SHOULDER
S
s h o u ld e r
The area of the body where the arm
attaches to the trunk. The rounded bony
surface at the front of the shoulder is
the upper part of the
h u m e ru s
(upper-
arm bone); the bony surfaces that form
the top and back of the shoulder are
parts of the
s c a p u la
(shoulderblade). The
c la v ic le
(collarbone) articulates with the
acromion (the bony prominence at the
outer top part of the scapula) at the
a c ro m io c la v ic u la r jo in t
and extends across
the top of the chest to the
s te rn u m
(breastbone), to w hich it is attached at
the sternoclavicular joint.
Just below
the
acromion,
on the
outer wall of the scapula, is a socket
(called the glenoid cavity) into w hich
the head of the humerus fits to form
the shoulder joint. A
b u rs a
(fluid-filled
sac) under the acromion reduces fric-
tion at the joint. The shoulder joint is a
ball-and-socket joint with the widest
range of movement of all joints; move-
ment is produced by part of the
b ic e p s
m u s c le
,
several small muscles that make
up the
ro ta to r c u ff
,
various muscles in
the chest wall, and the
d e lt o id
muscle at
the top of the upper arm and shoulder.
DISORDERS
Shoulder injuries are relatively com-
mon,
including
dislocation
of
the
shoulder joint (see
s h o u ld e r, d is lo c a t io n
o f
)
or of the acromioclavicular joint,
and
fra c tu re s
of the clavicle or of the
upper part of the humerus. Fractures of
the scapula are less common.
STRUCTURE OF THE SHOULDER
Three bones meet at the shoulder -
the scapula (shoulderblade), clavicle
(collarbone), and humerus (upper-
arm bone). The shoulder is an
example of a ball-and-socket joint.
The shoulder joint may be affected by
any joint disorder, including
a rth rit is
and
b u r s it is
(inflammation of a bursa).
In severe cases, a joint disorder may lead
to
fro z e n s h o u ld e r
(a condition in which
movements at the joint are
severely
restricted). Movement of the shoulder
may also be painful and/or restricted
because of
t e n d in itis
(inflammation of a
tendon). Tendinitis or bursitis can cause
p a in f u l a rc s y n d r o m e
,
in w hich raising
the arm to the side causes pain.
s h o u ld e rb la d e
The common name for the
s c a p u la
.
s h o u ld e r, d is lo c a tio n o f
Displacement
of
the
head
of
the
h u m e ru s
(upper-arm bone) out of the
shoulder joint. The main symptom is
pain, in the shoulder and upper arm,
made worse by movement. A forward
dislocation often produces obvious de-
formity; however, a backward disloc-
ation usually does not.
Diagnosis is by X-rays.The head of the
humerus is repositioned in the joint
socket, and the shoulder is immobilized
in a sling for about three weeks. In cases
of recurrent shoulder dislocation, sur-
gery may be required.
Complications of shoulder dislocation
include damage to nerves, causing tem-
porary weakness and numbness in the
shoulder; damage to an artery in the
upper arm, causing pain and discolor-
ation of the arm and hand; and damage
to the muscles that support the shoulder.
s h o u ld e r - h a n d s y n d ro m e
Pain and stiffness of one shoulder and
the hand on that side; the hand may also
become hot, sweaty, and swollen. Arm
muscles may waste through lack of use.
The
cause
of shoulder-hand
syn-
drome is not known, but the condition
may sometimes occur as a complication
of
m y o c a rd ia l in fa rc tio n
(heart
attack),
s tro k e
,
h e rp e s z o s te r
(shingles), or shoul-
der injury. Recovery usually occurs in
about two years. However, this recovery
period may be shortened by
p h y s io t h e ra -
p y
and
c o rt ic o s t e ro id d r u g s
.
In rare cases,
a cervical
s y m p a t h e c t o m y
is performed.
s h u n t
An abnormal passage between two nor-
mally unconnected body parts (as in a
s e p t a l d e fe c t
of the heart). The term also
refers to a passage created surgically
between unconnected areas for purpos-
es such as draining excess fluid.
S h y -D r a g e r s y n d ro m e
A rare degenerative disorder of unknown
cause that progressively damages
the
a u to n o m ic n e rv o u s s y s t e m
.
It begins grad-
ually between the ages of
60
and
70
and is more common in men. Symp-
toms include dizziness and fainting due
to postural
h y p o t e n s io n
; urinary incon-
tinence; impotence; reduced ability to
sweat; and
p a r k in s o n is m
.
The condition
eventually leads to disability and some-
times premature death. There is no cure
or means of slowing degeneration, but
many symptoms are relieved by drugs.
SIA D H
The
abbreviation
for
“syndrome
of
inappropriate antidiuretic hormone (se-
cretion)” , in w hich excessive secretion
of antidiuretic hormone (ADH) results
in water retention and a low sodium
level in the body SIADH is associated
with
certain lung
disorders such as
COPD
(see
p u lm o n a ry d is e a s e , c h ro n ic
o b s tru c tiv e
)
or
p n e u m o n ia
.
Other condi-
tions, for example brain disorders such
as
e n c e p h a litis
or
b ra in h a e m o rrh a g e
,
and
some cancers including small cell carci-
noma (see
lu n g c a n c e r
)
and cancer of
the pancreas (see
p a n c re a s , c a n c e r o f
) ,
may also be associated with SIADH.
S ia m e s e tw in s
See
tw in s, c o n jo in e d
.
s ib lin g riv a lry
A
term
that
describes
the
intense
competition
that
sometimes
occurs
between siblings.
s ib u tra m in e
A centrally acting
a p p e tite s u p p re s s a n t
drug that is used to treat obesity in peo-
ple who have not responded to other
methods of weight loss, such as dieting
and
exercise.
Common
side
effects
include constipation, dry mouth, and
h y p e rt e n s io n
.
People taking this
drug
should have regular follow-ups with their
blood pressure and pulse monitored.
s ic c a s y n d ro m e
Occurring in
S jo g re n ’s s y n d ro m e
,
dryness
of the eyes, mouth, and other mucous
membranes (such as the lining of the
vagina) due to destruction of exocrine
(such as tear, salivary, or sweat) glands.
s ic k b u ild in g s y n d ro m e
A collection of symptoms reported by
some
workers
in
office
buildings.
Symptoms
include
loss
of
energy,
688
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