Module 6: Forensic: blunt impact to firearms

Question 1

What are blunt impact injuries?

Answer 1

Rough edges and bridging strands of tissue

• -abrasions: scraping of outer layers of skin
• –contusion: disruption of subcutaneous blood vessels
• -laceration: tearing or rupture of skin by blunt force
• -skeletal fractures

Question 2

What is a scalp laceration?

Answer 2

Scalp lacerations: important to identify site and number of impacts
–single impact (assault or fall) and many impacts

Question 3

What is seen in a basal skull fracture?

Answer 3

Raccoon eyes (periorbital contusions), battle sign (Hemorrhage in mastoid process) and blood/CSF rhinorrhea or otorrhea

Question 4

What are the two different types of intracranial hemorrhage?

Answer 4

Epidural hemorrhage (b/w skull and dura)
–caused by blow to side of head with temporal bone skull fracture and laceration of middle meningeal artery
Subdural hemorrhage (b/w dura and arachnoid )
–due to torn bridging veins with or without fracture
–caused by rapid acceleration or rotational force

Question 5

What is a focal traumatic brain injury?

Answer 5

Cortical contusions: bruise of the brain (often seen with subarachnoid bruising)
–contrecoup contusion
Cerebral laceration

Question 6

What is a diffuse traumatic brain injury?

Answer 6

Concussion: transient and highly variable disturbance of neurological function following trauma
–blow to head is not required; pre disposition= APO-E

Question 7

What is a diffuse traumatic brain injury?

Answer 7

Diffuse axonal injury: rotational acceleration (Shearing of axons as they are stretched beyond elastic point with rotational force)

Question 8

What are the various types of chest injuries?

Answer 8

Fracture
Cardiac contusions and lacerations 
Aortic Lacerations (deceleration injury and crush injury)
Pulmonary contusions and lacerations 
Diaphragmatic lacerations

Question 9

What is the sequelae in chest injuries?

Answer 9

Flail chest 
Hemopericardium 
Hemothorax
SQ emphysema 
Pneumothorax

Question 10

In regards to chest injuries what is a deceleration injury?

Answer 10

Heavy heart keeps moving while tethered to vertebrae at distal arch

Question 11

In regards to chest injuries what is a crush injury?

Answer 11

Osseous pinch (Crushed between chest and spine)

Question 12

What are examples of abdominal and pelvic injuries?

Answer 12

Liver lacerations
spleen lacerations
mesenteric lacerations
Pelvic fractures

Question 13

What are examples of extremity injuries?

Answer 13

Soft tissue injury
Long bone fracture
Traumatic amputations

Question 14

What are pedestrian transportation injuries?

Answer 14

Primary impact with bumper
Secondary impact with windshield (spiderweb pattern of broken glass)
Tertiary impact with roadway

Question 15

What are the type of occupants in a transportation injury?

Answer 15

Child vs adults
Restrained/Unrestrained 
Type of vehicle (airbag and size)
Type of crash (frontal, side, rear, roll over and ejected)
Speed

Question 16

What types of injuries do you see in a head on collision?

Answer 16

Face and head injury, cervical spine injury, braced leg fracture and pelvic fracture

Question 17

What types of injuries do you see in a rear impact collision?

Answer 17

More neck injury at lower speed

–hyperflexion/extension of neck with cervical spine fractures

Question 18

What type of injuries do you see in a side impact collision?

Answer 18

Injuries from intrusion and lateral flexion of neck

Question 19

What type of injuries do you see in a rollover accident?

Answer 19

Unrestrained passengers commonly ejected – amputations and patterned injuries

Question 20

How would you tell the difference on exam in a fall vs an assault?

Answer 20

Fall: level of hat line, protuberant areas, one plane and contrecup contusions
Assault: above hat line, recessed areas, more than one plane, fracture contusions

Question 21

What is shaken baby syndrome?

Answer 21

Acceleration and deceleration forces lead to:

• -intracranial injuries
• -retinal hemorrhages
• -long bone fractures
• -posterior rib fractures

Question 22

What are the clinical feature of shaken baby syndrome?

Answer 22

Mental status changes
Increased ICP 
Resp changes 
Suggestive bruising 
Retinal hemorrhage

Question 23

What is found on clinical and autopsy findings?

Answer 23

Scalp hematomas, subdural, subarachnoid, perioptic nerve and retinal hemorrhages

Question 24

Who are the perpetrators in shaken baby syndrome?

Answer 24

Biological father 
BF
Female sitter 
Mother 
Male Sitter 
Stepfather

Question 25

What are common explanations in regards to shaken baby syndrome?

Answer 25

Accidental Injury 
SODDI 
No impact/assault 
Re-bleed of an old subdural hemorrhage
Second impact syndrome due to two minor injuries

Question 26

What are sharp injuries?

Answer 26

Incised (Cuts, slashes) or stab wounds

Question 27

Sharp injuries are variable in size and shape, what are the various sizes and shapes?

Answer 27

Type of weapon 
Depth of penetration: wound depth doesnt always match blade length b.c tissue is very compressible 
Movement of victim.perpetrator 
Movement of instrument 
Orientation of body

Question 28

What are hilt marks?

Answer 28

part of handle of the blade that leaves a mark

Question 29

What are Langer’s lines?

Answer 29

Lines of elasticity (orientation of collagen fibers in dermis) that determine scarring

• -wound perpendicular to the line: gashing wound
• -used by surgeons for suturing

Question 30

How can you tell the difference b/t self inflicted an homicide?

Answer 30

Self: history, hesitation marks, not through clothing and rarely head and neck
Homicide: multiple, deep/chops, defense wounds and neck

Question 31

What are considered small firearms and ammunition?

Answer 31

Handguns
Rifles
Shotguns
Ammunition: bullets, shotgun pellets and shotgun slugs

Question 32

What are wound ballistics?

Answer 32

Kinetic energy of bullet = weight x velocity2/2g
Temporal and Permanent Cavity:
–tem: shearing, compression and stretching of adjacent tissues as energy is lost from bullet
–perm: actual tract of crush injury by bullet
Density and strength of tissue
Angle of yaw or tumbling at impact
Configuration of bullet

Question 33

What are the various wound paths?

Answer 33

Perpendicular to skin = concentric abrasion

Angled entry = eccentric abrasion

Question 34

What is the appearance of an entrance wound?

Answer 34

Ovoid 
Muzzle abrasion 
Gunshot residue 
Marginal abrasion 
Tissue loss

Question 35

What is the appearance of an exit wound?

Answer 35

Irregular 
No muzzle abrasion 
No gunshot residue 
No abrasion ring 
No tissue loss