2- Upper Limb MSQs Only (2)

Question 1

1- A 6 year old sustains a supracondylar fracture of the distal humerus. There are concerns that the radial nerve may have been injured. What is the relationship of the radial nerve to the humerus at this point?

Answer 1

Anterolateral

‏The radial nerve lies anterolateral to the humerus in the supracondylar area.

Question 2

2- Which of the following fingers is not a point of attachment for the palmar interossei?

Answer 2

Middle finger

Question 3

3- A 73 year old lady with long standing atrial fibrillation develops a cold and pulseless white arm. A brachial embolus is suspected and a brachial embolectomy is performed. Which of the following structures is at greatest risk of injury during this procedure?

Answer 3

Median nerve

The median nerve lies close to the brachial artery in the antecubital fossa. This is the usual site of surgical access to the brachial artery for an embolectomy procedure. The median nerve may be damaged during clumsy application of vascular clamps to the artery.

Question 4

4- A 44 year old lady has undergone a mastectomy and axillary node clearance. Post operatively. she notices a patch of anaesthesia of her axillary skin when she applies an underarm deodorant. Which nerve has most likely been affected?

Answer 4

Intercostobrachial

The intercostobrachial nerves traverse the axilla and innervate the overlying skin. These can be injured or divided during axillary surgery and the result is anaesthesia of the overlying skin

Question 5

5- Which of the following muscles lies medial to the long thoracic nerve?

Answer 5

Serratus anterior

Question 6

6- The following are true of the ulnar nerve except:

Answer 6

Supplies the muscles of the thenar eminence

The muscles of the thenar eminence are supplied by the median nerve and atrophy of these is a feature of carpal tunnel syndrome.

Question 7

7- A 43 year old lady is undergoing an axillary node clearance for breast cancer. The nodal disease is bulky. During clearance of the level 3 nodes there is suddenly brisk haemorrhage. The most
likely vessel responsible is:

Answer 7

Thoracoacromial artery

The thoracoacromial artery pierces the pectoralis major and gives off branches within this space.
The level 3 axillary nodes lie between pectoralis major and minor.Although the thoracodorsal trunk may be injured during an axillary dissection it does not lie within the level 3 nodes.

Question 7

8- A 33 year old man sustains an injury to his forearm and wrist. When examined in clinic he is unable to adduct his thumb. What is the most likely underlying nerve lesion?

Answer 7

Deep branch of the ulnar nerve

Damage to the deep branch of the ulnar nerve may result in an inability to adduct the thumb. This is tested clinically by trying to withdraw a piece of paper from a patients hand grasped between thumb and index finger.

Question 8

9- A 24 year female is admitted to A&E with tingling of her hand after a fall. She is found to have a fracture of the medial epicondyle. What is the most likely nerve lesion?

Answer 8

Ulnar nerve

The radial nerve is located near the lateral epicondyle.

Question 9

10- A 58 year old lady presents with a mass in the upper outer quadrant of the right breast. Which of the following statements relating to the breast is untrue?

Answer 9

The internal mammary artery provides the majority of its arterial supply

Nipple retraction may occur as a result of tumour infiltration of the clavipectoral fascia ( Right)

The internal mammary artery is a branch of the subclavian artery

Up to 70% of lymphatic drainage is to the ipsilateral axillary nodes

None of the above

Both skin dimpling and nipple retraction are features of breast malignancy. However, they usually occur as a result of tumour infiltration of the breast ligaments and ducts respectively. The clavipectoral fascia encases the axillary contents. The lymphatic drainage of the breast is to the axilla and also to the internal mammary chain. The breast is well vascularised and the internal mammary artery is a branch of the subclavian artery.

Question 10

11- A 53 year old lady presents with pain and discomfort in her hand. She works as a typist and notices that the pain is worst when she is working. She also suffers symptoms at night. Her little finger is less affected by the pain. Which of the nerves listed below is most likely to be affected?

Answer 10

Median

Motor supply: LOAF
L ateral 2 lumbricals
O pponens pollicis
A bductor pollicisbrevis
F lexor pollicis brevis

The most likely diagnosis here is carpal tunnel syndrome, the median nerve is compressed in the
wrist and symptoms usually affect the fingers and wrist either at night or when the hand is being
used (e.g. as a typist).

Question 11

12- A 78 year old man is lifting a heavy object when he feels a pain in his forearm and is unable to
continue. He has a swelling over his upper forearm. An MRI scan shows a small cuff of tendon still attached to the radial tuberosity consistent with a recent tear. Which of the following muscles
has been injured?

Answer 11

Biceps brachii

Biceps inserts into the radial tuberosity. Distal injuries of this muscle are rare but are reported and are clinically more important than more proximal ruptures.

Question 12

13- From which of the following structures does the long head of the triceps muscle arise?

Answer 12

Infraglenoid tubercle

The long head arises from the infraglenoid tubercle. The fleshy lateral and medial heads are attached to the posterior aspect of the humerus between the insertion of the teres minor and the olecranon fossa.

Question 13

14- A 62 year old man presents with arm weakness. On examination, he has a weakness of elbow extension and loss of sensation on the dorsal aspect of the first digit. What is the site of the most likely underlying defect?

Answer 13

Radial nerve

The long head of the triceps muscle may be innervated by the axillary nerve and therefore complete loss of triceps muscles function may not be present even with proximally sited nerve lesions.

Question 14

15- As it exits the axilla the radial nerve passes over the inferior border which of the muscles listed below?

Answer 14

Teres major

The radial nerve passes through the triangular interval to leave the axilla. The superior border of this is bounded by the teres major muscle to which the radial nerve is closely related.

Question 15

16- A 32 year old man is stabbed in the neck and the inferior trunk of his brachial plexus is injured.
Which of the modalities listed below is least likely to be affected?

Answer 15

Initiating abduction of the shoulder

Inferior trunk of brachial plexus.
. C8 and T1 roots
. Contributes to ulnar nerve and part of median nerve

The inferior trunk of the brachial plexus is rarely injured. Nerve roots C8 and T1 are the maincontributors to this trunk. Therefore an injury to this site will most consistently affect the ulnar nerve. The inferior trunk also contributes to the median nerve by way of the medial cord and therefore some impairment of grip is almost inevitable.

Question 16

17- A 42 year old teacher is admitted with a fall. An x-ray confirms a fracture of the surgical neck of the humerus. Which nerve is at risk?

Answer 16

Axillary

The Axillary nerve winds around the bone at the neck of the humerus. The axillary nerve is also at risk during shoulder dislocation.

Question 17

18- Which of these muscles is not a component of the rotator cuff?

Answer 17

Subscapularis

Teres minor

Supraspinatus

Infraspinatus

Deltoid ( Right)

Deltoid may abduct the shoulder and is not a rotator cuff muscle.

Question 18

19- Which of the following is not a carpal bone?

Answer 18

Trapezium

Triquetrum

Trapezoid

Trapezius ( Right)

Lunate

Mnemonic for the Carpal Bones:
Sally Likes To Play The Tiny Chrome Harmonica
She Looks Too Pretty Try To Catch Her
Scared Lovers Try Positions That They Can’t Handle

Question 19

20- A 23 year old man has a cannula inserted into his cephalic vein. Through which structure does the cephalic vein pass?

Answer 19

Clavipectoral fascia

The cephalic vein is a favored vessel for arteriovenous fistula formation and should be preserved in patients with end stage renal failure
The cephalic vein penetrates the clavipectoral fascia (but not the pectoralis major) prior to terminating in the axillary vein.

Question 20

21- A man sustains a laceration between the base of the little finger and wrist. Several weeks after the injury there is loss of thumb adduction power. Which nerve is most likely to have been injured?

Answer 20

Deep ulnar nerve

Question 21

22- A motor cyclist is involved in a road traffic accident causing severe right shoulder injuries. He is found to have an adducted, medially rotated shoulder. The elbow is fully extended and the forearm pronated. Which is the most likely diagnosis?

Answer 21

C5, C6 root lesion

Erbs Palsy C5, C6 lesion
The features include:
· Waiter’s tip position
· Loss of shoulder abduction (deltoid and supraspinatus paralysis)
· Loss of external rotation of the shoulder (paralysis of infraspinatus)
· Loss of elbow flexion (paralysis of biceps, brachialis and brachioradialis)
· Loss of forearm supination (paralysis of Biceps)

The motorcyclist has had an Erb’s palsy (C5, C6 root lesion). This is commonly known to be associated with birth injury when a baby has a shoulder dystocia.

Question 22

23- A 56 year old machinist has his arm entrapped in a steel grinder and is brought to the emergency department. On examination, he is unable to extend his metacarpophalangeal joints and abduct his shoulder. He has weakness of his elbow and wrist. What has been injured?

Answer 22

Posterior cord of brachial plexus

The posterior cord gives rise to:
· Radial nerve ((innervates the triceps, brachioradialis, wrist extensors, and finger
extensors)
· Axillary nerve (innervates deltoid and teres minor)
· Upper subscapular nerve (innervates subscapularis)
· Lower subscapular nerve (innervates teres major and subscapularis)
· Thoracodorsal nerve (innervates latissimus dorsi)

This is a description of a posterior cord lesion. Remember that the posterior cord gives rise to the axillary and radial nerve.

Question 23

24- Which of the following is not a branch of the posterior cord of the brachial plexus?

Answer 23

Musculocutaneous nerve

Mnemonic branches off the posterior cord:
S ubscapular (upper and lower)
T horacodorsal
A xillary
R adial

The musculocutaneous nerve is a branch off the lateral cord.

Question 24

25- A 23 year old man falls and injures his hand. There are concerns that he may have a scaphoid fracture as there is tenderness in his anatomical snuffbox on clinical examination.
Which of the following forms the medial border of this structure?

Answer 24

Extensor pollicis longus

It’s boundaries are extensor pollicis longus medially and laterally by the tendons of abductor pollicis longus and extensor pollicis brevis.

Question 25

26- A 28 year teacher reports difficulty with writing. There is no sensory loss. She is known to have an aberrant Gantzer muscle. Which of the following nerves has been affected?

Answer 25

Anterior interosseous

Anterior interosseous lesions occur due to fracture, or rarely due to compression. The
Gantzer muscle is an aberrant accessory of the flexor pollicis longus and is a risk factor for anterior interosseous nerve compression. Remember loss of pincer grip and normal sensation indicates an interosseous nerve lesion.

Question 26

27- A 44 year old lady who works as an interior decorator has undergone a mastectomy and axillary node clearance to treat breast cancer. Post operatively, she comments that her arm easily becomes fatigued when she is painting walls. What is the most likely explanation?

Answer 26

Injury to the thoracodorsal nerve

The most likely explanation for this is that the thoracodorsal nerve has been injured. This will result in atrophy of latissimus dorsi and this will become evident with repetitive arm movements where the arm is elevated and moving up and down (such as in painting). Injury to the pectoral nerves may produce a similar picture but this pattern of injury is very rare and the pectoral nerves are seldom injured in breast surgery.

Question 27

28- The common peroneal nerve, or its branches, supply the following muscles except:

Answer 27

Peroneus longus
Tibialis anterior
Extensor hallucis longus
Flexor digitorum brevis (Right)
Extensor digitorum longus

Flexor digitorum is supplied by the tibial nerve.

Question 28

29- A 23 year old man falls over whilst intoxicated and a shard of glass transects his median nerve at the proximal border of the flexor retinaculum. His tendons escape injury. Which of the following features is least likely to be present?

Answer 28

Loss of sensation on the dorsal aspect of the thenar eminence

The median nerve may be injured proximal to the flexor retinaculum. This will result in loss of abductor pollicis brevis, flexor pollicis brevis, opponens pollicis and the first and second lumbricals. When the patient is asked to close the hand slowly there is a lag of the index and middle fingers reflecting the impaired lumbrical muscle function. The sensory changes are
minor and do not extend to the dorsal aspect of the thenar eminence.
Abductor pollicis longus will contribute to thumb abduction (and is innervated by the posterior interosseous nerve) and therefore abduction will be weaker than prior to the injury.

Question 29

30- A 28 year old man is stabbed outside a nightclub in the upper arm. The median nerve is transected. Which of the following muscles will demonstrate impaired function as a result?

Answer 29

Abductor pollicis brevis

Palmaris brevis - Ulnar nerve
Palmar interossei- Ulnar nerve
Adductor pollicis - Ulnar nerve
Abductor pollicis longus - Posterior interosseous nerve
Abductor pollicis brevis - Median nerve

The median nerve innervates all the short muscles of the thumb except the adductor and the deep head of the short flexor. Palmaris and the interossei are innervated by the ulnar nerve.

Question 30

31- In the distal third of the upper arm, where is the musculocutaneous nerve located?

Answer 30

Between the biceps brachii and brachialis muscles

………………………………………………………….
The musculocutaneous nerve lies between the biceps and brachialis muscles.

Question 31

32- Which of the following structures attaches periosteum to bone?

Answer 31

Sharpeys fibres

Periosteum is attached to bone by strong collagenous fibers called Sharpey’s fibres, which extend to the outer circumferential and interstitial lamellae. It also provides an attachment for muscles and tendons.

Question 32

33- An injured axillary artery is ligated between the thyrocervical trunk of the subclavian and subscapular artery. Subsequent collateral circulation is likely to result in reversal of blood flow in which of the vessels listed below?

Answer 32

Circumflex scapular artery

……………………………..
It’s an easy question really, we just made the wording difficult (on purpose). It is asking about the branches of the axillary artery and knowledge of the fact that there is an extensive collateral network around the shoulder joint. As a result, the occlusion of the proximal aspect of the circumflex humeral inflow (from the axillary artery) ceases and there is then retrograde flow through it from collaterals.

Question 33

34- An injury to the spinal accessory nerve will have the greatest effect on which of the following movements?

Answer 33

Upward rotation of the scapula

The spinal accessory nerve innervates trapezius. The entire muscle will retract the scapula. However,
its upper and lower fibres act together to upwardly rotate it.

Question 34

35- Which nerve supplies sensation to the nail bed of the index finger?

Answer 34

Median

Question 35

36- Which of the following is not closely related to the capitate bone?

Answer 35

Ulnar nerve

The ulnar nerve and artery lie adjacent to the pisiform bone. The capitate bone articulates with the
lunate, scaphoid, hamate and trapezoid bones, which are therefore closely related to it.

Question 36

37- A woman develops winging of the scapula following a Patey mastectomy. What is the most likely cause?

Answer 36

Damage to the long thoracic nerve during axillary dissection

The serratus anterior muscle is supplied by the long thoracic nerve which runs along the surface of serratus anterior and is liable to injury during nodal dissection. Although pectoralis minor is divided during a Patey mastectomy (now seldom performed) it is rare for this alone to produce winging of the scapula.

Question 36

39- During a difficult thyroidectomy haemorrhage is noted from the thyroidea ima vessel. From which structure does this vessel usually arise?

Answer 36

Brachiocephalic artery

Rhyme isthmus location:
Rings 2,3,4 make the isthmus floor

This accessory vessel which usually lies at the inferior aspect of the gland is derived either from the brachiocephalic artery or the arch of the aorta.

Question 36

40- A 72 year old male with end stage critical ischaemia is undergoing an axillo-femoral bypass. What structure is not closely related to the axillary artery?

Answer 36

Scalenus anterior muscle

The axillary artery is the continuation of the subclavian artery. It is surrounded by the cords of thebrachial plexus (from which they are named). The axillary vein runs alongside the axillary artery throughout its length.

Question 37

38- The cephalic vein pierces the clavipectoral fascia to terminate in which of the veins listed below?

Answer 37

Axillary

Question 38

41- During an arch aortogram the brachiocephalic artery is entered with an angiography catheter. The radiologist continues to advance the catheter. Into which of the following vessels is it likely to enter?

Answer 38

Right subclavian artery

The axillary artery is a branch of the subclavian artery and although developmental anomalies may occur they are rare. The catheter may also enter the right carotid. There is no brachiocephalic artery on the left side.

Question 38

42- Which of the following carpal bones is a sesamoid bone in the tendon of flexor carpi ulnaris?

Answer 38

Pisiform

This small bone has a single articular facet. It projects from the triquetral bone at the ulnar aspect of the wrist where most regard it as a sesamoid bone lying within the tendon of flexor carpi ulnaris.

Question 39

43- A 22 year old man develops an infection in the pulp of his little finger. What is the most proximal site to which this infection may migrate?

Answer 39

Proximal to the flexor retinaculum

The 5th tendon sheath extends from the little finger to the proximal aspect of the carpal tunnel. This carries a significant risk of allowing infections to migrate proximally.

Question 39

44- An 18 year old man develops a severe spreading sepsis of the hand. The palm is explored surgically and the flexor digiti minimi brevis muscle is mobilised to facilitate drainage of the infection. Which of the following structures is not closely related to this muscle?

Answer 39

Median nerve

The flexor digiti minimi brevis originates from the Hamate, on its under- surface lie the ulnar contribution to the superficial palmar arterial arch and digital nerves derived from the ulnar nerve. The median nerve overlies the flexor tendons.

Question 39

45- A well toned weight lifter attends clinic reporting weakness of his left arm. There is weakness of flexion and supination of the forearm. Which of the following nerves is likely to have been affected?

Answer 39

Musculocutaneous

Musculocutaneous nerve compression due to entrapment of the nerve between biceps and brachialis. Elbow flexion and supination of the arm are affected. This is a rare isolated injury.

Question 40

46-Which of the muscles listed below would be affected if the radial nerve were injured in a humeral shaft fracture?

Answer 40

Supinator ( Right)

Flexor digitorum profundus

Brachialis

Abductor pollicis brevis

Abductor digiti minimi

Question 41

47- A 73 year old lady is hit by a car. She suffers a complex fracture of the distal aspect of her humerus with associated injury to the radial nerve. Which of the following movements will be most impaired as a result?

Answer 41

Wrist extension

The triceps will not be affected so elbow extension will be preserved. Loss of wrist extension will be the most obvious effect.

Question 42

48- A 70 year old man falls and fractures his scaphoid bone. The fracture is displaced and the decision is made to insert a screw to fix the fracture. Which of the following structures lies directly medial to the scaphoid?

Answer 42

Lunate

The lunate lies medially in the anatomical plane. Fractures of the scaphoid that are associated with high velocity injuries may cause associated lunate dislocation.

Question 43

49- Into which of the following structures does the superior part of the fibrous capsule of the shoulder joint insert?

Answer 43

The anatomical neck of the humerus

The shoulder joint is a shallow joint, hence its great mobility. However, this comes at the expense of stability. The fibrous capsule attaches to the anatomical neck superiorly and the surgical neck inferiorly

Question 43

50- A 43 year old woman is due to undergo an axillary node clearance following a positive sentinel node biopsy. Which of the nerves below is at greatest risk?

Answer 43

Thoracodorsal

The long thoracic nerve is also at risk. The thoracodorsal nerve traverses the level 2 axillary nodes to supply latissimus dorsi and may be divided or damaged with diathermy.

Question 44

52- Which of the following muscles is not innervated by the deep branch of the ulnar nerve?

Answer 44

Opponens pollicis

Opponens pollicis is innervated by the deep branch of the median. If you answered the question incorrectly, note that it asks about which muscle is NOT innervated by the deep branch.

Question 44

51- Which of the following structures lie between the lateral and medial heads of the triceps muscle?

Answer 44

Radial nerve

The radial nerve runs in its groove on between the two heads. The ulnar nerve lies anterior to the medial head. The axillary nerve passes through the quadrangular space. This lies superior to lateral head of the triceps muscle and thus the lateral border of the quadrangular space is the humerus. Therefore the correct answer is the radial nerve.

Question 45

A 17 year old male presents to the clinic. He complains of difficulty using his left hand. It has been a persistent problem since he sustained a distal humerus fracture as a child. On examination, there is diminished sensation overlying the hypothenar eminence and medial one and half fingers. What is the most likely nerve lesion?

Answer 45

Ulnar nerve

This sensory deficit pattern is most consistent with ulnar nerve injury.

Question 46

54- A 20 year old man presents to the Emergency Department with a stab injury to the thenar eminence. On examination, he is found to have a 2 cm long laceration with loss of sensation in the thumb and index finger and weakness of the thenar muscles. Which of the following structures is most likely to have been injured?

Answer 46

Sensory and motor branches of the median nerve

The question describes both a motor and sensory deficit. This means that injury cannot be isolated to the recurrent branch of the median nerve in isolation as this only provides motor function. Sensation via the palmar cutaneous branches must also be compromised and it is for this reason the correct answer is injury to motor and sensory branches of the median nerve.

Question 47

55- A 42 year old lady has had an axillary node clearance for breast malignancy. Post operatively she reports weakness of the shoulder. She is unable to push herself forwards from a wall with the right arm and the scapula is pushed out medially from the chest wall. What is the most likely nerve injury?

Answer 47

Long thoracic nerve

The patient has a winged scapula caused by damage to the long thoracic nerve (C5,6,7) during surgery.
The long thoracic nerve innervates serratus anterior. Serratus anterior causes pushing out of the scapula during a punch.

NB winging of the scapular laterally may indicate trapezius muscle weakness. Innervated by the spinal accessory nerve.

Question 48

58- The anterior interosseous nerve is a branch of which of the following?

Answer 48

Median nerve

Question 48

56- Which of these muscles is supplied by the musculocutaneous nerve?

Answer 48

Brachialis

Mnemonic
muscles is supplied by the musculocutaneous nerve: BBC
Biceps brachii
Brachialis
Coracobrachialis

Question 49

57- In Froment’s test which muscle function is tested?

Answer 49

Adductor pollicis

Question 49

59- Which of the following is a branch of the third part of the axillary artery?

Answer 49

Posterior circumflex humeral

The other branches include:
· Subscapular
. Anterior circumflex humeral
The dorsal scapular artery arises from the third part of the subclavian artery in most cases

Question 50

60- Through which of the structures listed below does the axillary nerve pass?

Answer 50

Quadrangular space

Axillary nerve passes through the quadrangular space

Question 51

61- With respect to the basilic vein, which statement is false?

Answer 51

Its deep anatomical location makes it unsuitable for use as an arteriovenous access site infistula surgery

It is used in arteriovenous fistula surgery during a procedure known as a basilic vein transposition.

Question 51

62- A 19 year old man is playing rugby when he suddenly notices a severe pain at the posterolateral aspect of his right thigh. Which of the following muscle groups is most likely to have been injured?

Answer 51

Long head of biceps femoris

The biceps femoris is the laterally located hamstring muscle. The semitendinosus and
semimembranosus are located medially. Rupture of gastrocnemius and soleus may occur but is less common.

Question 52

64- Which of these vessels provides the greatest contribution to the arterial supply of the breast?

Answer 52

Internal mammary artery

60% of the arterial supply to the breast is derived from the internal mammary artery. The external mammary and lateral thoracic arteries also make a significant (but lesser) contribution. This is of importance clinically in performing reduction mammoplasty procedures.

Question 52

63- A baby is found to have a Klumpke’s palsy post delivery. Which of the following is most likely to be present?

Answer 52

Loss of flexors of the wrist

Features of Klumpkes Paralysis
· Claw hand (MCP joints extended and IP joints flexed)
· Loss of sensation over medial aspect of forearm and hand
· Horner’s syndrome
. Loss of flexors of the wrist

A C8, T1 root lesion is called Klumpke’s paralysis and is caused by delivery with the arm extended.

Question 53

65- Which of the following structures is not closely related to the brachial artery?

Answer 53

Cephalic vein

The cephalic vein lies superficially and on the contralateral side of the arm to the brachial artery. The relation of the ulnar nerves and others are demonstrated in the image below:

Question 54

66- Which ligament keeps the head of the radius connected to the radial notch of the ulna?

Answer 54

Annular (orbicular) ligament

The annular ligament connects the radial head to the radial notch of the ulna. This is illustrated below:

Question 55

67- Which of the following muscles does not adduct the shoulder?

Answer 55

Supraspinatus

Supraspinatus is an abductor of the shoulder.

Question 56

68- A 38 year old man presents to the clinic with shoulder weakness. On examination he has an inability to initiate shoulder abduction. Which of the nerves listed below is least likely to be functioning normally?

Answer 56

Suprascapular nerve

Question 57

69- A 28 year old man lacerates the posterolateral aspect of his wrist with a knife in an attempted suicide. On arrival in the emergency department the wound is inspected and found to be located over the lateral aspect of the extensor retinaculum (which is intact). Which of the following structures is at greatest risk of injury?

Answer 57

Superficial branch of the radial nerve

The superficial branch of the radial nerve passes superior to the extensor retinaculum in the position of this laceration and is at greatest risk of injury. The dorsal branch of the ulnar nerve and artery also pass superior to the extensor retinaculum but are located medially.

Question 58

70- Transection of the radial nerve at the level of the axilla will result in all of the following except:

Answer 58

Loss of elbow extension.
Loss of extension of the interphalangeal joints. ( Right)
Loss of metacarpophalangeal extension.
Loss of triceps reflex.

These may still extend by virtue of retained lumbrical muscle function.

Question 58

71- What is the first branch of the axillary artery?

Answer 58

Superior thoracic artery

The superior thoracic artery is the first branch of the axillary artery arises from the first part
Two branches arise from the second part, thoraco acromial and lateral thoracic
Three branches from the third part, subscapular artery, anterior and posterior circumflex humeral arteries

Mnemonic for axillary artery branches
Screw The Lawyer Save A patient
Superior thoracic artery
Thoracoacromial artery
Lateral thoracic artery
Subscapular artery
Anterior humeral circumflex artery
Posterior humeral circumflex artery

Question 59

72- An 18 year old man is stabbed in the axilla during a fight. His axillary artery is lacerated and repaired. However, the surgeon neglects to repair an associated injury to the upper trunk of the brachial plexus. Which of the following muscles is least likely to demonstrate impaired function as a result?

Answer 59

Palmar interossei

The palmar interossei are supplied by the ulnar nerve. Which lies inferiorly and is therefore less likely to be injured.

Question 59

73- Which muscle is responsible for causing flexion of the interphalangeal joint of the thumb?

Answer 59

Flexor pollicis longus

There are 8 muscles:
1. Two flexors (flexor pollicis brevis and flexor pollicis longus)
2. Two extensors (extensor pollicis brevis and longus)
3. Two abductors (abductor pollicis brevis and longus)
4. One adductor (adductor pollicis)
5. One muscle that opposes the thumb by rotating the CMC joint (opponens pollicis).

Flexor and extensor longus insert on the distal phalanx moving both the MCP and IP joints.

Question 60

74- Which of the following is not an intrinsic muscle of the hand?

Answer 60

Palmaris longus

Mnemonic for intrinsic hand muscles
‘A OF A OF A’

A bductor pollicis brevis
O pponens pollicis
F lexor pollicis brevis
A dductor pollicis (thenar muscles)
O pponens digiti minimi
F lexor digiti minimi brevis
A bductor digiti minimi (hypothenar muscles)

Palmaris longus originates in the forearm.

Question 60

77- A 23 year old man is involved in a fight, during the dispute he sustains a laceration to the posterior aspect of his right arm, approximately 2cm proximal to the olecranon process. On assessment in the emergency department he is unable to extend his elbow joint. Which of the following tendons is most likely to have been cut?

Answer 60

Triceps

The triceps muscle extends the elbow joint. The other muscles listed all produce flexion of the elbow joint.

Question 61

75- A 32 year old motorcyclist is involved in a road traffic accident. His humerus is fractured and severely displaced. At the time of surgical repair the surgeon notes that the radial nerve has been injured. Which of the following muscles is least likely to be affected by an injury at this site?

Answer 61

Extensor carpi radialis brevis
Brachioradialis
Abductor pollicis longus
Extensor pollicis brevis
None of the above ( Right)

Muscles supplied by the radial nerve

BEST
Brachioradialis
Extensors
Supinator
Triceps

The radial nerve supplies the extensor muscles, abductor pollicis longus and extensor pollicis brevis (the latter two being innervated by the posterior interosseous branch of the radial nerve).

Question 62

76- Which of the following structures passes through the quadrangular space near the humeral head?

Answer 62

Axillary nerve

The quadrangular space is bordered by the humerus laterally, subscapularis and teres minor superiorly, teres major inferiorly and the long head of triceps medially. It lies lateral to the triangular space. It transmits the axillary nerve and posterior circumflex humeral artery.

Question 63

79- Which of the following nerves does not contribute to the innervation of the elbow joint?

Answer 63

Posterior interosseous

The posterior interosseous nerve does not innervate the elbow joint.

Question 63

78- Which of the following structures separates the ulnar artery from the median nerve?

Answer 63

Pronator teres

It lies deep to pronator teres and this separates it from the median nerve.

Question 64

80- The following are true of the femoral nerve, except:

Answer 64

It is derived from L2, L3 and L4 nerve roots
It supplies sartorius
It supplies quadriceps femoris
It gives cutaneous innervations via the saphenous nerve
It supplies adductor longus (Right)

Adductor longus is supplied by the obturator nerve.

Question 65

81- A man has an incision sited that runs 8cm from the deltopectoral groove to the midline of the chest. Which of the following is not at risk of injury?

Answer 65

Shoulder joint capsule

This region will typically lie medial to the joint capsule. The diagram below illustrates the plane that this would transect and as it can be appreciated the other structures are all at risk of injury.

Question 65

83- A 23 year old man is injured during a game of rugby. He suffers a fracture of the distal third of his clavicle, it is a compound fracture and there is evidence of arterial haemorrhage. Which of the following vessels is most likely to be encountered first during subsequent surgical exploration?

Answer 65

Thoracoacromial artery

The thoracoacromial artery arises from the second part of the axillary artery. It is a short, wide trunk, which pierces the clavipectoral fascia, and ends, deep to pectoralis major by dividing into four branches.

Question 65

82- A 38 year old man falls onto an outstretched hand. Following the accident he is examined in the emergency department. On palpating his anatomical snuffbox there is tenderness noted in the base. What is the most likely injury in this scenario?

Answer 65

Scaphoid fracture

A fall onto an outstretched hand is a common mechanism of injury for a scaphoid fracture. This should be suspected clinically if there is tenderness in the base of the anatomical snuffbox. A tendon rupture would not result in bony tenderness.

Question 66

84- Which of the structures listed below overlies the cephalic vein?

Answer 66

Extensor retinaculum
Bicipital aponeurosis
Biceps muscle
Antebrachial fascia
None of the above (Right)

The cephalic vein is superficially located in the upper limb and overlies most the fascial planes. It pierces the coracoid membrane (continuation of the clavipectoral fascia) to terminate in the axillary vein. It lies anterolaterally to biceps.

Question 67

85- A 22 year old man is involved in a fight. He sustains a laceration to the posterior aspect of his wrist. In the emergency department the wound is explored and the laceration is found to be transversely orientated and overlies the region of the extensor retinaculum, which is intact. Which of the following structures is least likely to be injured in this scenario?

Answer 67

Tendon of extensor indicis

The extensor retinaculum attaches to the radius proximal to the styloid, thereafter it runs obliquely and distally to wind around the ulnar styloid (but does not attach to it). The extensor tendons lie deep to the extensor retinaculum and would therefore be less susceptible to injury than the superficial structures.

Question 68

86- A 23 year old man is involved in a fight and is stabbed in his upper arm. The ulnar nerve is transected. Which of the following muscles will not demonstrate compromised function as a result?

Answer 68

Pronator teres

M edial lumbricals
A dductor pollicis
F lexor digitorum profundus/Flexor digiti minimi
I nterossei
A bductor digiti minimi and opponens

Innervates all intrinsic muscles of the hand (EXCEPT 2: thenar muscles & first two lumbricals - supplied by median nerve)

Pronator teres is innervated by the median nerve. Palmaris brevis is innervated by the ulnar nerve

Question 68

87- A 22 year old man is involved in a fight and sustains a stab wound in his upper forearm. On examination there is a small, but deep laceration. There is an obvious loss of pincer movement involving the thumb and index finger with minimal loss of sensation. The most likely nerve injury is to the:

Answer 68

Anterior interosseous nerve

The anterior interosseous nerve is a motor branch of the median nerve just below the elbow. When damaged it classically causes:
. Pain in the forearm
. Loss of pincer movement of the thumb and index finger (innervates the long flexor muscles of flexor pollicis longus & flexor digitorum profundus of the index and middle finger)
. Minimal loss of sensation due to lack of a cutaneous branch

Question 68

88- A 32 year old attends neurology clinic complaining of tingling in his hand. He has radial deviation of his wrist and there is mild clawing of his fingers, with the 4th and 5th digits being relatively spared. What is the most likely lesion?

Answer 68

Ulnar nerve damage at the elbow

The ulnar paradox- the higher the lesion, the less the clawing of the fingers seen clinically.
At the elbow the ulnar nerve lesion affects the flexor carpi ulnaris and flexor digitorum profundus.

Question 69

89- A 45 year man presents with hand weakness. He is given a piece of paper to hold between his thumb and index finger. When the paper is pulled, the patient has difficulty maintaining a grip. Grip pressure is maintained by flexing the thumb at the interphalangeal joint. What is the most likely nerve lesion?

Answer 69

Deep branch of ulnar nerve

This is a description of Froment’s sign, which tests for ulnar nerve palsy. It mainly tests for the function of adductor pollicis. This is supplied by the deep branch of the ulnar nerve. Remember the anterior interosseous branch (of the median nerve), which innervates the flexor pollicis longus (hence causing flexion of the thumb IP joint), branches off more proximally to the wrist.

Question 69

90- An 18 year old lady with troublesome hyperhidrosis of the hands and arms is due to undergo a sympathectomy to treat the condition. Which of the following should the surgeons divide to most effectively treat her condition?

Answer 69

Sympathetic ganglia at T2 and T3

To treat hyperhidrosis the sympathetic ganglia at T2 and T3 should be divided. Dividing the other structures listed would either carry a risk of Horners syndrome or be ineffective.

Question 70

91- A 32 year old lady complains of carpal tunnel syndrome. The carpal tunnel is explored surgically. Which of the following structures will lie in closest proximity to the hamate bone within the carpal tunnel?

Answer 70

The tendons of flexor digitorum profundus

The carpal tunnel contains nine flexor tendons:
· Flexor digitorum profundus
· Flexor digitorum superficialis
· Flexor pollicis longus

The tendon of flexor digitorum profundus lies deepest in the tunnel and will thus lie nearest to the hamate bone.

Question 71

92- Which muscle is responsible for causing flexion of the distal interphalangeal joint of the ring finger?

Answer 71

Flexor digitorum profundus

Flexor digitorum superficialis and flexor digitorum profundus are responsible for causing flexion. The superficialis tendons insert on the bases of the middle phalanges; the profundus tendons insert on the bases of the distal phalanges. Both tendons flex the wrist, MCP and PIP joints; however, only the profundus tendons flex the DIP joints.

Question 72

94- Which nerve supplies the skin at the medial aspect of the palm?

Answer 72

Ulnar

Question 72

93- Which nerve supplies the interossei of the fourth finger?

Answer 72

Deep ulnar

Mnemonic:
PAD and DAB
Palmer interossei ADduct
Dorsal interossei ABduct

Question 72

95- Which of the following forms the floor of the anatomical snuffbox?

Answer 72

Scaphoid bone

The scaphoid bone forms the floor of the anatomical snuffbox. The cutaneous branch of the radial nerve
is much more superficially and proximally located.

Question 73

96- Which of the following upper limb muscles is not innervated by the radial nerve?

Answer 73

Abductor digiti minimi

Mnemonic for radial nerve muscles: BEST
B rachioradialis
E xtensors
S upinator
T riceps

Abductor digiti minimi is innervated by the ulnar nerve.

Question 74

97- A 73 year old lady suffers a fracture at the surgical neck of the humerus. The decision is made to operate. There are difficulties in reducing the fracture and a vessel lying posterior to the surgical neck is injured. Which of the following is this vessel most likely to be?

Answer 74

Posterior circumflex humeral artery

The circumflex humeral arteries lie at the surgical neck and is this scenario the posterior circumflex is likely to be injured. The thoracoacromial and transverse scapular arteries lie more superomedially. The posterior circumflex humeral artery is a branch of the axillary artery.

Question 74

99- A 23 year old rugby player sustains a Smiths Fracture. On examination, opposition of the thumb is markedly weakened. Which of the following nerves is least likely to be working normally?

Answer 74

Median

This high velocity injury can often produce significant angulation and displacement. Both of these may impair the function of the median nerve with loss of function of the muscles of the thenar eminence.

Question 74

98- Which structure separates the cephalic vein and the brachial artery in the antecubital fossa?

Answer 74

Bicipital aponeurosis

Question 75

102- Which of the following nerves is responsible for innervation of the triceps muscle?

Answer 75

Radial

To remember nerve roots and their reflexes:
1-2 Ankle (S1-S2)
3-4 Knee (L3-L4)
5-6 Biceps (C5-C6)
7-8 Triceps (C7-C8)

The radial nerve innervates all three heads of triceps, with a separate branch to each head.

Question 75

100- Which of the following muscles inserts onto the lesser tuberosity of the the humerus?

Answer 75

Subscapularis

With the exception of subscapularis which inserts into the lesser tuberosity, the muscles of the rotator cuff insert into the greater tuberosity.

Question 76

101- The cords of the brachial plexus are most closely related to which of the following vessels?

Answer 76

Axillary artery

The trunks are related to the subclavian artery superiorly. The cords of the plexus surround the axillary artery, they are named according to their positions relative to this structure.

Question 77

103- What is the largest branch of the brachial artery?

Answer 77

Profunda brachii artery

The profunda brachii artery is the largest branch and then continues in the radial groove of the humerus.

Question 78

104- A 23 year old climber falls and fractures his humerus. The surgeons decide upon a posterior approach to the middle third of the bone. Which of the following nerves is at greatest risk in this approach?

Answer 78

Radial

The radial nerve wraps around the humerus and may be injured during a posterior approach. An IM nail may be preferred as it avoids the complex dissection needed for direct bone exposure.

Question 79

105- A 43 year old lady is due to undergo an axillary node clearance as part of treatment for carcinoma of the breast. Which of the following fascial layers will be divided during the surgical approach to the axilla?

Answer 79

Clavipectoral fascia

The clavipectoral fascia is situated under the clavicular portion of pectoralis major. It protects both the axillary vessels and nodes. During an axillary node clearance for breast cancer the clavipectoral fascia is incised and this allows access to the nodal stations. The nodal stations are; level 1 nodes inferior to pectoralis minor, level 2 lie behind it and level 3 above it. During a Patey Mastectomy surgeons divide pectoralis minor to gain access to level 3 nodes. The use of sentinel node biopsy (and stronger assistants!) have made this procedure far less common.

Question 80

106- How many phalanges are there in the hand?

Answer 80

14

Each digit has 3 phalanges, the thumb has two the total is therefore 14.

Question 80

107- A 53 year old lady is recovering following a difficult mastectomy and axillary nodal clearance for carcinoma of the breast. She complains of shoulder pain and on examination has obvious winging of the scapula. Loss of innervation to which of the following is the most likely underlying cause?

Answer 80

Serratus anterior

Winging of the scapula is most commonly the result of long thoracic nerve injury or dysfunction.
latrogenic damage during the course of the difficult axillary dissection is the most likely cause in this scenario. Damage to the rhomboids may produce winging of the scapula but would be rare in the scenario given.

Question 80

108- A 48 year old lady is undergoing an axillary node clearance for breast cancer. Which of the structures listed below are most likely to be encountered during the axillary dissection?

Answer 80

Thoracodorsal trunk

Beware of damaging the thoracodorsal trunk if a latissimus dorsi flap reconstruction is planned.

The thoracodorsal trunk runs through the nodes in the axilla. If injured it may compromise the function and blood supply to latissimus dorsi, which is significant if it is to be used as a flap for a reconstructive procedure

Question 81

109- A motorcyclist is involved in a road traffic accident. He suffers a complex humeral shaft fracture which is plated. Post operatively he complains of an inability to extend his fingers. Which of the following structures is most likely to have been injured?

Answer 81

Radial nerve

Mnemonic for radial nerve muscles: BEST
B rachioradialis
E xtensors
S upinator
T riceps

The radial nerve is responsible for innervation of the extensor compartment of the forearm.

Question 82

110- A 22 year old falls over and lands on a shard of glass. It penetrates the palmar aspect of his hand, immediately lateral to the pisiform bone. Which of the following structures is most likely to be injured?

Answer 82

Ulnar artery

The ulnar nerve and artery are at most immediate risk in this injury

Question 83

111- A 35 year tennis player attends reporting tingling down his arm. He says that his ‘funny bone’ was hit very hard by a tennis ball. There is weakness of abduction and adduction of his extended fingers. Which nerve has been affected?

Answer 83

Ulnar

The ulnar nerve arises from the medial cord of the brachial plexus (C8, T1 and contribution from C7).
The nerve descends between the axillary artery and vein, posterior to the cutaneous nerve of the forearm and then lies anterior to triceps on the medial side of the brachial artery. In the distal half of the arm it passes through the medial intermuscular septum, and continues between this structure and the medial head of triceps to enter the forearm between the medial epicondyle of the humerus and the olecranon. It may be injured at this site in this scenario.

Question 84

112- A 73 year old man undergoes an excision biopsy of a lymph node that is closely applied to sternocleidomastoid. This muscle is mobilized and a nerve that is present is damaged. Which muscle below is most likely to be affected?

Answer 84

Trapezius

The accessory nerve has a number of lymph nodes applied to it near the sternocleidomastoid muscle. It is particularly at risk if SCM is mobilized. If injured, the trapezius muscle and SCM will be paralysed.

Question 85

114- Which of the muscles listed below is attached to the anterior aspect of the fibrous capsule that encases the elbow joint?

Answer 85

Brachialis

The brachialis inserts some of its fibres into the fibrous joint of the elbow capsule and when it contracts, it helps to flex the joint.

Question 85

113- A 32 year old rugby player is hit hard on the shoulder during a rough tackle. Clinically, his arm is hanging loose on the side. It is pronated and medially rotated. What structure is most likely to have been compromised?

Answer 85

Brachial trunks C5-6

The patient has an Erb’s palsy involving brachial trunks C5-6.

Question 85

115- The following statements relating to the musculocutaneous nerve are true except?

Answer 85

It arises from the lateral cord of the brachial plexus
It provides cutaneous innervation to the lateral side of the forearm
If damaged, then extension of the elbow joint will be impaired ( Right)
It supplies the biceps muscle
It runs beneath biceps

It supplies biceps, brachialis and coracobrachialis. If damaged then elbow flexion will be impaired.

Question 85

116- What is the course of the median nerve relative to the brachial artery in the upper arm?

Answer 85

Lateral to anterior to medial

Relations of median nerve to the brachial artery:
Lateral -> Anterior -> Medial

The median nerve descends lateral to the brachial artery, it usually passes anterior to the artery to lie on its medial side. It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. It enters the forearm between the two heads of the pronator teres muscle.

Question 86

117- A 25 year old man is stabbed in the upper arm. The brachial artery is lacerated at the level of the proximal humerus, and is being repaired. A nerve lying immediately lateral to the brachial artery is also lacerated. Which of the following is the nerve most likely to be?

Answer 86

Median nerve

The brachial artery begins at the lower border of teres major and terminates in the cubital fossa by branching into the radial and ulnar arteries. In the upper arm the median nerve lies closest to it in the lateral position. In the cubital fossa it lies medial to it.

Question 87

118- Which of the following muscles does not attach to the radius?

Answer 87

Brachialis

The brachialis muscle inserts into the ulna. The other muscles are all inserted onto the radius.

Question 87

119- A 21 year old man is stabbed in the antecubital fossa. A decision is made to surgically explore the wound. At operation, the surgeon dissects down onto the brachial artery. A nerve is identified medially, which nerve is it likely to be?

Answer 87

Median

Question 88

120- A 28 year old rugby player injures his right humerus and on examination is noted to have a minor sensory deficit overlying the point of deltoid insertion into the humerus. Which of the nerves listed below is most likely to have been affected?

Answer 88

Axillary

This patch of skin is supplied by the axillary nerve

Question 88

121- A 40 year old lady trips and falls through a glass door and sustains a severe laceration to her left arm. Amongst her injuries it is noticed that she has lost the ability to adduct the fingers of her left hand. Injury to which of the following nerves is most likely to account for her examination findings?

Answer 88

Ulnar

The interossei are supplied by the ulnar nerve.

Question 88

122- An 8 year old boy falls onto an outstretched hand and sustains a supracondylar fracture. In addition to a weak radial pulse the child is noted to have loss of pronation of the affected hand. Which nerve is compromised?

Answer 88

Median

This is a common injury in children. In this case the angulation and displacement have resulted in median nerve injury.

Question 89

123- A 56 year old man requires long term parenteral nutrition and the decision is made to insert a PICC line for long term venous access. This is inserted into the basilic vein at the region of the elbow. As the catheter is advanced, into which venous structure is the tip of the catheter most likely to pass from the basilic vein?

Answer 89

Axillary vein

The basilic vein drains into the axillary vein and although PICC lines may end up in a variety of fascinating locations the axillary vein is usually the commonest site following from the basilic. The posterior circumflex humeral vein is encountered prior to the axillary vein. However, a PICC line is unlikely to enter this structure because of its angle of entry into the basilic vein.

Question 90

125- When the brachial plexus is injured in the axilla as a result of a crutch palsy, which of the nerves listed is most commonly affected?

Answer 90

Radial nerve

The radial nerve is most commonly injured and results in a wrist drop. The ulnar nerve arises from the medial cord and is rarely affected as a result of this injury mechanism.

Question 90

124- During a neck dissection, a nerve is noted to pass posterior to the medial aspect of the first rib. Which of the nerves listed below is this most likely to be?

Answer 90

Phrenic nerve

The key point is that the phrenic nerve runs posterior to the medial aspect of the first rib. Superiorly, it lies on the surface of scalenus anterior.

Question 91

126- The first root of the brachial plexus commonly arises at which of the following levels?

Answer 91

C5

It begins at C5 and has 5 roots. It ends with a total of 15 nerves of these 5 are the main nerves to the upper limb (axillary, radial, ulnar, musculocutaneous and median)

Question 92

127- Which muscle initiates abduction of the shoulder?

Answer 92

Supraspinatus

The intermediate portion of the deltoid muscle is the chief abductor of the humerus. However, it can only do this after the movement has been initiated by supraspinatus. Damage to the tendon of supraspinatus is a common form of rotator cuff disease.

Question 93

128- Which of the structures listed below are most closely related to the axillary nerve within the
quadrangular space?

Answer 93

Posterior circumflex humeral vessels

The posterior circumflex humeral vessels which are branches of the axillary artery are related to the axillary nerve within the quadrangular space.

Question 94

129- Which of the nerves listed below is directly responsible for the innervation of the lateral aspect of flexor digitorum profundus?

Answer 94

Anterior interosseous nerve

The anterior interosseous nerve is a branch of the median nerve and is responsible for innervation o fthe lateral aspect of the flexor digitorum profundus.

Question 95

130- A patient sustains damage to the median nerve during a carpal tunnel release. Which of the following muscles will be affected?

Answer 95

Abductor pollicis brevis

Of the muscles listed, only the abductor pollicis brevis is innervated by the median. In questions like this one, ensure you don’t become confused between adductor and abductor.

Question 96

131- A 24 year old man falls and sustains a fracture through his scaphoid bone. From which of the following areas does the scaphoid derive the majority of its blood supply?

Answer 96

from the distal end

The blood supply to the scaphoid enters from a small non articular surface near its distal end.
Transverse fractures through the scaphoid therefore carry a risk of non union.

Question 96

133- At the level of the wrist joint, which of the statements below best describes the relationship of the ulnar artery to the ulnar nerve?

Answer 96

It lies on its radial side

In the middle of the forearm, the artery is overlapped by the flexor carpi ulnaris and on the flexor retinaculum it is covered by a superficial layer from that structure. In its distal two-thirds, flexor digitorum superficialis lies on its radial side, and the ulnar nerve is situated on its ulnar side.

Question 97

132- Which of the following anatomical structures lies within the spiral groove of the humerus?

Answer 97

Radial nerve

The radial nerve lies in this groove and may be compromised by fractures involving the shaft.

Question 98

134- Which of the structures listed below articulates with the head of the radius superiorly?

Answer 98

Capitulum

A useful revision aid : ‘Capital Radio’ is the articulation of the radial head superiorly.

The head of the radius articulates with the capitulum of the humerus.

Question 98

135- A 43 year old man is stabbed outside a nightclub. He suffers a transection of his median nerve just as it leaves the brachial plexus. Which of these features is least likely to ensue?

Answer 98

Complete loss of wrist flexion

Loss of the median nerve will result in loss of function of the flexor muscles. However, flexor carpi ulnaris will still function and produce ulnar deviation and some residual wrist flexion. High median nerve lesions result in complete loss of flexion at the thumb joint.

Question 99

136- A 23 year old man falls and slips at a nightclub. A shard of glass penetrates the skin at the level of the medial epicondyle, which of the following sequelae is least likely to occur?

Answer 99

Claw like appearance of the hand

Injury to the ulnar nerve in the mid to distal forearm will typically produce a claw hand. This consists of flexion of the 4th and 5th interphalangeal joints and extension of the metacarpophalangeal joints. The effects are potentiated when flexor digitorum profundus is not affected, and the clawing is more pronounced.More proximally sited ulnar nerve lesions produce a milder clinical picture owing to the simultaneous paralysis of flexor digitorum profundus (ulnar half).

This is the ‘ulnar paradox’, due to the more proximal level of transection the hand will typically not have a claw like appearance that may be seen following a more distal injury. The first dorsal interosseous muscle will be affected as it is supplied by the ulnar nerve.

Question 100

138- A 23 year old man is involved in a fight outside a nightclub and sustains a laceration to his right arm. On examination, he has lost extension of the fingers in his right hand. Which of the nerves listed below is most likely to have been divided?

Answer 100

Radial

The radial nerve supplies the extensor muscle group.

Question 100

137- A 43 year old typist presents with pain at the dorsal aspect of the upper part of her forearm. She also complains of weakness when extending her fingers. On examination triceps and supinator are both functioning normally. There is weakness of most of the extensor muscles. However, there is no sensory deficit. Which of the following nerves has been affected?

Answer 100

Posterior interosseous

The radial nerve may become entrapped in the arcade of Frohse which is a superficial part of the supinator muscle which overlies the posterior interosseous nerve. This nerve is entirely muscular and articular in its distribution. It passes postero-inferiorly and gives branches to extensor carpi radialis brevis and supinator. It enters supinator and curves around the lateral and posterior surfaces of the radius. On emerging from the supinator the posterior interosseous nerve lies between the superficial extensor muscles and the lowermost fibres of supinator. It then gives branches to the extensors.

Question 101

139- Which of the muscles listed below is not innervated by the median nerve?

Answer 101

Adductor pollicis

Adductor pollicis is innervated by the ulnar nerve.
Medial two lumbricals innervated by the ulnar nerve.

Question 102

140- A 35 year old farm labourer injures the posterior aspect of his hand with a mechanical scythe. He severs some of his extensor tendons in this injury. How many tunnels lie in the extensor retinaculum that transmit the tendons of the extensor muscles?

Answer 102

Six

There are six tunnels, each lined by its own synovial sheath.

Question 103

141- A 63 year old lady is undergoing an axillary sentinel lymph node biopsy as part of her breast cancer treatment. Which of the structures listed below is most likely to be encountered?

Answer 103

Intercostobrachial nerve

This can be a challenging question. A particularly careless surgeon could encounter all of these. However, during a routine level 1 axillary exploration which is where the majority of sentinel nodes will be located, the nerves most commonly encountered are the intercostobrachial nerves.

Question 103

142- Which of the following nerves supplies the majority of the skin on the palmar aspect of the thumb?

Answer 103

Median

The median nerve supplies cutaneous sensation to this region.

Question 104

143- A 10 year old boy is admitted to the emergency department following a fall. On examination, there is deformity and swelling of the forearm. The ability to flex the fingers of the affected limb is impaired. However, there is no sensory impairment. Imaging confirms a displaced forearm fracture. Which of the nerves listed below is likely to have been affected?

Answer 104

Anterior interosseous nerve

Forearm fractures may be complicated by neurovascular compromise. The anterior interosseous nerve may be affected. It has no sensory supply so the defect is motor alone.