Page 64 - Clinical Anatomy

ECA1 7/18/06 6:31 PM Page 49

On the examination of a chest radiograph 49

mesenteric, inferior mesenteric and renal ganglia from which they are
relayed as postganglionic fibres to the abdominal viscera. These splanchnic
nerves are the:
•◊◊greater splanchnic (T5–10);
•◊◊lesser splanchnic (T10–11);
•◊◊least splanchnic (T12).
They lie medial to the sympathetic trunk on the bodies of the thoracic verte-
bra and are quite easily visible through the parietal pleura (For their distrib-
ution see pages 429 and 430).

Clinical features

Ahigh spinal anaesthetic will produce temporary hypotension by
paralysing the sympathetic (vasoconstrictor) preganglionic outflow from
spinal segment T5 downwards, passing to the abdominal viscera.

On the examination of a

chest radiograph

The following features should be examined in every radiograph of
the chest.

Centering and density of film
The sternal ends of the two clavicles should be equidistant from the shadow
of the vertebral spines. The assessment of the density of the film can only be
learned by experience, but in a ‘normal’ film the bony cage should be
clearly outlined and the larger vessels in the lung fields clearly visible.

General shape
Any abnormalities in the general form of the thorax (scoliosis, kyphosis and
the barrel chest of emphysema, for example) should always be noted before
other abnormalities are described.

Bony cage
The thoracic vertebrae should be examined first, then each of the ribs in
turn (counting conveniently from their posterior ends and comparing each
one with its fellow of the opposite side), and finally clavicles and scapulae.
Unless this procedure is carried out systematically, important diagnostic
clues (e.g. the presence of a cervical rib, or notching of the ribs by enlarged
anastomotic vessels) are liable to be missed.