MSW UPDATED QUESTIONS AND ANSWERS GRADED A+
✔✔Examination of a 21-year-old female athlete with an injury of the radial nerve in the
spiral groove would typically demonstrate which of the following physical signs? -
✔✔Weakness of thumb abduction and thumb extension
Injury to the radial nerve in the spiral groove will paralyze the abductor pollicis longus
and both extensors of the thumb. This injury will also lead to wrist drop (inability to
extend the wrist). Weakness of grip would also occur, although this is not mentioned in
the question. If the wrist is flexed, finger flexion and grip strength are weakened
because the long flexor tendons are not under tension. Note how much your strength of
grip is increased when your wrist is extended versus when it is flexed.
✔✔The 58-year-old convenience store operator had received a superficial bullet wound
to the soft tissues on the medial side of the elbow in an attempted robbery. A major
nerve was repaired at the site where it passed behind the medial epicondyle. Bleeding
was stopped from an artery that accompanied the nerve in its path toward the
epicondyle. Vascular repair was - ✔✔The superior ulnar collateral artery
The superior ulnar collateral branch of the brachial artery accompanies the ulnar nerve
in its path posterior to the medial epicondyle and is important in the blood supply of the
nerve. The profunda brachii passes down the arm with the radial nerve. The radial
collateral artery arises from the profunda brachii and anastomoses with the radial
recurrent branch of the radial artery proximal to the elbow laterally. The inferior ulnar
collateral artery arises from the brachial artery and accompanies the median nerve into
the forearm. The anterior ulnar recurrent artery arises from the ulnar artery and
anastomoses with the inferior ulnar collateral anterior to the elbow.
✔✔A 60-year-old male butcher accidentally slashed his wrist with his butcher knife,
partially dividing the ulnar nerve. Which of the following actions would most likely be lost
as a result of this injury? - ✔✔Adduction of the fifth digit
Adduction of the fifth digit is produced by contraction of the third palmar interosseous
muscle. All of the interossei are innervated by the deep branch of the ulnar nerve.
Flexion of the proximal interphalangeal joint is a function of the flexor digitorum
superficialis, supplied by the median nerve. Opposition of the thumb is a function of the
opponens pollicis, supplied by the recurrent branch of the median nerve.
✔✔A 23-year-old male medical student fell asleep in his chair with Netters Atlas
wedged into his axilla. When he awoke in the morning, he was unable to extend the
forearm, wrist, or fingers. Movements of the ipsilateral shoulder joint appear to be
normal. Which of the following nerves was most likely compressed, producing the
symptoms described? - ✔✔Radial nerve
The radial nerve is the most likely nerve compressed to cause these symptoms. This
type of nerve palsy is often called Saturday night palsy. One reason for this nickname is
,that people would supposedly fall asleep after being intoxicated on a Saturday night
with their arm over the back of a chair, thereby compressing the nerve in the spiral
groove. The radial nerve innervates all of the extensors of the elbow, wrist, and fingers.
Paralysis of the lateral cord of the brachial plexus would result in loss of the
musculocutaneous nerve and the pectoral nerves, which do not mediate extension of
the forearm or hand. The medial cord of the brachial plexus branches into the median
nerve and ulnar nerve. Neither of these nerves innervates muscles that control
extension. The median nerve innervates flexors of the forearm and the thenar muscles.
The lateral and median pectoral nerves do not extend into the arm and innervate the
pectoralis major and minor muscles.
✔✔The fact that the kidneys of a 32-year-old female patient were failing required that
she be placed on dialysis. However, the search in her upper limb for a suitable vein was
unexpectedly difficult. The major vein on the lateral side of the arm was too small;
others were too delicate. Finally, a vein was found on the medial side of the arm that
passed through the superficial and deep fascia to join veins beside the brachial artery.
Which of the following veins was this? - ✔✔Basilic
The basilic vein can be used for dialysis, especially when the cephalic vein is judged to
be too small, as in this case. The basilic vein can be elevated from its position as it
passes through the fascia on the medial side of the arm. The cephalic vein passes more
laterally up the limb. The lateral cubital vein is a tributary to the cephalic vein, and the
medial cubital vein joins the basilic veinboth rather superficial in position. The medial
antebrachial vein courses up the midline of the forearm (antebrachium) ventrally.
✔✔A 29-year-old female had sustained a deep laceration in the proximal part of the
forearm. After the wound is closed, the following functional deficits are observed by the
neurologist on the service: The first three digits are in a position of extension and cannot
be flexed. Digits 4 and 5 are partially flexed at the metacarpophalangeal joints and
noticeably more flexed at the distal interphalangeal joints. Sensation is absent in the
lateral side of the palm and the palmar surfaces of digits 1 to 3 and half of the fourth
digit. Which of the following nerves has (have) most likely been injured? - ✔✔Median
Nerve
The patient exhibits the classic benediction attitude of the thumb and fingers from injury
to the median nerve proximally in the forearm. The thumb is somewhat extended (radial
supplied abductor and extensors unopposed); digits 2 and 3 are extended (by intact
interossei); digits 4 and 5 are partially flexed (by their intact flexor digitorum profundus).
A lesion of the median nerve would result in weakened flexion of the PIP joints of all
digits (flexor digitorum superficialis), loss of flexion of the interphalangeal joint of the
thumb, the DIP joints of digits 2 and 3 (flexor digitorum profundus), and weakened
flexion of the metacarpophalangeal joints of the second and third digits (first and second
lumbricals). A lesion of both the ulnar and median nerves would cause weakness or
paralysis of flexion of all of the digits. A lesion of the ulnar nerve would mostly cause
weakness in flexion of the DIP of the fourth and fifth digits and would affect all of the
interosseous muscles and the lumbricals of the third and fourth digits. A lesion of the
,radial nerve would cause weakness in extension of the wrist, thumb, and
metacarpophalangeal joints.
✔✔A 35-year-old male wrestler is admitted to the emergency department with
excruciating pain in his right shoulder and proximal arm. During physical examination
the patient clutches the arm at the elbow with his opposite hand and is unable to move
the injured limb. Radiographic studies show that the patient has a dislocation of the
humerus at the glenohumeral joint. Which of the following conditions is the most likely? -
✔✔The head of the humerus is displaced inferiorly.
The head of the humerus is displaced inferiorly because in that location it is not
supported by rotator cuff muscle tendons or the coracoacromial arch. It is also pulled
anteriorly beneath the coracoid process by pectoralis and subscapularis muscles. It
would not be displaced posteriorly because it is supported by the teres minor and
infraspinatus muscle tendons. It would not be displaced superiorly because the
acromioclavicular ligament and supraspinatus reinforce in that direction. A medial
dislocation is blocked by the subscapularis tendon.
✔✔The 35-year-old female patient has a hard nodule about 1 cm in diameter slightly
above and lateral to her right areola. A specific dye is injected into the tissue around the
tumor, and an incision is made to expose the lymphatic vessels draining the area, for
the lymphatic vessels take up the dyewhich is visible to the eye. The vessels can then
be traced to surgically expose the lymph nodes receiving the lymph from the tumor.
Which of the following nodes will most likely first encounter the lymph from the tumor? -
✔✔Anterior axillary (pectoral) nodes
The anterior axillary (or anterior pectoral) nodes are the first lymph nodes to receive
most of the lymph from the breast parenchyma, areola, and nipple. From there, lymph
flows through central axillary, apical, and supraclavicular nodes in sequence. Rotters
nodes lie between the pectoral muscles and are, unfortunately, an alternate route in
some patients, speeding the rate of metastasis. The parasternal nodes receive lymph
from the medial part of the breast and lie along the internal thoracic artery and vein.
✔✔During a fight in a tavern, a 45-year-old male construction worker received a shallow
stab wound from a broken beer bottle at a point near the middle of the left posterior
triangle of his neck. Upon physical examination it is observed that the left shoulder is
drooping lower than the right shoulder, and the superior angle of the scapula juts out
slightly. Strength in turning the head to the right or left appears to be symmetric. Which
of the following nerves is most likely injured? - ✔✔The spinal accessory nerve in the
posterior cervical triangle
The left spinal accessory nerve has been injured distal to the sternocleidomastoid
muscle, resulting in paralysis of the trapezius, allowing the shoulder to droop and the
superior angle to push out posteriorly. The sternocleidomastoid muscles are intact, as
demonstrated by symmetry in strength in turning the head to the right and left. There is
no indication of paralysis of the lateral rotators of the shoulder or elbow flexors
, (suprascapular nerve or upper trunk). Thoracodorsal nerve injury would result in
paralysis of the latissimus dorsi, an extensor, and medial rotator of the humerus.
✔✔A 44-year-old woman is diagnosed with radial nerve palsy. When muscle function is
examined at the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and
distal interphalangeal (DIP) joints, what findings are most likely to be present? -
✔✔Inability to extend the MCP joints only
Inability to extend MCP joints. The tendons of the extensor digitorum and extensor digiti
minimi, innervated by the radial nerve, are responsible for extension of the MCP, and to
a much lesser degree, the PIP and DIP joints. Abduction and adduction of the MCP
joints are functions of the interossei, all of which are innervated by the deep ulnar nerve.
Extension of the PIP and DIP joints is performed by the lumbricals and interossei. The
first two lumbricals are supplied by the median nerve; the other lumbricals and the
interossei, by the deep branch of the ulnar nerve.
✔✔A 27-year-old male painter is admitted to the hospital after falling from a ladder.
Physical examination reveals that the patient is unable to abduct his arm more than 15°
and cannot rotate the arm laterally. A radiographic examination reveals an oblique
fracture of the humerus. He has associated sensory loss over the shoulder area. Which
of the following injuries will most likely correspond to the symptoms of the physical
examination? - ✔✔Fracture of the surgical neck of the humerus
Fracture of the surgical neck of the humerus often injures the axillary nerve, which
innervates the deltoid and teres minor muscles. Abduction of the humerus between 15°
and the horizontal is performed by the deltoid muscle. Lateral rotation of the humerus is
mainly performed by the deltoid muscle, teres minor, and the infraspinatus. The deltoid
and teres minor are both lost in this case. Fracture of the glenoid fossa would lead to
drooping of the shoulder. Fracture of the anatomic neck of the humerus will similarly
lead to a drooping of the shoulder but would not necessarily affect abduction of the
humerus. It is also quite unusual. Fracture of the middle third of the humerus would
most likely injure the radial nerve. The ulnar nerve would be potentially compromised in
a fracture of the medial epicondyle of the humerus.
✔✔A 47-year-old female patients right breast exhibited characteristics of peau dorange;
that is, the skin resembled orange peel. This condition is primarily a result of which of
the following? - ✔✔Blockage of cutaneous lymphatic vessels
When cutaneous lymphatics of the breast are blocked by cancer, the skin becomes
edematous, except where hair follicles cause small indentations of the skin, giving an
overall resemblance to orange peel. Shortening of the suspensory ligaments or
retinacula cutis leads to pitting of the overlying skin, pitting that is intensified if the
patient raises her arm above her head. Invasion of the pectoralis major by cancer can
result in fixation of the breast, seen upon elevation of the ipsilateral limb. Inversion of
areolar skin with involvement of the ducts would also be due to involvement of the
retinacula cutis.
✔✔Examination of a 21-year-old female athlete with an injury of the radial nerve in the
spiral groove would typically demonstrate which of the following physical signs? -
✔✔Weakness of thumb abduction and thumb extension
Injury to the radial nerve in the spiral groove will paralyze the abductor pollicis longus
and both extensors of the thumb. This injury will also lead to wrist drop (inability to
extend the wrist). Weakness of grip would also occur, although this is not mentioned in
the question. If the wrist is flexed, finger flexion and grip strength are weakened
because the long flexor tendons are not under tension. Note how much your strength of
grip is increased when your wrist is extended versus when it is flexed.
✔✔The 58-year-old convenience store operator had received a superficial bullet wound
to the soft tissues on the medial side of the elbow in an attempted robbery. A major
nerve was repaired at the site where it passed behind the medial epicondyle. Bleeding
was stopped from an artery that accompanied the nerve in its path toward the
epicondyle. Vascular repair was - ✔✔The superior ulnar collateral artery
The superior ulnar collateral branch of the brachial artery accompanies the ulnar nerve
in its path posterior to the medial epicondyle and is important in the blood supply of the
nerve. The profunda brachii passes down the arm with the radial nerve. The radial
collateral artery arises from the profunda brachii and anastomoses with the radial
recurrent branch of the radial artery proximal to the elbow laterally. The inferior ulnar
collateral artery arises from the brachial artery and accompanies the median nerve into
the forearm. The anterior ulnar recurrent artery arises from the ulnar artery and
anastomoses with the inferior ulnar collateral anterior to the elbow.
✔✔A 60-year-old male butcher accidentally slashed his wrist with his butcher knife,
partially dividing the ulnar nerve. Which of the following actions would most likely be lost
as a result of this injury? - ✔✔Adduction of the fifth digit
Adduction of the fifth digit is produced by contraction of the third palmar interosseous
muscle. All of the interossei are innervated by the deep branch of the ulnar nerve.
Flexion of the proximal interphalangeal joint is a function of the flexor digitorum
superficialis, supplied by the median nerve. Opposition of the thumb is a function of the
opponens pollicis, supplied by the recurrent branch of the median nerve.
✔✔A 23-year-old male medical student fell asleep in his chair with Netters Atlas
wedged into his axilla. When he awoke in the morning, he was unable to extend the
forearm, wrist, or fingers. Movements of the ipsilateral shoulder joint appear to be
normal. Which of the following nerves was most likely compressed, producing the
symptoms described? - ✔✔Radial nerve
The radial nerve is the most likely nerve compressed to cause these symptoms. This
type of nerve palsy is often called Saturday night palsy. One reason for this nickname is
,that people would supposedly fall asleep after being intoxicated on a Saturday night
with their arm over the back of a chair, thereby compressing the nerve in the spiral
groove. The radial nerve innervates all of the extensors of the elbow, wrist, and fingers.
Paralysis of the lateral cord of the brachial plexus would result in loss of the
musculocutaneous nerve and the pectoral nerves, which do not mediate extension of
the forearm or hand. The medial cord of the brachial plexus branches into the median
nerve and ulnar nerve. Neither of these nerves innervates muscles that control
extension. The median nerve innervates flexors of the forearm and the thenar muscles.
The lateral and median pectoral nerves do not extend into the arm and innervate the
pectoralis major and minor muscles.
✔✔The fact that the kidneys of a 32-year-old female patient were failing required that
she be placed on dialysis. However, the search in her upper limb for a suitable vein was
unexpectedly difficult. The major vein on the lateral side of the arm was too small;
others were too delicate. Finally, a vein was found on the medial side of the arm that
passed through the superficial and deep fascia to join veins beside the brachial artery.
Which of the following veins was this? - ✔✔Basilic
The basilic vein can be used for dialysis, especially when the cephalic vein is judged to
be too small, as in this case. The basilic vein can be elevated from its position as it
passes through the fascia on the medial side of the arm. The cephalic vein passes more
laterally up the limb. The lateral cubital vein is a tributary to the cephalic vein, and the
medial cubital vein joins the basilic veinboth rather superficial in position. The medial
antebrachial vein courses up the midline of the forearm (antebrachium) ventrally.
✔✔A 29-year-old female had sustained a deep laceration in the proximal part of the
forearm. After the wound is closed, the following functional deficits are observed by the
neurologist on the service: The first three digits are in a position of extension and cannot
be flexed. Digits 4 and 5 are partially flexed at the metacarpophalangeal joints and
noticeably more flexed at the distal interphalangeal joints. Sensation is absent in the
lateral side of the palm and the palmar surfaces of digits 1 to 3 and half of the fourth
digit. Which of the following nerves has (have) most likely been injured? - ✔✔Median
Nerve
The patient exhibits the classic benediction attitude of the thumb and fingers from injury
to the median nerve proximally in the forearm. The thumb is somewhat extended (radial
supplied abductor and extensors unopposed); digits 2 and 3 are extended (by intact
interossei); digits 4 and 5 are partially flexed (by their intact flexor digitorum profundus).
A lesion of the median nerve would result in weakened flexion of the PIP joints of all
digits (flexor digitorum superficialis), loss of flexion of the interphalangeal joint of the
thumb, the DIP joints of digits 2 and 3 (flexor digitorum profundus), and weakened
flexion of the metacarpophalangeal joints of the second and third digits (first and second
lumbricals). A lesion of both the ulnar and median nerves would cause weakness or
paralysis of flexion of all of the digits. A lesion of the ulnar nerve would mostly cause
weakness in flexion of the DIP of the fourth and fifth digits and would affect all of the
interosseous muscles and the lumbricals of the third and fourth digits. A lesion of the
,radial nerve would cause weakness in extension of the wrist, thumb, and
metacarpophalangeal joints.
✔✔A 35-year-old male wrestler is admitted to the emergency department with
excruciating pain in his right shoulder and proximal arm. During physical examination
the patient clutches the arm at the elbow with his opposite hand and is unable to move
the injured limb. Radiographic studies show that the patient has a dislocation of the
humerus at the glenohumeral joint. Which of the following conditions is the most likely? -
✔✔The head of the humerus is displaced inferiorly.
The head of the humerus is displaced inferiorly because in that location it is not
supported by rotator cuff muscle tendons or the coracoacromial arch. It is also pulled
anteriorly beneath the coracoid process by pectoralis and subscapularis muscles. It
would not be displaced posteriorly because it is supported by the teres minor and
infraspinatus muscle tendons. It would not be displaced superiorly because the
acromioclavicular ligament and supraspinatus reinforce in that direction. A medial
dislocation is blocked by the subscapularis tendon.
✔✔The 35-year-old female patient has a hard nodule about 1 cm in diameter slightly
above and lateral to her right areola. A specific dye is injected into the tissue around the
tumor, and an incision is made to expose the lymphatic vessels draining the area, for
the lymphatic vessels take up the dyewhich is visible to the eye. The vessels can then
be traced to surgically expose the lymph nodes receiving the lymph from the tumor.
Which of the following nodes will most likely first encounter the lymph from the tumor? -
✔✔Anterior axillary (pectoral) nodes
The anterior axillary (or anterior pectoral) nodes are the first lymph nodes to receive
most of the lymph from the breast parenchyma, areola, and nipple. From there, lymph
flows through central axillary, apical, and supraclavicular nodes in sequence. Rotters
nodes lie between the pectoral muscles and are, unfortunately, an alternate route in
some patients, speeding the rate of metastasis. The parasternal nodes receive lymph
from the medial part of the breast and lie along the internal thoracic artery and vein.
✔✔During a fight in a tavern, a 45-year-old male construction worker received a shallow
stab wound from a broken beer bottle at a point near the middle of the left posterior
triangle of his neck. Upon physical examination it is observed that the left shoulder is
drooping lower than the right shoulder, and the superior angle of the scapula juts out
slightly. Strength in turning the head to the right or left appears to be symmetric. Which
of the following nerves is most likely injured? - ✔✔The spinal accessory nerve in the
posterior cervical triangle
The left spinal accessory nerve has been injured distal to the sternocleidomastoid
muscle, resulting in paralysis of the trapezius, allowing the shoulder to droop and the
superior angle to push out posteriorly. The sternocleidomastoid muscles are intact, as
demonstrated by symmetry in strength in turning the head to the right and left. There is
no indication of paralysis of the lateral rotators of the shoulder or elbow flexors
, (suprascapular nerve or upper trunk). Thoracodorsal nerve injury would result in
paralysis of the latissimus dorsi, an extensor, and medial rotator of the humerus.
✔✔A 44-year-old woman is diagnosed with radial nerve palsy. When muscle function is
examined at the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and
distal interphalangeal (DIP) joints, what findings are most likely to be present? -
✔✔Inability to extend the MCP joints only
Inability to extend MCP joints. The tendons of the extensor digitorum and extensor digiti
minimi, innervated by the radial nerve, are responsible for extension of the MCP, and to
a much lesser degree, the PIP and DIP joints. Abduction and adduction of the MCP
joints are functions of the interossei, all of which are innervated by the deep ulnar nerve.
Extension of the PIP and DIP joints is performed by the lumbricals and interossei. The
first two lumbricals are supplied by the median nerve; the other lumbricals and the
interossei, by the deep branch of the ulnar nerve.
✔✔A 27-year-old male painter is admitted to the hospital after falling from a ladder.
Physical examination reveals that the patient is unable to abduct his arm more than 15°
and cannot rotate the arm laterally. A radiographic examination reveals an oblique
fracture of the humerus. He has associated sensory loss over the shoulder area. Which
of the following injuries will most likely correspond to the symptoms of the physical
examination? - ✔✔Fracture of the surgical neck of the humerus
Fracture of the surgical neck of the humerus often injures the axillary nerve, which
innervates the deltoid and teres minor muscles. Abduction of the humerus between 15°
and the horizontal is performed by the deltoid muscle. Lateral rotation of the humerus is
mainly performed by the deltoid muscle, teres minor, and the infraspinatus. The deltoid
and teres minor are both lost in this case. Fracture of the glenoid fossa would lead to
drooping of the shoulder. Fracture of the anatomic neck of the humerus will similarly
lead to a drooping of the shoulder but would not necessarily affect abduction of the
humerus. It is also quite unusual. Fracture of the middle third of the humerus would
most likely injure the radial nerve. The ulnar nerve would be potentially compromised in
a fracture of the medial epicondyle of the humerus.
✔✔A 47-year-old female patients right breast exhibited characteristics of peau dorange;
that is, the skin resembled orange peel. This condition is primarily a result of which of
the following? - ✔✔Blockage of cutaneous lymphatic vessels
When cutaneous lymphatics of the breast are blocked by cancer, the skin becomes
edematous, except where hair follicles cause small indentations of the skin, giving an
overall resemblance to orange peel. Shortening of the suspensory ligaments or
retinacula cutis leads to pitting of the overlying skin, pitting that is intensified if the
patient raises her arm above her head. Invasion of the pectoralis major by cancer can
result in fixation of the breast, seen upon elevation of the ipsilateral limb. Inversion of
areolar skin with involvement of the ducts would also be due to involvement of the
retinacula cutis.
