VESTIBULOCOCHLEAR NERVE
v e rte b ra
Any of the
3
3
roughly cylindrical bones
that form the sp/ne.There are seven ver-
tebrae in the cervical spine; 12 in the
thoracic; five in the lumbar; five (fused)
in the
s a c ru m ;
and four (fused) in the
co ccy x.
The top
24
vertebrae are separ-
ated by discs of cartilage
(see
d /sc,
/n t e rv e rt e b ra l).
Each vertebra has a hole
in the centre through w hich the
s p /n a l
c o rd
runs, and processes to w hich mus-
cles are attached. (See also
L o ca t/o n a n d
s tru c tu re o f th e v e rte b ra e
box, overleaf.)
v e r t e b r o b a s ila r in s u f f ic ie n c y
Intermittent episodes of dizziness, weak-
ness, double vision, and difficulty in
speaking caused by reduced blood flow
to parts of the
b ra /n .
The condition is
usually a result of
a th e ro s c le ro s /s
(nar-
rowing due to accumulation of fatty
deposits) of the basilar and vertebral
arteries and other arteries in the base of
the brain. Vertebrobasilar insufficiency
sometimes precedes a
s tro k e .
v e rtig o
An illusion that an individual or his or
her surroundings are spinning. Vertigo
is usually the result of a disturbance of
the
s e m /c /rc u la r c a n a ls
in the inner ear
or the nerve tracts leading from them.
The condition may also be caused by
certain
b ra /n
disorders
affecting
the
brainstem, the cerebellum, or the cere-
bral cortex.
Sudden-onset vertigo is
treated
w ith
rest
and
a n t/h /sta m /n e
d ru g s ,
w hich, in some cases, are also
given to prevent recurrent attacks.
v e s ic le
A small
b l/s t e r,
usually filled w ith clear
fluid, that forms at a site of skin dam-
age. The term is also used to refer to
any small saclike structure in the body.
v e s ic o u r e t e r ic re flu x
Backflow of urine from the bladder
into the ureters (the tubes that carry
urine from the kidneys to the bladder).
Vesicoureteric reflux causes recurrent
urinary infection in children that often
results in acute
p y e lo n e p h r/t /s
and scar-
ring
of the kidneys. The
condition,
w hich is caused by a faulty valve mech-
anism, is diagnosed using micturating
cystourethrography (see
c y s t o u re t h ro g ra -
p h y ,
m /c tu ra t/n g ).
A n t/b /o t/c d r u g s
are
given to prevent infection, but correc-
tive surgery may also be needed.
v e s t ib u le
A chamber. The vestibule in the inner
ear is a hollow chamber that connects
the three
s e m /c /r c u la r c a n a ls
.
v e s t ib u lit is
Inflammation
of the nasal vestibule
(the part of the nasal cavity just inside
the nostril) or of the area between the
labia m inora in the vulva, usually as a
result of bacterial infection.
v e s t ib u lo c o c h le a r n e rv e
The eighth
c ra n /a l n e r v e
.
The vestibulo-
cochlear nerve consists of two branches:
the vestibular nerve (which is concer-
ned with balance)
and the cochlear
nerve (w hich is concerned with hear-
ing). Each vestibulocochlear nerve (one
on each side) carries sensory impulses
from the inner
e a r
to the
b ra /n
,
w hich it
enters between the pons and medulla
oblongata (in the
b ra /n s te m
) .
DISORDERS
A tumour of the cells that surround the
vestibulocochlear
nerve
(see
a c o u s t/c
n e u ro m a
) may result in loss of balance,
t/n n /tu s
(ringing in the ear), and
d e a f-
n e s s
.
Deafness may also be the result of
damage to the nerve, w hich may be
TYPES OF VENTRICULAR ARRHYTHMIA
The ventricles (lower chambers) of the heart usually beat
regularly in response to excitatory waves that spread from
the upper chambers. Any disturbances to that rhythm
r "
~v
y
r
V
U
Normal heartbeat
This is the normal ECG appearance of the heartbeat. The regular spikes
coincide with beats of the ventricles (lower heart chambers). The small rises
before each spike coincide with contractions of the atria (upper chambers).
Ventricular tachycardia
Here, there is a rapid succession of abnormal beats, caused by an abnormal
focus of electrical activity in a ventricle. It usually indicates serious
underlying heart disease. The rate of beating may be very high - up to
220 beats per minute.
(arrhythmia) may be associated with heart disease. The
different types of ventricular arrhythmia can be seen on
these electrocardiograph (ECG) recordings.
Ventricular ectopic beat
Here there is an abnormal beat, which has a broad, bizarre-looking waveform
on the ECG; it occurs just before the expected normal beat. To the patient,
the heart may seem to stop at time A and restart with a thump at time B.
Ventricular fibrillation
This pattern is seen only when the heart is in a state ofvirtual arrest, usually
after a heart attack, with the ventricles twitching in a rapid and totally
irregular manner. Unless a normal rhythm can be restored, the condition
is rapidly fatal.
V
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