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Nerve & Tendon MCQs

Practice Set 4 of 53

This practice set contains high-yield board review questions covering key concepts in Nerve & Tendon. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 61

Topic: Nerve & Tendon

A 45-year-old laborer complains of numbness in his ring and small fingers and hand weakness. He demonstrates a positive Froment sign when asked to pinch a piece of paper. Which nerve is compressed, and which muscle is compensating?

. Ulnar nerve; flexor pollicis longus
. Median nerve; adductor pollicis
. Ulnar nerve; abductor pollicis brevis
. Radial nerve; extensor pollicis longus
. Median nerve; flexor pollicis brevis

Correct Answer & Explanation

. Ulnar nerve; flexor pollicis longus

Explanation

A positive Froment sign indicates ulnar nerve palsy, leading to weakness of the adductor pollicis. The patient compensates by hyperflexing the thumb interphalangeal joint, a motion powered by the median nerve-innervated flexor pollicis longus (FPL).

Question 62

Topic: Nerve & Tendon
The most common nerve injury in a Monteggia fracture and the type of Monteggia fracture with which it is most commonly found is:
. Ulnar nerve, type I
. Posterior interosseous nerve, type IV
. Posterior interosseous nerve, type III
. Median nerve, type I
. Median nerve, type III

Correct Answer & Explanation

. Posterior interosseous nerve, type III

Explanation

The posterior interosseous branch of the radial nerve is injured in 10%-20% of Monteggia fractures. Most cases occur at the time of fracture, but some occur later. Spontaneous resolution is the usual outcome. The posterior interosseous nerve is the most commonly injured, and type I and type III are the most common types affected.

Question 63

Topic: Nerve & Tendon

A physeal fracture-separation of the distal humerus is seen in an 18-month- old boy. When the parents ask about the prognosis after this injury, you tell them that the most common complication is:

. C ubitus varus
. Median nerve palsy
. Ulnar nerve injury
. Brachial artery injury
. Undergrowth of the humerus

Correct Answer & Explanation

. C ubitus varus

Explanation

Cubitus varus occurred in seven out of twelve physeal fracture separations of the distal humerus in one series. This most likely occurred due to malalignment or avascular necrosis of the trochlea. Median nerve injury, ulnar nerve injury, and brachial artery injury are extremely uncommon after this injury because the surfaces of the metaphysis and the physis are relatively smooth in comparison to supracondylar fractures. Also, these injuries are relatively low-energy. Growth plate damage causing undergrowth is rare after this fracture.

Question 64

Topic: Nerve & Tendon

In a child with an extension-type supracondylar humerus fracture presenting with significant posteromedial displacement of the distal fragment, which nerve is most commonly at risk of injury?

. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Median nerve
. Radial nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In a posteromedially displaced supracondylar humerus fracture, the proximal fragment displaces anterolaterally, putting the radial nerve at the highest risk of injury. Posterolateral displacement primarily endangers the median nerve and AIN.

Question 65

Topic: Nerve & Tendon

What deformity can develop in a mistreated volar PIP joint dislocation?

. Swan neck deformity
. Extensor lag
. Boutonniere deformity
. Flexion contracture
. Hyperextension deformity

Correct Answer & Explanation

. Boutonniere deformity

Explanation

With volar PIP joint dislocations, there is almost always a disruption of the central slip of the extensor tendon. Because the central slip is involved, the PIP joint will hold a flexed position, and the lateral bands will fall volar to the axis of rotation of the PIP joint. The lateral bands will then exacerbate the flexion at the PIP joint, and due to their pull on the terminal tendon at the insertion on the distal phalanx, the DIP joint will hyperextend. This results in a boutonniere deformity.

Question 66

Topic: Nerve & Tendon

The nerve most commonly injured at the time of a supracondylar fracture is:

. Radial nerve
. Median nerve
. Ulnar nerve
. Anterior interosseous nerve
. Posterior interosseous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve is the most commonly injured nerve. The anterior interosseous nerve can be tested by asking the patient to make an "O" with the thumb and index fingers, and watching for active flexion of the distal interphalangeal joints. The radial nerve is the second most commonly injured, after the anterior interosseous nerve. The ulnar nerve is not the most commonly injured at time of fracture but is the most commonly injured at time of treatment. The posterior interosseous nerve is rarely injured.

Question 67

Topic: Nerve & Tendon
A 28-year-old carpenter suffers a laceration over the dorsal aspect of the proximal interphalangeal (PIP) joint, resulting in a Zone III extensor tendon disruption. If left untreated, this injury will classically lead to which of the following deformities?
. Mallet finger deformity
. Swan neck deformity
. Boutonniere deformity
. Jersey finger deformity
. Quadrigia effect

Correct Answer & Explanation

. Boutonniere deformity

Explanation

A Zone III extensor tendon injury disrupts the central slip attachment at the base of the middle phalanx. This leads to volar subluxation of the lateral bands, causing PIP flexion and DIP hyperextension, known as a Boutonniere deformity.

Question 68

Topic: Nerve & Tendon

The muscle that flexes the interphalangeal joint of the thumb is innervated by which roots of the brachial plexus:

. C 5, C 6
. C 5, C 6, C 7
. C 6, C 7, C 8
. C 5, C 6, C 7, C 8, T1
. C 7, C 8, T1

Correct Answer & Explanation

. C 5, C 6, C 7, C 8, T1

Explanation

The interphalangeal joint of the thumb is flexed secondary to actions of the flexor pollicis longus (FPL). The FPL is innervated by the anterior interosseous nerve, which is the longest branch of the median nerve. The median nerve is formed by the lateral (roots C 5, C 6, and C 7) and medial (roots C 8 and T1) cords of the brachial plexus.

Question 69

Topic: Nerve & Tendon

The anterior interosseous nerve (AIN) originates from the median nerve at what distance from the medial epicondyle:

. 6 cm distal
. 10 cm proximal
. 6 cm proximal
. 10 cm distal
. At the medial epicondyle

Correct Answer & Explanation

. 6 cm distal

Explanation

The AIN, the largest branch of the median nerve, originates 5 cm to 8 cm distal to the medial epicondyle from the posteroradial aspect of the median nerve just distal to the proximal border of the superficial head of the pronator teres.

Question 70

Topic: Nerve & Tendon
What is the innervation of the indicated muscle in the image (Slide)?
. Median nerve
. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Posterior interosseous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The arrow in the photograph (Slide) is pointing to the pronator teres - one of the most common sites for compression of the anterior interosseous nerve. The pronator teres is innervated by the median nerve.

Question 71

Topic: Nerve & Tendon
Which finger is most commonly involved in a flexor digitorum profundus (FDP) avulsion injury?
. Index
. Middle
. Ring
. Small
. Thumb

Correct Answer & Explanation

. Ring

Explanation

An FDP avulsion is caused by forceful extension of the distal interphalangeal (DIP) joint, occurring at the same time as a maximum contraction of the FDP tendon. Jersey finger is often seen in athletes, especially football or rugby players, who commonly get their fingers caught in an opposing player's jersey, thus the name. In most cases, this injury affects the ring finger.

Question 72

Topic: Nerve & Tendon
A 35-year-old carpenter presents with an inability to make an "OK" sign with his thumb and index finger. A diagnosis of anterior interosseous nerve (AIN) syndrome is suspected. Which of the following muscles will have normal function in this patient?
. Flexor pollicis longus
. Flexor digitorum profundus to the index finger
. Pronator quadratus
. Flexor carpi radialis
. Flexor digitorum profundus to the middle finger

Correct Answer & Explanation

. Flexor carpi radialis

Explanation

The AIN innervates the FPL, the FDP to the index and middle fingers, and the pronator quadratus. The flexor carpi radialis is innervated by the proper median nerve before the AIN branches off.

Question 73

Topic: Nerve & Tendon

During an in situ ulnar nerve decompression at the elbow, the surgeon releases the tissue spanning the two heads of the flexor carpi ulnaris (FCU). Which anatomical structure forms the primary roof of the cubital tunnel in this region?

. Ligament of Struthers
. Osborne's ligament
. Arcade of Struthers
. Lacertus fibrosus
. Arcade of Frohse

Correct Answer & Explanation

. Osborne's ligament

Explanation

Osborne's ligament (or Osborne's fascia) forms the roof of the cubital tunnel, bridging the olecranon and the medial epicondyle over the two heads of the FCU. The Arcade of Struthers is a potential compression site located approximately 8 cm proximal to the medial epicondyle.

Question 74

Topic: Nerve & Tendon

A 6-year-old child sustains a displaced extension-type supracondylar humerus fracture.

Based on typical displacement patterns, what is the most common neurological deficit associated with this specific injury?

. Radial nerve palsy
. Ulnar nerve palsy
. Anterior interosseous nerve palsy
. Median nerve proper palsy
. Musculocutaneous nerve palsy

Correct Answer & Explanation

. Anterior interosseous nerve palsy

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures, particularly those with posterolateral displacement. Flexion-type fractures place the ulnar nerve at higher risk.

Question 75

Topic: Nerve & Tendon

An 8-year-old child presents with an extension-type supracondylar humerus fracture as shown.

If the distal fragment demonstrates significant posteromedial displacement, which nerve is at the greatest risk of injury due to tethering across the fracture site?

. Ulnar nerve
. Radial nerve
. Median nerve
. Anterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

Posteromedial displacement of the distal fragment in an extension-type supracondylar fracture puts the radial nerve at greatest risk as the proximal fragment displaces anterolaterally. Conversely, posterolateral displacement predominantly endangers the median nerve and anterior interosseous nerve (AIN).

Question 76

Topic: Nerve & Tendon

During an electrodiagnostic evaluation for suspected cubital tunnel syndrome, a Martin-Gruber anastomosis is identified. This anatomical variant involves a neural connection between which two structures?

. From the median nerve to the ulnar nerve in the forearm
. From the ulnar nerve to the median nerve in the forearm
. From the superficial radial nerve to the ulnar nerve in the hand
. From the deep branch of the ulnar nerve to the median nerve in the palm
. From the median nerve to the musculocutaneous nerve in the arm

Correct Answer & Explanation

. From the median nerve to the ulnar nerve in the forearm

Explanation

The Martin-Gruber anastomosis is a motor crossover from the median nerve (often via the AIN) to the ulnar nerve in the forearm. It can confound nerve conduction studies by producing spuriously normal ulnar motor amplitudes.

Question 77

Topic: Nerve & Tendon

Posterior interosseous nerve palsy affects finger extension at the metacarpophalangeal and interphalangeal joints.

. True
. False Only the metacarpophalangeal joints are involved in posterior interosseous nerve palsy, as the muscles of the interphalangeal joints are innervated by the ulnar and median nerves.

Correct Answer & Explanation

. True

Explanation

Question 78

Topic: Nerve & Tendon
All of the following muscles are innervated by the median nerve except:
. The ulnar two lumbricals (lumbricals III and IV)
. Opponens pollicis
. Abductor pollicis brevis
. Flexor pollicis brevis
. Flexor digitorum profundus to the middle finger

Correct Answer & Explanation

. The ulnar two lumbricals (lumbricals III and IV)

Explanation

Lumbricals 1 and 2 are innervated by the median nerve, in addition to the opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis. The ulnar two lumbricals are innervated by the ulnar nerve.

Question 79

Topic: Nerve & Tendon

The nerve most at risk during arthroscopic debridement of lateral epicondylitis is the:

. Ulnar nerve
. Median nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

While the ulnar nerve is most at risk during elbow arthroscopy in general, debridement of the lateral capsule posterior to the midpoint of the radiocapitellar joint places the posterior interosseous branch of the radial nerve at risk.

Question 80

Topic: Nerve & Tendon

A patient is undergoing in situ decompression for cubital tunnel syndrome. Which of the following structures forms the roof of the cubital tunnel and must be released?

. Medial collateral ligament
. Osborne's ligament (cubital tunnel retinaculum)
. Struthers' ligament
. Lacertus fibrosus
. Arcade of Frohse

Correct Answer & Explanation

. Osborne's ligament (cubital tunnel retinaculum)

Explanation

The roof of the cubital tunnel is formed by Osborne's ligament (the cubital tunnel retinaculum) and the aponeurosis of the two heads of the flexor carpi ulnaris. Struthers' ligament is a potential site of median nerve compression proximal to the elbow.

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