Upper Limb

Question 1

(6.2) A patient suffered a fracture of the lateral border of the scapula. 6 weeks after the accident, physical examination reveals weakness in medial rotation and adduction of the humerus. Which nerve was most likely injured?

Answer 1

The lower subscapular nerve arises from C5 and C6. It innervates the subscapularis and teres major muscles. The subscapularis and teres major muscles are both responsible for adduction and medially rotating the arm.

Question 2

(6.3) A stenographer has carpal tunnel syndrome. Which muscles typically become weakened in this condition?

Answer 2

The thenar muscles (lumbricals I and II) are innervated by the median nerve, which runs through the carpal tunnel.

The carpal tunnel is formed anteriorly by the flexor retinaculum and posteriorly by the carpal bones.

The carpal tunnel contains the tendons of flexor pollicis longus, flexor digitorum profundus, and flexor digitorum superficialis muscles.

Question 3

(6.4) A patient has a fracture of the medial epicondyle and an injured ulnar nerve. Which muscles will most likely be paralyzed?

Answer 3

Fracture of the medial epicondyle causes damage to the ulnar nerve due to its position in the groove behind the epicondyle. The ulnar nerve innervates one and a half muscles in the forearm, the flexor carpi ulnaris and the medial half of the flexor digitorum profundus muscles.

The nerve continues on to innervate most of the muscles in the hand.

Question 4

(6.5) A patient has a midshaft fracture of the humerus. Which pair of structure was most likely injured at the fracture site?

Answer 4

A midshaft humeral fracture can result in injury to the radial nerve and deep brachial artery because they lie in the spiral groove located in the midshaft.

Question 5

(6.6) A patient has a transverse fracture of the humerus 1 inch proximal to the epicondyles. Which nerve is most frequently injured by the jagged edges of the broken bone at this location?

Answer 5

A supracondylar fracture often results in injury to the median nerve. The course of the median nerve is anterolateral and at the elbow it lies medial to the brachial artery on the brachialis muscle.

The axillary nerve passes posterioly through the quadrangular space, accompanied by the PCHA, and winds around the surgical neck of the humerus.

Question 6

(6.7) A patient has wrist drop and weakness of grasp but normal extension of the elbow joint. There is no loss of sensation. Which nerve is affected?

Answer 6

The radial nerve gives off the superficial and deep branches. The deep branch of the radial nerve continues as the posterior interosseous nerve, innervating extensor muscles of the forearm.

Because there is no loss of sensation, the superficial branch is not injured.

If the radial nerve were injured very proximally, the woman would not be able to extend her elbow.

Question 7

(6.8) A patient fractured her humerus. Flexion and supination of the forearm are severely weakened. She also has loss of sensation on the lateral surface of the forearm. Which nerve is injured?

Answer 7

The musculocutaneous nerve supplies the biceps brachii and brachialis muscles, 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.

Question 8

(6.9) A patient has a wound at the base of her thumb. The wound became infected and the infection spread into the radial bursa. The tendon of which muscle will most likely be affected?

Answer 8

Tenosynovitis can be due to an infxn of the synovial sheaths of the digits. Tenosynovitis may spread through the synovial sheaths of the flexor pollicis longus tendon, aka, the radial bursa.

Question 9

(6.10) Which artery is most likely at risk during venipuncture at the cubital fossa?

Answer 9

The 3 chief contents of the cubital fossa:

1. biceps brachii tendon

2. brachial artery

3. median nerve (lateral to medial)

Question 10

(6.11) Which lymph nodes receive most of the lymph from the xiphoid process and are most likely to be involved in metastasis of a tumor?

Answer 10

Lymph from the skin of the anterior chest wall primarily drains into the axillary lymph nodes.

Question 11

(6.12) A woman undergoes a bypass graft procedure using the internal thoracic artery. Which vessels will continue to supply blood to the anterior part of the upper intercostal spaces?

Answer 11

The anterior intercostal arteries are twelve 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.

Question 12

(6.13) The nurse takes a radial pulse. This pulse is felt lateral to which tendon?

Answer 12

The location for palpation of the radial pulse is lateral to the tendon of the flexor carpi radialis.

Question 13

(6.14) A patient is unable to flex the distal interphalangeal joints of the 4th and 5th digits. Which muscle is affected?

Answer 13

The flexor digitorum profundus muscle is dually innervated by the ulnar nerve to the medial 2 fingers and the median nerve for the middle and index finger.

Question 14

A patient cannot touch the pad of his index finger 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 nerve has been injured?

Answer 14

The recurrent branch of the median nerve is motor to the muscles of the thenar eminences. If the opponens pollicis is paralyzed, a patient cannot oppose the pad of the thumb to the pads of the other digits (this is the only muscle that can oppose the thumb).

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.

Question 15

(6.17) A mother tugs at her son’s arms. Thereafter, the child cannot straighten his forearm at the elbow. There is a dislocation of the head of the radius. Which ligament is associated with the injury?

Answer 15

The anular ligament functions to prevent displacement of the head of the radius from its socket. In a child of this age the head of the radius is almost the same diameter as the shaft of the bone, so the head is easy to dislocate.

Question 16

(6.18) After a forceps delivery of an infant boy, the baby presents with his left upper limb adducted, internally rotated and flexed at the wrist. Which part of the brachial plexus is injured?

Answer 16

This injury is also known as Erb’s paralysis (waiter’s tip hand). It 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.

Question 17

(6.19) A man has pain under the nail of his pinky finger. Which nerve would have to be anesthetized for a painless removal of the tumor?

Answer 17

The common palmar digital branch of the ulnar 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 cutaenous innervation to the radial (lateral) dorsum of the hand.

Question 18

A patient has a fractured carpal bone in the floor of the anatomic snuffbox. Radiograph is attached. Which bone is fractured?

Answer 18

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.

Question 19

(6.21) A man had a 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 injured?

Answer 19

The ulnar nerve innervates the palmar interossei, which adduct the fingers.

Question 20

(6.22) A man dislocated his shoulder. He has pain over the dorsal region of the shoulder and cannot abduct his arm normally. Which muscle is damaged?

Answer 20

The supraspinatus muscle is one of the four rotator cuff muscles, SItS (supraspinatus, infraspinatus, teres minor, subscapularis). The supraspinatus initiates abduction of the arm.

Question 21

(6.26) A man has a nerve severed after a street fight. He has weakness of elbow flexion and supination. What will also be seen?

Answer 21

The musculocutaenous nerve innervates the brachialis and biceps brachii muscles, which are the main flexors at the elbow. Since the musculocutaneous is damaged, it leads to loss of sensory perception to the lateral forearm, which is supplied by the distal continuation of the musculocutaneous nerve (lateral antebrachial cutaneous nerve).

Question 22

(6.28) A female has pain in her right hand when she fell with force on her outstretched hand. X-rays show an anterior dislocation of a carpal bone. Which bone is dislocated?

Answer 22

The lunate is the most commonly dislocated carpal bone because of its shape and relatively weak ligaments anteriorly.

Question 23

(6.29) The dorsal root ganglia of C8 and T1 would contain cell bodies of sensory fibers carried by which nerves?

Answer 23

The medial antebrachial cutaneous nerve carried sensory fibers derived from the C8 and T1 levels.

Question 24

(6.33) A patient has an injury to the medial cord of the brachial plexus. Which spinal nerve levels are affected?

Answer 24

The medial cord is the continuation of the inferior (lower) trunk of the brachial plexus, which is formed by C8 and T1.

C5 and C6 are typically associated with the superior (upper) trunk level and thus the lateral cord.

C7 forms the middle trunk.

Question 25

(6.35) An patient with an injury of the nerve in the spiral groove would demonstrate what physical signs?

Answer 25

Injury to the radial nerve in the spiral groove will paralyze the abductor pollicis longus muscle 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.

Question 26

(6.38) A patient fell asleep with a book wedged into this axilla. When he awoke in the morning, he was unable to extend his wrist or fingers. Which nerves were most likely compressed?

Answer 26

The raidal nerve is the most likely nerve compressed. This is called “Saturday night palsy.” The radial nerve innervates all of the extensors of the elbow, wrist and fingers. It innervates the triceps brachii muscle (innervated by the motor branch which comes off proximally, therefore unaffected here).

Question 27

(6.39) A physician looks for a vein in the patient to start dialysis. The physician found a vein on the medial side of the arm that passed through the superficial and deep fascia to join veins beside the brachial artery. Which vein is this?

Answer 27

The basilic vein can be used for dialysis, especially when the cephalic vein (lateral) is too small.

Question 28

(6.42) A woman has a tumor slight above and lateral to the right areola of her right breast. Which nodes will encounter the lymph from the tumor first?

Answer 28

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.

Question 29

(6.43) A patient has his left shoulder drooping lower than the right, 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 nerve is most likely injured?

Answer 29

The left spinal accessory nerve (CN XI) is injured distal to the SCM muscle, which resulted in paralysis of the trapezius, allowing the shoulder to droop and the superior angle to push out posteriorly. The SCM muscles are intact, indicated by symmetry in strength in turning the head to the right and left.

Question 30

(6.44) A woman has radial nerve palsy. When muscle function is examined at the MCP, PIP and DIP, what findings are present?

Answer 30

Inability to extend the MCP. The tendons of the extensor digitorum and ex

Question 31

(6.53) A man is unable to oppose the tip of the thumb to the tip of the index finger, as in making the OK sign. He is able to touch the tips of the ring and little fingers to the pad his thumb. What nerve is injured?

Answer 31

The anterior interosseious nerve is a branch of the median nerve that supplies the flexor pollicis longus, the lateral half of the flexor digitorum profundus and the pronator quadratus muscle.

Question 32

(6.57) A woman has weakness in wrist extension and paraesthesia on the back of her arm and forearm. Which spinal nerve is most likely injured?

Answer 32

C7 makes a major contribution to the radial nerve and this nerve is the prime mover in wrist extension.

Question 33

(6.63) The quadrangular space is greatly reduced in a person. Which structure would be compressed in this condition?

Answer 33

Both the axillary nerve and PCHA traverse this space.