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Nerve & Tendon MCQs

Practice Set 7 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 121

Topic: Nerve & Tendon

During the surgical exposure for a distal humerus fracture, which anatomical structure is at highest risk of iatrogenic injury, particularly during posteromedial dissection?

. Radial nerve
. Musculocutaneous nerve
. Median nerve
. Ulnar nerve
. Brachial artery

Correct Answer & Explanation

. Ulnar nerve

Explanation

Correct Answer: DThe ulnar nerve is the most vulnerable neurological structure during posterior approaches to the distal humerus. It courses through the cubital tunnel posterior to the medial epicondyle and is often directly exposed, mobilized, and protected (often transposed anteriorly) during complex distal humerus fracture fixation to prevent iatrogenic injury or secondary compression. The radial nerve is at risk more proximally in the humeral shaft, the median nerve and brachial artery are anterior and generally protected by muscle bellies, and the musculocutaneous nerve is even further anterior and lateral.

Question 122

Topic: Nerve & Tendon

A 25-year-old rock climber presents with chronic pain and a noticeable 'bowstringing' of his long finger flexor tendons during active flexion, following a previous injury that was initially managed non-operatively. He reports a significant loss of grip strength. Which of the following anatomical structures is most likely compromised?

. The C1 and C2 pulleys.
. The A1 pulley.
. The A2 and A4 pulleys.
. The FDS decussation.
. The lumbrical muscle origin.

Correct Answer & Explanation

. The A2 and A4 pulleys.

Explanation

Correct Answer: CRationale:The flexor pulley system consists of annular (A) and cruciate (C) pulleys that keep the flexor tendons closely apposed to the phalanges. This close apposition is crucial for maintaining the mechanical advantage of the flexor tendons, preventing 'bowstringing,' and ensuring efficient finger flexion.Option C (The A2 and A4 pulleys)is correct. The A2 pulley (over the proximal phalanx) and the A4 pulley (over the middle phalanx) are considered the most critical annular pulleys for preventing bowstringing and maintaining the mechanical efficiency of the flexor tendons. Rupture or compromise of these pulleys leads to the tendon lifting away from the bone during flexion (bowstringing), resulting in a significant loss of mechanical advantage and grip strength.Option A (The C1 and C2 pulleys)is incorrect. The cruciate pulleys (C1, C2, C3) are thinner and less critical for preventing bowstringing compared to the annular pulleys.Option B (The A1 pulley)is incorrect. The A1 pulley is located at the MCP joint and its rupture typically leads to trigger finger, not bowstringing along the length of the finger.Option D (The FDS decussation)is incorrect. The FDS decussation is where the FDS tendon splits to allow the FDP to pass through. While important for FDS function, its injury does not directly cause bowstringing of the entire flexor system.Option E (The lumbrical muscle origin)is incorrect. The lumbrical muscles originate from the FDP tendons and insert into the extensor mechanism. Their injury or dysfunction is associated with conditions like lumbrical plus phenomenon, not bowstringing.

Question 123

Topic: Nerve & Tendon

A 40-year-old patient presents with a chronic FDP rupture of the ring finger (6 months post-injury). When attempting to make a full fist, the patient exhibits paradoxical hyperextension of the DIP joint and hyperextension of the PIP joint of the affected finger. This specific clinical presentation is known as:

. Quadriga effect.
. Boutonniere deformity.
. Swan neck deformity.
. Lumbrical plus phenomenon.
. Mallet finger.

Correct Answer & Explanation

. Lumbrical plus phenomenon.

Explanation

Correct Answer: DRationale:The described clinical presentation is characteristic of the lumbrical plus phenomenon.Option D (Lumbrical plus phenomenon)is correct. This occurs when the FDP tendon is ruptured, slack, or excessively shortened (e.g., due to overtensioned repair or chronic retraction). When the patient attempts to flex the finger (activating the FDP muscle belly), the lumbrical muscle, which originates from the FDP tendon and inserts into the extensor mechanism, is pulled proximally. This tension on the lumbrical causes it to act as an extensor of the DIP joint and can also contribute to PIP joint hyperextension, resulting in paradoxical DIP extension (or hyperextension) when the patient tries to make a fist.Option A (Quadriga effect)is incorrect. The quadriga effect refers to the restriction of flexion in adjacent, uninjured fingers due to overtensioning or shortening of one FDP tendon, as they share a common muscle belly. It does not involve paradoxical DIP extension.Option B (Boutonniere deformity)is incorrect. A boutonniere deformity is characterized by PIP joint flexion and DIP joint hyperextension, typically due to a central slip rupture of the extensor mechanism.Option C (Swan neck deformity)is incorrect. A swan neck deformity is characterized by PIP joint hyperextension and DIP joint flexion, often seen in conditions like rheumatoid arthritis or due to FDS laxity.Option E (Mallet finger)is incorrect. A mallet finger is a flexion deformity of the DIP joint due to rupture or avulsion of the extensor tendon at its insertion on the distal phalanx.

Question 124

Topic: Nerve & Tendon

A surgeon performs a primary FDP repair for a Type I Jersey finger. Post-operatively, the patient complains that when attempting to make a full fist with the repaired finger, the adjacent middle and small fingers are unable to fully flex at their DIP joints. What is the most likely cause of this specific complication?

. Adhesions within the flexor sheath of the repaired finger.
. Re-rupture of the FDP tendon in the repaired finger.
. Excessive tension on the repaired FDP tendon.
. Lumbrical plus phenomenon in the repaired finger.
. Insufficient strength of the FDS tendons in the adjacent fingers.

Correct Answer & Explanation

. Excessive tension on the repaired FDP tendon.

Explanation

Correct Answer: CRationale:The described complication is a classic presentation of the quadriga effect.Option C (Excessive tension on the repaired FDP tendon)is correct. The quadriga effect occurs because the FDP tendons of the middle, ring, and small fingers share a common muscle belly (or are closely intertwined proximally). If one FDP tendon (in this case, the repaired ring finger FDP) is repaired with excessive tension or advanced too much, it restricts the full excursion of the entire FDP muscle group. When the patient attempts to flex the repaired finger, the overtensioned FDP prevents the adjacent, otherwise healthy FDP tendons from fully flexing their respective DIP joints.Option A (Adhesions within the flexor sheath of the repaired finger)is incorrect. Adhesions would primarily limit the range of motion (both flexion and extension) of therepairedfinger itself, not specifically restrict flexion in theadjacentfingers.Option B (Re-rupture of the FDP tendon in the repaired finger)is incorrect. Re-rupture would result in a complete loss of active DIP flexion in therepairedfinger, not restricted flexion in adjacent fingers.Option D (Lumbrical plus phenomenon in the repaired finger)is incorrect. Lumbrical plus phenomenon involves paradoxical DIP extension of therepairedfinger when attempting to flex, not restricted flexion in adjacent fingers.Option E (Insufficient strength of the FDS tendons in the adjacent fingers)is incorrect. The FDS tendons primarily flex the PIP joints. The complaint is about DIP joint flexion, which is controlled by the FDP.

Question 125

Topic: Nerve & Tendon

A 22-year-old athlete sustains a Type I Jersey finger injury. The FDP tendon is found to be retracted into the palm. What specific anatomical structures are most critical for providing blood supply to the FDP tendon in the distal finger, and why is their disruption a major concern in this injury type?

. The A2 and A4 pulleys; they provide direct arterial branches.
. The flexor sheath; it contains a rich vascular plexus.
. The vincula tendinum; they are mesotendinous structures supplying the tendon.
. The lumbrical muscles; they directly vascularize the FDP.
. The digital neurovascular bundles; they run adjacent to the tendon.

Correct Answer & Explanation

. The vincula tendinum; they are mesotendinous structures supplying the tendon.

Explanation

Correct Answer: CRationale:The blood supply to the flexor tendons within the fibro-osseous sheath is crucial for their viability and healing. This supply comes primarily from specific mesotendinous structures.Option C (The vincula tendinum; they are mesotendinous structures supplying the tendon)is correct. The vincula tendinum (vincula longa and vincula brevia) are delicate mesotendinous folds that connect the flexor tendons to the phalanges and the flexor sheath. They carry small arteries that provide the primary blood supply to the FDP and FDS tendons as they pass through the flexor sheath. In a Type I Jersey finger, the FDP tendon avulses without a bony fragment and retracts significantly into the palm. This retraction often strips the tendon of its vincula, leading to a loss of its intrinsic blood supply and placing it at high risk of necrosis, which is why urgent repair is critical.Option A (The A2 and A4 pulleys; they provide direct arterial branches)is incorrect. The A2 and A4 pulleys are crucial mechanical structures that prevent bowstringing and maintain mechanical advantage, but they are not the primary source of blood supply to the tendon substance itself.Option B (The flexor sheath; it contains a rich vascular plexus)is incorrect. While the flexor sheath provides a low-friction environment and contains some vascularity, the direct supply to the tendon comes via the vincula, not directly from the sheath itself as a primary source.Option D (The lumbrical muscles; they directly vascularize the FDP)is incorrect. The lumbrical muscles originate from the FDP tendons but do not provide the primary blood supply to the FDP tendon itself along its course in the finger.Option E (The digital neurovascular bundles; they run adjacent to the tendon)is incorrect. The digital neurovascular bundles run on the sides of the fingers and supply the skin, nerves, and bone, but they do not directly vascularize the FDP tendon within its sheath.

Question 126

Topic: Nerve & Tendon

A 19-year-old patient presents with an acute Jersey finger of the ring finger. Surgical repair is planned. Which of the following surgical incisions is most commonly preferred for accessing the flexor tendons in the finger and why?

. A straight longitudinal volar incision; it provides direct access.
. A midaxial incision along the side of the finger; it avoids neurovascular structures.
. A transverse volar incision at the level of the PIP joint; it minimizes scarring.
. A zigzag incision (Brunner's incision) over the volar aspect; it prevents flexion contracture.
. A dorsal approach with splitting of the extensor mechanism; it offers better visualization.

Correct Answer & Explanation

. A zigzag incision (Brunner's incision) over the volar aspect; it prevents flexion contracture.

Explanation

Correct Answer: DRationale:The choice of surgical incision for flexor tendon repair in the finger is critical to ensure adequate exposure while minimizing complications, particularly flexion contractures.Option D (A zigzag incision (Brunner's incision) over the volar aspect; it prevents flexion contracture)is correct. The Brunner's zigzag incision is the most commonly preferred and safest approach for accessing the flexor tendons and sheath in the finger. This incision provides excellent exposure of the underlying structures while avoiding the creation of a long, linear scar that would be prone to contracting across the flexion creases, thereby preventing a flexion contracture.Option A (A straight longitudinal volar incision; it provides direct access)is incorrect. While it provides direct access, a straight longitudinal volar incision is contraindicated in the finger due to the very high risk of developing a severe and debilitating flexion contracture as the scar matures.Option B (A midaxial incision along the side of the finger; it avoids neurovascular structures)is incorrect. A midaxial incision is typically used for bony procedures, joint access, or accessing the neurovascular bundles, but it does not provide optimal direct access to the flexor tendons within their sheath. It also runs close to the neurovascular bundles.Option C (A transverse volar incision at the level of the PIP joint; it minimizes scarring)is incorrect. While transverse incisions can minimize scarring, a single transverse incision would provide very limited exposure for a flexor tendon repair that often spans multiple zones.Option E (A dorsal approach with splitting of the extensor mechanism; it offers better visualization)is incorrect. A dorsal approach is used for extensor tendon injuries, dorsal bony injuries, or joint fusions. It does not provide access to the flexor tendons, which are on the volar aspect of the finger.

Question 127

Topic: Nerve & Tendon

A 16-year-old patient undergoes FDP repair for a Type I Jersey finger of the small finger. The surgeon notes that the small finger FDP tendon appears smaller in diameter and somewhat more friable than typically seen in other digits. What is the most likely long-term implication of this observation, specifically for the small finger?

. Increased risk of quadriga effect.
. Higher incidence of lumbrical plus phenomenon.
. Greater propensity for persistent stiffness and poorer functional outcomes.
. Reduced risk of re-rupture due to less tension.
. Faster healing time due to smaller size.

Correct Answer & Explanation

. Greater propensity for persistent stiffness and poorer functional outcomes.

Explanation

Correct Answer: CRationale:While FDP avulsion injuries can occur in any digit, the small finger is often cited as having unique challenges and potentially poorer outcomes.Option C (Greater propensity for persistent stiffness and poorer functional outcomes)is correct. The FDP tendon of the small finger is often anatomically smaller in diameter and can be inherently weaker or more friable compared to the FDP tendons of the other digits. This smaller caliber and potentially poorer tissue quality can make surgical repair more challenging, lead to less robust repairs, and contribute to a higher rate of persistent stiffness, less overall range of motion, and generally poorer functional outcomes (e.g., grip strength, dexterity) even with technically successful repairs and diligent rehabilitation.Option A (Increased risk of quadriga effect)is incorrect. The quadriga effect is related to excessive tension in the repair, not specifically to the small finger's inherent tendon quality.Option B (Higher incidence of lumbrical plus phenomenon)is incorrect. Lumbrical plus is related to FDP slackness or overtensioning, not specifically to the small finger's intrinsic tendon quality.Option D (Reduced risk of re-rupture due to less tension)is incorrect. A smaller, weaker tendon would likely have anincreasedrisk of re-rupture if not repaired adequately, not a reduced risk.Option E (Faster healing time due to smaller size)is incorrect. Tendon healing is a biological process that is not significantly accelerated by smaller tendon size; rather, smaller size can make the repair more delicate.

Question 128

Topic: Nerve & Tendon

A 35-year-old patient presents with a suspected Jersey finger. On physical examination, you stabilize the patient's adjacent fingers (long and small) in full extension and ask them to actively flex the PIP joint of the ring finger. The patient is able to flex the PIP joint against resistance. What information does this specific maneuver provide?

. It confirms a complete FDP rupture.
. It rules out a central slip rupture.
. It assesses the integrity and function of the FDS tendon.
. It indicates an intact lumbrical muscle.
. It suggests a partial FDP tear.

Correct Answer & Explanation

. It assesses the integrity and function of the FDS tendon.

Explanation

Correct Answer: CRationale:This maneuver is a classic test to isolate and assess the function of the Flexor Digitorum Superficialis (FDS) tendon.Option C (It assesses the integrity and function of the FDS tendon)is correct. The FDS tendons for the middle, ring, and small fingers share a common muscle belly (or are closely related proximally), as do the FDP tendons. To isolate the FDS of a specific finger, the adjacent fingers must be held in full extension. This maneuver prevents the FDP of the tested finger from acting (as the FDP of the adjacent fingers would also be activated, causing unwanted flexion). If the patient can then actively flex the PIP joint of the tested finger against resistance, it confirms the integrity and function of the FDS tendon for that digit.Option A (It confirms a complete FDP rupture)is incorrect. This test assesses FDS function, not FDP rupture. FDP rupture is assessed by the inability to actively flex the DIP joint.Option B (It rules out a central slip rupture)is incorrect. A central slip rupture affects the extensor mechanism at the PIP joint, leading to a boutonniere deformity. This test is for flexor function.Option D (It indicates an intact lumbrical muscle)is incorrect. While the lumbricals are intrinsic muscles, this test specifically isolates FDS function.Option E (It suggests a partial FDP tear)is incorrect. This test does not directly assess the FDP tendon.

Question 129

Topic: Nerve & Tendon

A 65-year-old patient with a history of poorly controlled diabetes and peripheral neuropathy sustains an acute Type I Jersey finger. He is scheduled for surgical repair. Compared to a healthy, non-diabetic patient, what is the most significant increased risk factor for a poor outcome in this patient?

. Increased risk of quadriga effect.
. Higher likelihood of lumbrical plus phenomenon.
. Significantly impaired wound healing and increased infection risk.
. Inability to tolerate early active motion protocols.
. Greater chance of associated nerve injury.

Correct Answer & Explanation

. Significantly impaired wound healing and increased infection risk.

Explanation

Correct Answer: CRationale:Systemic comorbidities can significantly impact the prognosis and outcome of flexor tendon repairs.Option C (Significantly impaired wound healing and increased infection risk)is correct. Poorly controlled diabetes, especially when accompanied by peripheral neuropathy, is a major risk factor for complications in surgical procedures, including flexor tendon repair. Diabetes impairs wound healing due to microvascular disease (reduced blood flow), neuropathy (impaired sensation and trophic changes), and compromised immune function. This leads to a substantially increased risk of surgical site infection, delayed tendon healing, and overall poorer functional outcomes.Option A (Increased risk of quadriga effect)is incorrect. The quadriga effect is primarily related to surgical technique (excessive tension in the repair), not directly to diabetes.Option B (Higher likelihood of lumbrical plus phenomenon)is incorrect. Lumbrical plus phenomenon is related to FDP tendon length/tension, not directly to diabetes.Option D (Inability to tolerate early active motion protocols)is incorrect. While neuropathy might affect sensation and compliance, the primary issue is biological healing, not necessarily tolerance of motion protocols, which are carefully controlled.Option E (Greater chance of associated nerve injury)is incorrect. While peripheral neuropathy is present, it doesn't inherently increase the chance of anassociatednerve injury from the initial trauma or during surgery more than in a healthy individual. The concern is more about the healing process.

Question 130

Topic: Nerve & Tendon

A 21-year-old rugby player presents 2 days after violently grabbing an opponent's jersey. He cannot actively flex the DIP joint of his ring finger. MRI confirms the FDP tendon is retracted completely into the palm. According to the Leddy-Packer classification, what is the optimal timing for surgical repair of this Type I injury?

. Within 24 hours
. Within 7 to 10 days
. Within 3 to 4 weeks
. After 3 months with a two-stage tendon reconstruction
. Immediate non-operative management

Correct Answer & Explanation

. Within 7 to 10 days

Explanation

A Leddy-Packer Type I "jersey finger" involves the FDP tendon retracting into the palm, severing all vincular blood supply. It must be repaired within 7 to 10 days before the tendon retracts permanently and undergoes myostatic contracture.

Question 131

Topic: Nerve & Tendon

A 22-year-old rugby player felt a "pop" in his right ring finger while grabbing an opponent's jersey. He cannot actively flex the distal interphalangeal (DIP) joint. Imaging reveals a small bony avulsion retracted into the palm. What is the optimal timing for surgical intervention?

. Immediate surgical exploration within 12 hours
. Within 7 to 10 days to prevent irreversible tendon retraction and contracture
. Within 3 to 4 weeks after swelling subsides
. After 6 weeks, utilizing a two-stage tendon reconstruction
. Nonoperative management with a dorsal blocking splint for 8 weeks

Correct Answer & Explanation

. Within 7 to 10 days to prevent irreversible tendon retraction and contracture

Explanation

This is a Leddy and Packer Type I "jersey finger" (FDP avulsion retracted into the palm). Because the vincula are disrupted, blood supply is severely compromised, necessitating repair within 7 to 10 days before irreversible retraction and tendon necrosis occur.

Question 132

Topic: Nerve & Tendon

During an open carpal tunnel release, the longitudinal incision should be made in line with the radial border of the ring finger. Making the incision significantly radial to this axis most increases the risk of injuring which structure?

. Recurrent motor branch of the median nerve
. Palmar cutaneous branch of the median nerve
. Superficial palmar arch
. Ulnar artery
. Hook of the hamate

Correct Answer & Explanation

. Palmar cutaneous branch of the median nerve

Explanation

The palmar cutaneous branch of the median nerve lies in the interval between the palmaris longus and flexor carpi radialis. An incision placed too far radially risks injuring this nerve, potentially causing a painful neuroma.

Question 133

Topic: Nerve & Tendon
During percutaneous pinning of a Gartland Type III supracondylar humerus fracture, the surgeon opts for a medial and lateral crossed pin configuration. Which of the following is the most critical step to minimize the risk of iatrogenic ulnar nerve injury during medial pin placement?
. Inserting the medial pin with the elbow in 90 degrees of flexion.
. Using a smaller diameter K-wire for the medial pin.
. Performing a mini-open technique to palpate and protect the ulnar nerve.
. Inserting the medial pin from a more anterior entry point.
. Ensuring the lateral pin is placed first to stabilize the fracture.

Correct Answer & Explanation

. Performing a mini-open technique to palpate and protect the ulnar nerve.

Explanation

Medial and lateral crossed pins offer theoretically greater stability but carry a higher risk of iatrogenic ulnar nerve injury. Performing a mini-open technique to palpate and protect the ulnar nerve directly is an effective method of protection. Alternatively, the elbow must be fully extended to move the ulnar nerve posteriorly, away from the medial epicondyle.

Question 134

Topic: Nerve & Tendon

A 28-year-old patient presents with a 1.5 cm laceration to the radial aspect of the left index finger, sustained 48 hours prior. Examination reveals complete loss of sensation on the radial side of the index finger, with a positive Tinel's sign at the injury site. The digit is well-perfused. Surgical exploration confirms a complete transection of the radial proper digital nerve of the index finger with a 5 mm gap after minimal debridement. Based on the case's guidelines for nerve repair, what is the most appropriate initial surgical management?

. Secondary repair with an autologous nerve graft due to the 5 mm gap.
. Delayed primary repair with a nerve conduit to bridge the gap.
. Epineurial repair (direct primary repair) of the nerve.
. Observation for spontaneous regeneration, as the gap is small.
. Excision of the nerve ends and relocation into a muscle belly to prevent neuroma formation.

Correct Answer & Explanation

. Epineurial repair (direct primary repair) of the nerve.

Explanation

Correct Answer: CThe case states under 'Indications for Surgical Intervention' that 'Acute Repair: Indicated for clean lacerations identified within 72 hours, ideally within 24 hours.' The patient presents within 48 hours, making acute primary repair appropriate. For nerve repair technique, the case states 'Epineurial Repair: This is the most common technique for proper digital nerves... The goal is to align the nerve without rotation and achieve precise coaptation of the fascicular bundles.' A 5 mm gap after minimal debridement is generally manageable with direct, tension-free epineurial repair, especially with gentle mobilization, and does not typically necessitate grafting or conduits which are reserved for larger gaps (>1 cm).Option A is incorrectbecause secondary repair is for missed injuries or failed primary repairs (after 3 weeks), and a 5 mm gap is usually amenable to direct repair, not requiring a graft unless significant tension is present after mobilization.Option B is incorrectbecause delayed primary repair is for conditions preventing immediate repair, which is not the case here (48 hours is within the acute window). Conduits are typically considered for smaller gaps, but direct repair is preferred if tension-free.Option D is incorrectas a complete transection of a proper digital nerve requires surgical repair to optimize functional recovery; observation for spontaneous regeneration is not indicated for complete transections.Option E is incorrectbecause excision and relocation are management strategies for painful neuromas, not for acute nerve transections where the goal is to restore continuity and function.

Question 135

Topic: Nerve & Tendon

A 48-year-old patient is recovering from a repair of a complete transection of the ulnar proper digital nerve of the small finger. Three weeks post-operatively, the patient complains of severe hypersensitivity and shooting pain in the small finger, particularly when touching the scar. Examination reveals a positive Tinel's sign at the repair site and significant allodynia. Conservative management with NSAIDs and topical analgesics has provided minimal relief. According to the case, which of the following is a recognized surgical option for managing this complication?

. Immediate revision neurorrhaphy with a nerve conduit.
. Excision of the painful neuroma and relocation of the nerve end into a well-vascularized, soft tissue bed.
. Systemic administration of high-dose corticosteroids to reduce inflammation.
. Application of a dynamic splint to promote early motion and desensitization.
. Observation for 3 more months, as this is a normal part of nerve regeneration.

Correct Answer & Explanation

. Excision of the painful neuroma and relocation of the nerve end into a well-vascularized, soft tissue bed.

Explanation

Correct Answer: BThe patient's symptoms (severe hypersensitivity, shooting pain, positive Tinel's, allodynia, and failure of conservative management) are highly suggestive of a painful traumatic neuroma. The case, under 'Neuroma Excision and Management,' lists several surgical options: 'For symptomatic neuromas, surgical options include: ... Excision and Relocation: The neuroma is excised, and the nerve end is transposed into a well-vascularized, soft tissue bed (e.g., muscle, bone tunnel) away from external pressure.' This directly addresses the described complication.Option A is incorrectbecause revision neurorrhaphy with a conduit is for nerve gaps or failed repairs, not specifically for a painful neuroma where the goal is to manage the nerve stump.Option C is incorrectas systemic corticosteroids are not a primary treatment for painful neuromas and carry significant side effects.Option D is incorrectbecause while desensitization is part of rehabilitation, a dynamic splint is for motion, and this patient's severe pain and allodynia suggest a more aggressive approach is needed after conservative failure.Option E is incorrectas severe, debilitating pain and allodynia are not a 'normal part of nerve regeneration' and warrant intervention, especially after conservative measures fail.

Question 136

Topic: Nerve & Tendon

A 50-year-old patient presents with a 2 cm laceration to the volar aspect of the thumb, sustained 3 days ago. Examination reveals complete loss of sensation on the radial side of the thumb. The common digital nerves arise from the median and ulnar nerves in the palm. Based on the anatomical description in the case, which nerve is primarily responsible for the sensory innervation of the radial side of the thumb?

. The ulnar nerve via a common digital nerve.
. The median nerve via a proper digital nerve directly from the median nerve.
. The radial nerve via its superficial branch.
. The median nerve via a common digital nerve that bifurcates.
. The ulnar nerve via a proper digital nerve directly from the ulnar nerve.

Correct Answer & Explanation

. The median nerve via a proper digital nerve directly from the median nerve.

Explanation

Correct Answer: BThe 'Surgical Anatomy & Biomechanics' section states: 'Each digit, excluding the thumb and the radial aspect of the index finger which have specific innervation from the median nerve, typically receives two proper digital nerves and two proper digital arteries.' This indicates that the thumb's innervation is somewhat distinct. Specifically, the radial side of the thumb is innervated by a proper digital nerve that branches directly from the median nerve, not via a common digital nerve that then bifurcates for the thumb. The median nerve gives rise to three common digital nerves, but the thumb's innervation is mentioned as a specific exception.Option A is incorrectbecause the ulnar nerve primarily innervates the small finger and the ulnar side of the ring finger.Option B is correctas per the case's specific exclusion for the thumb's innervation.Option C is incorrectbecause while the radial nerve innervates the dorsum of the hand and some dorsal digits, its contribution to the volar aspect of the thumb is not described as primary for the proper digital nerve.Option D is incorrectbecause the case implies a direct innervation for the thumb from the median nerve, rather than through a common digital nerve that then bifurcates, which is the pattern for other digits.Option E is incorrectas the ulnar nerve does not innervate the radial side of the thumb.

Question 137

Topic: Nerve & Tendon

A 5-year-old child sustains a displaced lateral condyle fracture of the humerus that goes unrecognized for 6 weeks, resulting in an established nonunion. If left untreated into adulthood, what is the most likely long-term complication associated with this specific nonunion?

. Cubitus varus and median nerve palsy
. Cubitus valgus and tardy ulnar nerve palsy
. Genu valgum and common peroneal nerve palsy
. Cubitus varus and tardy radial nerve palsy
. Recurrent elbow dislocations and profound stiffness

Correct Answer & Explanation

. Cubitus valgus and tardy ulnar nerve palsy

Explanation

An untreated or non-united lateral condyle fracture typically results in progressive growth arrest laterally, leading to a profound cubitus valgus deformity. Over time, the valgus angulation stretches the ulnar nerve, often causing a tardy ulnar nerve palsy years later.

Question 138

Topic: Nerve & Tendon

During the utility posterior approach for a terrible triad repair, the ulnar nerve is identified, decompressed, and protected in situ. What is the primary reason for protecting the ulnar nerve in situ rather than routinely transposing it anteriorly in this specific surgical context?

. A. Anterior transposition increases the risk of elbow stiffness.
. B. The utility posterior approach does not typically expose the ulnar nerve sufficiently for transposition.
. C. In situ protection minimizes devascularization and avoids potential iatrogenic injury associated with transposition.
. D. Transposition is only indicated for pre-existing ulnar neuropathy.
. E. The ulnar nerve is not typically at risk during a terrible triad repair.

Correct Answer & Explanation

. C. In situ protection minimizes devascularization and avoids potential iatrogenic injury associated with transposition.

Explanation

Correct Answer: CThe teaching case specifies 'The ulnar nerve would be identified, decompressed, and protected in situ.' Protecting the nerve in situ, when feasible, minimizes the risk of devascularization and iatrogenic injury (e.g., traction neuropathy, scarring) that can be associated with formal anterior transposition. Transposition is a more extensive procedure with its own set of potential complications, and it is not always necessary if the nerve can be safely protected in its anatomical groove.Option A (Anterior transposition increases the risk of elbow stiffness)is incorrect. While any extensive surgery around the elbow can contribute to stiffness, transposition itself is not a primary cause of elbow stiffness in this context.Option B (The utility posterior approach does not typically expose the ulnar nerve sufficiently for transposition)is incorrect. The utility posterior approach can certainly expose the ulnar nerve, and transposition can be performed if deemed necessary. The decision is based on risk/benefit, not exposure limitations.Option D (Transposition is only indicated for pre-existing ulnar neuropathy)is incorrect. While pre-existing neuropathy is a strong indication, transposition may also be considered if the nerve is highly unstable in its groove, or if extensive hardware placement or soft tissue repair might impinge upon it, even without pre-existing neuropathy. However, the default is in situ protection if possible.Option E (The ulnar nerve is not typically at risk during a terrible triad repair)is incorrect. The ulnar nerve is very much at risk during elbow trauma and surgical approaches to the posterior and medial elbow, hence the emphasis on identifying and protecting it.

Question 139

Topic: Nerve & Tendon

During the surgical exposure for a distal humerus fracture via a posterior approach, which anatomical structure is at highest risk of iatrogenic injury, particularly during posteromedial dissection and mobilization?

. Radial nerve
. Musculocutaneous nerve
. Median nerve
. Ulnar nerve
. Brachial artery

Correct Answer & Explanation

. Ulnar nerve

Explanation

Correct Answer: DThe ulnar nerve is the most vulnerable neurological structure during posterior approaches to the distal humerus. It courses through the cubital tunnel posterior to the medial epicondyle and is often directly exposed, mobilized, and protected (often transposed anteriorly) during complex distal humerus fracture fixation to prevent iatrogenic injury or secondary compression. The radial nerve is at risk more proximally in the humeral shaft or during lateral approaches. The median nerve and brachial artery are anterior and generally protected by muscle bellies. The musculocutaneous nerve is even further anterior and lateral, making it less susceptible during a posterior approach.

Question 140

Topic: Nerve & Tendon

A 19-year-old basketball player presents with a suspected Jersey finger of his small finger. On examination, he has full active flexion of his PIP joint but lacks active flexion of his DIP joint. A modified tabletop test reveals a normal cascade for all fingers except the small finger, which remains extended at the DIP joint. What is the most reliable maneuver to confirm an FDP rupture in this digit?

. Assessing passive range of motion of the DIP joint.
. Palpating for a tender gap in the distal palm.
. Stabilizing the PIP joint and asking the patient to flex the DIP joint.
. Comparing grip strength to the contralateral hand.
. Performing a Finkelstein's test to rule out De Quervain's tenosynovitis.

Correct Answer & Explanation

. Stabilizing the PIP joint and asking the patient to flex the DIP joint.

Explanation

Correct Answer: CThe most reliable maneuver to confirm an FDP rupture is to isolate the action of the FDP tendon. This is done by stabilizing the PIP joint in full extension and asking the patient to actively flex the DIP joint. If the FDP is ruptured, active DIP flexion will be absent. Assessing passive range of motion will typically be full, as the FDP rupture is an active deficit. Palpating a tender gap can be indicative but is not always reliable, especially with swelling. Grip strength is a global measure and not specific enough. Finkelstein's test is for De Quervain's tenosynovitis and is irrelevant in this context.

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