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


opsonocytophagic
(op″sә-no-si″to-faj´ik) denoting the phagocytic activity of blood in the presence of serum opsonins and homologous leukocytes.

optic
(op´tik) ocular (def. 1).

optic angle
visual angle.

optic atrophy
atrophy of the optic disk resulting from degeneration of the nerve fibers of the optic nerve and optic tract.

optic axis
a line connecting the center of the anterior curvature of the cornea (anterior pole) with that of the posterior curvature of the sclera (posterior pole). Axes of the eye. the hypothetical straight line passing through the centers of curvature of the front and back surfaces of...

optic canal
optic foramen a passage for the optic nerve and ophthalmic artery at the apex of the orbit.

optic disk
the part of the optic nerve that is inside the eyeball, formed by fibers converging from the retina and appearing as a pink to white disk in the retina; there are no sensory receptors in the region and hence no response to stimuli. Called also blind spot. Optic disk.

optic nerve
the second cranial nerve, which is purely sensory and is concerned with carrying impulses for the sense of sight; see also vision. The rods and cones of the retina are connected with this nerve. The point at which it leaves the eye is the optic disk or “blind spot,” so called because there are no rods or cones there.

optic neuritis
inflammation of the optic nerve; it may affect the part of the nerve within the eyeball (neuropapillitis) or behind the eyeball (retrobulbar neuritis).

optic papilla
optic disk.

optic radiation
either of two large fan-shaped fiber tracts in the brain extending from the lateral geniculate body on either side to the striate cortex

optic tract
the nerve tract proceeding backward from the optic chiasm, around the cerebral peduncle, and dividing into a lateral and medial root, which end in the superior colliculus and lateral geniculate body, respectively.

optic vesicle
an evagination on either side of the forebrain of the early embryo, from which the percipient parts of the eye develop.

optical
(op´tĭ-kәl) visual; see vision.

optical activity
the ability of a chemical compound to rotate the plane of polarization of plane-polarized light.

optician
(op-tish´әn) a specialist in opticianry. Although this is an exact and intricate science, the optician does not need a state license to practice and is not qualified to examine eyes or prescribe eyeglasses.

opticianry
(op-tish´әn-re) the translation, filling, and adapting of ophthalmic prescriptions, products, and accessories.

opticociliary
(op″tĭ-ko-sil´e-ar-e) pertaining to the optic and ciliary nerves.

opticofacial winking reflex
closure of the lids when an object is brought suddenly into the field of vision.

opticokinetic drum test
optokinetic testoptokinetic drum test (for vision) a rotating drum or other figure is used, painted with vertical black and white stripes; because the eye involuntarily follows such a figure, this can be used in the differential diagnosis of psychogenic blindness, to detect the presence of vision in infants, and to check f...

opticopupillary
(op″tĭ-ko-pu´pĭ-lar-e) pertaining to the optic nerve and pupil.

optics
(op´tiks) the science of light and vision.

optogram
(op´to-gram) the visual image formed on the retina by bleaching of visual purple under the influence of light.

optokinetic
(op″to-kĭ-net´ik) pertaining to movement of the eyes in response to the movement of objects across the visual field, as in optokinetic nystagmus.

optokinetic nystagmus
nystagmus induced by looking at objects moving across the visual field.

optometer
(op-tom´ә-tәr) a device for measuring ocular refraction.

optometrist
(op-tom´ә-trist) a specialist in optometry; an independent primary health care provider who examines the eyes to evaluate health and visual abilities, diagnoses diseases and other conditions of the eye and visual apparatus, and provides necessary treatment such as eyeglasses, contact lenses, vision therapy, ...

optometry
(op-tom´ә-tre) the professional practice of eye and vision care for the diagnosis, treatment, and prevention of diseases and conditions of the eye and visual system. See optometrist.

optomyometer
(op″to-mi-om´ә-tәr) a device for measuring the power of ocular muscles.

Opuntia
(o-pun´she-ә) the prickly pears, a large genus of cacti. Opuntia ficus-indica has edible fruit called the Indian fig or sabra, but its spines cause sabra dermatitis. Opunta vulga´ris is used as a remedy in homeopathy.

OPV
poliovirus vaccine live oral.

OR
operating room.

ora
(o´rә) pl. o´rae an edge or margin. ora serrata retinae the zigzag margin of the retina.

ora
(o´rә) plural of os, mouth.

orad
(o´rad) toward the mouth.

oral
(or´әl) pertaining to the mouth; taken through or applied in the mouth. denoting that aspect of the teeth that faces inward towards the oral cavity or tongue.

oral and maxillofacial surgery
that branch of dental practice that deals with the diagnosis and the surgical and adjunctive treatment of diseases, injuries, and defects of the human mouth and dental structures. Called also maxillofacial or oral surgery.

oral candidiasis
thrush.

oral cavity
the cavity of the mouth, bounded by the jaw bones and associated structures (muscles and mucosa).

oral contraceptive
a compound, usually hormonal, taken orally in order to block ovulation and prevent the occurrence of pregnancy.

oral pathology
that which treats of conditions causing or resulting from morbid anatomic or functional changes in the structures of the mouth.

oral rehydration salts
(ORS) a dry mixture of sodium chloride, potassium chloride, dextrose, and either sodium citrate or sodium bicarbonate; dissolved in water for use in oral rehydration therapy.

oral rehydration therapy
(ORT) oral administration of a solution of electrolytes and carbohydrates in the treatment of dehydration.

oral stage
in psychoanalytic theory, the earliest stage of psychosexual development, lasting from birth to about 18 months, during which the oral zone is the center of the infant's needs, expression, and pleasurable erotic experiences. It is followed by the anal stage.

oral surface
lingual surface.

oral surgery
oral and maxillofacial surgery.

oral thermometer
a clinical thermometer whose mercury containing bulb is placed under the tongue.

oral tuberculosis
a rare condition usually occurring after spread of pulmonary tuberculosis via the bloodstream; it usually involves the gums and tongue, with small, painless ulcers that bleed readily and are surrounded by edema or reddish nodules.

oral-facial-digital syndrome
any of a group of congenital syndromes characterized by oral, facial, and digital anomalies. Type I, a male-lethal X-linked dominant disorder, is characterized by camptodactyly, polydactyly, and syndactyly; by cranial, facial, lingual, and dental anomalies; and by mental retardation, familial trembling, alopecia, and seborrhea ...

orality
(o-ral´ĭ-te) the psychic organization of all the sensations, impulses, and personality traits derived from the oral stage of psychosexual development.

orange
(or´әnj) the trees Citrus aurantium and Citrus sinensis or their fruits; the flowers and peels are used in pharmaceutical preparations. a color between red and yellow, produced by energy of wavelengths between 590 and 630 nm. a dye or stain with this color. methyl orange&...

orange oil
the volatile oil obtained by expression from the fresh peel of the ripe fruit of Citrus sinensis; used as a flavoring agent in pharmaceuticals. Called also sweet orange oil. Cf. bitter orange oil.

orbicular
(or-bik´u-lәr) circular; rounded.

orbicular muscle
one that encircles a body opening, such as the eye or mouth.

orbicularis oculi muscle
the oval sphincter muscle surrounding the eyelids, consisting of three parts: origin,ORBITAL PART—medial margin of orbit, including frontal process of maxilla, PALPEBRAL PART— medial palpebral ligament, LACRIMAL PART—posterior lacrimal crest; insertion,ORBITAL PART—near origin after encircling orbit, PALPEBRAL...

orbicularis oculi reflex
normal contraction of the orbicularis oculi muscle, with resultant closing of the eye, on percussion at the outer aspect of the supraorbital ridge, over the glabella, or around the margin of the orbit.

orbicularis oris muscle
a name applied to a complicated sphincter muscle of the mouth, consisting of a labial part, fibers restricted to the lips, and a marginal part, fibers blending with those of adjacent muscles; innervation, facial nerve; action, closes and protrudes lips.

orbicularis phenomenon
orbicularis pupillary reflex.

orbicularis pupillary reflex
unilateral contraction of the pupil, followed by dilatation after closure or attempted closure of eyelids that are forcibly held apart.

orbicularis sign
in hemiplegia, inability to close the eye on the paralyzed side without closing the other eye.

orbit
(or´bit) the bony cavity containing the eyeball and its associated muscles, vessels, and nerves; the ethmoid, frontal, lacrimal, nasal, palatine, sphenoid, and zygomatic bones and the maxilla contribute to its formation. the path of an electron around the nucleus of an atom. adj., or´bital., adj.

orbital apex syndrome
ophthalmoplegia with impairment of vision that may lead to blindness, swelling of the eyelids, ptosis, hyper- or hypoesthesia of the upper eyelid, one half of the forehead, and cornea, and vasomotor disturbances; it is caused by traumatic, inflammatory, or neoplastic processes involving the sphenoidal fissure and optic ca...

orbital cellulitis
facial cellulitis around the orbit of an eye, most often secondary to sinusitis in children, characterized by drooping and swelling of the eyelid.

orbital floor syndrome
exophthalmos, diplopia, and anesthesia in the areas innervated by the trigeminal nerve, occurring with a lesion in the floor of the orbit. Called also Dejean syndrome

orbital gyri
irregular gyri on the orbital surface of the frontal lobe.

orbitalis muscle
orbital muscle: a thin layer of nonstriated muscle that bridges the inferior orbital fissure; innervation, sympathetic branches.

orbitonasal
(or″bĭ-to-na´zәl) pertaining to the orbit and nose.

orbitonometer
(or″bĭ-to-nom´ә-tәr) an instrument for measuring backward displacement of the eyeball produced by a given pressure on its anterior aspect.

orbitopathy
(or″bĭ-top´ә-the) disease affecting the orbit and its contents.

orbitotomy
(or″bĭ-tot´ә-me) incision into the orbit.

orbivirus
(or´bĭ-vi″rәs) any virus of the genus Orbivirus.

Orbivirus
a genus of RNA viruses of the family Reoviridae, some of which cause fevers in humans in areas of the world such as Central Africa and Siberia. Mosquitoes, ticks, and sandflies are vectors.

orcein
(or-se´in) a brownish-red coloring substance obtained from orcinol; used as a stain for elastic tissue.

orchialgia
(or″ke-al´jә) pain in a testis; called also testalgia.

orchidectomy
(or″kĭ-dek´tә-me) orchiectomy.

orchiectomy
(or″ke-ek´tә-me) excision of one or both testes, done when a testis is seriously injured or diseased (as in testicular cancer).If both testes are removed (bilateral orchiectomy or castration), the ability to reproduce is ended. There is also a decrease in production of testosterone, and although bilateral orchiect...

orchiepididymitis
(or″ke-ep″ĭ-did″ә-mi´tis) epididymo-orchitis.

orchiocele
(or´ke-o-sēl″) hernial protrusion of a testis. protrusion of a testis due to a hernia. scrotal hernia.

orchiopathy
(or″ke-op´ә-the) any disease of the testes.

orchiopexy
(or´ke-o-pek″se) surgical fixation of an undescended testis in the scrotum.

orchioplasty
(or´ke-o-plas″te) plastic surgery of a testis.

orchiotomy
(or″ke-ot´ә-me) incision and drainage of a testis.

orchitis
(or-ki´tis) inflammation of a testis, which occurs occasionally in infectious diseases such as syphilis, tuberculosis, glanders, leprosy, and certain parasitic diseases. It usually accompanies epididymitis. Acute orchitis may also occur in diseases such as typhoid fever, pneumonia, or mumps in adult males. The symptoms of acu...

orcinol test
Bial test.

order
(or´dәr) a taxonomic category subordinate to a class and superior to a family (or suborder). the prescription of a physician regarding treatment of a patient. standing order a physician's order that can be exercised by other health care workers when specific conditions...

orderly
(or´dәr-le) an attendant in a hospital who works under the direction of a nurse.

ordinate
(or´dĭ-nәt) the vertical line in a graph along which is plotted one of the variables considered in the study, as temperature in a time-temperature study. The other line is called the abscissa.

orexigenic
(o-rek″sĭ-jen´ik) increasing or stimulating the appetite.

orf
(orf) a contagious pustular viral dermatitis of sheep, sometimes communicable to humans.

orf virus
a virus of the genus Parapoxvirus that is the etiologic agent of contagious ecthyma (orf).

organ
(or´gәn) a somewhat independent part of the body that is arranged according to a characteristic structural plan, and performs a special function or functions; it is composed of various tissues, one of which is primary in function.

organ of Corti
the organ lying against the basilar membrane in the cochlear duct, containing special sensory receptors for hearing, and consisting of neuroepithelial hair cells and several types of supporting cells. Click here to view image Detail of the organ...

organ-specific
(or´gan-spĕ-sif´ik) restricted to, or having an effect only on, a particular organ, as an organ-specific antigen.

organ-specific antigen
any antigen that occurs exclusively in a particular organ and serves to distinguish it from other organs. Two types of organ specificity have been proposed: (1) first-order or tissue specificity is attributed to the presence of an antigen characteristic of a particular organ in a single species; (2) second-order organ spe...

organelle
(or″gә-nel´) any of the organized cytoplasmic structures of distinctive morphology and function present in all eukaryotic cells, such as the nucleus, mitochondria, lysosomes, peroxisomes, Golgi apparatus, and endoplasmic reticulum. In plant cells, there are also chloroplasts, and in protozoa there are also cilia a...

organic
(or-gan´ik) pertaining to an organ or organs. having an organized structure. arising from an organism. pertaining to substances derived from living organisms. denoting chemical substances containing covalently bonded carbon atoms. pertaining to or cultivate...

organic anxiety syndrome
in a former system of classification, an organic mental syndrome characterized by prominent, recurrent panic attacks or generalized anxiety caused by a specific organic factor and not associated with delirium. Such disorders are now mainly classified as substance-induced anxiety disorders and anxiety disorders due to a general ...

organic brain syndrome
organic mental syndrome.

organic delusional syndrome
in a former system of classification, an organic mental syndrome characterized by delusions caused by a specific organic factor and not associated with clouding of consciousness (delirium), intellectual impairment (dementia), or prominent hallucinations (organic hallucinosis). The disorders are now mainly classified as substance-indu...

organic disease
a disease due to or accompanied by structural changes in organs or tissues.