Sharp Force Injuries

Front 1

How many types of sharp force injuries are there and what are they?

Back 1

-Cut/incised wound
-Stabs

Front 2

Definition of sharp wounds

Back 2

Wounds caused by objects that have a sharp edge or by pointed instruments

Front 3

Definition of stab wounds

Back 3

Depth of wound is greater than length on skin

Front 4

Factors affecting size and shape of stab wound

Back 4

-Weapon used
-Direction of thrust (turning or dragging blade)
-Movement of the blade within the wound, or movement of the victim
-Characteristics of the skin (Langer's lines)
-State of tension or relaxation of the skin stabbed

Front 5

How long are stab wounds?

Back 5

Equal to, greater or less than width of blade

Front 6

How deep are stab wounds?

Back 6

Equal to, or greater than length of knife blade

Front 7

Langer's lines and how they affect wounds

Back 7

-Elastic fibers in the dermis
-Wounds parallel to these lines tend to be slit-like
-Wounds perpendicular to these lines are gaping since elasticity is cut

Front 8

Appearance of a single-edged blade wound

Back 8

-One sharp and one blunt edge
-Some may have 2 sharp edges if the back of the blade is sharp at the point or if the blade is inserted at an angle
-Ricasso can transform a sharp edge into a blunt one
-May have a tail continuing the sharp edge, where the blade was pulled out and dragged across the skin

Front 9

Ricasso

Back 9

An unsharpened length of blade just above the handle on a knife, dagger, sword, or bayonet

Front 10

Appearance of a double-edged blade wound

Back 10

Two sharp edges

Front 11

Appearance of serrated knife wounds

Back 11

May show serration of the sharp edge

Front 12

Appearance of scissor wounds

Back 12

-Closed blades give "Z" or zigzag appearance with blunt edges
-Completely separated blades will give appearance of wounds caused by singe-edged blade
-Incompletely separated blades will give appearance of a different combination of blades

Front 13

Appearance of icepick wounds

Back 13

Small, round or slit-like wounds

Front 14

Appearance of barbecue fork wounds

Back 14

Cluster of 2 or 3 wounds

Front 15

Appearance of screwdriver wounds

Back 15

-Rectangular wound with two blunt edges
-Circular wound with abraded margins and four equally separated cuts (Phillips head)

Front 16

Estimating length of blade

Back 16

-Difficult to estimate
-Only time you can truly estimate is when you have the blade going all the way in
-Varies with indentation of body (chest, abdomen) from the impact
-Presence of abrasion at blunt edge usually indicates the full length of the blade penetrated the body

Front 17

Factors that determine amount of force needed

Back 17

-Sharpness of the tip of the blade
-Clothing: type and amount
-Toughness or thickness of the skin in the area stabbed

Front 18

Sharp vs. blunt objects - effect on human body

Back 18

-Sharp object cut and divides tissues
-A blunt object tears, shears, and crushes

Front 19

Definition of incised wounds

Back 19

Wound is longer on the skin than it is deep

Front 20

Can incised wounds give information on type of weapon used?

Back 20

No

Front 21

Homicidal wounds of neck

Back 21

-Usually single cut
-If inflicted from the back, the incision starts high up on the side of the neck opposite the hand used and ends lower on the opposite side of the neck
-If inflicted from the front, cut tends to be short, oblique

Front 22

Suicidal wounds of neck

Back 22

-Resemble homicidal wounds inflicted from the back
-Usually accompanied by several more superficial wounds, "hesitation marks"

Front 23

Suicidal wounds of the extremities

Back 23

Occur on volar and radial aspects of the wrists and are usually multiple

Front 24

Homicidal wounds of the extremities

Back 24

Most commonly found on posterior aspect of arm, forearm, on palmar surface of hands

Front 25

Chop wounds

Back 25

-Caused by heavy instruments
-Incised wounds of skin with underlying comminuted (splintered or crushed) fractures or deep grooves in bone

Front 26

Cause of death

Back 26

Issue that led to mechanism of death (e.g., cut to the neck, stab to the heart, intoxication)

Front 27

Mechanism of death

Back 27

Ultimate physiological reason for death (e.g., bleeding out, air embolism)

Front 28

Manner of death

Back 28

Homicide, suicide, accident, natural

Front 29

Evidence in sharp force injury deaths

Back 29

-Transfer of DNA, hair/fiber
-Tool marks in firm tissues (cartilage, cortical bone)
-Retained knife/weapon or fragments (take radiographs prior to undressing)

Front 30

Mechanisms of early death in sharp force injuries

Back 30

-Exsanguination
-Air embolism
-Other injuries

Front 31

Mechanisms of delayed death in sharp force injuries

Back 31

-Infection
-Paralysis/immobilization
-Other complications of the original injury

Front 32

Manner of death in sharp force injuries

Back 32

-Homicidal
-Suicidal