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Nerve & Tendon MCQs

Practice Set 21 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 401

Topic: Nerve & Tendon

During surgical repair of a Zone II flexor tendon injury, maintaining the integrity of the A2 and A4 pulleys is crucial to prevent bowstringing. If the A2 pulley is inadvertently excised, what is the most significant biomechanical consequence regarding the function of the flexor tendon?

. Decreased moment arm
. Decreased required tendon excursion to achieve full digit flexion
. Increased required tendon excursion to achieve full digit flexion
. Increased active grip strength
. Decreased passive resistance to extension

Correct Answer & Explanation

. Increased required tendon excursion to achieve full digit flexion

Explanation

The flexor pulleys keep the tendon closely applied to the bone. If the A2 or A4 pulley is excised, the tendon bowstrings away from the center of rotation of the joint. This increases the moment arm. Biomechanically, an increased moment arm means that a greater length of tendon excursion is required to achieve the same angular range of motion. Because the muscle's excursion is finite, this often results in incomplete active finger flexion.

Question 402

Topic: Nerve & Tendon

A 45-year-old woman presents with isolated weakness in her right hand. On examination, she is unable to form an 'OK' sign with her thumb and index finger, instead demonstrating an extended posture of the distal interphalangeal joint of the index finger and the interphalangeal joint of the thumb. She reports no sensory deficits. Entrapment of the affected nerve most commonly occurs at which of the following anatomical structures?

. Ligament of Struthers
. Arcade of Frohse
. Tendinous edge of the deep head of the pronator teres
. Cubital tunnel retinaculum
. Guyon's canal

Correct Answer & Explanation

. Tendinous edge of the deep head of the pronator teres

Explanation

The patient is presenting with Anterior Interosseous Nerve (AIN) syndrome, characterized by weakness of the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index (and sometimes middle) finger, and the pronator quadratus. This results in the inability to make the 'OK' sign, leading to a pinch with extended distal joints (Kiloh-Nevin sign). Because the AIN is a purely motor branch, there is no sensory loss. The most common site of AIN entrapment is the tendinous edge of the deep head of the pronator teres (or the fibrous arcade of the FDS).

Question 403

Topic: Nerve & Tendon

During surgical release of a severe trigger finger, a surgeon inadvertently incises the entire A2 pulley of the middle finger. What biomechanical consequence is most likely to occur as a direct result of this specific iatrogenic injury?

. Swan neck deformity
. Boutonniere deformity
. Bowstringing of the flexor tendons
. Inability to actively extend the distal interphalangeal joint
. Ulnar drift of the digits

Correct Answer & Explanation

. Bowstringing of the flexor tendons

Explanation

The A2 and A4 pulleys are the critical biomechanical pulleys in the flexor tendon sheath of the digits, holding the flexor tendons close to the phalanx. Laceration or incompetence of the A2 or A4 pulley leads to bowstringing of the flexor tendons during active flexion, decreasing mechanical efficiency (excursion) and causing flexion contractures and weakness.

Question 404

Topic: Nerve & Tendon

During an ulnar nerve transposition, a surgeon must release several potential sites of compression. The Arcade of Struthers is one such site and is defined as a fascial band extending from the:

. Medial intermuscular septum to the medial head of the triceps
. Bicipital aponeurosis to the pronator teres
. Medial epicondyle to the olecranon
. Supracondylar process to the medial epicondyle
. Osborne's ligament to the flexor carpi ulnaris heads

Correct Answer & Explanation

. Medial intermuscular septum to the medial head of the triceps

Explanation

The Arcade of Struthers is a fascial band located approximately 8 cm proximal to the medial epicondyle, extending from the medial intermuscular septum to the medial head of the triceps. It is a potential site of ulnar nerve compression. Do not confuse it with the ligament of Struthers, which can compress the median nerve.

Question 405

Topic: Nerve & Tendon
A 25-year-old rugby player presents with an inability to actively flex the distal interphalangeal (DIP) joint of his ring finger after grabbing an opponent's jersey. Radiographs reveal a bony avulsion fragment localized at the level of the proximal interphalangeal (PIP) joint. According to the Leddy and Packer classification, what type of injury is this, and what is the typical status of the vincula?
. Type I, vincula intact
. Type I, vincula ruptured
. Type II, vincula intact
. Type III, vincula ruptured
. Type IV, vincula intact

Correct Answer & Explanation

. Type II, vincula intact

Explanation

This is a Leddy and Packer Type II 'Jersey finger' injury, where the Flexor Digitorum Profundus (FDP) tendon retracts to the level of the PIP joint. In Type II injuries, the vincula longus is typically intact, which preserves some blood supply and prevents the tendon from retracting into the palm (as seen in Type I injuries, where vincula are ruptured).

Question 406

Topic: Nerve & Tendon

During a primary repair of a Zone II flexor tendon injury, extensive trauma to the flexor tendon sheath is noted. To prevent clinically significant bowstringing of the tendon, which of the following combinations of pulleys must be preserved or reconstructed as an absolute minimum?

. A1 and A2 pulleys
. A2 and A4 pulleys
. A1 and A5 pulleys
. A3 and A5 pulleys
. C1 and C2 pulleys

Correct Answer & Explanation

. A2 and A4 pulleys

Explanation

The flexor tendon sheath in the fingers consists of five annular (A1-A5) and three cruciform (C1-C3) pulleys. The A2 and A4 pulleys arise directly from the periosteum of the proximal and middle phalanges, respectively. They are the most critical biomechanical pulleys for preventing tendon bowstringing during finger flexion. Loss of both A2 and A4 results in profound mechanical disadvantage and loss of digital motion.

Question 407

Topic: Nerve & Tendon

A 45-year-old avid cyclist presents with intrinsic muscle weakness in his right hand. Sensation is decreased over the volar aspect of the little finger and the ulnar half of the ring finger, but normal over the dorsal ulnar aspect of the hand. Where is the most likely site of nerve compression?

. Cubital tunnel
. Zone 1 of Guyon's canal
. Zone 2 of Guyon's canal
. Zone 3 of Guyon's canal
. Arcade of Struthers

Correct Answer & Explanation

. Zone 1 of Guyon's canal

Explanation

Compression in Zone 1 of Guyon's canal (proximal to the bifurcation of the ulnar nerve) results in both motor (intrinsic weakness) and sensory (volar ulnar digits) deficits. The dorsal ulnar cutaneous nerve branches off proximal to the wrist; thus, dorsal sensation is spared, differentiating it from cubital tunnel syndrome. Zone 2 causes isolated motor deficits, and Zone 3 causes isolated sensory deficits.

Question 408

Topic: Nerve & Tendon

A 45-year-old cyclist presents with isolated weakness of finger abduction and adduction, and an inability to cross his fingers. Sensation over the volar aspect of his small finger and the ulnar half of the ring finger is completely intact. Where is the most likely site of ulnar nerve compression?

. Cubital tunnel
. Guyon's canal - Zone 1
. Guyon's canal - Zone 2
. Guyon's canal - Zone 3
. Arcade of Struthers

Correct Answer & Explanation

. Guyon's canal - Zone 2

Explanation

Guyon's canal is divided into three zones. Zone 1 is proximal to the nerve bifurcation and contains both motor and sensory fibers; compression here causes mixed deficits. Zone 2 surrounds the deep motor branch; compression here causes isolated motor deficits of the ulnar-innervated intrinsic hand muscles. Zone 3 contains the superficial sensory branch; compression here causes isolated sensory deficits. 'Cyclist's palsy' frequently presents as an isolated motor deficit due to Zone 2 compression.

Question 409

Topic: Nerve & Tendon
A patient presents with a chronic Boutonniere deformity following an untreated injury to the extensor mechanism of the finger. The development of this deformity is mechanically driven by the rupture or attenuation of the central slip, followed by which of the following biomechanical shifts?
. Rupture of the terminal extensor slip
. Volar subluxation of the lateral bands
. Dorsal subluxation of the lateral bands
. Rupture of the sagittal band
. Avulsion of the volar plate

Correct Answer & Explanation

. Volar subluxation of the lateral bands

Explanation

A Boutonniere deformity is characterized by proximal interphalangeal (PIP) joint flexion and distal interphalangeal (DIP) joint hyperextension. It is initiated by the disruption of the central slip of the extensor tendon (Zone III). This failure allows the triangular ligament to attenuate, leading to the volar (palmar) subluxation of the lateral bands past the axis of rotation of the PIP joint. The lateral bands then become flexors of the PIP joint while continuing to exert a hyperextension force on the DIP joint.

Question 410

Topic: Nerve & Tendon
A 25-year-old rugby player presents with the inability to flex the distal interphalangeal (DIP) joint of his right ring finger after grasping an opponent's jersey. Radiographs are negative for a fracture. Ultrasound demonstrates the flexor digitorum profundus (FDP) tendon retracted to the level of the palm. What is the Leddy-Packer classification of this injury and the optimal timing for surgical repair?
. Type I, requiring surgery within 7-10 days
. Type II, requiring surgery within 7-10 days
. Type III, requiring surgery within 3-4 weeks
. Type I, requiring surgery within 3-4 weeks
. Type II, requiring surgery within 3-4 weeks

Correct Answer & Explanation

. Type I, requiring surgery within 7-10 days

Explanation

This is a Type I Leddy-Packer FDP avulsion (Jersey finger), where the tendon retracts completely into the palm. Because both vincula (longa and brevia) are ruptured, the tendon loses its blood supply and undergoes rapid necrosis and contraction. It must be repaired early, ideally within 7 to 10 days. Type II injuries retract to the level of the proximal interphalangeal (PIP) joint (vincula intact) and can be repaired up to a few weeks later. Type III involves a large bony avulsion that gets caught at the A4 pulley.

Question 411

Topic: Nerve & Tendon

A 45-year-old carpenter presents with progressive weakness of the intrinsic hand muscles and numbness isolated to his ring and small fingers. Examination reveals a positive Tinel's sign approximately 8 cm proximal to the medial epicondyle. Which of the following structures is most likely compressing the involved nerve at this specific location?

. Osborne's ligament
. Arcade of Struthers
. Ligament of Struthers
. Lacertus fibrosus
. Aponeurosis of the two heads of the flexor carpi ulnaris

Correct Answer & Explanation

. Arcade of Struthers

Explanation

The patient has ulnar neuropathy. While the most common site of compression is at the cubital tunnel (Osborne's ligament / between the two heads of the FCU), compression can also occur proximally at the Arcade of Struthers. The Arcade of Struthers is a fascial band extending from the medial head of the triceps to the medial intermuscular septum, located approximately 8 cm proximal to the medial epicondyle. (Note: The Ligament of Struthers is associated with median nerve compression at the supracondylar process).

Question 412

Topic: Nerve & Tendon

The Martin-Gruber anastomosis is a well-documented anatomical variant involving communicating neural branches. Which of the following best describes the most common neural transmission pathway in this anomaly?

. Ulnar nerve fibers crossing to the median nerve in the forearm to innervate the thenar eminence
. Median nerve fibers crossing to the ulnar nerve in the forearm to innervate the intrinsic hand muscles
. Radial nerve fibers crossing to the median nerve in the arm to innervate the lumbricals
. Median nerve fibers crossing to the radial nerve in the forearm to innervate the wrist extensors
. Ulnar nerve fibers crossing to the median nerve in the hand to innervate the superficial head of the flexor pollicis brevis

Correct Answer & Explanation

. Median nerve fibers crossing to the ulnar nerve in the forearm to innervate the intrinsic hand muscles

Explanation

The Martin-Gruber anastomosis occurs in the proximal forearm and involves motor fibers crossing from the median nerve (often via the anterior interosseous nerve) to the ulnar nerve. These fibers typically travel down the ulnar nerve to innervate intrinsic muscles of the hand (such as the first dorsal interosseous, adductor pollicis, and hypothenar muscles) that are normally supplied by the ulnar nerve.

Question 413

Topic: Nerve & Tendon

A 40-year-old female undergoes an open carpal tunnel release. Postoperatively, her nocturnal paresthesias resolve, but she reports an inability to oppose her thumb to her little finger. Which structure was most likely iatrogenically injured during the procedure?

. Palmar cutaneous branch of the median nerve
. Recurrent motor branch of the median nerve
. Deep branch of the ulnar nerve
. Superficial branch of the radial nerve
. Anterior interosseous nerve

Correct Answer & Explanation

. Recurrent motor branch of the median nerve

Explanation

The recurrent motor branch of the median nerve supplies the thenar intrinsic muscles (opponens pollicis, abductor pollicis brevis, and the superficial head of the flexor pollicis brevis), which are responsible for thumb opposition. Its iatrogenic injury is a classic and devastating complication if the dissection strays too far radially during a carpal tunnel release.

Question 414

Topic: Nerve & Tendon

A 65-year-old male complains of deteriorating handwriting and clumsiness in his hands. Neurological examination reveals a positive Hoffman's sign and the inability to rapidly adduct and abduct his ulnar digits, causing the small finger to rest in an abducted position. This specific spontaneous abduction of the small finger is known as:

. Wartenberg's sign
. Froment's sign
. Finger escape sign
. Lhermitte's sign
. Tinel's sign

Correct Answer & Explanation

. Finger escape sign

Explanation

The 'finger escape sign' is a clinical finding in cervical spondylotic myelopathy (part of the 'myelopathy hand'). The patient is unable to hold the ulnar digits adducted and extended, causing them to drift into abduction and flexion. While Wartenberg's sign also involves abduction of the small finger, it is classically due to ulnar nerve palsy (loss of third palmar interosseous muscle with unopposed EDQ).

Question 415

Topic: Nerve & Tendon

A 40-year-old male undergoes electromyography (EMG) for suspected cubital tunnel syndrome. The nerve conduction study demonstrates a drop in the amplitude of the compound muscle action potential (CMAP) when stimulating the ulnar nerve at the elbow while recording from the abductor digiti minimi (ADM). However, the CMAP recorded from the first dorsal interosseous (FDI) is normal. This discrepancy is most likely explained by which anatomic variant?

. Riche-Cannieu anastomosis
. Marinacci anastomosis
. Martin-Gruber anastomosis
. Berrettini anastomosis
. Struthers ligament compression

Correct Answer & Explanation

. Martin-Gruber anastomosis

Explanation

A Martin-Gruber anastomosis involves crossover fibers from the median nerve to the ulnar nerve in the forearm. These fibers often supply the FDI. Because the crossover occurs distal to the elbow, a compressive lesion at the elbow will not affect the median-to-ulnar fibers innervating the FDI, leading to sparing of the FDI CMAP, while the ADM (supplied strictly by the ulnar nerve) will show a deficit.

Question 416

Topic: Nerve & Tendon

An electromyographic (EMG) study reveals a Martin-Gruber anastomosis. Which of the following accurately describes the anatomic pathway of this common neural communication?

. Motor fibers cross from the median nerve to the ulnar nerve in the forearm
. Sensory fibers cross from the ulnar nerve to the median nerve in the forearm
. Motor fibers cross from the deep branch of the ulnar nerve to the median nerve in the hand
. Motor fibers cross from the median nerve to the ulnar nerve in the hand
. Sensory fibers cross between the superficial radial nerve and the dorsal ulnar sensory nerve

Correct Answer & Explanation

. Motor fibers cross from the median nerve to the ulnar nerve in the forearm

Explanation

A Martin-Gruber anastomosis is a common anatomical variant (present in roughly 15-20% of individuals) in which motor nerve fibers communicate from the median nerve (or its anterior interosseous branch) to the ulnar nerve in the proximal forearm. This anomaly can complicate the diagnosis of ulnar neuropathy at the elbow.

Question 417

Topic: Nerve & Tendon

A 9-year-old boy falls off monkey bars and presents with forearm pain. Radiographs demonstrate a fracture of the proximal third of the ulna and an anterior dislocation of the radial head. Which nerve is most commonly injured in this specific fracture-dislocation pattern?

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

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

This is a Monteggia fracture-dislocation. The radial head dislocation (especially anterior or lateral) can stretch or directly injure the Posterior Interosseous Nerve (PIN), leading to weakness in finger and thumb extension.

Question 418

Topic: Nerve & Tendon

A 50-year-old female requires dual plating for a severely comminuted intra-articular distal humerus fracture (AO/OTA 13C3). Based on current orthopedic consensus, what is the recommended management of the ulnar nerve during this procedure?

. Routine anterior subcutaneous transposition is mandatory
. In situ decompression is preferred unless hardware impingement requires transposition
. Submuscular transposition must be performed to avoid neuroma
. Excision of the medial epicondyle to relieve tension
. The nerve should remain unexposed to prevent devascularization

Correct Answer & Explanation

. In situ decompression is preferred unless hardware impingement requires transposition

Explanation

Current evidence suggests that routine anterior transposition of the ulnar nerve is unnecessary and may increase the risk of neuritis. In situ decompression is preferred, with transposition reserved for cases where the nerve subluxates or rubs against implants.

Question 419

Topic: Nerve & Tendon

A 42-year-old male undergoes tension band wiring for a transverse olecranon fracture. Postoperatively, he is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. What structure was likely injured?

. Median nerve at the ligament of Struthers
. Ulnar nerve at the cubital tunnel
. Anterior interosseous nerve from prominent K-wires
. Posterior interosseous nerve from surgical approach
. Radial nerve at the spiral groove

Correct Answer & Explanation

. Anterior interosseous nerve from prominent K-wires

Explanation

The anterior interosseous nerve (AIN) can be injured by overly long Kirschner wires penetrating the anterior cortex of the ulna during tension band wiring. AIN palsy presents with weakness of the FPL and FDP to the index finger.

Question 420

Topic: Nerve & Tendon

An 18-year-old male sustains a complete distal biceps tendon rupture. He undergoes repair via a single-incision anterior approach. Which of the following nerves is most at risk of injury with this specific surgical approach?

. Radial nerve
. Posterior interosseous nerve
. Lateral antebrachial cutaneous nerve
. Median nerve
. Ulnar nerve

Correct Answer & Explanation

. Lateral antebrachial cutaneous nerve

Explanation

The lateral antebrachial cutaneous nerve (LABC) is the most commonly injured nerve during a single-incision distal biceps repair. The posterior interosseous nerve is more commonly injured with the two-incision technique.

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