Bma Illustrated Medical Dictionary

radiusThe shorter

of the 2 long bones

of the forearm; the

other is the ulna.

The radius is the

bone on the thumb

side of the arm. It

articulates with the

humerus at the el-

bow and the carpal

bones at the wrist.

It takes most of the

strain when weight

is placed on the

wrist and is a com-

mon site of fractures

(see radius, fracture

of; Colles’ fracture).

radius, fracture of

A common type of

fracture that may

affect the lower end,

upper end, or shaft

of the radius. Fracture of the radius just

above the wrist (see Colles’ fracture) is

the most common of all fractures in

people over 40. Fracture of the head of

the radius just below the elbow is one

of the most common fractures in young

adults. Treatment involves immobilizing

the broken bone in a castor surgically.

Healing takes approximately 6 weeks.

radonA colourless, odourless, tasteless,

radioactive gaseous element produced

by the radioactive decay of radium.

randomized controlled trialsA form

of controlled trialthat evaluates the

effectiveness of a drug, or other treat-

ment, in which subjects are randomly

allocated to one of the study groups.

This random allocation means individu-

als are equally likely to be selected for

the particular treatment being investiga-

ted or for the control group of the trial.

ranitidineAn ulcer-healing drug belong-

ing to the H 2 -receptor antagonist group.

It is used to prevent and treat peptic

ulcersand to treat oesophagitis. Side

effects may include headache, skin rash,

nausea, constipation, and lethargy.

ranulaA cyst in the floor of the mouth,

which produces a translucent bluish

swelling. Ranulas probably arise from

damage to a salivary gland. They are

removed surgically.

rapeSexual intercourse with an unwill-

ing partner, which is achieved by the

use or the threat of force or violence.

rashA group of spots or an area of red,

inflamed skin. A rash is usually tempo-

rary and is only rarely a sign of a serious

underlying problem. It may be accom-

panied by itching or fever.

Rashes are classified according to

whether they are localized (affecting a

small area of skin) or generalized (cov-

ering the entire body), and the type of

spots. A bullous rash has large blisters,

a vesicular rash has small blisters, and

a pustular one has pus-filled blisters. A

macular rash consists of spots level

with the surrounding skin and dis-

cernible from it by a difference in colour

or texture. Nodular and papular rashes

are composed of small, raised bumps.

Rashes are the main sign of many

infectious diseases (such as chicken-

pox), and are a feature of manyskin

disorders, such as eczemaand psoriasis.

They may also indicate an underlying

medical problem, such as the rashes of

scurvyor pellagra, which are caused by

vitamin deficiency. The rashes of urti-

caria or contact dermatitis may be

caused by an allergic reaction. Drug

reactions, particularly to antibiotic drugs,

are a common cause of rashes.

A diagnosis is based on the appear-

ance and distribution of the rash, the

presence of any accompanying symp-

toms, and the possibility of allergy (for

example, to drugs). Any underlying

cause is treated if possible. An itching

rash may be relieved by a lotion, such

as calamine, or an antihistamine drug.

RASTAn abbreviation for radioallergo-

sorbent test. RAST is a type of radio-

immunoassayused to detect antibodies

to specific antigens.

rats, diseases fromRats are rodents

that live close to human habitation.

They damage and contaminate crops

and food stores and can spread disease.

The organisms responsible for plague

and a type of typhusare transmitted to

humans by the bites of rat fleas. Lep-

tospirosisis caused by contact with

anything contaminated by rat’s urine.

Rat-bite fever is a rare infection trans-

mitted directly by a rat bite. There are 2

RADIUS RATS, DISEASES FROM

R

RADIUS

Radius

Carpal

bones

Ulna

Humerus