BRS upper limb questions

1. The answer is C. A lesion of the upper trunk of the brachial plexus results in a condition called "waiter's tip hand," in which the arm tends to lie in medial rotation because of paralysis of lateral rotators and abductors of the arm. The long thoracic nerve, which arises from the root (C5-C7) of the brachial plexus, innervates the serratus anterior muscle that can elevate the arm above the horizontal. The dorsal scapular nerve, which arises from the root (C5), innervates the rhomboid major. The medial side of the arm receives cutaneous innervation from the medial brachial cutaneous nerve of the medial cord. The adductor pollicis is innervated by the ulnar nerve.

1. A 21-year-old patient has a lesion of the upper trunk of the brachial plexus (Erb- Duchenne paralysis). Which of the following is the most likely diagnosis? (A) Paralysis of the rhomboid major (B) Inability to elevate the arm above the horizontal (C) Arm tending to lie in medial rotation (D) Loss of sensation on the medial side of the arm (E) Inability to adduct the thumb

13. The answer is D. The scaphoid bone forms the floor of the anatomic snuffbox, through which the radial artery passes to enter the palm. The radial artery divides into the prin- ceps pollicis artery and the deep palmar arch.

13. A 14-year-old boy falls on his out- stretched hand and has a fracture of the scaphoid bone. The fracture is most likely accompanied by a rupture of which of the following arteries? (A) Brachial artery (B) Ulnar artery (C) Deep palmar arterial arch (D) Radial artery (E) Princeps pollicis artery

14. The answer is C. The axillary nerve passes posteriorly around the surgical neck of the humerus, and the radial nerve lies in the radial groove of the middle of the shaft of the humerus. The ulnar nerve passes behind the medial epicondyle, and the median nerve is vulnerable to injury by supracondylar fracture of the humerus, but these nerves lie close to or in contact with the lower portion of the humerus. The musculocutaneous nerve is not in direct contact with the humerus.

14. A 12-year-old boy walks in; he fell out of a tree and fractured the upper portion of his humerus. Which of the following nerves are intimately related to the humerus and are most likely to be injured by such a fracture? (A) Axillary and musculocutaneous (B) Radial and ulnar (C) Radial and axillary (D) Median and musculocutaneous (E) Median and ulnar

10. The answer is E. The contents of the cubital fossa from medial to lateral side are the median nerve, the brachial artery, the biceps brachii tendon, and the radial nerve. Thus, the median nerve is damaged. The radial recurrent artery ascends medial to the radial nerve.

10. A 35-year-old man walks in with a stab wound to the most medial side of the proxi- mal portion of the cubital fossa. Which of the following structures would most likely be damaged? (A) Biceps brachii tendon (B) Radial nerve (C) Brachial artery (D) Radial recurrent artery (E) Median nerve

11. The answer is D. Injury to the median nerve produces the ape hand (a hand with the thumb permanently extended). Injury to the radial nerve results in loss of wrist extension, leading to wrist drop. Damage to the upper trunk of the brachial plexus produces waiter's tip hand. A claw hand and flattening of the hypothenar eminence or atrophy of the hypothenar muscles result from damage to the ulnar nerve.

11. The police bring in a murder suspect who has been in a gunfight with a police officer. The suspect was struck by a bullet in the arm; his median nerve has been dam- aged. Which of the following symptoms is likely produced by this nerve damage? (A) Waiter's tip hand (B) Claw hand (C) Wrist drop (D) Ape hand (E) Flattening of the hypothenar eminence

12. The answer is C. The extensor digitorum, flexor digitorum profundus, dorsal interosseous, and lumbrical muscles are attached to the middle digit, but no palmar interosseous mus- cle is attached to the middle digit.

12. An automobile body shop worker has his middle finger crushed while working on a transmission. Which of the following mus- cles is most likely to retain function? (A) Extensor digitorum (B) Flexor digitorum profundus (C) Palmar interosseous (D) Dorsal interosseous (E) Lumbrical

15. The answer is D. Structures entering the palm superficial to the flexor retinaculum include the ulnar nerve, ulnar artery, palmaris longus tendon, and palmar cutaneous branch of the median nerve. The median nerve, the flexor pollicis longus, and the flexor digitorum superficialis and profundus run deep to the flexor retinaculum.

15. A man injures his wrist on broken glass. Which of the following structures entering the palm superficial to the flexor retinacu- lum may be damaged? (A) Ulnar nerve and median nerve (B) Median nerve and flexor digitorum pro- fundus (C) Median nerve and flexor pollicis longus (D) Ulnar artery and ulnar nerve (E) Ulnar nerve and flexor digitorum super- ficialis

16. The answer is C. The opponens pollicis inserts on the first metacarpal. All other intrinsic muscles of the thumb, including the abductor pollicis brevis, the flexor pollicis brevis, and the adductor pollicis muscles, insert on the proximal phalanges.

16. A patient with Bennett's fracture (a frac- ture of the base of the first metacarpal bone) experiences an impaired thumb movement. Which of the following intrinsic muscles of the thumb is most likely injured? (A) Abductor pollicis brevis (B) Flexor pollicis brevis (superficial head) (C) Opponens pollicis (D) Adductor pollicis (E) Flexor pollicis brevis (deep head)

17. The answer is C. The median nerve innervates the abductor pollicis brevis, opponens pol- licis, and two lateral lumbricals. The ulnar nerve innervates all interossei (palmar and dor- sal), the adductor pollicis, and the two medial lumbricals.

17. A 27-year-old pianist with a known car- pal tunnel syndrome experiences difficulty in finger movements. Which of the following intrinsic muscles of her hand is paralyzed? (A) Palmar interossei and adductor pollicis (B) Dorsal interossei and lateral two lumbri- cals (C) Lateral two lumbricals and opponens pollicis (D) Abductor pollicis brevis and palmar interossei (E) Medial two and lateral two lumbricals

18. The answer is C. The ulnar bursa, or common synovial flexor sheath, contains the tendons of both the flexor digitorum superficialis and profundus muscles. The radial bursa envel- ops the tendon of the flexor pollicis longus. The tendons of the flexor carpi ulnaris and the palmaris longus are not contained in the ulnar bursa.

18. A 31-year-old roofer walks in with teno- synovitis resulting from a deep penetrated wound in the palm by a big nail. Examina- tion indicates that he has an infection in the ulnar bursa. This infection most likely resulted in necrosis of which of the following tendons? (A) Tendon of the flexor carpi ulnaris (B) Tendon of the flexor pollicis longus (C) Tendon of the flexor digitorum profun- dus (D) Tendon of the flexor carpi radialis (E) Tendon of the palmaris longus

19. The answer is A. The abductors of the arm are the deltoid and supraspinatus muscles, which are innervated by the axillary and suprascapular nerves, respectively. The thoraco- dorsal nerve supplies the latissimus dorsi, which can adduct, extend, and rotate the arm medially. The upper and lower subscapular nerves supply the subscapularis, and the lower subscapular nerve also supplies the teres major; both of these structures can adduct and rotate the arm medially. The musculocutaneous nerve supplies the flexors of the arm, and the radial nerve supplies the extensors of the arm. The dorsal scapular nerve supplies the levator scapulae and rhomboid muscles; these muscles elevate and adduct the scapula, respectively.

19. An 18-year-old boy involved in an auto- mobile accident presents with arm that cannot abduct. His paralysis is caused by damage to which of the following nerves? (A) Suprascapular and axillary (B) Thoracodorsal and upper subscapular (C) Axillary and musculocutaneous (D) Radial and lower subscapular (E) Suprascapular and dorsal scapular

2. The answer is E. The superior thoracic artery is a direct branch of the axillary artery. The thoracoacromial trunk has four branches: the pectoral, clavicular, acromial, and deltoid.

2. A patient comes in with a gunshot wound and requires surgery in which his thoracoac- romial trunk needs to be ligated. Which of the following arterial branches would main- tain normal blood flow? (A) Acromial (B) Pectoral (C) Clavicular (D) Deltoid (E) Superior thoracic

20. The answer is C. The posterior humeral circumflex artery anastomoses with an ascending branch of the profunda brachii artery, whereas the lateral thoracic and subscapular arter- ies do not. The superior ulnar collateral and radial recurrent arteries arise inferior to the origin of the profunda brachii artery. rpophalangeal joints of the index and middle fingers.

20. A 17-year-old boy with a stab wound received multiple injuries on the upper part of the arm and required surgery. If the bra- chial artery were ligated at its origin, which of the following arteries would supply blood to the profunda brachii artery? (A) Lateral thoracic (B) Subscapular (C) Posterior humeral circumflex (D) Superior ulnar collateral (E) Radial recurrent

21. The answer is D. The metacarpophalangeal joint of the ring finger is flexed by the lumbri- cal, palmar, and dorsal interosseous muscles, which are innervated by the ulnar nerve. The extensor digitorum, which is innervated by the radial nerve, extends this joint. The muscu- locutaneous and axillary nerves do not supply muscles of the hand. The median nerve supplies the lateral two lumbricals, which can flex metaca

21. A 23-year-old woman who receives a deep cut to her ring finger by a kitchen knife is unable to move the metacarpophalangeal joint. Which of the following pairs of nerves was damaged? (A) Median and ulnar (B) Radial and median (C) Musculocutaneous and ulnar (D) Ulnar and radial (E) Radial and axillary

22. The answer is B. The brachialis and supinator muscles form the floor of the cubital fossa. The brachioradialis and pronator teres muscles form the lateral and medial boundaries, respectively. The pronator quadratus is attached to the distal ends of the radius and the ulna.

22. A 27-year-old baseball player is hit on his forearm by a high-speed ball during the World Series, and the muscles that form the floor of the cubital fossa appear to be torn. Which of the following groups of muscles have lost their functions? (A) Brachioradialis and supinator (B) Brachialis and supinator (C) Pronator teres and supinator (D) Supinator and pronator quadratus (E) Brachialis and pronator teres

23. The answer is B. The medial brachial cutaneous nerve contains sensory (general somatic afferent [GSA]) fibers that have cell bodies in the dorsal root ganglia, and an injury of these GSA fibers causes numbness of the medial side of the arm. It also contains sympathetic postganglionic fibers that have cell bodies in the sympathetic chain ganglia. The anterior horn of the spinal cord contains cell bodies of skeletal motor (general somatic efferent [GSE]) fibers, and the lateral horn contains cell bodies of sympathetic preganglionic fibers. The posterior horn contains cell bodies of interneurons.

23. A 23-year-old man complains of numb- ness on the medial side of the arm following a stab wound in the axilla. On examination, he is diagnosed with an injury of his medial brachial cutaneous nerve. In which of the following structures are the cell bodies of the damaged nerve involved in numbness located? (A) Sympathetic chain ganglion (B) Dorsal root ganglion (C) Anterior horn of the spinal cord (D) Lateral horn of the spinal cord (E) Posterior horn of the spinal cord

24. The answer is D. The supinator and biceps brachii muscles, which are innervated by the radial and musculocutaneous nerves, respectively, produce supination of the forearm. This is a question of two muscles that can supinate the forearm.

24. A 38-year-old homebuilder was involved in an accident and is unable to supinate his forearm. Which of the following nerves are most likely damaged? (A) Suprascapular and axillary (B) Musculocutaneous and median (C) Axillary and radial (D) Radial and musculocutaneous (E) Median and ulnar

25. The answer is D. The ulnar nerve supplies sensory fibers to the skin over the palmar and dorsal surfaces of the medial third of the hand and the medial one and one-half fingers. The median nerve innervates the skin of the lateral side of the palm; the palmar side of the lateral three and one-half fingers; and the dorsal side of the index finger, the middle finger, and one-half of the ring finger. The radial nerve innervates the skin of the radial side of the hand and the radial two and one-half digits over the proximal phalanx.

25. A 31-year-old patient complains of sen- sory loss over the anterior and posterior sur- faces of the medial third of the hand and the medial one and one-half fingers. He is diag- nosed by a physician as having "funny bone" symptoms. Which of the following nerves is injured? (A) Axillary (B) Radial (C) Median (D) Ulnar (E) Musculocutaneous

26. The answer is C. The anterior interosseous nerve is a branch of the median nerve and sup- plies the flexor pollicis longus, half of the flexor digitorum profundus, and the pronator quadratus. The median nerve supplies the pronator teres, flexor digitorum superficialis, palmaris longus, and flexor carpi radialis muscles. A muscular branch (the recurrent branch) of the median nerve innervates the thenar muscles.

26. A patient with a deep stab wound in the middle of the forearm has impaired move- ment of the thumb. Examination indicates a lesion of the anterior interosseous nerve. Which of the following muscles is paralyzed? (A) Flexor pollicis longus and brevis (B) Flexor pollicis longus and opponens pollicis (C) Flexor digitorum profundus and prona- tor quadratus (D) Flexor digitorum profundus and superfi- cialis (E) Flexor pollicis brevis and pronator quad- ratus

27. The answer is C. The flexor digitorum profundus muscle flexes the DIP joints of the index and middle fingers and is innervated by the median nerve, which also supplies sensation over the distal part of the second digit. The same muscle flexes the DIP joints of the ring and little fingers but receives innervation from the ulnar nerve, which also innervates the hypothenar muscles. The median nerve innervates the thenar muscles. The radial nerve innervates the supinator, abductor pollicis longus, and extensor pollicis longus and brevis muscles. The ulnar nerve innervates the adductor pollicis. The musculocutaneous nerve supplies the biceps brachii that can supinate the arm.

27. A 29-year-old patient comes in; he can- not flex the distal interphalangeal (DIP) joint of the index finger. His physician determines that he has nerve damage from a supra- condylar fracture. Which of the following conditions is also a symptom of this nerve damage? (A) Inability to flex the DIP joint of the ring finger (B) Atrophy of the hypothenar eminence (C) Loss of sensation over the distal part of the second digit (D) Paralysis of all the thumb muscles (E) Loss of supination

28. The answer is C. The ulnar nerve innervates the two medial lumbricals. However, the median nerve innervates the two lateral lumbricals, the flexor digitorum superficialis, the opponens pollicis, and the pronator teres muscles.

28. A 27-year-old man with cubital tunnel syndrome complains of numbness and tin- gling in the ring and little finger and back and sides of his hand because of damage to a nerve in the tunnel at the elbow. Which of the following muscles is most likely to be paralyzed? (A) Flexor digitorum superficialis (B) Opponens pollicis (C) Two medial lumbricals (D) Pronator teres (E) Supinator

29. The answer is C. The carpal tunnel contains the median nerve and the tendons of flexor pollicis longus, flexor digitorum profundus, and flexor digitorum superficialis muscles. Carpal tunnel syndrome results from injury to the median nerve, which supplies the the- nar muscle. Thus, injury to this nerve causes the flattened thenar eminence. The middle finger has no attachment for the adductors. The ulnar nerve innervates the medial half of the flexor digitorum profundus muscle, which allows flexion of the DIP joints of the ring and little fingers. The ulnar nerve supplies the skin over the medial one and one-half fin- gers and adductor pollicis muscle.

29. A secretary comes in to your office com- plaining of pain in her wrists from typing all day. You determine that she likely has carpal tunnel syndrome. Which of the following conditions would help you determine the diagnosis? (A) Inability to adduct the little finger (B) Inability to flex the DIP joint of the ring finger (C) Flattened thenar eminence (D) Loss of skin sensation of the medial one and one-half fingers (E) Atrophied adductor pollicis muscle

3. The answer is D. Winged scapula is caused by paralysis of the serratus anterior muscle that results from damage to the long thoracic nerve, which arises from the roots of the brachial plexus (C5-C7).

3. A 29-year-old man comes in with a stab wound, cannot raise his arm above horizon- tal, and exhibits a condition known as "winged scapula." Which of the following structures of the brachial plexus would most likely be damaged? (A) Medial cord (B) Posterior cord (C) Lower trunk (D) Roots (E) Upper trunk

30. The answer is C. To hold a typing paper, the index finger is adducted by the palmar inter- osseous muscle, and the middle finger is abducted by the dorsal interosseous muscle. Both muscles are innervated by the ulnar nerve.

30. A man is unable to hold typing paper between his index and middle fingers. Which of the following nerves was likely injured? (A) Radial nerve (B) Median nerve (C) Ulnar nerve (D) Musculocutaneous nerve (E) Axillary nerve

31. The answer is D. The proximal row of carpal bones consists of the scaphoid, lunate, tri- quetrum, and pisiform bones, whereas the distal row consists of the trapezium, trapezoid, capitate, and hamate bones.

31. The victim of an automobile accident has a destructive injury of the proximal row of carpal bones. Which of the following bones is most likely damaged? (A) Capitate (B) Hamate (C) Trapezium (D) Triquetrum (E) Trapezoid

32. The answer is C. The rotator cuff consists of the tendons of the supraspinatus, infraspina- tus, subscapularis, and teres minor muscles. It stabilizes the shoulder joint by holding the head of the humerus in the glenoid cavity during movement. The teres major inserts on the medial lip of the intertubercular groove of the humerus.

32. A patient has a torn rotator cuff of the shoulder joint as the result of an automobile accident. Which of the following muscle ten- dons is intact and has normal function? (A) Supraspinatus (B) Subscapularis (C) Teres major (D) Teres minor (E) Infraspinatus

33. The answer is D. The radial artery divides into the princeps pollicis artery and the deep palmar arterial arch. Thus, stenosis of the radial artery results in a decreased blood flow in the princeps pollicis artery. The superficial palmar arterial arch is formed primarily by the ulnar artery, which passes superficial to the flexor retinaculum. The extensor compart- ment of the forearm receives blood from the posterior interosseous artery, which arises from the common interosseous branch of the ulnar artery. However, the radial and radial recurrent arteries supply the brachioradialis and the extensor carpi radialis longus and brevis.

33. A patient complains of having pain with repeated movements of his thumb (claudi- cation). His physician performs the Allen test and finds an insufficiency of the radial artery. Which of the following conditions would be a result of the radial artery steno- sis? (A) A marked decrease in the blood flow in the superficial palmar arterial arch (B) Decreased pulsation in the artery pass- ing superficial to the flexor retinaculum (C) Ischemia of the entire extensor muscles of the forearm (D) A marked decrease in the blood flow in the princeps pollicis artery (E) A low blood pressure in the anterior interosseous artery

34. The answer is A. The dorsal scapular artery arises directly from the third part of the sub- clavian artery and replaces the deep (descending) branch of the transverse cervical artery. The suprascapular and transverse cervical arteries are branches of the thyrocervical trunk of the subclavian artery. The thoracoacromial artery is a short trunk from the first or second part of the axillary artery and has pectoral, clavicular, acromial, and deltoid branches.

34. A patient bleeding from the shoulder secondary to a knife wound is in fair condi- tion because there is vascular anastomosis around the shoulder. Which of the following arteries is most likely a direct branch of the subclavian artery that is involved in the anastomosis? (A) Dorsal scapular artery (B) Thoracoacromial artery (C) Circumflex scapular artery (D) Transverse cervical artery (E) Suprascapular artery

35. The answer is D. Breast cancer may cause dimpling of the overlying skin because of short- ening of the suspensory (Cooper's) ligaments and inverted or retracted nipple because of pulling on the lactiferous ducts. Polymastia is a condition in which more than two breasts are present.

35. During a breast examination of a 56-year-old woman, the physician found a palpable mass in her breast. Which of the following characteristics of breast cancer and its diagnosis is correct? (A) Elevated nipple (B) Polymastia (C) Shortening of the clavipectoral fascia (D) Dimpling of the overlying skin (E) Enlargement of the breast

36. The answer is A. The musculocutaneous nerve contains sympathetic postganglionic fibers that supply sweat glands and blood vessels on the lateral side of the forearm as the lateral antebrachial cutaneous nerve. The musculocutaneous nerve does not supply the exten- sors of the forearm and the brachioradialis. This nerve also supplies tactile sensation on the lateral side of the forearm but not the arm and supplies blood vessels on the lateral side of the forearm but not the hand.

36. A patient with a stab wound receives a laceration of the musculocutaneous nerve. Which of the following conditions is most likely to have occurred? (A) Lack of sweating on the lateral side of the forearm (B) Inability to extend the forearm (C) Paralysis of brachioradialis muscle (D) Loss of tactile sensation on the arm (E) Constriction of blood vessels on the hand

37. The answer is E. The pectoralis major is innervated by the lateral and medial pectoral nerves originating from the lateral and medial cords of the brachial plexus, respectively. The subscapularis, teres major, latissimus dorsi, and teres minor muscles are innervated by nerves originating from the posterior cord of the brachial plexus.

37. A 20-year-old man fell from the parallel bar during the Olympic trial. A neurologic examination reveals that he has a lesion of the lateral cord of the brachial plexus. Which of the following muscles is most likely weak- ened by this injury? (A) Subscapularis (B) Teres major (C) Latissimus dorsi (D) Teres minor (E) Pectoralis major

38. The answer is D. The dorsal interossei are abductors of the fingers. The little finger has no attachment for the dorsal interosseous muscle because it has its own abductor. Therefore, the dorsal interosseous muscle is not affected. Other muscles are attached to the little fin- ger, thus they are injured.

38. A 24-year-old carpenter suffers a crush injury of his entire little finger. Which of the following muscles is most likely to be spared? (A) Flexor digitorum profundus (B) Extensor digitorum (C) Palmar interossei (D) Dorsal interossei (E) Lumbricals

39. The answer is D. Inferior dislocation of the head of the humerus may damage the axillary nerve, which arises from the posterior cord of the brachial plexus, runs through the quad- rangular space accompanied by the posterior humeral circumflex vessels around the sur- gical neck of the humerus, and supplies the deltoid and teres minor, which are lateral rotators of the arm.

39. A 7-year-old boy falls from a tree house and is brought to the emergency department of a local hospital. On examination, he has weakness in rotating his arm laterally because of an injury of a nerve. Which of the following conditions is most likely to cause a loss of this nerve function? (A) Injury to the lateral cord of the brachial plexus (B) Fracture of the anatomic neck of the humerus (C) Knife wound on the teres major muscle (D) Inferior dislocation of the head of the humerus (E) A tumor in the triangular space in the shoulder region

4. The answer is E. The dorsal and palmar interosseous and lumbrical muscles can flex the metacarpophalangeal joints and extend the interphalangeal joints. The palmar interos- seous muscles adduct the fingers, while the dorsal interosseous muscles abduct the fingers. The flexor digitorum profundus flexes the distal interphalangeal (DIP) joints.

4. A 16-year-old patient has weakness flex- ing the metacarpophalangeal joint of the ring finger and is unable to adduct the same finger. Which of the following muscles is most likely paralyzed? (A) Flexor digitorum profundus (B) Extensor digitorum (C) Lumbrical (D) Dorsal interosseous (E) Palmar interosseous

40. The answer is B. Lymph from the breast drains mainly (75%) to the axillary nodes, more specifically to the anterior (pectoral) nodes.

40. A 49-year-old woman is diagnosed as having a large lump in her right breast. Lymph from the cancerous breast drains primarily into which of the following nodes? (A) Apical nodes (B) Anterior (pectoral) nodes (C) Parasternal (internal thoracic) nodes (D) Supraclavicular nodes (E) Nodes of the anterior abdominal wall

41. The answer is C. The axillary nerve contains no preganglionic sympathetic general visceral efferent (GVE) fibers, but it contains postganglionic sympathetic GVE fibers. The axillary nerve also contains GSA, GSE, and general visceral afferent (GVA) fibers.

41. A 17-year-old boy fell from his motorcy- cle and complains of numbness of the lat- eral part of the arm. Examination reveals that the axillary nerve is severed. Which of the following types of axons is most likely spared? (A) Postganglionic sympathetic axons (B) Somatic afferent axons (C) Preganglionic sympathetic axons (D) General somatic efferent axons (E) General visceral afferent axons

42. The answer is E. The radial artery lies on the floor of the anatomic snuffbox. Other struc- tures are not related to the snuffbox. The tendons of the extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus muscles form the boundaries of the anatomic snuffbox. The scaphoid and trapezium bones form its floor.

42. A construction worker suffers a destruc- tive injury of the structures related to the anatomic snuffbox. Which of the following structures would most likely be damaged? (A) Triquetral bone (B) Trapezoid bone (C) Extensor indicis tendon (D) Abductor pollicis brevis tendon (E) Radial artery

43. The answer is C. The subscapularis muscle inserts on the lesser tubercle of the humerus. The supraspinatus, infraspinatus, and teres minor muscles insert on the greater tubercle of the humerus. The coracohumeral ligament attaches to the greater tubercle.

43. A rock climber falls on his shoulder, resulting in a chipping off of the lesser tubercle of the humerus. Which of the fol- lowing structures would most likely have structural and functional damage? (A) Supraspinatus muscle (B) Infraspinatus muscle (C) Subscapularis muscle (D) Teres minor muscle (E) Coracohumeral ligament

44. The answer is C. The supinator and biceps brachii muscles supinate the forearm. The supinator is innervated by the radial nerve, and the biceps brachii is innervated by the musculocutaneous nerve.

44. A 22-year-old female Macarena dancer fell from the stage and complains of elbow pain and inability to supinate her forearm. Which of the following nerves are most likely injured from this accident? (A) Median and ulnar nerves (B) Axillary and radial nerves (C) Radial and musculocutaneous nerves (D) Ulnar and axillary nerves (E) Musculocutaneous and median nerves

46. The answer is D. The sternocleidomastoid muscle is attached to the superior border of the medial third of the clavicle, and the medial fragment of a fractured clavicle is displaced upward by the pull of the muscle.

46. Whichofthefollowingmusclescauses upward displacement of the medial fragment? (A) Pectoralis major (B) Deltoid (C) Trapezius (D) Sternocleidomastoid (E) Scalenus anterior

47. The answer is B. The fractured clavicle may damage the subclavian vein, resulting in a pulmonary embolism; cause thrombosis of the subclavian artery, resulting in embolism of the brachial artery; or damage the lower trunk of the brachial plexus.

47. Which of the following conditions is most likely to occur secondary to the frac- tured clavicle? (A) A fatal hemorrhage from the brachio- cephalic vein (B) Thrombosis of the subclavian vein, caus- ing a pulmonary embolism (C) Thrombosis of the subclavian artery, causing an embolism in the ascending aorta (D) Damage to the upper trunk of the bra- chial plexus (E) Damage to the long thoracic nerve, caus- ing the winged scapula

49. The answer is D. The ulnar nerve innervates the adductor pollicis muscle. The radial nerve innervates the abductor pollicis longus and extensor pollicis brevis muscles, whereas the median nerve innervates the abductor pollicis brevis and opponens pollicis muscles.

49. Which of the following muscles is most likely paralyzed as a result of this acci- dent? (A) Extensor pollicis brevis (B) Abductor pollicis longus (C) Abductor pollicis brevis (D) Adductor pollicis (E) Opponens pollicis

5. The answer is C. The pectoralis minor inserts on the coracoid process, originates from the second to the fifth ribs, and is innervated by the medial and lateral pectoral nerves that arise from the medial and lateral cords of the brachial plexus. It depresses the shoulder and forms the anterior wall of the axilla. The pectoralis minor has no attachment on the clavicle.

5. A 27-year-old patient presents with an inability to draw the scapula forward and downward because of paralysis of the pecto- ralis minor. Which of the following would most likely be a cause of his condition? (A) Fracture of the clavicle (B) Injury to the posterior cord of the brachial plexus (C) Fracture of the coracoid process (D) Axillary nerve injury (E) Defects in the posterior wall of the axilla

60. The answer is D. The superficial branch of the radial nerve runs distally to the dorsum of the hand to innervate the radial side of the hand, including the area of the anatomic snuff- box and the radial two and one-half digits over the proximal phalanx. The medial aspect of the arm is innervated by the medial brachial cutaneous nerve; the lateral aspect of the forearm is innervated by the lateral antebrachial cutaneous nerve of the musculocutane- ous nerve; the palmar aspect of the second and third digits is innervated by the median nerve; and the medial one and one-half fingers are innervated by the ulnar nerve.

60. Following this accident, the patient has no cutaneous sensation in which of the fol- lowing areas? (A) Medial aspect of the arm (B) Lateral aspect of the forearm (C) Palmar aspect of the second and third digits (D) Area of the anatomic snuffbox (E) Medial one and one-half fingers

50. The answer is E. The fingers are adducted by the palmar interosseous muscles; abduction is performed by the dorsal interosseous muscles. The palmar and dorsal interosseous muscles are innervated by the ulnar nerve. The proximal interphalangeal joints are flexed by the flexor digitorum superficialis, which is innervated by the median nerve. However, the DIP joints of the index and middle fingers are flexed by the flexor digitorum profun- dus, which is innervated by the median nerve (except the medial half of the muscle, which is innervated by the ulnar nerve). The median nerve supplies sensory innervation on the palmar aspect of the middle finger. The abductor pollicis brevis is innervated by the median nerve; the abductor pollicis longus is innervated by the radial nerve.

50. After this injury, the patient is unable to do which of the following? (A) Flex the proximal interphalangeal joint of his ring finger (B) Flex the DIP joint of his index finger (C) Feel sensation on his middle finger (D) Abduct his thumb (E) Adduct his index finger Questions 51-55: A 10-year-old boy falls off his bike, has difficulty in moving his shoulder, and is brought to an emergency department. His radiogram and angiogram reveal fracture of the surgical neck of his humerus and bleeding from the point of the fracture.

51. The answer is B. The axillary nerve runs posteriorly around the surgical neck of the humerus and is vulnerable to injury such as fracture of the surgical neck of the humerus or inferior dislocation of the humerus. The other nerves listed are not in contact with the surgical neck of the humerus.

51. Which of the following nerves is most likely injured as a result of this accident? (A) Musculocutaneous (B) Axillary (C) Radial (D) Median (E) Ulnar

52. The answer is C. The (injured) axillary nerve contains GSE fibers whose cell bodies are located in the anterior horn of the spinal cord, and these GSE fibers supply the deltoid and teres minor muscles. The axillary nerve also contains GSA and GVA fibers, whose cell bodies are located in the dorsal root ganglia, and sympathetic postganglionic fibers, whose cell bodies are located in sympathetic chain ganglia. The lateral horn of the spinal cord between T1 and L2 contains cell bodies of sympathetic preganglionic fibers. The posterior horn of the spinal cord contains cell bodies of interneurons.

52. Following this accident, the damaged nerve causes difficulty in abduction, exten- sion, and lateral rotation of his arm. Cell bodies of the injured nerve involved in movement of his arm are located in which of the following structures? (A) Dorsal root ganglion (B) Sympathetic chain ganglion (C) Anterior horn of the spinal cord (D) Lateral horn of the spinal cord (E) Posterior horn of the spinal cord

53. The answer is D. Axillary nerve contains GSE, GSA, GVA, and sympathetic postganglionic GVE fibers. Cell bodies of GSA and GVA fibers are located in the dorsal root ganglia. Cell bodies of GSE fibers are located in the anterior horn of the spinal cord. Cell bodies of sympathetic postganglionic GVE fibers are located in the sympathetic chain ganglia, but cell bodies of sympathetic preganglionic GVE fibers lie in the lateral horn of the spinal cord.

53. Thedamagednervecausesnumbnessof thelateralsideofthearm.Cellbodiesofthe injured nerve fibers involved in sensory loss arelocatedinwhichofthefollowingstruc- tures? (A) Anterior horn of the spinal cord (B) Posterior horn of the spinal cord (C) Lateral horn of the spinal cord (D) Dorsal root ganglia (E) Sympathetic chain ganglia

54. The answer is C. The posterior humeral circumflex artery accompanies the axillary nerve that passes around the surgical neck of the humerus. None of the other arteries are involved.

54. This accident most likely leads to dam- age of which of the following arteries? (A) Axillary (B) Deep brachial (C) Posterior humeral circumflex (D) Superior ulnar collateral (E) Scapular circumflex

55. The answer is B. The lateral rotators of the arm include the teres minor, deltoid, and infra- spinatus muscles, but the infraspinatus muscle is innervated by the suprascapular nerve.

55. Following this accident, the boy has weakness in rotating his arm laterally. Which of the following muscles are paralyzed? (A) Teres major and teres minor (B) Teres minor and deltoid (C) Infraspinatus and deltoid (D) Supraspinatus and subscapularis (E) Teres minor and infraspinatus

57. The answer is B. The median nerve is damaged because it lies medial to the brachial artery. The bicipital aponeurosis lies on the brachial artery and the median nerve. The V-shaped cubital fossa contains (from medial to lateral) the median nerve, brachial artery, biceps tendon, and radial nerve. The ulnar nerve runs behind the medial epicondyle; the lateral and medial antebrachial cutaneous nerves are not closely related to the brachial artery.

57. During the procedure, the needle hits a nerve medial to the artery. Which of the fol- lowing nerves is most likely damaged? (A) Radial (B) Median (C) Ulnar (D) Lateralantebrachial (E) Medialantebrachial

59. The answer is D. The (damaged) radial nerve contains sympathetic postganglionic nerve fibers whose cell bodies are located in the sympathetic chain ganglion. Sympathetic postganglionic fibers supply sweat glands, blood vessels, and hair follicles (arrector pili muscles). The radial nerve also contains GSE fibers whose cell bodies are located in the anterior horn of the spinal cord, and GSA and GVA fibers whose cell bodies are located in the dorsal root ganglion. The lateral horn of the spinal cord between T1 and L2 contains cell bodies of sympathetic preganglionic nerve fibers.

59. As a result of this fracture, the patient shows lack of sweating on the back of the arm and forearm. Cell bodies of the dam- aged nerve fibers involved in sweating are located in which of the following structures? (A) Anterior horn of the spinal cord (B) Posterior horn of the spinal cord (C) Lateral horn of the spinal cord (D) Sympathetic chain ganglion (E) Dorsal root ganglion

6. The answer is D. The intercostobrachial nerve arises from the lateral cutaneous branch of the second intercostal nerve and pierces the intercostal and serratus anterior muscles. It may communicate with the medial brachial cutaneous nerve, and it supplies skin on the medial side of the arm. It contains no skeletal motor fibers but does contain sympathetic postganglionic fibers, which supply sweat glands.

6. A 22-year-old patient received a stab wound in the chest that injured the intercos- tobrachial nerve. Which of the following conditions results from the described lesion of the nerve? (A) Inability to move the ribs (B) Loss of tactile sensation on the lateral aspect of the arm (C) Absence of sweating on the posterior aspect of the arm (D) Loss of sensory fibers from the second intercostal nerve (E) Damage to the sympathetic pregangli- onic fibers

61. The answer is C. The radial nerve accompanies the profunda brachii artery in the radial groove on the posterior aspect of the shaft of the humerus. The posterior humeral circum- flex artery accompanies the axillary nerve around the surgical neck of the humerus. Other arteries are not associated with the radial groove of the humerus.

61. Which of the following arteries may be damaged? (A) Brachial artery (B) Posterior humeral circumflex artery (C) Profunda brachii artery (D) Radial artery (E) Radial recurrent artery

62. The answer is D. A lesion of the radial nerve causes paralysis of the supinator and brachio- radialis. The biceps brachii muscle is a flexor of the elbow and also a strong supinator; thus, supination is still possible through action of the biceps brachii muscle. Other mus- cles cannot supinate the forearm.

62. After this accident, supination is still possible through contraction of which of the following muscles? (A) Supinator (B) Pronator teres (C) Brachioradialis (D) Biceps brachii (E) Supraspinatus

64. The answer is D. Fracture of the surgical neck of the humerus occurs commonly and dam- ages the axillary nerve and the posterior humeral circumflex artery.

64. If the structure indicated by the letter B is fractured, which of the following struc- tures is most likely injured? (A) Musculocutaneous nerve (B) Radial nerve (C) Deep brachial artery (D) Posterior humeral circumflex artery (E) Scapular circumflex artery

66. The answer is E. The medial epicondyle is the site of origin for the common flexor tendon and pronator teres. The common flexors include the flexor carpi radialis and ulnaris and palmaris longus muscles, which can flex the elbow and wrist joints. Thus, destruction of this area causes weakness of pronation because the pronator teres is paralyzed but the pronator quadratus is normal. Similarly, destruction of this area causes paralysis of the flexors of the wrist. However, it can be weakly flexed by the flexor pollicis longus, flexor digitorum superficialis, and profundus muscles.

66. Destruction of this area would most likely cause weakness of pronation of the forearm and flexion of the wrist joints.

67. The answer is D. The olecranon is the site for insertion of the triceps brachii, which is innervated by the radial nerve. When the olecranon is destroyed, the triceps brachii is par- alyzed.

67. A lesion of the radial nerve would most likely cause paralysis of muscles that are attached to this area.

69. The answer is B. The scaphoid forms the floor of the anatomic snuffbox and provides a site for origin of the abductor pollicis brevis.

69. If the floor of the anatomic snuffbox and origin of the abductor pollicis brevis are damaged, which of the following bones is most likely to be involved? (A) A (B) B (C) C (D) D (E) E

7. The answer is A. Injury to the radial nerve results in loss of wrist extension, leading to wrist drop. The median nerve innervates the pronator teres, pronator quadratus, and opponens pollicis muscles and the skin over the ventral aspect of the thumb. The ulnar nerve innervates the dorsal interosseous muscles, which act to abduct the fingers.

7. A 16 year-old boy fell from a motorcycle, and his radial nerve was severely damaged because of a fracture of the midshaft of the humerus. Which of the following condi- tions would most likely result from this accident? (A) Loss of wrist extension leading to wrist drop (B) Weakness in pronating the forearm (C) Sensory loss over the ventral aspect of the base of the thumb (D) Inability to oppose the thumb (E) Inability to abduct the fingers

71. The answer is A. This is the flexor pollicis longus, which is innervated by the median nerve.

71. A lesion of the median nerve causes paralysis of this structure.

72. The answer is G. This is the third palmar interosseous muscle, which adducts the little finger.

72. The patient is unable to adduct her little finger because of paralysis of this structure.

73. The answer is E. The extensor digitorum extends both the metacarpophalangeal and interphalangeal joints.

73. Atrophy of this structure impairs exten- sion of both the metacarpophalangeal and interphalangeal joints.

8. The answer is D. The flexor digitorum superficialis muscle flexes the proximal inter- phalangeal joints. The flexor digitorum profundus muscle flexes the DIP joints. The pal- mar and dorsal interossei and lumbricals can flex metacarpophalangeal joints and extend the interphalangeal joints. The palmar interossei adduct the fingers, and the dorsal inter- ossei abduct the fingers.

8. A patient comes in complaining that she cannot flex her proximal interphalangeal joints. Which of the following muscles appear(s) to be paralyzed on further exami- nation of her finger? (A) Palmar interossei (B) Dorsal interossei (C) Flexor digitorum profundus (D) Flexor digitorum superficialis (E) Lumbricals

9. The answer is C. The latissimus dorsi adducts the arm, and the supraspinatus muscle abducts the arm. The infraspinatus and the teres minor rotate the arm laterally. The serra- tus anterior rotates the glenoid cavity of the scapula upward, abducts the arm, and ele- vates it above a horizontal position.

9. A 21-year-old woman walks in with a shoulder and arm injury after falling during horseback riding. Examination indicates that she cannot adduct her arm because of paralysis of which of the following muscles? (A) Teres minor (B) Supraspinatus (C) Latissimus dorsi (D) Infraspinatus (E) Serratus anterior

45. The answer is E. The lateral fragment of the clavicle is displaced downward by the pull of the deltoid muscle and gravity. The medial fragment is displaced upward by the pull of the sternocleidomastoid muscle. None of the other muscles are involved.

Qeustion 45-47: A 37-year-old female patient has a fracture of the clavicle. The junction of the middle and lateral thirds of the bone exhibits overriding of the medial and lateral fragments. The arm is rotated medially, but it is not rotated laterally. 45. The lateral portion of the fractured clavi- cle is displaced downward by which of the following? (A) Deltoid and trapezius muscles (B) Pectoralis major and deltoid muscles (C) Pectoralis minor muscle and gravity (D) Trapezius and pectoralis minor muscles (E) Deltoid muscle and gravity

48. The answer is E. The ulnar nerve runs down the medial aspect of the arm and behind the medial epicondyle in a groove, where it is vulnerable to damage by fracture of the medial epicondyle. Other nerves are not in contact with the medial epicondyle.

Questions 48-50: A 21-year-old man injures his right arm in an automobile accident. Radiographic examination reveals a fracture of the medial epicondyle of the humerus. 48. Which of the following nerves is most likely injured as a result of this accident? (A) Axillary (B) Musculocutaneous (C) Radial (D) Median (E) Ulnar

56. The answer is A. The median cubital vein lies superficial to the bicipital aponeurosis and thus separates it from the brachial artery, which can be punctured during intravenous injections and blood transfusions.

Questions 56 and 57: A 64-year-old man with a history of liver cirrhosis has been examined for hepatitis A, B, and C viruses. In an attempt to obtain a blood sample from the patient's median cubital vein, a registered nurse inadvertently procures arterial blood. 56. The blood most likely comes from which of the following arteries? (A) Brachial (B) Radial (C) Ulnar (D) Common interosseous (E) Superior ulnar collateral

68. The answer is C. The hook of hamate and the pisiform provide insertion for the flexor carpi ulnaris.

Questions 68 and 69: Choose the appropriate lettered site or structure in the following radio- graph of the wrist and hand (see figure below). 68. Destruction of the structure indicated by the letter E most likely causes weakness of which of the following muscles? (A) Flexor carpi radialis (B) Palmaris longus (C) Flexor carpi ulnaris (D) Brachioradialis (E) Flexor digitorum superficialis

70. The answer is D. This is the second dorsal interosseous muscle, which abducts the middle finger.

Questions 70-73: Choose the appropriate let- tered site or structure in this transverse mag- netic resonance imaging through the middle of the palm of a woman's right hand (see fig- ure below) that matches the following descriptions. 70. The patient is unable to abduct her mid- dle finger because of paralysis of this struc- ture.

58. The answer is B. The radial nerve runs in the radial groove on the back of the shaft of the humerus with the profunda brachii artery. The axillary nerve passes around the surgical neck of the humerus. The ulnar nerve passes the back of the medial epicondyle. The mus- culocutaneous and median nerves are not in contact with the bone, but the median nerve can be damaged by supracondylar fracture.

Questions58-62: A17-year-oldboyisinjured in an automobile accident. He has a fracture of the shaft of the humerus. 58. Which of the following nerves is most likely damaged? (A) Axillary nerve (B) Radial nerve (C) Musculocutaneous nerve (D) Median nerve (E) Ulnar nerve

65. The answer is B. The radial tuberosity is the site for tendinous attachment of the biceps brachii muscle, which supinates and flexes the forearm. When the tuberosity is destroyed, the biceps brachii is paralyzed.

Questions65-67: Choosetheappropriatelet- tered site or structure in the radiograph of the elbow joint (see figure below) and its associated structures to match the following descriptions. 65. Destruction of this area would most likely cause weakness of supination and flexion of the forearm.

63. The answer is D. The scapular notch transmits the suprascapular nerve below the superior transverse ligament, whereas the suprascapular artery and vein run over the ligament. The suprascapular nerve supplies the supraspinatus and infraspinatus muscles. The axillary nerve innervates the deltoid and teres minor muscles. The subscapular nerves innervate the teres major and subscapularis muscles.

uestions 63 and 64: An 11-year-old boy falls down the stairs. A physician examines a radi- ograph of the boy's shoulder region (see figure below). 63. If the structure indicated by the letter A is calcified, which of the following muscles is most likely paralyzed? (A) Deltoid (B) Teres major (C) Teres minor (D) Infraspinatus (E) Subscapularis