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

racemic
(ra-se´mik) optically inactive, being composed of equal amounts of dextrorotatory and levorotatory isomers.

racemization
(ra″sә-mĭ-za´shәn) the transformation of one-half of the molecules of an optically active compound into molecules that possess exactly the opposite (mirror-image) configuration, with complete loss of rotatory power because of the statistical balance between equal numbers of dextrorotatory an...

racemized protein
protein so changed by chemical or other agents, usually dilute alkali, that its optical activity is lowered and it becomes more resistant to enzymatic hydrolysis. Acid hydrolysis of a racemized protein shows inactivation (racemization) of several of its constituent amino acids.

racemose
(ras´ә-mōs) shaped like a bunch of grapes on its stalk.

racemose aneurysm
cirsoid aneurysm.

rachialgia
(ra″ke-al´jә) rachiodynia.

rachicentesis
(ra″ke-sen-te´sis) lumbar puncture.

rachidial
(ra-kid´e-әl) spinal (def. 2).

rachidian
(ra-kid´e-әn) spinal (def. 2).

rachigraph
(ra´ke-graf) an instrument for recording the outlines of the vertebral column and the back.

rachilysis
(ra-kil´ĭ-sis) correction of lateral curvature of the vertebral column by combined traction and pressure.

rachiocampsis
(ra″ke-o-kamp´sis) spinal curvature.

rachiodynia
(ra″ke-o-din´e-ә) pain in the vertebral column; called also rachialgia.

rachiometer
(ra″ke-om´ә-tәr) an apparatus for measuring spinal curvature.

rachiomyelitis
(ra″ke-o-mi″ә-li´tis) myelitis (def. 1).

rachiotomy
(ra″ke-ot´ә-me) incision of a vertebra or of the vertebral column.

rachipagus
(ra-kip´ә-gәs) conjoined twins joined at the vertebral column.

rachis
(ra´kis) vertebral column.

rachischisis
(ra-kis´kĭ-sis) congenital fissure of the vertebral column; see also spina bifida. rachischisis posterior spina bifida.

rachitic
(ra-kit´ik) pertaining to rickets.

rachitic dwarf
a person dwarfed by rickets, having a high forehead with prominent bosses, bent long bones, and a Harrison groove on the thorax.

rachitic pelvis
one distorted as a result of rickets.

rachitic scoliosis
scoliosis due to rickets.

rachitis
(ra-ki´tis) rickets. spondylitis.

rachitogenic
(rә-kit″o-jen´ik) causing rickets.

rachitomy
(rә-kit´ә-me) rachiotomy.

racket amputation
one in which there is a single longitudinal incision continuous below with a spiral incision on either side of the limb.

racket cell
one shaped like a tennis racket, with a swollen outer end, found in the racket hyphae of various dermatophytes.

racket nail
a thumbnail, or occasionally a fingernail, that is much shorter than it is wide; usually the distal phalanx is shortened as well.

rad
(rad) acronym for radiation absorbed dose; a unit of measurement of the absorbed dose of ionizing radiation. It corresponds to an energy transfer of 100 ergs per gram of any absorbing material (including tissue). The biological effect of 1 rad of radiation varies with the type of radiation. When the dose is in rem...

radectomy
(ra-dek´tә-me) root amputation.

radiability
(ra″de-ә-bil´ĭ-te) the property of being readily penetrated by x-rays or other rays.

radiad
(ra´de-ad) toward the radius or radial side.

radial
(ra´de-әl) radiating; spreading outward from a common center. pertaining to a radius. pertaining to the radial (lateral) aspect of the arm as opposed to the ulnar (medial) aspect.

radial arteries of uterus
branches of the uterine arcuate arteries that supply the deeper layers of the myometrium and penetrate the endometrium, giving rise to the spiral arteries.

radial artery
an artery in the forearm, wrist, and hand; the one usually used for taking the pulse. origin, brachial artery; branches, palmar carpal, superficial palmar and dorsal carpal branches, recurrent radial artery, princeps pollicis artery, deep palmar arch; distribution, forearm, wrist, hand.

radial collateral artery
origin, profunda brachii artery; branches, none; distribution, brachioradialis and brachialis muscles.

radial dorsal digital nerves
dorsal digital nerves of radial nerve.

radial nerve
origin, posterior cord of brachial plexus (C6–C8, and sometimes C5 and T1); branches, posterior cutaneous and inferior lateral cutaneous nerves of arm, posterior cutaneous nerve of forearm, muscular, deep, and superficial branches; distribution, descending in the back of arm and forearm, it then goes to skin on back of ar...

radial paralysis
musculospiral paralysis.

radial pulse
that felt over the radial artery at the wrist.

radial recurrent artery
origin, radial artery; branches, none; distribution, brachioradialis and brachialis muscles, elbow region.

radial reflex
flexion of the forearm, following tapping on the lower end of the radius; when the fingers flex as well, it indicates hyperreflexia.

radial veins
veins following the distribution of the radial artery, which open into the brachial veins.

radialis
(ra″de-a´lis) Latin word meaning radial; a term used in anatomy.

radialis indicis artery
origin, princeps pollicis artery; branches, none; distribution, index finger.

radialis sign
inability to close the fist without marked dorsal extension of the wrist, seen in hemiplegia; called also Strümpell sign.

radiant
(ra´de-әnt) diverging from a center. emitting rays, as of light or heat.

radiate
(ra´de-āt) to diverge or spread from a common point. arranged in a radiating manner.

radiate arteries of kidney
interlobular arteries of kidney.

radiathermy
(ra-di″ә-ther´me) short wave diathermy.

radiation
(ra″de-a´shәn) a proceeding outward from a common center. a structure made up of parts that go outward from a center, especially a tract of the central nervous system made up of fibers that go out in different directions. energy carried by waves or a stream of particles. Electroma...

radiation alopecia
radiation-induced alopecia transient alopecia following exposure to ionizing radiation.

radiation burn
a burn caused by exposure to ionizing radiation; sunburn and burning from x-rays are two common types.

radiation cataract
a subcapsular opacity caused by ionizing radiation such as x-rays, gamma rays, and neutrons, and by nonionizing radiation such as infrared rays (heat rays), ultraviolet rays, microwaves, and laser radiation.

radiation colitis
colitis resulting from radiation therapy to the abdominal region; it is manifested clinically by tenesmus, pain, rectal bleeding, diarrhea, and telangiectases. Malabsorption, ulceration, and partial or complete obstruction may follow.

radiation cystitis
inflammatory changes in the urinary bladder caused by ionizing radiation; called also radiocystitis.

radiation dermatitis
radiodermatitis.

radiation nephritis
kidney damage caused by ionizing radiation; symptoms include glomerular and tubular damage, hypertension, and proteinuria, sometimes leading to renal failure. It may be acute or chronic, and some varieties do not manifest until years after the radiation exposure.

radiation pericarditis
postirradiation pericarditis.

radiation physicist
a physicist who is responsible for certain technical aspects of radiology and radiation therapy, such as computer estimations, preparation of isodose curves, preparation of wedge and compensating filters, and calibration of teletherapy equipment, and who supervises quality assurance and control and radiation safety procedures.

radiation sickness
a condition sometimes seen in persons who have received excessive doses of radiation, including some patients after radiation therapy; its severity varies according to factors such as the individual's physical condition, the body areas exposed, and the amount, kind, and intensity of the exposure. The disease may be slight and b...

radiation therapist
a specialist in the treatment of disease by means of ionizing radiation; see radiation therapy.

radiation therapy
the treatment of disease, usually cancer, by ionizing radiation in order to deliver an optimal dose of either particulate or electromagnetic radiation to a particular area of the body with minimal damage to normal tissues. The source of radiation may be outside the body of the patient (external beam irradiation) or it may be an...

radical
(rad´ĭ-kәl) thorough or sweeping; directed to the cause or root of a morbid process. a group of atoms that enters into and goes out of chemical combination without change and that forms one of the fundamental constituents of a molecule.

radical hysterectomy
hysterectomy with excision of the pelvic lymph nodes and wide lateral excision of parametrial and paravaginal supporting structures.

radical mastectomy
removal of the breast, pectoral muscles, lymph nodes in the armpit, and associated skin and subcutaneous tissue in treatment of breast cancer.

radical operation
one involving extensive resection of tissues for the complete extirpation of disease.

radicle
(rad´ĭ-kәl) one of the smallest branches of a vessel or nerve.

radicotomy
(rad″ĭ-kot´ә-me) rhizotomy; division or transection of a nerve root.

radiculalgia
(rә-dik″u-lal´jә) pain due to disorder of the spinal nerve roots.

radicular
(rә-dik´u-lәr) of or pertaining to a root or radicle.

radicular cyst
an epithelium-lined sac at the apex of a tooth.

radicular fibers
fibers in the roots of the spinal nerves.

radicular syndrome
a syndrome due to lesion of the roots of the spinal nerves, consisting of restricted mobility of the spine and root pain.

radiculitis
(rә-dik″u-li´tis) inflammation of a spinal nerve root, especially of the portion of the root that lies between the spinal cord and the spinal canal.

radiculoganglionitis
(rә-dik″u-lo-gang″gle-o-ni´tis) inflammation of the posterior spinal nerve roots and their ganglia.

radiculomedullary
(rә-dik″u-lo-med´u-lar″e) affecting the nerve roots and spinal cord.

radiculomeningomyelitis
(rә-dik″u-lo-mә-ning″go-mi″ә-li´tis) meningomyeloradiculitis.

radiculomyelopathy
(rә-dik″u-lo-mi″ә-lop´ә-the) myeloradiculopathy.

radiculoneuritis
(rә-dik″u-lo-ndbobr-ri´tis) acute febrile polyneuritis.

radiculoneuropathy
(rә-dik″u-lo-ndbobr-rop´ә-the) disease of the nerve roots and spinal nerves.

radiculopathy
(rә-dik″u-lop´ә-the) disease of the nerve roots. spondylotic caudal radiculopathy compression of the cauda equina due to encroachment upon a congenitally small spinal canal by spondylosis, resulting in neural disorders of the lower limbs.

radiectomy
(ra″de-ek´tә-me) root amputation.

radio waves
electromagnetic waves of wavelength between 10−1 and 106 cm and frequency of about 1011 to 104 hertz.

radioactive
(ra″de-o-ak´tiv) characterized by radioactivity.

radioactive element
a chemical element that does not contain an optimal proton-to-neutron ratio in its atomic nuclei and therefore readily gives off nuclear particles until all nuclei have attained the optimal combination of protons and neutrons. The spontaneous releasing of its nuclear particles changes the radioactive atom into a new atom ...

radioactive iodine
radioiodine.

radioactive iodine uptake test
radioiodine uptake test.

radioactivity
(ra″de-o-ak-tiv´ĭ-te) the emission of particulate or electromagnetic radiation as a result of decay of the nuclei of unstable elements, a property of all chemical elements of atomic number above 83, and possibly inducible in all other known elements. the quality of having such emissions.

radioallergosorbent test
(RAST) (ra″de-o-al″er-go-sor´bent) a radioimmunoassay for the measurement of extremely small amounts of specific immunoglobulin E (IgE) antibody to a variety of allergens in the serum of a patient. It uses an allergen complex fixed in a solid-phase matrix, passes the serum over the matrix so...

radioautogram
(ra″de-o-aw´to-gram) autoradiogram.

radioautography
(ra″de-o-aw-tog´rah-fe) autoradiography.

radiobicipital
(ra″de-o-bi-sip´ĭ-tәl) pertaining to the radius and biceps muscle of the upper limb.

radiobiologist
(ra″de-o-bi-ol´ә-jist) an expert in radiobiology.

radiobiology
(ra″de-o-bi-ol´ә-je) the branch of science concerned with effects of light and of ultraviolet and ionizing radiations on living tissue or organisms. adj., radiobiolog´ical., adj.

radiocardiogram
(ra″de-o-kahr´de-o-gram) the graphic record produced by radiocardiography.

radiocardiography
(ra″de-o-kahr″de-og´rә-fe) graphic recording of variation with time of the concentration, in a selected chamber of the heart, of a radioactive isotope, usually injected intravenously. radioelectrocardiography.

radiocarpal
(ra″de-o-kahr´pәl) pertaining to the radius and carpus.

radiochemistry
(ra″de-o-kem´is-tre) the branch of chemistry dealing with radioactive materials.