How is rigor mortis formed?
A postmortem phenomenon. Refers to the process in which the body gradually hardens and becomes stiff after death.
It usually takes about 1-3 hours after death, the muscles contract slightly, the joints can't flex, and rigor mortis begins to appear; 12- 16 hours later, rigor mortis spread all over the body. Because of the different external temperature, constitution and cause of death, it can be early or late.
The order of rigor mortis can be used as an aspect to judge the length of time after death.
After death, the muscles of the whole body relax rapidly, such as facial muscles, losing the face with rich expressions before death; Masseter muscle relaxation makes the jaw droop: the smooth muscle of the pupil relaxes, making the pupil in a medium size, and most of the pupils contract or disperse and disappear shortly after death; Anal sphincter relaxation, fecal outflow; Due to muscle relaxation, the pressed part of the corpse will form an indentation corresponding to the pressed object. However, this phenomenon of muscle relaxation will soon pass. After a short time, the muscles gradually become stiff and hard, accompanied by mild contraction, so that all joints are fixed, such as mouth can not be opened, neck can not be bent, limbs can not be extended and flexed. This phenomenon of stiff muscles after death is called rigor mortis.
The cause of rigor mortis is still under discussion in forensic science in China, and there is no unified conclusion. Most people think that rigor mortis will occur after death because of hypoxia in body tissues, the cessation of aerobic metabolism in the body, the decline or even termination of adenosine triphosphate synthesis in muscles, and the continuous decomposition, so that its content continues to decrease. Because muscle can only remain elastic and soft when there is enough adenosine triphosphate, if its content decreases or even disappears, it will make muscle contraction stiff.
In general, rigor mortis appears at 1 ~ 3 hours after death, some as early as 10 minutes or 7 ~ 8 hours after death, but generally not earlier than 10 minutes or 7 ~ 8 hours later. In rare cases, there are 16 ~ 18 after death. After 4 ~ 6 hours, it spread to the whole body, forming rigor mortis. The development order of rigor mortis can be divided into ascending order and descending order. Generally speaking, rigor mortis starts from the masseter muscle and gradually develops to the neck, upper limbs and lower limbs, which is in descending order. In a few cases, on the contrary, rigor mortis develops upward from the lower limbs, which is called ascending order. Under the condition that the temperature is suitable and the corpse will not rot quickly, the rigor mortis will begin to ease after 24-48 hours or more. The order of relieving rigor mortis is the same as the order of forming rigor mortis, that is, the muscle group with rigor mortis first relieves first. In most cases, complete remission of rigor mortis will occur within 3-7 days after death.
Before the rigor mortis is fully formed, that is, within 4-6 hours after death, if the rigor mortis that has already occurred is forcibly destroyed, it will soon reappear. If rigor mortis is completely formed, that is, 7-8 hours after death, rigor mortis will not appear again. Therefore, for the moved corpse, it is usually necessary to test whether the mandibular joint is stiff to judge whether the rigor mortis exists or relieves. Because the intensity of rigor mortis varies from place to place, the strongest of which is the mandibular joint.
The appearance, disappearance and strength of rigor mortis are influenced by many factors inside and outside the corpse. First of all, it is affected by the ambient temperature. When the ambient temperature is high, rigor mortis appears early and disappears early, otherwise, it appears late and disappears late. Secondly, it will be affected by its own physical condition. The rigor mortis of the elderly, children and the infirm will appear early and disappear early, and the degree is not strong.
Mature infant rigor mortis is obvious, while immature infant rigor mortis is weak and lasts for a short time, which is sometimes difficult to detect. Muscular adult rigor mortis appears slowly and lasts for a long time. Third, affected by the cause of death.
Spastic drug poisoning, tetanus, neck strangulation, gunshot wound, electric shock, septicemia or wasting diseases can all promote the development of rigor mortis, which occurs early and disappears early. Phosphate poisoning, mushroom poisoning, edema and muscle paralysis, due to muscle degeneration, rigor mortis appears slowly and weakly.
Stiffness of corpse is of great significance in forensic medicine. Because it is an early postmortem phenomenon, as long as there is a dead body, death can be confirmed. Therefore, it is often used as a criterion for judging death. Because it can fix the posture after death, it is also helpful to judge the state at death. The occurrence and development of zombies are regular and can be used to infer the time of death. According to the damaged and fixed posture of the stiff corpse, it can be inferred whether it moves after death.