ATLS MCQs EXAM
Questions and Answers
1.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
over his arm at the area of the triceps muscle. Which
of the following nerves innervates the triceps
muscle?
A. Radial
B. Axillary
C. Median
D. Ulnar
E. Musculocutaneous
ANS A. The nerve most likely affected is the radial nerve which
innervates the triceps brachii muscle. The axillary, median and ulnar
nerves do not innervate any
muscles in the arm. The musculocutaneous
nerve is innervating the coracobrachialis, biceps
brachii, and brachialis muscles in the anterior
compartment of the arm.
2.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
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,over his arm. A radiograph shows a fracture at the
radial groove of the humerus. Which of the
following nerves will most likely be injured?
A. Radial
B. Axillary
C. Median
D. Ulnar
E. Musculocutaneous
ANS A. The nerve most likely affected is the radial nerve as it travels
in the radial groove as it descends along the
humerus to the forearm. The axillary nerve runs
around the surgical neck of the humerus, the
median nerve passes superficial to the muscles
of the arm, the ulnar
nerve runs at the medial epicondyle, and the
musculocutaneous nerve pierces the coracobrachialis
muscle
and then runs
3.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
over his arm. A radiograph shows a fracture at the
radial groove of the humerus. Which of the
following muscles will most likely be paralyzed?
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,A. Triceps brachii
B. Biceps brachii
C. Coracobrachialis
D. Brachialis
E. Deltoid
ANS A. The nerve most likely affected in the radiograph
is the radial nerve as it travels in the radial groove
along
the humerus as it descends to the forearm. The
radial nerve innervates the triceps brachii muscle
(and extensors
in the forearm), whereas the biceps brachii,
coracobrachialis, and brachialis muscles are innervated
by
the musculocutaneous nerve and the deltoid
muscle by the axillary nerve.
4.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
over his arm. A radiograph shows a fracture at the
radial groove of the humerus. Which of the
following will be present during physical
examination?
A. Wrist drop
B. Inability to flex his hand and loss
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, of pronation
C. Inability to flex index and middle fingers
at the distal interphalangeal (DIP) and
proximal interphalangeal (PIP) joints
D. Inability to flex ring and little fingers at DIP
E. Paralysis of lumbricals and interosseous
muscles
ANS A. The nerve likely affected in the radiograph is the radial nerve as
it travels in the radial groove as it descends along the humerus to the
forearm. The radial nerve innervates the extensor muscles of the
forearm. Once these muscles have lost their inability to contract
because the radial nerve is injured, the wrist cannot be extended. This is
referred to as wrist drop.
B
Inability to flex the hand and loss of pronation
is an unlikely choice as flexion of the hand is
performed via innervation of muscles by the
median and ulnar nerves, pronation of the
hand is also performed by muscles innervated
by the median nerve.
of the median nerve.
D
Inability to flex the ring and little fingers at the
distal interphalangeal joints describes an ulnar
nerve branch deficit.
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Questions and Answers
1.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
over his arm at the area of the triceps muscle. Which
of the following nerves innervates the triceps
muscle?
A. Radial
B. Axillary
C. Median
D. Ulnar
E. Musculocutaneous
ANS A. The nerve most likely affected is the radial nerve which
innervates the triceps brachii muscle. The axillary, median and ulnar
nerves do not innervate any
muscles in the arm. The musculocutaneous
nerve is innervating the coracobrachialis, biceps
brachii, and brachialis muscles in the anterior
compartment of the arm.
2.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
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176
,over his arm. A radiograph shows a fracture at the
radial groove of the humerus. Which of the
following nerves will most likely be injured?
A. Radial
B. Axillary
C. Median
D. Ulnar
E. Musculocutaneous
ANS A. The nerve most likely affected is the radial nerve as it travels
in the radial groove as it descends along the
humerus to the forearm. The axillary nerve runs
around the surgical neck of the humerus, the
median nerve passes superficial to the muscles
of the arm, the ulnar
nerve runs at the medial epicondyle, and the
musculocutaneous nerve pierces the coracobrachialis
muscle
and then runs
3.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
over his arm. A radiograph shows a fracture at the
radial groove of the humerus. Which of the
following muscles will most likely be paralyzed?
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176
,A. Triceps brachii
B. Biceps brachii
C. Coracobrachialis
D. Brachialis
E. Deltoid
ANS A. The nerve most likely affected in the radiograph
is the radial nerve as it travels in the radial groove
along
the humerus as it descends to the forearm. The
radial nerve innervates the triceps brachii muscle
(and extensors
in the forearm), whereas the biceps brachii,
coracobrachialis, and brachialis muscles are innervated
by
the musculocutaneous nerve and the deltoid
muscle by the axillary nerve.
4.A 25-year-old man falls on a slippery trail and
injures his upper limb. Inspection reveals abrasions
over his arm. A radiograph shows a fracture at the
radial groove of the humerus. Which of the
following will be present during physical
examination?
A. Wrist drop
B. Inability to flex his hand and loss
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176
, of pronation
C. Inability to flex index and middle fingers
at the distal interphalangeal (DIP) and
proximal interphalangeal (PIP) joints
D. Inability to flex ring and little fingers at DIP
E. Paralysis of lumbricals and interosseous
muscles
ANS A. The nerve likely affected in the radiograph is the radial nerve as
it travels in the radial groove as it descends along the humerus to the
forearm. The radial nerve innervates the extensor muscles of the
forearm. Once these muscles have lost their inability to contract
because the radial nerve is injured, the wrist cannot be extended. This is
referred to as wrist drop.
B
Inability to flex the hand and loss of pronation
is an unlikely choice as flexion of the hand is
performed via innervation of muscles by the
median and ulnar nerves, pronation of the
hand is also performed by muscles innervated
by the median nerve.
of the median nerve.
D
Inability to flex the ring and little fingers at the
distal interphalangeal joints describes an ulnar
nerve branch deficit.
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