Muscle stiffness

Muscle stiffness is a kind of muscular tissue state of the corpse, which begins to manifest itself after 2-4 hours after the time of death. Skeletal muscle corpse gradually begin to thicken, which leads to their shortening. Shortening of the muscles in turn creates an obstacle for making "passive movements in joints of the lower jaw, upper and lower extremities. Extension of the limbs in a state of apparent rigor, you must use considerable physical effort.
In the formation, development and change of rigor Mortis muscle crucial belongs biochemical processes. As is known, contractility live muscle tissue due to the presence of the myofibrils muscles specific contractile protein - actomyosin. Muscle contraction is a complicated physiological process, consisting of a series of consecutive biochemical transformations, which are mainly determined by the state of adenosine triphosphate (ATP). In her presence made the reduction of myofibrils, in its synthesis it's their relaxation. ATP synthesis is because the myosin has the property adenosinetriphosphatase, which breaks down ATP, releasing a great amount of energy, causing the muscle goes into a relaxed state of mind. The resynthesis of ATP is the enzyme transfer of a phosphate group from creatine phosphate to ADP. ATP synthesis is associated with glycolytic and oxidative processes.
Breach education ATF fast-acting poisons (e.g. strychnine poisoning)that suppress the glycolytic and oxidative processes, leading to the complete exhaustion of ATF and kreatinfosfata. The resulting high concentration of ions of calcium leads to the formation of long contractures.
Muscles of a living organism are always in a good shape due to the fact that the majority of ATP in muscle tissue is in a bound state. After the death of a certain amount of ATP is free. This is enough to muscles were relaxed within 2-4 hours after death. The gradual disappearance of ATP leads to the formation of rigor Mortis. The muscle development of rigor Mortis in the corpse is a consequence of the qualitatively another process. In muscle tissue leads to irreversible process, expressed in the formation of insoluble gel - F-actomyosin, which is why muscle lose flexibility, becomes dense. Full development of rigor Mortis in all groups of muscles is achieved after days from the moment of death, and then begins the process of gradual resolution of rigor Mortis. Because actomyosin in terms of loss of viability of muscle tissue and the unfolding processes of rotting and autolysis becomes soluble, comes its disorganization, it loses its original quality. Externally this is manifested in muscle relaxation - the resolution of rigor Mortis. Resolution muscle rigor mainly depends on the ambient temperature. Thus, at room temperature relaxation of muscles usually observed by the end of the second - the beginning of the third day, at low temperature modes muscle stiffness persists over a long time.
Muscle stiffness you can break artificially enough to use physical force and stretching stiff muscles (extension of the joint limb). ATF completely disappears from the muscle tissue not earlier than in 10 hours after death. Abnormal muscle stiffness in this period has the ability to recover, but not completely. Given this possibility, attached to the arm of the corpse of a gun, knife or other objects can be tightly clamped, imitating allegedly lifetime actions that may lead to wrong conclusions.
After a full breakdown of ATP, after 10-12 hours after the time of death, abnormal muscle stiffness is not restored (the muscles remain in a relaxed state).
Muscle stiffness develops not only in the skeletal muscles, but in the smooth. The origin of muscular rigor in the heart and the smooth muscle of other bodies develops simultaneously with the same process in skeletal muscles, but its resolution is attained earlier. After stopping the heart is in a state of diastole. In process of increase muscle rigor Mortis is developing so-called post-mortem systole. Especially strongly expressed stiffness in the muscle of the left ventricle of the heart with strong muscular wall, so the blood from the left ventricle relatively quickly squeezed. In the right ventricle of the heart muscle layer of thin, so in his oral amount of blood, as a rule, is much more than in the left. If the myocardium painful changed, such as when fatty, stiffness of heart muscle almost never happens.
In the empty stomach and intestines can be pronounced folds of mucous membrane. After the resolution of rigor Mortis muscle layer mucosa appears to be smoothed. You can often see in a reduced state of the bladder.
Develop muscle rigor Mortis is affected by both external and internal factors. At high ambient temperatures and dry air stiffness is developing faster and at lower temperatures in a wet environment slower. Well-developed muscles promotes rapid development of rigor Mortis and, on the contrary, people who died from severe sepsis and other diseases accompanied by exhaustion, muscle stiffness are weak or even absent.
Muscle stiffness is developing simultaneously in all groups of muscles, but ends at different times depending on their weight, physiological diameter of muscles, localization of points of attachment to the bone formations and temperature of parts of a corpse.
The literature describes rare cases of so-called cataleptic muscle rigor Mortis, that is, when it occurs in the moment of death, keeping a lifetime position. Cataleptic stiffness may occur when death was preceded by a sharp cramping and reserves ATP has been sharply depleted before the onset of death, such as the poisoning of convulsive toxins, at death from tetanus, etc. In these cases lifetime contraction of the muscles pass directly to stiffness. Cataleptic muscle stiffness can also occur when the destruction of the medulla oblongata, especially with gunshot injuries.
The presence or absence of rigor Mortis is logged when the initial examination of the corpse on the spot detection (accidents), as well as in the study of the corpse in the morgue. To identify the muscle rigor determine whether density (or relaxation) of the muscles and the opportunity to make a "passive" movement in large joints, it should be remembered that the stiffness could be broken before, for example when removing clothes.
The definition of muscle rigor Mortis at external examination of the corpse allows you to do some expert conclusions. Stiffness is a reliable sign of death, allows to judge about the limitations of its occurrence, sometimes contributes to the conservation lifetime posture and in some cases may be of diagnostic value judgments about the possible cause of death.
In forensic practice meets another kind of posthumous muscle contracture, which is formed due to coagulation of protein from exposure to high (above 50 C) temperature. This heat muscle stiffness observed, for example, at the dead bodies recovered from fires. While the corpse takes a peculiar situation of "posture boxer" (see Chapter 24).