5. Forensic Autopsy – Trauma & Injury

Connolly (Atlas): Ch. 4 (injury documentation sections), Ch. 7 (photography – injury documentation) Di Maio (Handbook): Ch. 6 (Blunt Force Injury) Ch. 7 (Sharp Injuries) Ch. 8 (Gunshot Wounds) Ch. 9 (Asphyxia)

What are the primary purposes of a medicolegal (forensic) death investigation?

• Determine the cause and manner of death. • Identify the deceased. • Estimate the time of death. • Collect and preserve evidence. • Document injuries and natural disease. • Determine how injuries occurred. • Provide expert testimony in legal proceedings.

Which categories of death require medicolegal investigation?

• Violent deaths (accident, homicide, suicide) • Suspicious deaths • Sudden and unexpected deaths • Deaths without a physician in attendance.

Which two categories account for the majority of medicolegal deaths?

• Sudden, unexpected natural deaths • Accidental deaths (e.g., motor vehicle collisions, drug overdoses, falls in the elderly).

Why are many natural deaths investigated by the medical examiner?

Because they are sudden and unexpected and often occur without a documented medical history or recent physician care.

Which accidental deaths commonly become medicolegal cases?

• Motor vehicle accidents • Drug overdoses • Falls in elderly individuals.

Where did the coroner system originate?

Feudal England.

What is the primary difference between a coroner and a medical examiner?

A coroner is usually an elected official who is not required to be a physician, whereas a medical examiner is a physician.

Which five factors determine the severity of a blunt force injury?

• Amount of force delivered • Duration over which the force is applied • Region of the body struck • Surface area over which the force is distributed • Nature of the weapon

What are the four major types of blunt force injuries?

• Abrasions • Contusions • Lacerations • Fractures

What is an abrasion?

Removal of the superficial layer of skin caused by friction.

How do antemortem and postmortem abrasions differ grossly?

• Antemortem: reddish-brown • Postmortem: yellow and translucent

What are the three types of abrasions?

• Scrape abrasion • Impact abrasion • Patterned abrasion

What is a scrape abrasion?

An abrasion produced by friction that removes the superficial epidermis.

What finding indicates a scrape abrasion extends into the dermis?

Serosanguinous fluid on the wound surface.

What foreign materials may be embedded within a scrape abrasion?

Gravel, dirt, or glass.

What type of abrasion may be produced by a ligature or noose?

A scrape abrasion.

What is an impact abrasion?

A focal abrasion produced when blunt force strikes the skin perpendicular to its surface, crushing the epidermis.

Where are impact abrasions most commonly found?

Over bony prominences such as the eyebrow, cheekbone, and lateral nose.

What is a patterned abrasion?

An impact abrasion that reproduces the shape or pattern of the object causing the injury.

What is the forensic significance of a patterned abrasion?

It may identify the object or weapon that produced the injury.

What is the timeline for healing of abrasions?

• Scab formation: 4–18 hours • Epithelial regeneration: 30–72 hours • Subepithelial granulation tissue and epithelial hyperplasia: 5–8 days • Regression of epithelium and granulation tissue: ~12 days

What is a contusion?

A bruise produced by blunt force causing hemorrhage into tissues without breaking the skin.

Where can contusions occur?

In the skin and in internal organs.

Can the size or severity of a contusion accurately estimate the amount of force applied?

No. Contusion size is influenced by tissue location and the victim's health, not just the force of impact.

What factors influence the appearance of a contusion?

• Victim's health • Location of the injury • Age of the bruise

How is the age of a contusion estimated?

By histologic examination and color changes.

What is the color progression of a healing contusion?

Red → Dark blue/purple/black → Violet → Green → Dark yellow → Pale yellow → Resolution

What is the only reliable color conclusion when aging a bruise?

A yellow contusion is at least 18 hours old.

What is a laceration?

A tear of tissue caused by shearing or crushing blunt force.

What tissues may sustain lacerations?

Skin, soft tissue, and internal organs.

What type of object commonly produces a linear laceration?

A long, thin object.

What type of object commonly produces an irregular or Y-shaped laceration?

A broad, flat object.

Compare abrasions, contusions, and lacerations.

• Abrasion: superficial loss of epidermis due to friction. • Contusion: hemorrhage into tissue without skin disruption. • Laceration: tear of tissue caused by blunt force.

Compare the three major soft tissue injuries caused by blunt force trauma.

Abrasion

• Superficial epidermal injury

• Caused by friction

• Minimal bleeding

Contusion

• Hemorrhage into tissue

• Skin remains intact

• Caused by blunt impact

Laceration

• Tear of tissue

• Caused by crushing or shearing force

• May involve skin, soft tissue, or internal organs.

What are the two major fracture mechanisms emphasized in blunt force forensic pathology?

• Penetration fractures • Crush fractures

What is a penetration fracture?

A fracture produced by a penetrating object, such as a gunshot wound.

What is a crush fracture?

A fracture produced when a large force is applied over a broad surface area, resulting in extensive soft tissue injury and often comminuted fractures.

Which type of fracture is commonly associated with extensive soft tissue injury?

Crush fractures.

Which fracture pattern is commonly produced by crush injuries?

Comminuted fractures.

What is the most common cause of crush fractures in forensic practice?

Pedestrian-versus-motor vehicle accidents.

What indirect mechanisms can produce fractures?

• Traction • Angulation • Rotation • Vertical compression • Angulation + compression • Angulation + rotation + compression

Which fracture results from traction?

A fracture produced when bone is pulled apart by tensile forces.

Which fracture mechanism occurs when a bone is bent until it snaps?

Angulation.

Which fracture pattern is classically produced by rotational forces?

Spiral fracture.

What fracture mechanism occurs when one bone is driven into another?

Vertical compression.

What fracture pattern is produced by angulation combined with compression?

A curved fracture line.

What fracture pattern is produced by angulation, rotation, and compression?

An oblique fracture.

How does fracture healing differ between children and adults?

• Children: solid healing in approximately 2–3 months. • Adults: solid healing in approximately 3–5 months.

Where are blunt force defense wounds most commonly found?

The hands, wrists, forearms, and arms.

What are the two major mechanisms of blunt force injury to the head and neck?

• Impact injuries • Acceleration/deceleration injuries

What are impact injuries?

Injuries that occur when the head strikes, or is struck by, an object.

What injuries may result from impact injuries?

• Soft tissue injuries • Skull fractures • Brain contusions • Epidural hematoma • Subdural hematoma • Intracerebral hemorrhage

What are acceleration/deceleration injuries?

Injuries caused by rapid movement of the brain within the skull, producing shearing and tensile forces.

Which intracranial hemorrhage is classically associated with acceleration/deceleration injuries?

Subdural hematoma.

Which facial bones are most commonly fractured in assaults and motor vehicle accidents?

• Mandible • Maxilla • Zygoma • Zygomatic arch

What are the five categories of maxillary fractures?

• Dentoalveolar • Le Fort I • Le Fort II • Le Fort III • Sagittal

Which factors influence whether a skull fracture occurs?

• Thickness of the overlying scalp • Magnitude and direction of force • Whether the head strikes a hard surface

Why are basilar skull fractures relatively common?

Because the base of the skull is structurally weaker than the calvarium.

What is the most common direct traumatic injury to the brain?

Cerebral contusions.

Which lobes are most commonly affected by cerebral contusions?

The frontal and temporal lobes.

What is a contrecoup injury?

A brain injury that occurs on the side opposite the point of impact.

What are the four general types of rib fractures?

1. Spontaneous 2. Therapeutic (CPR-related) 3. Direct violence 4. Indirect violence

What causes spontaneous rib fractures?

Primary bone disease or bone tumors.

Which rib fractures are commonly associated with CPR?

Therapeutic rib fractures, most commonly involving the left ribs.

What injuries may result from direct rib fractures?

• Pulmonary contusions • Lung laceration • Pneumothorax

What commonly causes indirect rib fractures?

Falls from height or compression injuries such as a vehicle rolling over the chest.

What complications can result from rib fractures?

• Hemothorax

• Pneumothorax

• Cardiac impalement

• Pleurisy

• Empyema

• Pneumonia

Compare impact injuries and acceleration/deceleration injuries of the head.

Impact injuries

• Head strikes or is struck by an object

• Cause skull fractures, scalp injuries, cerebral contusions, epidural hematomas, intracerebral hemorrhage

Acceleration/deceleration injuries

• Brain moves within the skull

• Produce shearing and tensile forces

• Classically cause subdural hematomas