Early post-mortem changes | Thanatology ~ Forensic medicine | Med Vids Made Simple

Summary

In this video, the early post-mortem changes after death are explained, focusing on algor mortis (post-mortem cooling), livor mortis (post-mortem staining), and rigor mortis (muscle stiffening). The video covers how body temperature drops in phases after death, the discoloration of dependent areas due to blood pooling, and the process of muscle stiffening caused by calcium buildup. It also highlights how these changes help determine the time since death, body position, and possible causes of death. Viewers are encouraged to subscribe for more forensic content.

Takeaways

• 😀 Algor mortis (post-mortem cooling) begins after death as the body temperature starts to fall, initially influenced by residual metabolic activity in remaining tissues.
• 😀 The cooling process progresses through three phases: plateau, linear decrease, and terminal plateau due to bacterial activity, with the temperature never reaching baseline.
• 😀 Factors such as heat stroke, tetanus, and septicemia can delay the decline of body temperature after death.
• 😀 Liver mortis (post-mortem staining) is characterized by a bluish-purple discoloration caused by blood pooling in dependent body parts, helping forensic experts determine the body's position at death.
• 😀 Liver mortis occurs in stages: initiation (30 minutes), confluent staining (4 hours), and fixation (6-8 hours), after which the staining pattern is fixed, regardless of body position.
• 😀 Secondary lividity occurs if the body is repositioned before fixation, leading to new areas of staining in dependent body parts.
• 😀 Special staining patterns, such as the 'glove and stocking' pattern in hanging, help forensic experts determine the cause of death.
• 😀 Rigor mortis (muscle rigidity) develops after death, starting with primary flaccidity (relaxed muscles), followed by muscle rigidity, and finally secondary flaccidity as the rigor fades.
• 😀 Rigor mortis onset typically occurs 1-2 hours after death, becomes fully established after 6 hours, and lasts longer in cooler environments (24-48 hours) and shorter in warmer climates (18-36 hours).
• 😀 The process of rigor mortis is caused by calcium leakage into muscle cells, leading to sustained muscle contraction due to the lack of ATP for muscle relaxation.
• 😀 Forensic investigators use algor mortis, liver mortis, and rigor mortis to estimate the time of death, body position at death, and the sequence of post-mortem changes.

Q & A

What is Algor Mortis and how does it affect the body after death?

Algor Mortis, also known as post-mortem cooling, is the process where the body's temperature starts to decrease after death. Initially, the body maintains its temperature due to ongoing metabolic activity in the still-living tissues. After the tissues die, the metabolism slows down, and the body temperature starts to fall. This decrease occurs in three phases: an initial plateau phase, a linear decrease in temperature, and a terminal plateau phase, where the temperature stabilizes but does not return to baseline due to bacterial activity.

What are the phases of temperature change during Algor Mortis?

The three phases of Algor Mortis are: 1) the initial plateau phase where there is no temperature decrease due to ongoing metabolic activity; 2) a linear decrease phase where the temperature falls at a rate of 0.4 to 0.6°C per hour for 12-16 hours; and 3) the terminal plateau phase where the temperature stabilizes, but bacterial activity keeps it above baseline.

How does external temperature affect the rate of Algor Mortis?

External temperature plays a role in how quickly Algor Mortis occurs. In cooler environments, the cooling process is slower, while in warmer environments, it happens more rapidly. This can influence the time frame used to estimate the time since death.

What is the significance of measuring core body temperature after death?

Measuring core body temperature, typically at the rectum or sub-hepatic space, helps estimate the time of death. The temperature decline pattern gives forensic investigators clues about how long it has been since death occurred, aiding in the determination of the time since death.

What is Liver Mortis and how does it occur?

Liver Mortis, also known as post-mortem staining or hypostasis, is the pooling of blood in the body’s dependent parts, creating a bluish-purple discoloration. This occurs as gravity causes blood to settle in the lowest parts of the body. In the first 30 minutes, discoloration starts in the dependent areas, and by 6-8 hours, the staining becomes fixed, even if the body’s position changes.

What is secondary lividity, and how does it affect post-mortem staining?

Secondary lividity occurs if the body’s position is changed before the staining becomes fixed. For example, if a person dies in a supine position but is moved to a prone position before liver mortis is fixed, post-mortem staining will occur in the front of the body instead of the back.

What are some conditions that can prevent or alter the appearance of liver mortis?

Conditions such as drowning (where the body’s position changes continuously in water) or severe blood loss (which leaves insufficient blood to pool in the dependent areas) can prevent liver mortis from appearing. Additionally, certain poisons may alter the color of post-mortem staining.

What is rigor mortis and how does it differ from cadaveric spasm?

Rigor mortis, or post-mortem rigidity, is the stiffening of muscles due to chemical changes after death. It does not occur immediately after death, unlike cadaveric spasm, which is the immediate and sustained contraction of muscles, typically seen in cases like suicide by firearms. Rigor mortis develops in stages, starting with primary flaccidity, followed by rigidity, and then secondary flaccidity.

What causes rigor mortis and how does it progress?

Rigor mortis is caused by the accumulation of calcium in muscle cells after death, which leads to sustained muscle contraction. This process begins when ATP levels drop significantly. Rigor mortis progresses from the involuntary muscles (like the heart) to the voluntary muscles (like the eyelids, face, limbs, and toes). It typically begins 1-2 hours after death and becomes fully established within 6 hours.

How do temperature and environmental conditions affect the duration of rigor mortis?

The duration of rigor mortis is influenced by the temperature of the environment. In cooler environments, rigor mortis lasts longer (up to 24-48 hours), while in warmer environments, it lasts for a shorter time (18-36 hours). This variability helps forensic experts estimate the time of death.