PHTLS EXAM PREP 2026/2027 | NAEMT 9th Edition
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Section 1: Trauma Fundamentals & Kinematics (Questions 1-18)
Q1. A passenger vehicle strikes a concrete bridge abutment at 45 mph. The driver,
who was wearing a lap belt only, sustains a flexion-distraction injury to the lumbar
spine. Which Newton's law best explains the mechanism of this injury?
A. Newton's First Law (Law of Inertia) - the body continues in motion until acted
upon by the seatbelt
B. Newton's Second Law (F = ma) - the force of the collision is proportional to mass
and deceleration
C. Newton's Third Law (Action-Reaction) - the seatbelt exerts equal and opposite
force on the body
D. Law of Conservation of Energy - kinetic energy is converted entirely to heat energy
Rationale: Newton's First Law explains that the body continues moving forward at 45
mph until the lap belt applies an external force, causing the torso to stop while the
head and upper body continue forward, creating a flexion-distraction force across
the lumbar spine. Option B describes force calculation but not the inertial
mechanism. Option C describes the force pair but not the inertial injury mechanism.
Option D misapplies energy conservation principles.
Correct Answer: A
Q2. A motorcyclist is thrown from his bike at 60 mph and impacts a guardrail. Which
type of energy dissipation accounts for the majority of traumatic injuries in this
scenario?
,A. Chemical energy from fuel combustion
B. Kinetic energy converted to deformation energy in the motorcycle and rider's
body tissues
C. Thermal energy from friction between the tires and road surface
D. Potential energy stored in the motorcycle's suspension system
Rationale: Traumatic injuries result from kinetic energy (½mv²) being dissipated
through tissue deformation, compression, shearing, and cavitation. The motorcycle
and rider's body absorb this energy through structural failure and tissue damage.
Options A, C, and D describe other energy forms that do not directly cause traumatic
injury.
Correct Answer: B
Q3. A pedestrian is struck by a vehicle traveling 35 mph. The primary impact occurs
at the bumper level (tibial plateau), and the secondary impact occurs when the head
strikes the hood. Which kinematic principle describes the relationship between
vehicle speed and pedestrian injury severity?
A. Injury severity is directly proportional to vehicle speed (linear relationship)
B. Injury severity is proportional to the square of the velocity (kinetic energy increases
exponentially with speed)
C. Injury severity decreases as vehicle speed increases due to the "throw effect"
reducing direct impact
D. Injury severity is unrelated to vehicle speed and depends only on pedestrian mass
Rationale: Kinetic energy = ½mv²; doubling speed quadruples kinetic energy. This
exponential relationship explains why higher-speed impacts cause disproportionately
more severe injuries. Option A understates the relationship. Option C is incorrect—
the throw effect does not reduce injury severity. Option D ignores the dominant role
of velocity.
Correct Answer: B
,Q4. A driver in a frontal collision sustains a ruptured descending thoracic aorta at the
isthmus. Which mechanism of injury is responsible for this deceleration injury?
A. Shear forces between the relatively mobile aortic arch and the fixed descending
aorta at the ligamentum arteriosum
B. Direct compression of the aorta by the steering wheel
C. Hyperextension of the aortic wall from whiplash forces
D. Penetration by a fractured sternum fragment
Rationale: The aortic isthmus is anchored by the ligamentum arteriosum; during
rapid deceleration, the mobile arch moves forward while the descending aorta
remains fixed, creating shear forces that rupture the wall. Option B describes direct
blunt trauma, not deceleration. Option C describes a different mechanism. Option D
describes a penetrating mechanism, not the classic deceleration injury.
Correct Answer: A
Q5. A gunshot wound to the thigh from a high-velocity rifle (2,800 ft/sec) produces
extensive tissue destruction beyond the bullet's path. Which phenomenon explains
this injury pattern?
A. Low-velocity cavitation with minimal tissue displacement
B. Permanent cavity formation only, with no temporary cavity
C. Temporary cavitation producing tissue stretch, compression, and remote injury at
distances from the bullet path
D. Chemical burn from propellant gases entering the wound
Rationale: High-velocity projectiles create a temporary cavity 10-30× the bullet
diameter as tissue is accelerated radially, then collapses, causing stretch,
compression, and injury distant from the permanent cavity. Option A describes low-
velocity wounds. Option B ignores temporary cavitation entirely. Option D describes
close-range contact wounds, not high-velocity rifle injuries.
Correct Answer: C
, Q6. An unrestrained rear-seat passenger in a frontal collision sustains a "seatbelt
sign" across the lower abdomen and a Chance fracture of L2. Which mechanism
produces this combination of injuries?
A. The passenger's body submarines under the front seat, causing hyperflexion at the
lap belt level
B. The passenger is ejected through the windshield, striking the hood
C. The passenger experiences pure axial loading from roof compression
D. The passenger is struck by the deploying side airbag
Rationale: Submarining occurs when the pelvis slides under the lap belt during
deceleration, causing hyperflexion at the belt level. This produces the abdominal
seatbelt sign (bowel/mesenteric injuries) and flexion-distraction spinal fractures
(Chance fractures). Option B describes ejection injuries. Option C describes vertical
compression. Option D describes a different mechanism entirely.
Correct Answer: A
Q7. A construction worker falls 20 feet from scaffolding and lands on his feet. Which
injury pattern should the prehospital provider anticipate based on the kinematics of
vertical deceleration?
A. Isolated calcaneal fractures only
B. Axial loading transmission through the skeleton causing calcaneal fractures,
tibial/femoral fractures, pelvic ring disruption, and spinal compression fractures
C. Lateral compression injuries to the ribs and flail chest
D. Pure soft tissue injuries with no bony involvement
Rationale: Vertical deceleration on the feet transmits axial loading force upward
through the kinetic chain: calcaneus → tibia → femur → pelvis → spine. Each level can
sustain compression or burst fractures. Option A is incomplete. Option C describes
lateral forces, not axial loading. Option D is incorrect—significant energy transfer
causes bony injury.
Correct Answer: B
Provider Certification | Comprehensive Question Bank |
Complete Solution | Pass Guaranteed - A+ Graded
Section 1: Trauma Fundamentals & Kinematics (Questions 1-18)
Q1. A passenger vehicle strikes a concrete bridge abutment at 45 mph. The driver,
who was wearing a lap belt only, sustains a flexion-distraction injury to the lumbar
spine. Which Newton's law best explains the mechanism of this injury?
A. Newton's First Law (Law of Inertia) - the body continues in motion until acted
upon by the seatbelt
B. Newton's Second Law (F = ma) - the force of the collision is proportional to mass
and deceleration
C. Newton's Third Law (Action-Reaction) - the seatbelt exerts equal and opposite
force on the body
D. Law of Conservation of Energy - kinetic energy is converted entirely to heat energy
Rationale: Newton's First Law explains that the body continues moving forward at 45
mph until the lap belt applies an external force, causing the torso to stop while the
head and upper body continue forward, creating a flexion-distraction force across
the lumbar spine. Option B describes force calculation but not the inertial
mechanism. Option C describes the force pair but not the inertial injury mechanism.
Option D misapplies energy conservation principles.
Correct Answer: A
Q2. A motorcyclist is thrown from his bike at 60 mph and impacts a guardrail. Which
type of energy dissipation accounts for the majority of traumatic injuries in this
scenario?
,A. Chemical energy from fuel combustion
B. Kinetic energy converted to deformation energy in the motorcycle and rider's
body tissues
C. Thermal energy from friction between the tires and road surface
D. Potential energy stored in the motorcycle's suspension system
Rationale: Traumatic injuries result from kinetic energy (½mv²) being dissipated
through tissue deformation, compression, shearing, and cavitation. The motorcycle
and rider's body absorb this energy through structural failure and tissue damage.
Options A, C, and D describe other energy forms that do not directly cause traumatic
injury.
Correct Answer: B
Q3. A pedestrian is struck by a vehicle traveling 35 mph. The primary impact occurs
at the bumper level (tibial plateau), and the secondary impact occurs when the head
strikes the hood. Which kinematic principle describes the relationship between
vehicle speed and pedestrian injury severity?
A. Injury severity is directly proportional to vehicle speed (linear relationship)
B. Injury severity is proportional to the square of the velocity (kinetic energy increases
exponentially with speed)
C. Injury severity decreases as vehicle speed increases due to the "throw effect"
reducing direct impact
D. Injury severity is unrelated to vehicle speed and depends only on pedestrian mass
Rationale: Kinetic energy = ½mv²; doubling speed quadruples kinetic energy. This
exponential relationship explains why higher-speed impacts cause disproportionately
more severe injuries. Option A understates the relationship. Option C is incorrect—
the throw effect does not reduce injury severity. Option D ignores the dominant role
of velocity.
Correct Answer: B
,Q4. A driver in a frontal collision sustains a ruptured descending thoracic aorta at the
isthmus. Which mechanism of injury is responsible for this deceleration injury?
A. Shear forces between the relatively mobile aortic arch and the fixed descending
aorta at the ligamentum arteriosum
B. Direct compression of the aorta by the steering wheel
C. Hyperextension of the aortic wall from whiplash forces
D. Penetration by a fractured sternum fragment
Rationale: The aortic isthmus is anchored by the ligamentum arteriosum; during
rapid deceleration, the mobile arch moves forward while the descending aorta
remains fixed, creating shear forces that rupture the wall. Option B describes direct
blunt trauma, not deceleration. Option C describes a different mechanism. Option D
describes a penetrating mechanism, not the classic deceleration injury.
Correct Answer: A
Q5. A gunshot wound to the thigh from a high-velocity rifle (2,800 ft/sec) produces
extensive tissue destruction beyond the bullet's path. Which phenomenon explains
this injury pattern?
A. Low-velocity cavitation with minimal tissue displacement
B. Permanent cavity formation only, with no temporary cavity
C. Temporary cavitation producing tissue stretch, compression, and remote injury at
distances from the bullet path
D. Chemical burn from propellant gases entering the wound
Rationale: High-velocity projectiles create a temporary cavity 10-30× the bullet
diameter as tissue is accelerated radially, then collapses, causing stretch,
compression, and injury distant from the permanent cavity. Option A describes low-
velocity wounds. Option B ignores temporary cavitation entirely. Option D describes
close-range contact wounds, not high-velocity rifle injuries.
Correct Answer: C
, Q6. An unrestrained rear-seat passenger in a frontal collision sustains a "seatbelt
sign" across the lower abdomen and a Chance fracture of L2. Which mechanism
produces this combination of injuries?
A. The passenger's body submarines under the front seat, causing hyperflexion at the
lap belt level
B. The passenger is ejected through the windshield, striking the hood
C. The passenger experiences pure axial loading from roof compression
D. The passenger is struck by the deploying side airbag
Rationale: Submarining occurs when the pelvis slides under the lap belt during
deceleration, causing hyperflexion at the belt level. This produces the abdominal
seatbelt sign (bowel/mesenteric injuries) and flexion-distraction spinal fractures
(Chance fractures). Option B describes ejection injuries. Option C describes vertical
compression. Option D describes a different mechanism entirely.
Correct Answer: A
Q7. A construction worker falls 20 feet from scaffolding and lands on his feet. Which
injury pattern should the prehospital provider anticipate based on the kinematics of
vertical deceleration?
A. Isolated calcaneal fractures only
B. Axial loading transmission through the skeleton causing calcaneal fractures,
tibial/femoral fractures, pelvic ring disruption, and spinal compression fractures
C. Lateral compression injuries to the ribs and flail chest
D. Pure soft tissue injuries with no bony involvement
Rationale: Vertical deceleration on the feet transmits axial loading force upward
through the kinetic chain: calcaneus → tibia → femur → pelvis → spine. Each level can
sustain compression or burst fractures. Option A is incomplete. Option C describes
lateral forces, not axial loading. Option D is incorrect—significant energy transfer
causes bony injury.
Correct Answer: B
