Applied Ballistics Flashcards
Entrance wounds have
endocranial bevelling
Exits wounds have
ectocranial bevelling
What are bone chips?
A small chip or chipping on an entrance point that occurs at entrance. Can be mistaken for exit wounds
How does double bevelling happen?
Hard pressure of gun pressed to a head and causes double entrance bevelling. Gas causes it. Spinning may also, or backwards release of pressure.
Where is double bevelling only found?
Entrance wounds
What bones wont show bevelling well or at all?
Thinner bones (temporals, orbital etc)
What gives bone some elasticity?
Periosteum
What natural bone feature can be mistaken for bevelling?
natural formen. They are smooth and no trabecular bone seen.
What are the two common exit wounds?
round or oval. Mostly irregular from yaw
What is bigger, exit or entrance?
Exit
What causes the larger exit woulds?
usually yawing or tunbling
What are the two secondary fractures?
radiating and concentric
What are the determinants of secondary skull fractures?
kinetic energy and distance from muzzle to target
What are some examples of secondary fractures being dependent on?
intracranial pressure, bone thickness, density, morphology, sutures formina etc
Bone is being ____ on impact side and _____ on opposite side
compressed, distracted (tension)
How are secondary fractures formed from bullet brain interactions?
emporary cavity being formed and increased pressure against endocranium. cavitation.
What does brain cavitation causing secondary fractures depend on?
range of discharge and KE of bullet.
Where is the most common site for secndary fracture?
orbital plates
When are secondary fractures common?
hard contact wounds (gun pressed to head). increase intracranial pressure bu temporary cavity
Distant wounds causing secondary fractures are cause by?
cavitation, NOT gases
What is the size of the temp cavity dependent on?
amount of KE lost by bullet and tissue shedding
What is created first in secondary fracturing?
radial then concentric
Speed of fracture is faster than bullet in some cases?
yeye dawg
What stress causes concenttic?
tension on the inner table and proceed externally. The shearing force may bevel outward
When the brain absorbs the bullet KE, what happens?
the KE blows out plates of plates of bone by the expanding of brain tissue.
What is refective of the amount of KE
More generations of concentric fractures
If radial fratcure beats bullet, what does the exit wound look like?
its like a half circle becuase it absorbs some of the KE
If signficant KE at exit?
There may be radiating fractures at the exit site that stop at the entrance concentric or radial fracture lines
Radial fractures are longer and more generations of concentric in entrance or exit?
entrance
Blunt vs ballistic?
blunt force bone in, ballistic force bone out. Opposite bevelling
Tangential has what shape and at what angle?
keyhole «90
Tangential may cause what
scuffing/scratching, gutter wounds, superficial penetrating and keyhole wounds
What are the three gutter wounds?
1- barely nick the ectocranium
2- reach diploe and some fracturing
3- all three layer impacted but no brain contact. there is fratcuring and shattering
What are superficial penetrating wounds?
very shallow with formal entrance and exit. common in sucide attempts
Raised bone (fractures) on key hole is _____ to direction of travel?
anterior. the chip could peace
When are irregular wound entrances found?
When the bullet has been deformed (either designed or by external contact etc). Yaw and tumbling. fragmentation.
When are irregular wound exits found?
internal richoet, bullet deformity, tangential mpact pre existing fractures or radial fracture. sometimes if FMJ are high enough energy they will cause a huge hole
What is a difference between secondary fracturing in long bne ans skull?
Long bones secondary may happen so quite on thinner bones that it shatters bone prior to exit
What makes exit wounds in long bones unrecognizable?
antecedent fragmentation
What kind of factures can be formed from a long bone bullet wound?
butterfly fractures
What happens in small bones?
they usually shatter completely and are unrecognizable
What type of examination may revial presence of metal?
radiographic exams
Why are kid bones hard to identify exit and entrance wounds?
the bones are so thin
What is a bullet wipe?
a coating a bullet gets by travelling through the bore of a gun froma variety of elements. Rubbed off onto skin or clothing
What are lead wipes?
Lead deposits left on entrance and exits wounds
What reduces terminal velocity?
long trajectory, intermediate targets, rocochet and energy dissipation in tissue
What happens to teeth>
sharp-edged entance and bevelling on exits
Alteration of entrance and exit wounds?
surgical intervention, incomplete recovery, animal gnawing, severe weather, close wounds impringing on each other
Sequencing of fractures approach
define in order:
entrance, exit, radaiting, concentric
then trace radiating fractur line from entrance or exit to its end. follow puppes rule
What are indirect cerebral injuries?
cranial injurt with no contact from energy dissipatin for a wound site (ex at petrous temporal)
Bullet calibre and wound size? Why?
no direct linear relationship b/w bullet calibre and wound size
due to yawing and fragmentation, sutures etc
Joint positioning?
Deduce direction of wound from allignment of injuries in jointed bones
What is a souvenir bone?
Find bullet embedded in bone in a nonvital area and the person lives their life.
to injure bone:
direct bullet bone contact, or indirectly through cavitation
what is bullet lodgement?
where the bullet ended up
GSWs can be
1) glancing off
2) fracturing
3) penetrating
4) perforating
scalp penetration
scalp will impact, usually low velocity and slide a short distance
if penetrate but not perforate skull?
penetrate one side but leave only a plastic change on the other side where exit would occur
what increases liklihood of perforation
larger calibre and FMJ and close up and more gun powder and thinner bones
richocet external vs internal?
external, outside body
internal, inside the body like on a bone
internal skull richocet?
usually will hit the other side of the skull and just follow the flow of the skull perimeter
primary and secondary fractures?
primary- plug and spall
secondary- radiating and concentric fracturs
plug vs spall?
plu- bone directly from the nose of the bullet
spall- produces the bevelling
High energy vs low energy
low energy- just plug and spall
high energy- causes the secondary fracturing
WHat are the 4 bullet wound shapes?
1) round
2) oval
3) keyhole
4) irregular
which would shapes are commonly found in entrance vs exit wounds?
entrance (round, oval, keyhole)
exit (oval, keyhole. irregular)
bevel
a slanted or sloping edge
why is bevelling important
primary indicator of bullet direction
