Bma Illustrated Medical Dictionary

In paraphimosis, the foreskin becomes
stuck in the retracted position, causing
painful swelling of the glans that needs
emergency treatment.
forgetfulnessThe inability to remem-
ber (see memory).
formaldehydeA colourless, pungent,
irritant gas. In medicine, a solution of
formaldehyde and a small amount of
alcohol in water, a preparation known
as formalin, is used to preserve tissue
specimens or to harden them before
they are stained and examined. Forma-
lin is also used as a disinfectant.
formicationAn unpleasant sensation,
as if ants were crawling over the skin.
This may occur following abuse of cer-
tain drugs, such as alcohol or morphine.
formula, chemicalA way of expressing
the constituents of a chemical in sym-
bols and numbers. Water, for example,
has the formula H 2 O, indicating that
each molecule is composed of 2 atoms
of hydrogen (H 2 ) and 1 of oxygen (O).
formularyA book of formulae. The term
formulary is commonly used to refer to
a publication that lists drug prepara-
tions and their components and effects.
The contents of a formulary can be
decided by a group of medical profes-
sionals working together to ensure
similar patterns of drug usage.
foveaAn area of the retinain the eye
that has the highest concentration of
light-sensitive cells. It is responsible for
detailed vision. (See also colour vision.)
fractureA break in a bone, usually across
its width. There are 2 main types: closed
(simple) or open (compound) fractures.
In a closed fracture, the broken bone
ends remain beneath the skin and little
surrounding tissue is damaged; in an
open fracture, 1 or both bone ends pro-
ject through the skin. If the bone ends
are not aligned, the fracture is termed
“displaced”. Fractures can be further
divided according to the pattern of the
break, for example, transverse or spiral
fractures of long bones. In a greenstick
fracture, the break is not through the
full width of the bone. This type of frac-
ture occurs only in children because
their bones are more pliable. In an avul-
sion fracture, a small piece of bone is
pulled off by a tendon.

Most fractures are the result of a fall,

but in osteoporosisthe bone is weak-

ened, and fractures such as compression

fractures of the vertebrae are common.

Common sites of fracture include the

hand, wrist (see Colles’ fracture), ankle

joint, clavicle, and the neck of the femur

(see femur, fracture of). There is usually

swelling and tenderness at the fracture

site. The pain is often severe and is usu-

ally made worse by movement.

X-rays can confirm a fracture. Because

bone begins to heal soon after it has

broken, the first aim of treatment is to

ensure that the bone ends are aligned.

Displaced bone ends are manoeuvred

back into position, under general

anaesthetic, by manipulation either

through the skin or through an incision.

The bone is then immobilized. In some

cases the ends of the bone may be fixed

with metal pins or plates.

Most fractures heal without any prob-

lems. Healing is sometimes delayed

because the blood supply to the affec-

ted bone is inadequate (as a result of

damaged blood vessels) or because the

bone ends are not close enough together.

If the fracture fails to unite, internal fix-

ation or a bone graft may be needed.

Osteomyelitisis a possible complication

of open fractures. (See also Monteggia’s

FORGETFULNESS FRACTURE

F

FRACTURE

TRANSVERSE

FRACTURE

SPIRAL

FRACTURE

GREENSTICK

FRACTURE

AVULSION

FRACTURE

COMMINUTED

FRACTURE

COMPRESSION

FRACTURE