.

When the tension caused by the extravasated blood threatens the vitality
of the skin, incisions may be made, if asepsis can be assured. The blood
from a haematoma may be withdrawn by an exploring needle, and the
puncture sealed with collodion. Infective complications must be looked
for and dealt with on general principles.

WOUNDS

A wound is a solution in the continuity of the skin or mucous membrane
and of the underlying tissues, caused by violence.

Three varieties of wounds are described: incised, punctured, and
contused and lacerated.

#Incised Wounds.#--Typical examples of incised wounds are those made by
the surgeon in the course of an operation, wounds accidentally inflicted
by cutting instruments, and suicidal cut-throat wounds. It should be
borne in mind in connection with medico-legal inquiries, that wounds of
soft parts that closely overlie a bone, such as the skull, the tibia, or
the patella, although, inflicted by a blunt instrument, may have all the
appearances of incised wounds.

_Clinical Features._--One of the characteristic features of an incised
wound is its tendency to gape. This is evident in long skin wounds, and
especially when the cut runs across the part, or when it extends deeply
enough to divide muscular fibres at right angles to their long axis. The
gaping of a wound, further, is more marked when the underlying tissues
are in a state of tension--as, for example, in inflamed parts. Incised
wounds in the palm of the hand, the sole of the foot, or the scalp,
however, have little tendency to gape, because of the close attachment
of the skin to the underlying fascia.

Incised wounds, especially in inflamed tissues, tend to bleed profusely;
and when a vessel is only partly divided and is therefore unable to
contract, it continues to bleed longer than when completely cut across.

The _special risks_ of incised wounds are: (1) division of large blood
vessels, leading to profuse haemorrhage; (2) division of nerve-trunks,
resulting in motor and sensory disturbances; and (3) division of tendons
or muscles, interfering with movement.

_Treatment._--If haemorrhage is still going on, it must be arrested by
pressure, torsion, or ligature, as the accumulation of blood in a wound
interferes with union. If necessary, the wound should be purified by
washing with saline solution or eusol, and the surrounding skin painted
with iodine, after which the edges are approximated by sutures. The raw
sur