CADAVERIC CHANGES IN THE ZMIISCLES 129
delivered a quadripara, aged 28, of a full-term dead female child, which was
in a state of rigor mortis. The labour was tedious and prolonged as com-
pared to her previous labours.20
In adolescent and healthy adult bodies the occurrence o£ rigor mortis is
slow, but well marked, while it is feeble and rapid in the bodies of children
and old people.
(b) Muscular Condition.—The onset is slower, and the duration longer,
in those cases where the muscles have been healthy and at rest before death
than in those cases where the muscles have been feeble and exhausted, and
thus have lost a greater degree of muscular irritability.
(c) Manner of Death.—Rigor mortis sets in early, and disappears soon in
deaths from diseases causing great exhaustion and wasting of the muscles,
as in cholera, plague, typhus, typhoid, phthisis, cancer, uremia and chronic
Bright's disease. Its onset is delayed in deaths occurring from pneumonia,
apoplexy, asphyxia and nervous diseases causing paralysis of the muscles.
In cases of strychnine and other spinal poisons the onset is rapid and the
duration longer, if death has occurred in a short time after the symptoms first
appeared when the muscles had not been exhausted owing to convulsive fits.
(d) Atmospheric Conditions.—Rigor mortis commences slowly, but lasts
for a long time in dry, cold air. On the other hand, its commencement is
rapid, and duration short, in warm, moist air. It comes on rapidly and dis-
appears late in bodies immersed in cold water.
Conditions simulating Rigor Mortis.—The conditions which simulate
rigor mortis are (a) heat stiffening, (b) cold stiffening, and (c) cadaveric
spasm or instantaneous rigor.
(a) Heat Stiffening.—The phenomenon known as heat stiffening is seen
in the hardening and stiffening of the muscles in a body exposed to a tempe-
rature exceeding 75°C. This is due to the coagulation of other albuminates
besides myosin, which coagulates ordinarily at a lower temperature, say 50 °C.
Heat stiffening is commonly observed in the body of a person who has
met his death from burning or from sudden immersion in a boiling fluid, or
in a body which has been burnt soon after death while the muscles were still
warm. The body assumes an attitude, called " pugilistic attitude " with the
lower limbs and arms flexed and the hands clenched.
(b) Cold Stiffening.—The stiffening of the muscles occurs in a body
from solidification of its faTlvhen it is exposed to a freezing temperature, if
the body is moved to a warm atmosphere, the stiffening rapidly disappears
and,normal rigor mortis develops, but it lasts only for a short time.
(c) Cadaveric Spasm or Instantaneous Rigor.—This is a phenomenon
in which the muscles that have been in a state of contraction during life
become stiff and rigid immediately after death without passing into an initial
stage of relaxation; hence the attitude of the body adopted at the time of'
death is maintained for several hours afterwards. It is due to the fact that
the last voluntary muscular contraction of life does not stop after death, but
is continuous with an act of cadaveric rigidity and thus occurs hi cases where
there have been great muscular exertion and mental excitement before death,
as observed among soldiers killed on a battlefield. It is also found in sudden
asphyxial deaths, and in deaths from irritation of the medulla. It is quite
different from cadaveric rigidity or rigor mortis. In the case of cadaveric
spasm, a weapon held in the hand before death is firmly grasped, and can
only be removed with difficulty ; whereas in cadaveric rigidity the weapon
placed in the hand before rigor mortis has set in is not grasped, but drops
20. For other cases of ante-natal rigor mortis see Brit. Med. Jour., 1304, Vol. I, pp.
1,014 and 1,312; Jour. Surg. Gynazc. and Obstet., May 1925, p. 725.