Abrasion | What are the causes of abrasion? | What are types of abrasion

Summary

In this video, The Nerd Medic explains abrasions, which are mechanical injuries that remove the outer layers of the skin (epidermis and papillary dermis). The video details the types of abrasions based on the direction of force, such as scratches, grazes, pressure abrasions, and pattern abrasions. It also covers the importance of factors like force direction, time since injury, and whether an abrasion occurred before or after death (antemortem vs. postmortem). The medical and legal significance of abrasions is also discussed, including their use in determining injury timing and weapon type.

Takeaways

• 🔍 Abrasions are mechanical injuries that involve the removal of the superficial layer of the skin, specifically the epidermis and the upper layer of the dermis.
• 🛠️ Abrasions can occur due to two types of force: tangential (along the surface) and perpendicular (90-degree angle to the surface).
• ✏️ Tangential force abrasions include scratches (single-line injury) and grazes (multiple scratches in a small area).
• 💥 Perpendicular force abrasions result in pressure abrasions or pattern abrasions (like tire marks or ligature marks).
• 📏 Examination of abrasions includes noting the site, size, shape, direction of force, edges, discharge, contamination, time since injury, and whether it was caused before or after death.
• 📅 The color of the abrasion’s scab can indicate its age: raw (less than 12 hours), red (12+ hours), reddish-brown (2-3 days), brown (4-5 days), and black (6-7 days).
• 🕵️‍♂️ Anti-mortem abrasions have vital reactions, healing, and are often bright red. Postmortem abrasions lack these reactions and are usually found on bony prominences.
• ⚖️ Medico-legal significance: Abrasions can reveal the type of weapon used, the direction of force, and the time since injury based on scab color.
• 👁️ Corneal abrasions are considered grievous, while most other abrasions are classified as simple hurt.
• 📚 The content emphasizes the educational importance of understanding abrasions for medical and legal purposes.

Q & A

What are abrasions?

Abrasions are mechanical injuries that involve the removal of the superficial layer of the skin, specifically the epidermis and the upper layer of the dermis, known as the papillary dermis.

How are abrasions classified based on the direction of force?

Abrasions are classified based on the direction of force applied. If the force is tangential to the body surface, abrasions can be scratches or grazes. If the force is perpendicular, they can result in pressure abrasions or pattern abrasions.

What is the difference between a scratch and a graze?

A scratch is a single linear abrasion caused by a tangential force, while a graze is multiple scratches in a small area, representing a more extensive abrasion in a 2D arrangement.

What causes a pressure abrasion, and how does it differ from a pattern abrasion?

A pressure abrasion occurs due to tight or forceful pressure over an area of the body, such as a ligature mark. A pattern abrasion occurs when an object, like a tire, imprints its pattern on the skin due to pressure.

What are some key parameters to consider when examining an abrasion?

Important parameters when examining an abrasion include the site, size, shape (pattern), direction of force, edges, discharge, contamination, time since injury, and whether it is an antimortem or postmortem abrasion.

How can the direction of force in an abrasion be determined?

The direction of force in an abrasion can be determined by the presence of epithelial tags, which are found at the end of the force's pathway. The force is always directed towards the epithelial tag.

How can the age of an abrasion be estimated?

The age of an abrasion can be estimated by the color of the scab. A raw abrasion is less than 12 hours old, a red scab indicates more than 12 hours, a reddish-brown scab suggests it is 2-3 days old, a brown scab means 4-5 days, and after 6-7 days, the abrasion becomes black and heals completely.

What are the differences between antimortem and postmortem abrasions?

Antimortem abrasions occur before death and are characterized by a bright red color, presence of a scab, vital reactions, and healing processes. Postmortem abrasions occur after death, usually on bony prominences, and are yellowish, with no scab, vital reactions, or healing.

What is the medical and legal significance of abrasions?

Medically and legally, abrasions are significant wounds, with most being considered simple injuries. However, corneal abrasions are classified as grievous hurt. Abrasions can provide information about the type of weapon used, the direction of force, and the time since the injury occurred.

What are some clues that can indicate whether an abrasion occurred before or after death?

Clues indicating an antimortem abrasion include a bright red color, presence of a scab, vital reactions, and signs of healing. In contrast, postmortem abrasions are usually yellowish with no scab or healing and are typically found on bony prominences.