. aortic opening the aperture in the diaphragm for passage of the descending aorta. aort...

operable
(op´әr-ә-bәl) subject to being operated upon with a reasonable degree of safety; appropriate for surgical intervention with a reasonable expectation of cure or relief.

operant
(op´әr-әnt) in psychology, said of a response not elicited by specific external stimuli but that recurs at a given rate under particular circumstances. See operant conditioning.

operant conditioning
learning in which a particular response is elicited by a stimulus because that response produces desirable consequences (reward). It differs from classical conditioning in that the reinforcement takes place only after the subject performs a specific act that has been previously designated. The principles and techniques re...

operate
(op´әr-āt) to perform an operation. the subject of an experiment who has undergone a specific surgical procedure.

operating field
operative field an isolated area where surgery is performed; it must be kept sterile by aseptic techniques (see surgical asepsis). Called also surgical field.

operating microscope
one designed for use in performance of delicate surgical procedures, such as on the middle ear or small vessels of the heart. Called also surgical m.

operating room
one especially equipped for the performance of surgical operations.

operating room nurse
perioperative nurse.

operation
(op″әr-a´shәn) any action performed with instruments or by the hands of a surgeon; see also method, procedure, surgery, and technique. For specific operations, see the specific name, such as Blalock-Taussig operation.

operative
(op´әr-ә-tiv) pertaining to an operation. effective; not inert.

operator
(op´әr-a-tәr) a DNA sequence preceding the coding sequence of a structural gene in an operon, to which a regulator protein binds to control transcription of the structural genes in that operon.

operculum
(o-pur´ku-lәm) Latin word meaning lid or covering. the folds of pallium from the frontal, parietal, and temporal lobes of the cerebrum overlying the insula. adj., oper´cular., adj. dental operculum the hood of gingival tissue overlying the crown of an erupting...

operon
(op´әr-on) in prokaryotes, a chromosomal segment constituting a functional unit of transcription and so of genetic regulation. It is made up of one or more structural genes, their promoter, and an operator region that through interaction with a regulator protein controls the structural genes.

ophiasis
(o-fi´ә-sis) a form of alopecia areata involving the temporal and occipital margins of the scalp in a continuous band.

ophidism
(o´fĭ-diz-әm) poisoning by snake venom.

ophryon
(of´re-on) the middle point of the transverse supraorbital line.

ophryosis
(of″re-o´sis) spasm of the eyebrow.

ophthalmagra
(of″thәl-mag´rә) sudden pain in the eye.

ophthalmalgia
(of″thәl-mal´jә) pain in the eye; called also ophthalmodynia.

ophthalmectomy
(of″thәl-mek´tә-me) excision of an eye; enucleation of the eyeball.

ophthalmencephalon
(of″thәl-mәn-sef´ә-lon) the retina, optic nerve, and visual apparatus of the brain.

ophthalmia
(of-thal´me-ә) severe inflammation of the eye or of the conjunctiva or deeper structures of the eye.

ophthalmia neonatorum
(of-thal´me-ә ne″o-na-tor´әm) any hyperacute purulent conjunctivitis, such as gonorrheal conjunctivitis, occurring during the first 10 days of life, usually contracted during birth from infected vaginal discharge of the mother. The term formerly referred only to gonorrheal conjunctivitis, but now other...

ophthalmic
(of-thal´mik) ocular (def. 1).

ophthalmic artery
origin, internal carotid artery; branches, lacrimal and supraorbital arteries, central artery of retina, ciliary, muscular, posterior and anterior ethmoidal, palpebral, supratrochlear, and dorsal nasal arteries, and recurrent meningeal branch; distribution, eye, orbit, adjacent facial structures.

ophthalmic nerve
one of the three terminal divisions of the trigeminal nerve; origin, trigeminal ganglion; branches, recurrent meningeal (tentorial) branch, frontal, lacrimal, and nasociliary nerves; distribution, eyeball and conjunctiva, lacrimal gland and sac, nasal mucosa and frontal sinus, external nose, upper eyelid, forehead, and scalp; m...

ophthalmic solution
a sterile solution, free from foreign particles, for instillation into the eye.

ophthalmitis
(of″thәl-mi´tis) inflammation of the eyeball. adj., ophthalmit´ic., adj.

ophthalmoblennorrhea
(of-thal″mo-blen″o-re´ә) gonorrheal conjunctivitis.

ophthalmocele
(of-thal´mo-sēl) exophthalmos.

ophthalmodonesis
(of-thal″mo-dә-ne´sis) trembling motion of the eyes.

ophthalmodynamometry
(of-thal″mo-di″nә-mom´ә-tre) determination of the blood pressure in the retinal artery.

ophthalmodynia
(of-thal″mo-din´e-ә) ophthalmalgia.

ophthalmoeikonometer
(of-thal″mo-i″kә-nom´ә-tәr) an instrument used to determine both the refraction of the eye and the relative size and shape of the ocular images.

ophthalmography
(of″thәl-mog´rә-fe) description of the eye and its diseases.

ophthalmogyric
(of-thal″mo-ji´rik) oculogyric.

ophthalmolith
(of-thal´mo-lith) dacryolith.

ophthalmologist
(of″thәl-mol´ә-jist) a physician who specializes in ophthalmology, including diagnosing and prescribing treatment for defects, injuries, and diseases of the eye, and is skilled at delicate eye surgery, such as that required to remove cataracts. Called also oculist.

ophthalmology
(of″thәl-mol´ә-je) the branch of health science dealing with the eye, including its anatomy, physiology, pathology, and other aspects. adj., ophthalmolog´ic., adj.

ophthalmomalacia
(of-thal″mo-mә-la´shә) abnormal softness of the eyeball.

ophthalmomandibulomelic dysplasia
an autosomal dominant syndrome consisting of blindness caused by corneal opacities, temporomandibular fusion, absent coronoid process, obtuse mandibular angle, radiohumeral and radioulnar dislocations, and aplasia of the lateral condyle of the humerus, radial head, and distal ulna. Called also OMM syndrome.

ophthalmometer
(of″thәl-mom´ә-tәr) an instrument used in ophthalmometry.

ophthalmometry
(of″thәl-mom´ә-tre) determination of the refractive powers and defects of the eye.

ophthalmomyotomy
(of-thal″mo-mi-ot´ә-me) surgical division of the muscles of the eyes.

ophthalmoneuritis
(of-thal″mo-ndbobr-ri´tis) inflammation of the optic nerve.

ophthalmopathy
(of″thәl-mop´ә-the) any disease of the eye. infiltrative ophthalmopathy ocular changes, most often seen in thyroid disorders, caused by increased water content of the orbital contents, including discomfort, lacrimation, edema, chemosis, and conjunctival infectio...

ophthalmoplasty
(of-thal´mo-plas″te) plastic surgery of the eye or its appendages.

ophthalmoplegia
(of-thal″mo-ple´jә) paralysis of the eye muscles. adj., ophthalmople´gic., adj.

ophthalmoplegia externa
(of-thal″mo-ple´jә ek-stur´nә) paralysis of the extraocular muscles.

ophthalmoplegia interna
(of-thal″mo-ple´jә in-tur´nә) paralysis of the iris and ciliary apparatus.

ophthalmoptosis
(of-thal″mop-to´sis) (of-thal″mo-to´sis) exophthalmos.

ophthalmorrhagia
(of-thal″mo-ra´jә) hemorrhage from the eye.

ophthalmorrhea
(of-thal″mo-re´ә) oozing of blood from the eye.

ophthalmorrhexis
(of-thal″mo-rek´sis) rupture of an eyeball.

ophthalmoscope
(of-thal´mә-skōp) an instrument for examining the interior of the eye. direct ophthalmoscope one that produces an upright image of approximately 15× magnification. This type is used to inspect the fundus of the eye (inner surface of the back of the eyeball). The examiner looks ...

ophthalmoscopy
(of″thәl-mos´kә-pe) examination of the eye by means of the ophthalmoscope. medical ophthalmoscopy that performed for diagnostic purposes. metric ophthalmoscopy that performed for measurement of refraction.

ophthalmostasis
(of″thәl-mos´tә-sis) fixation of the eye with the ophthalmostat.

ophthalmostat
(of-thal´mo-stat″) an instrument for holding the eye steady during operation.

ophthalmosteresis
(of-thal″mo-stә-re´sis) loss of an eye.

ophthalmosynchysis
(of-thal″mo-sin´kĭ-sis) effusion into the eye.

ophthalmotomy
(of″thәl-mot´ә-me) incision of the eye.

ophthalmotrope
(of-thal´mo-trōp) a mechanical eye that moves like a real eye.

ophthalmoxerosis
(of-thal″mo-ze-ro´sis) xerophthalmia.

opiate
(o´pe-әt) any narcotic sedative containing opium or any of its derivatives; the most common ones are codeine, heroin, methadone, and morphine. hypnotic (def. 2). endogenous opiates endorphins and enkephalins that are released by the body as a defense against pain or du...

opiate receptors
opioid receptors receptors that combine with particular opiates to create analgesia and certain other effects. Several different ones have been identified and assigned Greek letters; the μ receptor gives superior analgesia, and the κ receptor is associated with a low degree of physical dependency.

opioid
(o´pe-oid) any synthetic narcotic that has opiatelike activities but is not derived from opium. denoting naturally occurring peptides, such as enkephalins, that exert opiate-like effects by interacting with opiate receptors of cell membranes. See also opioid analgesic.

opisthorchiasis
(o″pis-thor-ki´ә-sis) infection of the biliary tract by a liver fluke, either Opisthorchis felineus or O. viverrini.

Opisthorchis
(o″pis-thor´kis) a genus of liver flukes that are parasitic in various birds and mammals, including humans; see opisthorchiasis. O. feli´neus is found from the Philippines, Japan, and Vietnam across Asia to Eastern Europe. O. viverri´ni is found in Southeast Asia.

opisthotonos
(o″pis-thot´ә-nәs) a form of spasm in which the head and heels are bent backward and the body bowed forward. adj., opisthoton´ic., adj.

Opitz disease
(o´pits) enlargement of the spleen due to thrombosis of the splenic vein; called also thrombophlebitic splenomegaly.

Opitz syndrome
(o´pits) Opitz-Frias syndrome (o´pits fre´ahs) an autosomal dominant syndrome consisting of hypertelorism and hernias, and in males hypospadias, cryptorchidism, and bifid scrotum. Cardiac anomalies, laryngotracheal malformations, imperforate anus, renal defects, lung hypoplasia, and downslanted pal...

opium
(o´pe-әm) the air-dried milky exudation from unripe capsules of Papaver somniferum and P.album (the opium poppies). It contains some 25 alkaloids, the most important being codeine, morphine (from which heroin is derived), noscapine, papaverine, and thebaine, all of which can be used for their narcotic and analgesic effe...

opocephalus
(o″po-sef´ә-lәs) a malformed fetus with ears fused to the head, one orbit, no mouth, and no nose.

opodidymus
(o″po-did´ĭ-mәs) conjoined twins with one body, two fused heads, and sense organs partly fused.

Oppenheim gait
a gait marked by irregular oscillation of the head, limbs, and body; seen in some cases of multiple sclerosis.

Oppenheim reflex
dorsiflexion of the big toe on stroking downward along the medial side of the tibia, seen in pyramidal tract disease.

Oppenheim sign
(op´en-hīm) dorsiflexion of the big toe on stroking the medial aspect of the tibia in a downward motion; seen in pyramidal tract disease.

opponens digiti minimi muscle
origin, hook of hamate bone, flexor retinaculum of hand; insertion, ulnar margin of fifth metacarpal; innervation, eighth cervical nerve through ulnar nerve; action, rotates, abducts, and flexes fifth metacarpal.

opponens pollicis muscle
origin, tubercle of trapezium, flexor retinaculum of hand; insertion, radial side of first metacarpal; innervation, sixth and seventh cervical nerves through median nerve; action, flexes and opposes thumb.

opportunistic
(op″әr-too-nis´tik) denoting a microorganism that does not ordinarily cause disease but becomes pathogenic under certain circumstances, such as in immunodeficiency conditions. denoting a disease or infection caused by such an organism.

opportunistic infection
infection by an organism that does not ordinarily cause disease but becomes pathogenic under certain circumstances, such as when the patient is immunocompromised.

oppositional defiant disorder
a type of disruptive behavior disorder characterized by a recurrent pattern of defiant, hostile, disobedient, and negativistic behavior directed toward those in authority.

oprelvekin
(o-prel´vә-kin″) recombinant interleukin-11, used as a stimulator of hematopoiesis to prevent thrombocytopenia following myelosuppressive chemotherapy.

opsiuria
(op″se-u´re-ә) excretion of urine more rapidly during fasting than after a meal.

opsoclonia
(op″so-klo´ne-ә) opsoclonus.

opsoclonus
(op″so-klo´nәs) involuntary, nonrhythmic horizontal and vertical oscillations of the eyes, seen in certain disorders of the brainstem or cerebellum.

opsoclonus-myoclonus syndrome
a syndrome of movements of the eyes (opsoclonus) and trunk (myoclonus), occurring in conjunction with a number of conditions, including viral infections, trauma, drug toxicity, tumors, and hyperosmolar nonketotic coma. It also occurs as a paraneoplastic syndrome; in some cases of small cell lung carcinoma or breast or fal...

opsonin
(op´sә-nin) an antibody that renders bacteria and other cells susceptible to phagocytosis. adj., opson´ic., adj. immune opsonin an antibody that sensitizes a particulate antigen to phagocytosis.

opsonization
(op″sә-nĭ-za´shәn) the rendering of bacteria and other cells subject to phagocytosis.

opsonize
(op´sә-nīz) to subject to opsonization.