MSW REVISION EXAM TEST UPDATED QUESTIONS AND
ANSWERS GRADED A+
✔✔A 32-year-old woman is admitted to the emergency department after an automobile
collision. Radiographic examination reveals multiple fractures of the humerus. Flexion
and supination of the forearm are severely weakened. She also has loss of sensation
on the lateral surface of the forearm. Which of the following nerves has most likely been
injured? - ✔✔Musculocutaneous
The musculocutaneous nerve supplies the biceps brachii and brachialis, which are the
flexors of the forearm at the elbow. The musculocutaneous nerve continues as the
lateral antebrachial cutaneous nerve, which supplies sensation to the lateral side of the
forearm (with the forearm in the anatomic position). The biceps brachii is the most
powerful supinator muscle. Injury to this nerve would result in weakness of supination
and forearm flexion and lateral forearm sensory loss. Injury to the radial nerve would
result in weakened extension and a characteristic wrist drop. Injury to the median nerve
causes paralysis of flexor digitorum superficialis and other flexors in the forearm and
results in a characteristic flattening of the thenar eminence. The lateral cord of the
brachial plexus gives origin both to the musculocutaneous and lateral pectoral nerves.
There is no indication of pectoral paralysis or weakness. Injury to the lateral cord can
result in weakened flexion and supination in the forearm, and weakened adduction and
medial rotation of the arm. The lateral cutaneous nerve of the forearm is a branch of the
musculocutaneous nerve and does not supply any motor innervation. Injury to the
musculocutaneous nerve alone is unusual but can follow penetrating injuries.
✔✔A 24-year-old medical student was bitten at the base of her thumb by her dog. The
wound became infected and the infection spread into the radial bursa. The tendon(s) of
which muscle will most likely be affected? - ✔✔Flexor pollicis longus
Tenosynovitis can be due to an infection of the synovial sheaths of the digits.
Tenosynovitis in the thumb may spread through the synovial sheath of the flexor pollicis
longus tendon, also known as the radial bursa. The tendons of the flexor digitorum
superficialis and profundus muscles are enveloped in the common synovial flexor
sheath, or ulnar bursa. Neither the flexor carpi radialis nor flexor pollicis brevis tendons
are contained in synovial flexor sheaths.
✔✔Laboratory studies in the outpatient clinic on a 24-year-old female included
assessment of circulating blood chemistry. Which of the following arteries is most likely
at risk during venipuncture at the cubital fossa? - ✔✔Brachial
The three chief contents of the cubital fossa are the biceps brachii tendon, brachial
artery, and median nerve (lateral to medial). The common and anterior interosseous
arteries arise distal to the cubital fossa; the ulnar and radial arteries are the result of the
bifurcation of the brachial artery distal to the cubital fossa
,✔✔A 22-year-old male is diagnosed with metastatic malignant melanoma of the skin
over the xiphoid process. Which nodes receive most of the lymph from this area and are
therefore most likely to be involved in metastasis of the tumor? - ✔✔Axillary
Lymph from the skin of the anterior chest wall primarily drains to the axillary lymph
nodes.
✔✔A 49-year-old female who had suffered a myocardial infarction must undergo a
bypass graft procedure using the internal thoracic artery. Which vessels will most likely
continue to supply blood to the anterior part of the upper intercostal spaces? -
✔✔Posterior intercostal
The anterior intercostal arteries are 12 small arteries, two in each of the upper six
intercostal spaces at the upper and lower borders. The upper artery lying in each space
anastomoses with the posterior intercostal arteries, whereas the lower one usually joins
the collateral branch of the posterior intercostal artery. The musculophrenic artery
supplies the pericardium, diaphragm, and muscles of the abdominal wall. It
anastomoses with the deep circumflex iliac artery. The superior epigastric artery
supplies the diaphragm, peritoneum, and the anterior abdominal wall and anastomoses
with the inferior epigastric artery. The lateral thoracic artery runs along the lateral border
of the pectoralis minor muscle and supplies the pectoralis major, pectoralis minor, and
serratus anterior. The thoracodorsal artery accompanies the thoracodorsal nerve in
supplying the latissimus dorsi muscle and lateral thoracic wall.
✔✔A 22-year-old woman is admitted to the emergency department in an unconscious
state. The nurse takes a radial pulse to determine the heart rate of the patient. This
pulse is felt lateral to which tendon? - ✔✔Flexor carpi radialis
The location for palpation of the radial pulse is lateral to the tendon of the flexor carpi
radialis, where the radial artery can be compressed against the distal radius. The radial
pulse can also be felt in the anatomic snuffbox between the tendons of the extensor
pollicis brevis and extensor pollicis longus muscles, where the radial artery can be
compressed against the scaphoid.
✔✔A 45-year-old male is admitted to the hospital after accidentally walking through a
plate glass door in a bar while intoxicated. Physical examination shows multiple
lacerations to the upper limb, with inability to flex the distal interphalangeal joints of the
fourth and fifth digits. Which of the following muscles is most likely affected? - ✔✔Flexor
digitorum profundus
The flexor digitorum profundus is dually innervated by the ulnar nerve to the medial
phalanges and the median nerve for the lateral phalanges. Because of the superficial
course of the ulnar nerve, it is vulnerable to laceration. Such an injury would result in an
inability to flex the distal interphalangeal joints of the fourth and fifth digits. The flexor
digitorum superficialis is innervated by the median nerve only, and the course of this
,nerve runs too deep to be affected by lacerations. The lumbricals function to flex the MP
joints and assist in extending the IP joints. The interossei adduct and abduct the fingers.
✔✔A 24-year-old man is admitted with a wound to the palm of his hand. He cannot
touch the pads of his fingers with his thumb but can grip a sheet of paper between all
fingers and has no loss of sensation on the skin of his hand. Which of the following
nerves has most likely been injured? - ✔✔Recurrent branch of Median
The recurrent branch of the median nerve is motor to the muscles of the thenar
eminence, which is an elevation caused by the abductor pollicis brevis, flexor pollicis
brevis, and opponens pollicis. If the opponens pollicis is paralyzed, one cannot oppose
the pad of the thumb to the pads of the other digits. The recurrent branch does not have
a cutaneous distribution. Holding a piece of paper between the fingers is a simple test of
adduction of the fingers. These movements are controlled by the deep branch of the
ulnar nerve, which is not injured in this patient.
✔✔A 55-year-old male is examined in a neighborhood clinic after receiving blunt trauma
to his right axilla in a fall. He has difficulty elevating the right arm above the level of his
shoulder. Physical examination shows the inferior angle of his right scapula protrudes
more than the lower part of the left scapula. The right scapula protrudes far more when
the patient pushes against resistance. Which of the following neural structures has most
likely been injured? - ✔✔The long thoracic
Winging of the scapula occurs when the medial border of the scapula lifts off the chest
wall when the patient pushes against resistance, such as a wall. The serratus anterior
muscle holds the medial border of the scapula against the chest wall and is innervated
by the long thoracic nerve. The serratus anterior assists in abduction of the arm above
the horizontal plane.
✔✔A mother tugs violently on her male childs hand to pull him out of the way of an
oncoming car and the child screams in pain. Thereafter, it becomes obvious that the
child cannot straighten his forearm at the elbow. When the child is seen in the
emergency department, radiographic examination reveals a dislocation of the head of
the radius. Which of the following ligaments is most likely directly associated with this
injury? - ✔✔Anular
The anular ligament is a fibrous band that encircles the head of the radius, forming a
collar that fuses with the radial collateral ligament and articular capsule of the elbow.
The anular ligament functions to prevent displacement of the head of the radius from its
socket. The joint capsule functions to allow free rotation of the joint and does not
function in its stabilization. The interosseous membrane is a fibrous layer between the
radius and ulna helping to hold these two bones together. The radial collateral ligament
extends from the lateral epicondyle to the margins of the radial notch of the ulnar and
the anular ligament of the radius. The ulnar collateral ligament is triangular ligament and
extends from the medial epicondyle to the olecranon of the ulna.
, ✔✔After a forceps delivery of a male infant, the baby presents with his left upper limb
adducted, internally rotated, and flexed at the wrist. The startle reflex is absent on the
ipsilateral side. Which part of the brachial plexus was most likely injured during this
delivery? - ✔✔Roots of the upper trunk
The injury being described is also known as Erb-Duchenne paralysis or waiters tip-
hand. This usually results from an injury to the upper trunk of the brachial plexus,
presenting with loss of abduction, flexion, and lateral rotation of the arm. The superior
trunk of the brachial plexus consists of spinal nerve roots C5-6.
✔✔A 35-year-old patient has a small but painful tumor under the nail of the little finger.
Which of the following nerves would have to be anesthetized for a painless removal of
the tumor? - ✔✔Common palmar digital of Ulnar
The common palmar digital branch comes off the superficial branch of the ulnar nerve
and supplies the skin of the little finger and the medial side of the ring finger. The
superficial branch of the radial nerve provides cutaneous innervation to the radial
(lateral) dorsum of the hand and the radial two and a half digits over the proximal
phalanx. The common palmar digital branch of the median nerve innervates most of the
lateral aspect of the palmar hand and the dorsal aspect of the second and third finger as
well as the lateral part of the fourth digit. The deep radial nerve supplies the extensor
carpi radialis brevis and supinator muscles and continues as the posterior interosseous
nerve. The recurrent branch of the median nerve supplies the abductor pollicis brevis,
flexor pollicis brevis, and opponens pollicis muscles.
✔✔A 25-year-old male athlete is admitted to the emergency department after a bad
landing in the pole vault. Radiographic examination of his hand reveals a fractured
carpal bone in the floor of the anatomic snuffbox. Which bone has most likely been
fractured? - ✔✔Scaphoid
The anatomic snuffbox is formed by the tendons of the extensor pollicis brevis, the
abductor pollicis longus, and the extensor pollicis longus. The floor is formed by the
scaphoid bone, and it is here that one can palpate for a possible fractured scaphoid.
✔✔A 36-year-old man is brought to the emergency department because of a deep knife
wound on the medial side of his distal forearm. He is unable to hold a piece of paper
between his fingers and has sensory loss on the medial side of his hand and little finger.
Which nerve is most likely injured? - ✔✔Ulnar
The ulnar nerve innervates the palmar interossei, which adduct the fingers. This is the
movement that would maintain the paper between the fingers. The axillary nerve does
not innervate muscles of the hand. The median nerve supplies the first and second
lumbricals, the opponens pollicis, abductor pollicis brevis, and the flexor pollicis brevis.
None of these muscles would affect the ability to hold a piece of paper between the
fingers. The musculocutaneous and radial nerves do not supply muscles of the hand.
ANSWERS GRADED A+
✔✔A 32-year-old woman is admitted to the emergency department after an automobile
collision. Radiographic examination reveals multiple fractures of the humerus. Flexion
and supination of the forearm are severely weakened. She also has loss of sensation
on the lateral surface of the forearm. Which of the following nerves has most likely been
injured? - ✔✔Musculocutaneous
The musculocutaneous nerve supplies the biceps brachii and brachialis, which are the
flexors of the forearm at the elbow. The musculocutaneous nerve continues as the
lateral antebrachial cutaneous nerve, which supplies sensation to the lateral side of the
forearm (with the forearm in the anatomic position). The biceps brachii is the most
powerful supinator muscle. Injury to this nerve would result in weakness of supination
and forearm flexion and lateral forearm sensory loss. Injury to the radial nerve would
result in weakened extension and a characteristic wrist drop. Injury to the median nerve
causes paralysis of flexor digitorum superficialis and other flexors in the forearm and
results in a characteristic flattening of the thenar eminence. The lateral cord of the
brachial plexus gives origin both to the musculocutaneous and lateral pectoral nerves.
There is no indication of pectoral paralysis or weakness. Injury to the lateral cord can
result in weakened flexion and supination in the forearm, and weakened adduction and
medial rotation of the arm. The lateral cutaneous nerve of the forearm is a branch of the
musculocutaneous nerve and does not supply any motor innervation. Injury to the
musculocutaneous nerve alone is unusual but can follow penetrating injuries.
✔✔A 24-year-old medical student was bitten at the base of her thumb by her dog. The
wound became infected and the infection spread into the radial bursa. The tendon(s) of
which muscle will most likely be affected? - ✔✔Flexor pollicis longus
Tenosynovitis can be due to an infection of the synovial sheaths of the digits.
Tenosynovitis in the thumb may spread through the synovial sheath of the flexor pollicis
longus tendon, also known as the radial bursa. The tendons of the flexor digitorum
superficialis and profundus muscles are enveloped in the common synovial flexor
sheath, or ulnar bursa. Neither the flexor carpi radialis nor flexor pollicis brevis tendons
are contained in synovial flexor sheaths.
✔✔Laboratory studies in the outpatient clinic on a 24-year-old female included
assessment of circulating blood chemistry. Which of the following arteries is most likely
at risk during venipuncture at the cubital fossa? - ✔✔Brachial
The three chief contents of the cubital fossa are the biceps brachii tendon, brachial
artery, and median nerve (lateral to medial). The common and anterior interosseous
arteries arise distal to the cubital fossa; the ulnar and radial arteries are the result of the
bifurcation of the brachial artery distal to the cubital fossa
,✔✔A 22-year-old male is diagnosed with metastatic malignant melanoma of the skin
over the xiphoid process. Which nodes receive most of the lymph from this area and are
therefore most likely to be involved in metastasis of the tumor? - ✔✔Axillary
Lymph from the skin of the anterior chest wall primarily drains to the axillary lymph
nodes.
✔✔A 49-year-old female who had suffered a myocardial infarction must undergo a
bypass graft procedure using the internal thoracic artery. Which vessels will most likely
continue to supply blood to the anterior part of the upper intercostal spaces? -
✔✔Posterior intercostal
The anterior intercostal arteries are 12 small arteries, two in each of the upper six
intercostal spaces at the upper and lower borders. The upper artery lying in each space
anastomoses with the posterior intercostal arteries, whereas the lower one usually joins
the collateral branch of the posterior intercostal artery. The musculophrenic artery
supplies the pericardium, diaphragm, and muscles of the abdominal wall. It
anastomoses with the deep circumflex iliac artery. The superior epigastric artery
supplies the diaphragm, peritoneum, and the anterior abdominal wall and anastomoses
with the inferior epigastric artery. The lateral thoracic artery runs along the lateral border
of the pectoralis minor muscle and supplies the pectoralis major, pectoralis minor, and
serratus anterior. The thoracodorsal artery accompanies the thoracodorsal nerve in
supplying the latissimus dorsi muscle and lateral thoracic wall.
✔✔A 22-year-old woman is admitted to the emergency department in an unconscious
state. The nurse takes a radial pulse to determine the heart rate of the patient. This
pulse is felt lateral to which tendon? - ✔✔Flexor carpi radialis
The location for palpation of the radial pulse is lateral to the tendon of the flexor carpi
radialis, where the radial artery can be compressed against the distal radius. The radial
pulse can also be felt in the anatomic snuffbox between the tendons of the extensor
pollicis brevis and extensor pollicis longus muscles, where the radial artery can be
compressed against the scaphoid.
✔✔A 45-year-old male is admitted to the hospital after accidentally walking through a
plate glass door in a bar while intoxicated. Physical examination shows multiple
lacerations to the upper limb, with inability to flex the distal interphalangeal joints of the
fourth and fifth digits. Which of the following muscles is most likely affected? - ✔✔Flexor
digitorum profundus
The flexor digitorum profundus is dually innervated by the ulnar nerve to the medial
phalanges and the median nerve for the lateral phalanges. Because of the superficial
course of the ulnar nerve, it is vulnerable to laceration. Such an injury would result in an
inability to flex the distal interphalangeal joints of the fourth and fifth digits. The flexor
digitorum superficialis is innervated by the median nerve only, and the course of this
,nerve runs too deep to be affected by lacerations. The lumbricals function to flex the MP
joints and assist in extending the IP joints. The interossei adduct and abduct the fingers.
✔✔A 24-year-old man is admitted with a wound to the palm of his hand. He cannot
touch the pads of his fingers with his thumb but can grip a sheet of paper between all
fingers and has no loss of sensation on the skin of his hand. Which of the following
nerves has most likely been injured? - ✔✔Recurrent branch of Median
The recurrent branch of the median nerve is motor to the muscles of the thenar
eminence, which is an elevation caused by the abductor pollicis brevis, flexor pollicis
brevis, and opponens pollicis. If the opponens pollicis is paralyzed, one cannot oppose
the pad of the thumb to the pads of the other digits. The recurrent branch does not have
a cutaneous distribution. Holding a piece of paper between the fingers is a simple test of
adduction of the fingers. These movements are controlled by the deep branch of the
ulnar nerve, which is not injured in this patient.
✔✔A 55-year-old male is examined in a neighborhood clinic after receiving blunt trauma
to his right axilla in a fall. He has difficulty elevating the right arm above the level of his
shoulder. Physical examination shows the inferior angle of his right scapula protrudes
more than the lower part of the left scapula. The right scapula protrudes far more when
the patient pushes against resistance. Which of the following neural structures has most
likely been injured? - ✔✔The long thoracic
Winging of the scapula occurs when the medial border of the scapula lifts off the chest
wall when the patient pushes against resistance, such as a wall. The serratus anterior
muscle holds the medial border of the scapula against the chest wall and is innervated
by the long thoracic nerve. The serratus anterior assists in abduction of the arm above
the horizontal plane.
✔✔A mother tugs violently on her male childs hand to pull him out of the way of an
oncoming car and the child screams in pain. Thereafter, it becomes obvious that the
child cannot straighten his forearm at the elbow. When the child is seen in the
emergency department, radiographic examination reveals a dislocation of the head of
the radius. Which of the following ligaments is most likely directly associated with this
injury? - ✔✔Anular
The anular ligament is a fibrous band that encircles the head of the radius, forming a
collar that fuses with the radial collateral ligament and articular capsule of the elbow.
The anular ligament functions to prevent displacement of the head of the radius from its
socket. The joint capsule functions to allow free rotation of the joint and does not
function in its stabilization. The interosseous membrane is a fibrous layer between the
radius and ulna helping to hold these two bones together. The radial collateral ligament
extends from the lateral epicondyle to the margins of the radial notch of the ulnar and
the anular ligament of the radius. The ulnar collateral ligament is triangular ligament and
extends from the medial epicondyle to the olecranon of the ulna.
, ✔✔After a forceps delivery of a male infant, the baby presents with his left upper limb
adducted, internally rotated, and flexed at the wrist. The startle reflex is absent on the
ipsilateral side. Which part of the brachial plexus was most likely injured during this
delivery? - ✔✔Roots of the upper trunk
The injury being described is also known as Erb-Duchenne paralysis or waiters tip-
hand. This usually results from an injury to the upper trunk of the brachial plexus,
presenting with loss of abduction, flexion, and lateral rotation of the arm. The superior
trunk of the brachial plexus consists of spinal nerve roots C5-6.
✔✔A 35-year-old patient has a small but painful tumor under the nail of the little finger.
Which of the following nerves would have to be anesthetized for a painless removal of
the tumor? - ✔✔Common palmar digital of Ulnar
The common palmar digital branch comes off the superficial branch of the ulnar nerve
and supplies the skin of the little finger and the medial side of the ring finger. The
superficial branch of the radial nerve provides cutaneous innervation to the radial
(lateral) dorsum of the hand and the radial two and a half digits over the proximal
phalanx. The common palmar digital branch of the median nerve innervates most of the
lateral aspect of the palmar hand and the dorsal aspect of the second and third finger as
well as the lateral part of the fourth digit. The deep radial nerve supplies the extensor
carpi radialis brevis and supinator muscles and continues as the posterior interosseous
nerve. The recurrent branch of the median nerve supplies the abductor pollicis brevis,
flexor pollicis brevis, and opponens pollicis muscles.
✔✔A 25-year-old male athlete is admitted to the emergency department after a bad
landing in the pole vault. Radiographic examination of his hand reveals a fractured
carpal bone in the floor of the anatomic snuffbox. Which bone has most likely been
fractured? - ✔✔Scaphoid
The anatomic snuffbox is formed by the tendons of the extensor pollicis brevis, the
abductor pollicis longus, and the extensor pollicis longus. The floor is formed by the
scaphoid bone, and it is here that one can palpate for a possible fractured scaphoid.
✔✔A 36-year-old man is brought to the emergency department because of a deep knife
wound on the medial side of his distal forearm. He is unable to hold a piece of paper
between his fingers and has sensory loss on the medial side of his hand and little finger.
Which nerve is most likely injured? - ✔✔Ulnar
The ulnar nerve innervates the palmar interossei, which adduct the fingers. This is the
movement that would maintain the paper between the fingers. The axillary nerve does
not innervate muscles of the hand. The median nerve supplies the first and second
lumbricals, the opponens pollicis, abductor pollicis brevis, and the flexor pollicis brevis.
None of these muscles would affect the ability to hold a piece of paper between the
fingers. The musculocutaneous and radial nerves do not supply muscles of the hand.
