displaced backwards. In young children,
similar displacement results from a frac-
ture through the epiphysis (growing end)
of the radius. A spraincan affect liga-
ments at the wrist joint, but most wrist
sprains are not severe. (See also carpal
tunnel syndrome; wrist-drop; tenosyn-
ovitis;and osteoarthritis.)
wrist-dropInability to straighten the
wrist, so that the back of the hand can-
not be brought into line with the back
of the forearm. This causes weakness of
grip because the hand muscles can func-
tion efficiently only when the wrist is
held straight.
Wrist-drop is caused by damage to the
radial nerve, either by prolonged pres-
sure in the armpit (see crutch palsy) or
by fracture of the humerus (see humerus,
fracture of). Treatment involves holding
the wrist straight. This may be achieved
by means of a splint, but if damage to
the radial nerve is permanent, the usual
treatment is arthrodesis(surgical fusion)
of the wrist bones in a straight position.
writer’s crampSee cramp, writer’s.
wry neckAbnormal tilting and twisting of
the head. It may be due to injury to, or
spasm of, the muscles on one side of the
neck (see torticollis), among other factors.WRIST
Wounds can be divided into the follow-
ing categories: an incised wound; an
abrasion (or graze); a laceration; a pene-
trating wound; and a contusion.
wound infectionAny type of woundis
susceptible to the entry of bacteria; the
resultant infection can delay healing,
result in disability, and may even cause
death. Infection of a wound is indicated
by redness, swelling, warmth, pain, and
sometimes by the presence of pus or
the formation of an abscess. Infection
may spread locally to adjacent organs
or tissue, or to more distant parts of the
body via the blood.
The type of infection depends upon
how the wound occurred. For example,
wounds brought into contact with soil
can result in tetanus. STAPHYLOCOCCI,
including MRSA, are also common
wound infections.
Once infection is discovered, a sample
of blood or pus is taken and the patient
is given an antibiotic drug. Any abscess
should be drained surgically.
wrinkleA furrow in the skin. Wrinkling is
a natural feature of aging and is caused
by a loss of skin elasticity. Premature
deep wrinkling is usually due to overex-
posure to the ultraviolet rays in sunlight,
and to smoking.
No treatment can permanently restore
skin elasticity, although some vitamin A
derivatives are believed to reduce wrin-
kling. A face-liftsmoothes out wrinkles
by stretching the skin, but the effects
last only about 5 years.
wristThe joint between the handand
the arm that allows the hand to be bent
forward and backward relative to the
arm and also to be moved side to side.
The wrist contains 8 bones (known
collectively as the carpus) arranged in 2
rows, one articulating with the bones of
the forearm, and the other connecting
to the bones of the palm. Tendons con-
nect the forearm muscles to the fingers
and thumb, and arteries and nerves sup-
ply the muscles, bones, and skin of the
hand and fingers.
Wrist injuries may lead to serious dis-
ability by limiting hand movement. A
common injury in adults is Colles’ frac-
ture, in which the lower end of the radius
is fractured and the wrist and hand are
WOUND INFECTION WRY NECK
W
Lunate
Scaphoid
TrapeziumTrapezoidCapitateHamatePisiformTriquetrumUlnaRadiusBONES OF WRIST