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7. Hand and Wrist MCQs

Practice Set 205 of 266

This practice set contains high-yield board review questions covering key concepts in 7. Hand and Wrist. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 4081

Topic: 7. Hand and Wrist

Electrodiagnostic testing is often used to evaluate peripheral nerve injuries. During nerve conduction studies (NCS), what specific physiologic parameter does the F-wave primarily assess?

. Function of the neuromuscular junction
. Integrity of sensory nerve action potentials
. Conduction across proximal nerve segments and nerve roots
. Distal motor latency across the carpal tunnel
. Spontaneous activity of denervated muscle fibers

Correct Answer & Explanation

. Function of the neuromuscular junction

Explanation

The F-wave is a late motor response that evaluates conduction along the entire length of the nerve, particularly the proximal segments and nerve roots. It occurs when a supramaximal stimulus travels antidromically to the anterior horn cell, causing a backfire that travels orthodromically down to the muscle, making it highly useful for detecting radiculopathies.

Question 4082

Topic: Hand Trauma & Infection

A 32-year-old carpenter sustains a puncture wound to his index finger and presents 48 hours later with swelling. Which of Kanavel's four cardinal signs is typically the earliest and most sensitive indicator of infectious flexor tenosynovitis?

. Fusiform swelling of the digit
. Flexed resting posture of the digit
. Tenderness along the flexor tendon sheath
. Pain with passive extension of the digit
. Erythema extending to the palm

Correct Answer & Explanation

. Fusiform swelling of the digit

Explanation

Pain with passive extension of the affected digit is generally considered the earliest and most sensitive of Kanavel's cardinal signs for infectious flexor tenosynovitis. The other signs typically develop as the infection progresses.

Question 4083

Topic: 7. Hand and Wrist

A 24-year-old male sustains a proximal pole scaphoid fracture. The risk of avascular necrosis (AVN) is exceptionally high due to the retrograde blood supply to the scaphoid. The predominant blood supply enters the scaphoid at which of the following anatomic locations?

. The volar tubercle via the volar carpal branch of the radial artery
. The dorsal ridge via the dorsal carpal branch of the radial artery
. The proximal pole directly from the anterior interosseous artery
. The waist via the superficial palmar arch
. The distal pole via the ulnar artery anastomoses

Correct Answer & Explanation

. The volar tubercle via the volar carpal branch of the radial artery

Explanation

The scaphoid receives 70-80% of its blood supply from the dorsal carpal branch of the radial artery. This vessel enters at the dorsal ridge near the waist and flows retrogradely to the proximal pole.

Question 4084

Topic: Wrist & Carpus

When evaluating a clinically suspected occult scaphoid fracture with negative plain radiographs, which of the following MRI sequences is most sensitive for detecting the early bone marrow edema associated with the injury?

. T1-weighted spin echo
. T2-weighted spin echo
. Short tau inversion recovery (STIR)
. Gradient echo (GRE)
. Proton density without fat saturation

Correct Answer & Explanation

. T1-weighted spin echo

Explanation

STIR sequences suppress fat signal and are highly sensitive for detecting increased water content. This makes them excellent for identifying early bone marrow edema associated with occult fractures, stress responses, or early avascular necrosis.

Question 4085

Topic: 7. Hand and Wrist
A 30-year-old sustains a knife laceration over the volar proximal phalanx of the index finger, resulting in a complete loss of active flexion at both the proximal and distal interphalangeal joints. Which flexor tendon zone is injured?
. Zone I
. Zone II
. Zone III
. Zone IV
. Zone V

Correct Answer & Explanation

. Zone II

Explanation

Zone II (historically termed no man's land) extends from the proximal A1 pulley to the insertion of the flexor digitorum superficialis. Injuries in this zone typically involve both the superficialis and profundus tendons.

Question 4086

Topic: 7. Hand and Wrist

A 45-year-old patient presents with numbness in the thumb and index finger. Which of the following physical examination findings best differentiates a C6 cervical radiculopathy from severe carpal tunnel syndrome?

. Positive Tinel sign at the wrist
. Weakness in the abductor pollicis brevis
. Weakness in active wrist extension
. Diminished sensation over the volar tip of the index finger
. Nighttime awakening due to hand paresthesias

Correct Answer & Explanation

. Positive Tinel sign at the wrist

Explanation

Wrist extensors are innervated by the C6 nerve root via the radial nerve, which is unaffected in carpal tunnel syndrome. Weakness in wrist extension therefore indicates a more proximal lesion, such as a C6 radiculopathy.

Question 4087

Topic: Nerve & Tendon

A 40-year-old man undergoes an electromyography (EMG) study for a suspected nerve entrapment. The neurologist notes the presence of a Martin-Gruber anastomosis. What does this anatomic variant typically represent?

. Motor branches from the median nerve cross to the ulnar nerve in the forearm.
. Sensory branches from the ulnar nerve cross to the median nerve in the hand.
. Motor branches from the ulnar nerve cross to the median nerve in the forearm.
. Motor branches from the median nerve cross to the radial nerve in the arm.
. An arterial anastomosis between the superficial and deep palmar arches.

Correct Answer & Explanation

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

Explanation

The Martin-Gruber anastomosis is a common anomalous connection in the forearm where motor fibers from the median nerve (or anterior interosseous nerve) cross over to join the ulnar nerve. This can result in atypical EMG findings and spared intrinsic hand function in proximal ulnar nerve injuries.

Question 4088

Topic: Wrist & Carpus

The triangular fibrocartilage complex (TFCC) is the major stabilizer of the distal radioulnar joint (DRUJ). Which specific part of the TFCC has a rich blood supply and is therefore more amenable to primary surgical repair?

. The central articular disc
. The radial attachment
. The peripheral (ulnar) aspect
. The deep foveal attachment exclusively
. The midsubstance of the palmar radioulnar ligament

Correct Answer & Explanation

. The central articular disc

Explanation

The blood supply to the TFCC is limited to its peripheral 10-20%, which receives vessels from the ulnar artery and the palmar/dorsal branches of the anterior interosseous artery. The central and radial portions are avascular. Therefore, peripheral (ulnar-sided) tears have healing potential and are often amenable to primary repair.

Question 4089

Topic: 7. Hand and Wrist

De Quervain's tenosynovitis affects the first dorsal extensor compartment of the wrist. Intersection syndrome involves friction between the first and second dorsal compartments. Which muscles comprise the second dorsal compartment?

. Abductor pollicis longus and Extensor pollicis brevis
. Extensor carpi radialis longus and Extensor carpi radialis brevis
. Extensor pollicis longus
. Extensor digitorum communis and Extensor indicis proprius
. Extensor carpi ulnaris

Correct Answer & Explanation

. Abductor pollicis longus and Extensor pollicis brevis

Explanation

The first dorsal compartment contains the APL and EPB. The second compartment contains the ECRL and ECRB. Intersection syndrome occurs where the muscle bellies of the first compartment cross over the tendons of the second compartment.

Question 4090

Topic: 7. Hand and Wrist

When performing an open carpal tunnel release, the surgeon must be mindful of the recurrent motor branch of the median nerve (the "million dollar nerve"). According to the Lanz classification, which anatomical variation of the recurrent motor branch is the most common?

. Extraligamentous
. Subligamentous
. Transligamentous
. Ulnarward branching
. Supraligamentous

Correct Answer & Explanation

. Extraligamentous

Explanation

The extraligamentous course is the most common anatomical variation of the recurrent motor branch of the median nerve (occurring in approximately 50-75% of individuals). It branches off the median nerve distal to the transverse carpal ligament and recurrently turns to enter the thenar musculature.

Question 4091

Topic: Nerve & Tendon

During the volar (Russe) approach to the scaphoid for open reduction and internal fixation of a waist fracture, the surgical interval for deep exposure involves incising the sheath of which of the following tendons?

. Flexor pollicis longus
. Flexor carpi radialis
. Palmaris longus
. Abductor pollicis longus
. Flexor digitorum superficialis

Correct Answer & Explanation

. Flexor pollicis longus

Explanation

The volar approach to the scaphoid requires an incision centered over the flexor carpi radialis (FCR) tendon. The FCR tendon sheath is opened, and the tendon is retracted ulnarly (to protect the median nerve) or radially (to protect the radial artery). The deep floor of the FCR sheath is incised to access the volar radiocarpal capsule and the scaphoid.

Question 4092

Topic: 7. Hand and Wrist

A patient presents with tenderness in the anatomical snuffbox after a fall on an outstretched hand. Which of the following describes the correct tendinous boundaries of the anatomical snuffbox when the hand is in the standard anatomical position?

. Medial boundary: Extensor pollicis longus; Lateral boundary: Abductor pollicis longus and Extensor pollicis brevis
. Medial boundary: Extensor pollicis brevis; Lateral boundary: Extensor pollicis longus and Abductor pollicis longus
. Medial boundary: Abductor pollicis longus; Lateral boundary: Extensor pollicis longus and Extensor pollicis brevis
. Medial boundary: Extensor carpi radialis longus; Lateral boundary: Extensor pollicis longus
. Medial boundary: Extensor pollicis longus; Lateral boundary: Flexor carpi radialis

Correct Answer & Explanation

. Medial boundary: Extensor pollicis longus; Lateral boundary: Abductor pollicis longus and Extensor pollicis brevis

Explanation

In the standard anatomical position (palms facing anteriorly), the thumb is lateral. The anatomical snuffbox is bounded medially (ulnarly) by the tendon of the Extensor pollicis longus (EPL), and laterally (radially) by the tendons of the Abductor pollicis longus (APL) and Extensor pollicis brevis (EPB). The radial artery runs through its floor.

Question 4093

Topic: 7. Hand and Wrist

Which flexor tendon pulleys of the hand are mechanically most critical to preserve during surgery to prevent bowstringing of the flexor tendons?

. A1 and A3
. A2 and A4
. A3 and A5
. A1 and A5
. A2 and A3

Correct Answer & Explanation

. A1 and A3

Explanation

The A2 (proximal phalanx) and A4 (middle phalanx) pulleys are the major mechanical pulleys of the digital flexor sheath. They must be preserved to prevent bowstringing and subsequent loss of mechanical advantage.

Question 4094

Topic: 7. Hand and Wrist

During a dorsal approach to the wrist, Lister's tubercle serves as a key landmark. The tendon of the extensor pollicis longus (EPL) typically runs in which direction relative to this structure?

. Immediately ulnar to Lister's tubercle
. Immediately radial to Lister's tubercle
. Superficial to Lister's tubercle
. Deep to Lister's tubercle
. It does not pass near Lister's tubercle

Correct Answer & Explanation

. Immediately ulnar to Lister's tubercle

Explanation

The EPL tendon courses in the third dorsal extensor compartment, which is located immediately ulnar to Lister's tubercle. It uses the tubercle as a fulcrum to redirect its path toward the thumb.

Question 4095

Topic: Nerve & Tendon

A patient with an isolated nerve injury is unable to actively flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger, resulting in a positive "OK" sign. Which of the following muscles is ALSO innervated by the affected nerve?

. Flexor carpi radialis
. Pronator teres
. Pronator quadratus
. Flexor digitorum superficialis
. Abductor pollicis brevis

Correct Answer & Explanation

. Flexor carpi radialis

Explanation

The patient has an anterior interosseous nerve (AIN) palsy. The AIN is a pure motor branch of the median nerve that innervates the flexor pollicis longus, the flexor digitorum profundus to the index and middle fingers, and the pronator quadratus.

Question 4096

Topic: Nerve & Tendon

The recurrent motor branch of the median nerve (the "million dollar nerve") innervates the thenar musculature. Which of the following muscles is primarily innervated by the deep branch of the ulnar nerve rather than the median nerve?

. Opponens pollicis
. Abductor pollicis brevis
. Superficial head of the flexor pollicis brevis
. Adductor pollicis
. First lumbrical

Correct Answer & Explanation

. Opponens pollicis

Explanation

The adductor pollicis and the deep head of the flexor pollicis brevis are innervated by the deep branch of the ulnar nerve. The median nerve supplies the LOAF muscles: Lumbricals 1 & 2, Opponens pollicis, Abductor pollicis brevis, and the superficial head of the Flexor pollicis brevis.

Question 4097

Topic: Nerve & Tendon

A patient develops an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger following a forearm injury. Sensation is completely intact. Which of the following structures is most likely causing compression of the involved nerve?

. Arcade of Frohse
. Ligament of Struthers
. Tendinous edge of the deep head of the pronator teres
. Osborne's fascia
. Arcade of Struthers

Correct Answer & Explanation

. Arcade of Frohse

Explanation

This presentation describes anterior interosseous nerve (AIN) syndrome, characterized by pure motor loss to the FPL, FDP (index/middle), and pronator quadratus. The AIN is most commonly compressed by the tendinous edge of the deep head of the pronator teres or the fibrous arch of the FDS.

Question 4098

Topic: 7. Hand and Wrist

A 14-year-old boy is evaluated for short stature and multiple hard, painless bumps around his knees and wrists. Radiographs confirm multiple pedunculated bone projections pointing away from the joints. The genetic mutations responsible for this syndrome directly impair the synthesis of which of the following?

. Type I collagen
. Heparan sulfate
. Hyaluronic acid
. Fibronectin
. Chondroitin sulfate

Correct Answer & Explanation

. Heparan sulfate

Explanation

Multiple hereditary exostoses (MHE) is caused by mutations in EXT1 or EXT2. These genes encode glycosyltransferases essential for the polymerization of heparan sulfate chains.

Question 4099

Topic: 7. Hand and Wrist

A 55-year-old female undergoes volar locking plate fixation for a displaced distal radius fracture. At 6 months postoperatively, she presents with an inability to actively flex the interphalangeal joint of her thumb. What is the most likely cause of this complication?

. Rupture of the extensor pollicis longus (EPL) due to prominent dorsal screws
. Rupture of the flexor pollicis longus (FPL) tendon secondary to plate prominence distal to the watershed line
. Iatrogenic transection of the anterior interosseous nerve (AIN)
. Adhesions of the flexor digitorum profundus (FDP) tendons
. Median nerve entrapment in the carpal tunnel

Correct Answer & Explanation

. Rupture of the extensor pollicis longus (EPL) due to prominent dorsal screws

Explanation

Flexor tendon ruptures, specifically the Flexor Pollicis Longus (FPL), are a recognized and severe complication of volar plating of the distal radius. This typically occurs when the plate is placed too distally, crossing the 'watershed line' (the prominence of the volar margin of the radius). The FPL tendon anatomically rests on this area and rubs against the prominent plate edge, eventually leading to attrition and rupture. EPL rupture is more classically associated with nonoperatively treated distal radius fractures.

Question 4100

Topic: Wrist & Carpus

A 32-year-old male sustains a Galeazzi fracture-dislocation. Intraoperatively, after achieving anatomic open reduction and rigid internal fixation of the radial shaft with a compression plate, the distal radioulnar joint (DRUJ) remains unstable in both supination and pronation. What is the most appropriate next step in management?

. Pinning the DRUJ with Kirschner wires in neutral rotation
. Pinning the DRUJ with Kirschner wires in maximum supination
. Pinning the DRUJ with Kirschner wires in maximum pronation
. Immediate open repair of the triangular fibrocartilage complex (TFCC) from a dorsal approach
. Application of an external fixator across the wrist joint

Correct Answer & Explanation

. Pinning the DRUJ with Kirschner wires in neutral rotation

Explanation

A Galeazzi injury involves a fracture of the distal third of the radial shaft with associated disruption of the DRUJ. The initial step is stable anatomic fixation of the radius. If the DRUJ remains unstable, it should be assessed in different forearm rotations. Supination tension the palmar radioulnar ligament and often reduces the DRUJ. If it is unstable, the DRUJ should be reduced and pinned with K-wires in supination for 4 to 6 weeks. Primary open repair of the TFCC is generally reserved for irreducibility of the DRUJ (e.g., due to interposed extensor carpi ulnaris tendon).

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