Menu

Surgical Anatomy & Approaches MCQs

Practice Set 12 of 102

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

Question 221

Topic: Surgical Anatomy & Approaches

Fourteen days after initial external fixation, the patient's soft tissue envelope shows significant improvement, with resolution of edema and a positive 'wrinkle sign.' Definitive reconstruction is planned using a dual incision strategy. The primary approach is an anterolateral incision. Which of the following describes the correct internervous plane for this approach and a critical nerve to protect?

. Between the Tibialis Anterior and the Extensor Hallucis Longus; protect the saphenous nerve.
. Between the Extensor Digitorum Longus and the Peroneus Tertius; protect the superficial peroneal nerve.
. Between the Peroneus Longus and the Peroneus Brevis; protect the deep peroneal nerve.
. Between the Flexor Digitorum Longus and the Tibialis Posterior; protect the sural nerve.
. Between the Gastrocnemius and Soleus; protect the posterior tibial nerve.

Correct Answer & Explanation

. Between the Extensor Digitorum Longus and the Peroneus Tertius; protect the superficial peroneal nerve.

Explanation

Correct Answer: BThe case explicitly states, 'The deep dissection utilizes the internervous plane between the extensor digitorum longus (innervated by the deep peroneal nerve) and the peroneus tertius.' It also highlights the critical need for 'meticulous identification and protection of the superficial peroneal nerve, which frequently crosses the operative field from medial to lateral in the distal third of the leg.' This accurately describes the anatomical considerations for the anterolateral approach to the distal tibia.Option A is incorrectbecause the plane between the Tibialis Anterior and Extensor Hallucis Longus is more medial, and the saphenous nerve is on the medial side of the leg, not typically at risk in the anterolateral approach.Option C is incorrectbecause the plane between the Peroneus Longus and Brevis is more lateral and posterior, and while the deep peroneal nerve is important, the superficial peroneal nerve is more directly at risk with the skin incision and initial dissection of the anterolateral approach.Option D is incorrectbecause this describes a posterior approach, and the sural nerve is lateral.Option E is incorrectbecause this describes a posterior approach, and the posterior tibial nerve is in the deep posterior compartment.

Question 222

Topic: Surgical Anatomy & Approaches

When utilizing an anterolateral approach to the distal tibia for definitive fixation of a pilon fracture (Chaput fragment), the internervous plane is developed. Which neurologic structure is at highest risk of iatrogenic injury during superficial dissection in this approach?

. Sural nerve
. Deep peroneal nerve
. Superficial peroneal nerve
. Saphenous nerve
. Medial plantar nerve

Correct Answer & Explanation

. Superficial peroneal nerve

Explanation

The anterolateral approach to the distal tibia involves an incision aligned with the fourth ray, typically placing the superficial peroneal nerve at risk during the superficial dissection. It must be carefully identified and protected. The deep peroneal nerve and anterior tibial artery lie deeper and more medial, between the tibialis anterior and EHL.

Question 223

Topic: Surgical Anatomy & Approaches

When utilizing a posterolateral approach to the distal tibia for internal fixation of a posterior malleolar fragment in a pilon fracture, which of the following neurologic structures is most at risk during the superficial dissection?

. Deep peroneal nerve
. Superficial peroneal nerve
. Sural nerve
. Saphenous nerve
. Tibial nerve

Correct Answer & Explanation

. Sural nerve

Explanation

The posterolateral approach utilizes the internervous plane between the peroneus brevis (superficial peroneal nerve) and the flexor hallucis longus (tibial nerve). The sural nerve runs superficially in this region alongside the small saphenous vein and is highly vulnerable during the initial surgical exposure.

Question 224

Topic: Surgical Anatomy & Approaches

During the surgical approach for open reduction internal fixation of a proximal humerus fracture, the deltopectoral interval is utilized. Which of the following anatomical landmarks is crucial for identifying and safely developing this interval?

. A. The posterior border of the deltoid and the anterior border of the teres major.
. B. The lateral border of the pectoralis major and the medial border of the deltoid.
. C. The cephalic vein, which lies within the interval between the deltoid and pectoralis major muscles.
. D. The axillary nerve, which runs along the inferior border of the subscapularis.
. E. The long head of the biceps tendon, which marks the lateral extent of the interval.

Correct Answer & Explanation

. C. The cephalic vein, which lies within the interval between the deltoid and pectoralis major muscles.

Explanation

Correct Answer: CThe cephalic vein is the crucial anatomical landmark for identifying and safely developing the deltopectoral interval. This vein consistently runs within the groove between the deltoid and pectoralis major muscles. By identifying the cephalic vein, the surgeon can safely separate these two muscles, either retracting the deltoid laterally and the pectoralis major medially, or vice versa, while protecting the vein (often retracted laterally with the deltoid) to gain access to the anterior aspect of the shoulder joint and proximal humerus.Option A is incorrect. The posterior border of the deltoid and anterior border of the teres major define a different surgical interval (posterior approach to the shoulder), not the deltopectoral interval.Option B is incorrect. While the deltopectoral interval is indeed between the deltoid and pectoralis major, simply stating their borders doesn't identify the specific, consistent landmark (the cephalic vein) that guides the dissection.Option D is incorrect. The axillary nerve runs around the surgical neck of the humerus and is a structure to be protectedafterthe deltopectoral interval is developed and deeper dissection proceeds. It does not define the interval itself.Option E is incorrect. The long head of the biceps tendon is an intra-articular structure and is encountered much deeper in the dissection, not as a landmark for the initial deltopectoral interval.

Question 225

Topic: Surgical Anatomy & Approaches

During a surgical approach to the sternoclavicular joint for chronic instability, the surgeon aims to identify and reconstruct the primary static stabilizer of the joint, which resists superior displacement and provides significant resistance to anterior, posterior, and medial translation.

Which ligament is the surgeon primarily targeting for reconstruction based on its described function?

. Anterior sternoclavicular ligament
. Posterior sternoclavicular ligament
. Interclavicular ligament
. Costoclavicular ligament
. Coracoclavicular ligament

Correct Answer & Explanation

. Costoclavicular ligament

Explanation

Correct Answer: DThecostoclavicular ligament (rhomboid ligament)is described in the case as the primary static stabilizer of the SC joint. It consists of two laminae extending from the inferior surface of the medial clavicle to the superior surface of the first rib. It strongly resists superior displacement of the clavicle and provides significant resistance to anterior, posterior, and medial translation, as well as axial rotation. Its integrity is paramount for SC joint stability. The anterior (A) and posterior (B) sternoclavicular ligaments primarily resist posterior and anterior translation, respectively. The interclavicular ligament (C) primarily resists inferior displacement. The coracoclavicular ligament (E) stabilizes the acromioclavicular joint, not the sternoclavicular joint.

Question 226

Topic: Surgical Anatomy & Approaches

A 32-year-old male sustains a closed, isolated mid-diaphyseal humeral shaft fracture after a fall from a bicycle. Initial radiographs confirm a spiral fracture pattern with 15 degrees of varus angulation and 1 cm of shortening. He presents with a new-onset radial nerve palsy, characterized by wrist drop and inability to extend his thumb and fingers. After 3 months of non-operative management with a functional brace, repeat radiographs show early callus formation but no significant change in angulation or shortening. Clinically, there is no improvement in his radial nerve function. What is the MOST appropriate next step in management?

. Continue non-operative management with the functional brace for another 3 months, as most radial nerve palsies recover spontaneously.
. Proceed with surgical exploration of the radial nerve and internal fixation of the fracture, as there is no sign of recovery after 3 months.
. Initiate aggressive physical therapy focusing on wrist and finger extension, and re-evaluate nerve function in 6 months.
. Perform an EMG/NCS study immediately to assess the extent of nerve injury before any surgical intervention.
. Offer a dynamic wrist-hand orthosis to support the wrist and fingers, and schedule for tendon transfers in 6 months if no recovery.

Correct Answer & Explanation

. Proceed with surgical exploration of the radial nerve and internal fixation of the fracture, as there is no sign of recovery after 3 months.

Explanation

Correct Answer: BThe patient presents with a closed humeral shaft fracture and a new radial nerve palsy. The case states that after 3 months of non-operative management, there is no improvement in radial nerve function. According to the teaching case and current literature, for closed humeral shaft fractures with a new radial nerve palsy, initial non-operative management (observation) is generally recommended, with 70-90% spontaneous recovery expected within 3-6 months. However, if there is no sign of recovery after this period (typically 3-6 months), surgical exploration is indicated. Given the 3-month mark with no recovery, and the presence of a fracture that could benefit from fixation (even if angulation is borderline acceptable, the persistent nerve palsy warrants exploration), proceeding with surgical exploration of the radial nerve and internal fixation of the fracture is the most appropriate next step.Option A is incorrectbecause while most radial nerve palsies recover spontaneously, waiting another 3 months without any signs of recovery after the initial 3 months would delay potential nerve repair or decompression, especially when surgical fixation of the fracture is also a consideration.Option C is incorrectbecause while physical therapy is important, it does not address the lack of nerve recovery. Re-evaluating in 6 months without intervention for a non-recovering nerve at 3 months is a delay in definitive management.Option D is incorrectbecause while an EMG/NCS study can provide valuable information about the extent of nerve injury, the clinical absence of recovery after 3 months is a strong enough indication for exploration, especially when combined with the need for fracture fixation. The study might confirm the lack of recovery but would delay surgical intervention.Option E is incorrectbecause while a dynamic wrist-hand orthosis is appropriate for supporting the wrist and fingers in radial nerve palsy, scheduling for tendon transfers at 6 months without first exploring the nerve for potential repair or decompression would be premature. Tendon transfers are typically considered for permanent deficits after nerve recovery potential has been exhausted or exploration has confirmed irreparable damage.

Question 227

Topic: Surgical Anatomy & Approaches

During an anterolateral approach to the mid-shaft humerus for a comminuted fracture, the surgeon retracts the biceps brachii muscle medially. The image below depicts the next layer of muscle encountered, which is then longitudinally incised to expose the humerus. Which of the following statements regarding the neurovascular structures in this immediate vicinity is MOST accurate?

. The main trunk of the musculocutaneous nerve typically lies deep to the brachialis muscle and is at high risk during its incision.
. The radial nerve is located anterior to the brachialis muscle in the mid-shaft and must be identified and protected laterally.
. The musculocutaneous nerve is usually found in the fascial plane between the biceps and the exposed muscle, and should be retracted medially with the biceps.
. The profunda brachii artery accompanies the musculocutaneous nerve and is a primary concern during the longitudinal incision of the exposed muscle.
. The axillary nerve is a significant risk in this mid-shaft region, especially during the initial incision of the deep fascia.

Correct Answer & Explanation

. The musculocutaneous nerve is usually found in the fascial plane between the biceps and the exposed muscle, and should be retracted medially with the biceps.

Explanation

Correct Answer: CThe image depicts the brachialis muscle, which is encountered deep to the biceps brachii after medial retraction. The teaching case explicitly states: 'The musculocutaneous nerve (C5-C7) is located in the fascial plane between the biceps and brachialis. It typically pierces the coracobrachialis and then runs between the biceps and brachialis, supplying both. It then continues as the lateral antebrachial cutaneous nerve. Identify and protect the main trunk of the musculocutaneous nerve, usually by retracting it medially with the biceps.'Option A is incorrectbecause the main trunk of the musculocutaneous nerve typically lies superficial to the brachialis (between biceps and brachialis) and enters the brachialis in its mid-belly, not deep to it. Longitudinal incision of the brachialis can injure its distal branches, but the main trunk is usually protected by medial retraction of the biceps.Option B is incorrectbecause in the mid-shaft, the radial nerve is located in the spiral groove on the posterior aspect of the humerus. It only becomes more anterior in the distal third of the humerus. Therefore, it is not anterior to the brachialis in the mid-shaft and is not typically identified and protected laterally in the primary dissection plane of the anterolateral approach, though it is at risk from overly long screws or aggressive posterior dissection.Option D is incorrectbecause the profunda brachii artery accompanies the radial nerve in the spiral groove, on the posterior aspect of the humerus, not the musculocutaneous nerve, and is not a primary concern during the longitudinal incision of the brachialis muscle itself, unless dissection extends too far posteriorly.Option E is incorrectbecause the axillary nerve is a critical structure in the proximal humerus (approximately 5-7 cm distal to the acromion), not typically in the mid-shaft region where the brachialis is being incised. Its risk is primarily during proximal extension of the approach or aggressive deltoid retraction.

Question 228

Topic: Surgical Anatomy & Approaches

A 68-year-old female with osteopenia presents with a comminuted mid-diaphyseal humeral fracture after a low-energy fall. She is scheduled for open reduction and internal fixation via an anterolateral approach. During pre-operative templating, the surgeon plans to use a locking compression plate (LCP) and bicortical screws. Which of the following statements regarding screw placement and potential neurovascular injury is MOST critical to consider?

. The primary risk to the musculocutaneous nerve is during bicortical screw placement through the brachialis muscle.
. The axillary nerve is at highest risk when placing distal bicortical screws due to its anterior course.
. Careful measurement of screw length is paramount to avoid iatrogenic injury to the radial nerve, which lies posteriorly in the spiral groove.
. The brachial artery and veins are directly posterior to the humerus and are at risk from overly long bicortical screws.
. The cephalic vein, if not ligated, can be injured by bicortical screws placed in the proximal humerus.

Correct Answer & Explanation

. Careful measurement of screw length is paramount to avoid iatrogenic injury to the radial nerve, which lies posteriorly in the spiral groove.

Explanation

Correct Answer: CThe teaching case explicitly highlights the radial nerve as the most commonly injured nerve in humeral shaft fractures and their surgical treatment. It states: 'Though posterior, careless anterior dissection, overly aggressive subperiosteal stripping, or placement of excessively long bicortical screws can endanger the radial nerve.' The radial nerve runs in the spiral groove on the posterior aspect of the humerus in the mid-shaft, making it vulnerable to penetration by screws that are too long.Option A is incorrectbecause while the musculocutaneous nerve supplies the brachialis, the primary risk to its main trunk is during the initial dissection between the biceps and brachialis, or if the brachialis split is too lateral. Bicortical screw placement through the brachialis is not the primary mechanism of injury for the musculocutaneous nerve, especially compared to the radial nerve's vulnerability to screw length.Option B is incorrectbecause the axillary nerve wraps around the surgical neck of the humerus (proximal humerus), approximately 5-7 cm distal to the acromion. It is not at highest risk from distal bicortical screws; rather, it is at risk during proximal extension of the approach or aggressive deltoid retraction.Option D is incorrectbecause the brachial artery and veins are located medial to the biceps and coracobrachialis, generally not directly posterior to the humerus. While aggressive medial retraction could injure them, they are not typically at risk from bicortical screws placed from the anterolateral aspect through the posterior cortex.Option E is incorrectbecause the cephalic vein is a superficial vein in the subcutaneous tissue, typically retracted laterally. It is not at risk from bicortical screws placed into the bone, as these screws pass through the bone itself, not the superficial soft tissues where the cephalic vein resides.

Question 229

Topic: Surgical Anatomy & Approaches

A 45-year-old construction worker undergoes an anterolateral approach for a mid-diaphyseal humeral fracture. Post-operatively, he develops a new radial nerve palsy. Which of the following is the LEAST likely cause of this iatrogenic injury during the surgical procedure?

. Aggressive subperiosteal stripping of the posterior aspect of the humerus.
. Placement of an excessively long bicortical screw from the anterolateral plate.
. Direct trauma from a reduction clamp applied to the posterior cortex.
. Excessive medial retraction of the biceps brachii muscle during exposure.
. Drilling through the far cortex without adequate protection or measurement.

Correct Answer & Explanation

. Excessive medial retraction of the biceps brachii muscle during exposure.

Explanation

Correct Answer: DThe teaching case describes the radial nerve's course in the spiral groove on the posterior aspect of the humerus. It explicitly states that 'careless anterior dissection, overly aggressive subperiosteal stripping, or placement of excessively long bicortical screws can endanger the radial nerve.' The radial nerve is vulnerable to direct injury from instruments or screws that extend too far posteriorly.Option A is incorrectbecause aggressive subperiosteal stripping on the posterior aspect of the humerus can directly injure the radial nerve, which lies in the spiral groove.Option B is incorrectbecause placement of an excessively long bicortical screw from the anterolateral plate is a classic mechanism of iatrogenic radial nerve injury, as the screw can penetrate the posterior cortex and impinge or transect the nerve.Option C is incorrectbecause a reduction clamp applied to the posterior cortex, especially if placed blindly or without careful consideration of the radial nerve's location, can directly compress or injure the nerve.Option D is the correct answer because excessive medial retraction of the biceps brachii muscle is LEAST likely to cause radial nerve injury.The biceps brachii is retracted medially to expose the brachialis. The radial nerve is located posteriorly in the spiral groove in the mid-shaft. Medial retraction of the biceps primarily risks the musculocutaneous nerve (which lies between the biceps and brachialis) or the brachial artery/veins (if retraction is excessively medial and deep), but not the radial nerve directly.Option E is incorrectbecause drilling through the far cortex without adequate protection or measurement is a direct precursor to placing an excessively long screw, thus putting the radial nerve at risk.

Question 230

Topic: Surgical Anatomy & Approaches

A 55-year-old male undergoes an anterolateral approach for a proximal third humeral shaft fracture. During the approach, the surgeon needs to extend the dissection proximally to ensure adequate plate purchase. Which of the following anatomical considerations is MOST critical when extending the approach proximally?

. Identifying and protecting the cephalic vein as it enters the deltopectoral groove.
. Avoiding excessive medial retraction of the biceps brachii to prevent musculocutaneous nerve injury.
. Protecting the axillary nerve, which wraps around the surgical neck approximately 5-7 cm distal to the acromion.
. Ensuring the radial nerve is not entrapped as it pierces the lateral intermuscular septum.
. Limiting the longitudinal incision of the brachialis muscle to prevent dual innervation compromise.

Correct Answer & Explanation

. Protecting the axillary nerve, which wraps around the surgical neck approximately 5-7 cm distal to the acromion.

Explanation

Correct Answer: CThe teaching case specifically addresses the proximal humerus (proximal third) approach: 'The axillary nerve is the most critical structure in this region. It wraps around the surgical neck of the humerus approximately 5-7 cm distal to the acromion, supplying the deltoid and teres minor. Meticulous protection of this nerve is essential, particularly when reflecting the deltoid or extending the approach proximally.'Option A is incorrectbecause while the cephalic vein is an important superficial landmark, its identification and protection are generally part of the initial superficial dissection and less critical than the axillary nerve when extending the approach proximally into the deeper structures around the surgical neck.Option B is incorrectbecause the musculocutaneous nerve is primarily at risk during the mid-shaft approach, between the biceps and brachialis. While it's important to protect, the axillary nerve is the paramount concern in the proximal third.Option D is incorrectbecause the radial nerve pierces the lateral intermuscular septum in the distal third of the humerus to reach the anterior compartment. This is a concern for distal extensions, not proximal.Option E is incorrectbecause the brachialis muscle is typically incised in the mid-shaft and distal approaches. While it has dual innervation, the primary concern for proximal extension is the axillary nerve, not the brachialis incision.

Question 231

Topic: Surgical Anatomy & Approaches

A 38-year-old male presents with a distal third humeral shaft fracture extending towards the elbow joint. He is scheduled for an anterolateral approach. As the surgeon extends the approach distally, which neurovascular structure requires the MOST vigilant identification and protection due to its changing anatomical course?

. The axillary nerve, as it becomes more superficial distally.
. The musculocutaneous nerve, as it exits the brachialis muscle.
. The radial nerve, as it pierces the lateral intermuscular septum and courses anteriorly.
. The brachial artery, due to its close proximity to the distal humerus.
. The ulnar nerve, as it enters the cubital tunnel.

Correct Answer & Explanation

. The radial nerve, as it pierces the lateral intermuscular septum and courses anteriorly.

Explanation

Correct Answer: CThe teaching case specifically addresses the distal approach: 'As the approach is extended distally, the radial nerve becomes increasingly superficial and anterior. Below the spiral groove, the radial nerve pierces the lateral intermuscular septum to lie between the brachialis and brachioradialis. Careful identification and protection of the radial nerve are critical when dissecting in the distal third. It should be located, mobilized, and protected laterally or posterolaterally.'Option A is incorrectbecause the axillary nerve is a proximal structure, wrapping around the surgical neck, and does not become more superficial distally.Option B is incorrectbecause while the musculocutaneous nerve does exit the brachialis and continues as the lateral antebrachial cutaneous nerve, its primary risk is in the mid-shaft. The radial nerve's course change in the distal third makes it the most critical structure to protect during distal extension of this approach.Option D is incorrectbecause the brachial artery is located medial to the biceps and coracobrachialis. While always important to protect, its course does not change in a way that makes it uniquely vulnerable during distal extension of an anterolateral approach compared to the radial nerve.Option E is incorrectbecause the ulnar nerve is located posteromedially in the distal arm and enters the cubital tunnel behind the medial epicondyle. It is not typically encountered or at risk during an anterolateral approach to the humeral shaft.

Question 232

Topic: Surgical Anatomy & Approaches

During open reduction of a traumatic, irreducible posterior sternoclavicular dislocation, the surgeon dissects posterior to the medial clavicle. Which of the following vascular structures is at greatest risk of iatrogenic injury directly posterior to the SC joint?

. Subclavian artery
. Internal jugular vein
. Brachiocephalic (innominate) vein
. Superior vena cava
. Common carotid artery

Correct Answer & Explanation

. Brachiocephalic (innominate) vein

Explanation

The brachiocephalic (innominate) vein lies directly posterior to the sternoclavicular joint. It is the structure most immediately at risk during posterior dislocations and surgical approaches to the medial clavicle.

Question 233

Topic: Surgical Anatomy & Approaches

A 24-year-old male presents to the emergency department after a football injury, complaining of severe right shoulder pain. His arm is held in slight abduction and external rotation. On inspection, the anterior aspect of his shoulder appears prominent, and there is a palpable void beneath the acromion. Which of the following physical exam findings is MOST concerning for an associated neurovascular injury in this patient?

. Loss of sensation over the lateral deltoid
. Inability to actively abduct the arm
. Weakness in wrist extension
. Absent radial pulse
. Ecchymosis over the anterior shoulder

Correct Answer & Explanation

. Absent radial pulse

Explanation

Correct Answer: DAn absent radial pulse is a critical finding indicating potential compromise of the brachial artery, which is a surgical emergency. While axillary nerve injury (loss of sensation over the lateral deltoid, weakness in abduction) is the most common nerve injury with anterior shoulder dislocations, it is rarely an acute limb-threatening condition unless it's a traction injury without spontaneous recovery. Weakness in wrist extension would suggest radial nerve involvement, which is less common. Ecchymosis is a common finding but not acutely life- or limb-threatening.

Question 234

Topic: Surgical Anatomy & Approaches

A 68-year-old woman falls directly onto her shoulder. She presents with severe pain and an inability to move her arm. On exam, the shoulder appears abducted, and a prominent hard mass is palpable inferior to the glenoid, consistent with a Luxatio Erecta. Which neurovascular structure is at highest risk of injury in this type of dislocation?

. Axillary nerve
. Brachial plexus
. Axillary artery
. Radial nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Axillary artery

Explanation

Correct Answer: CLuxatio Erecta (inferior dislocation) involves extreme abduction, forcing the humeral head inferiorly. The head can impinge upon or stretch the neurovascular bundle in the axilla. The axillary artery is at significant risk due to its proximity and the severe displacement. While the axillary nerve and brachial plexus are also at risk, arterial compromise (axillary artery) is a more acute and limb-threatening complication associated with the extreme force and direction of displacement in luxatio erecta, often leading to intimal tears or thrombosis.

Question 235

Topic: Surgical Anatomy & Approaches

A 30-year-old motorcyclist is brought to the trauma bay after a high-speed collision. His right upper extremity is pulseless, pale, and massively swollen. Chest radiograph demonstrates marked lateral displacement of the right scapula. Which of the following neurologic injuries is most characteristically associated with this condition?

. Complete avulsion of the brachial plexus
. Isolated axillary nerve neuropraxia
. Spinal accessory nerve transection
. Isolated musculocutaneous nerve rupture
. Suprascapular nerve entrapment

Correct Answer & Explanation

. Complete avulsion of the brachial plexus

Explanation

This patient has scapulothoracic dissociation, characterized by massive high-energy trauma pulling the forequarter laterally. It is highly associated with devastating neurovascular injuries, most notably complete avulsion of the brachial plexus and subclavian/axillary artery disruption.

Question 236

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach for proximal humerus fracture fixation, the axillary nerve is at risk when placing inferior retractors. The nerve exits the axilla through the quadrangular space. What are the correct anatomic borders of this space?

. Superior: Teres minor, Inferior: Teres major, Medial: Long head of triceps, Lateral: Humeral shaft
. Superior: Teres major, Inferior: Teres minor, Medial: Lateral head of triceps, Lateral: Humeral shaft
. Superior: Infraspinatus, Inferior: Teres minor, Medial: Long head of triceps, Lateral: Humeral shaft
. Superior: Subscapularis, Inferior: Pectoralis major, Medial: Coracobrachialis, Lateral: Humeral shaft
. Superior: Teres minor, Inferior: Teres major, Medial: Humeral shaft, Lateral: Long head of triceps

Correct Answer & Explanation

. Superior: Teres minor, Inferior: Teres major, Medial: Long head of triceps, Lateral: Humeral shaft

Explanation

The quadrangular space transmits the axillary nerve and posterior circumflex humeral artery. Its borders are the teres minor (superiorly), teres major (inferiorly), long head of the triceps (medially), and the surgical neck of the humerus (laterally).

Question 237

Topic: Surgical Anatomy & Approaches

Which neurologic injury is most commonly associated with a significantly displaced fracture of the surgical neck of the humerus?

. Musculocutaneous nerve
. Axillary nerve
. Radial nerve
. Median nerve
. Ulnar nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

The axillary nerve courses intimately around the surgical neck of the humerus. It is the most commonly injured nerve in surgical neck fractures and anterior shoulder dislocations.

Question 238

Topic: Surgical Anatomy & Approaches

A patient undergoes ORIF of a midshaft clavicle fracture using a superiorly applied pre-contoured locking plate. Postoperatively, the patient notes numbness over the anterior chest wall just inferior to the incision. Which nerve was likely injured during the surgical approach?

. Suprascapular nerve
. Axillary nerve
. Medial pectoral nerve
. Supraclavicular nerves
. Intercostobrachial nerve

Correct Answer & Explanation

. Supraclavicular nerves

Explanation

The intermediate and lateral branches of the supraclavicular nerve cross superficial to the clavicle. They are frequently injured or sacrificed during the superior approach to the clavicle, causing anterior chest wall numbness.

Question 239

Topic: Surgical Anatomy & Approaches

When utilizing an anterolateral acromial approach (deltoid-splitting) for open reduction and internal fixation of a proximal humerus fracture, which anatomical landmark best predicts the location of the axillary nerve?

. 1 to 2 cm distal to the lateral acromion
. 5 to 7 cm distal to the lateral acromion
. 3 cm proximal to the deltoid tuberosity
. Posterior to the long head of the biceps
. Anterior to the coracoid process

Correct Answer & Explanation

. 5 to 7 cm distal to the lateral acromion

Explanation

The axillary nerve courses transversely across the deep surface of the deltoid approximately 5 to 7 cm distal to the lateral edge of the acromion. A deltoid split must not extend beyond this "safe zone" to prevent denervation of the anterior deltoid.

Question 240

Topic: Surgical Anatomy & Approaches

During surgical exposure for a mid-diaphyseal radial shaft fracture via the Henry (anterior) approach, which neurovascular structure is most directly at risk and requires careful identification and protection?

. Posterior interosseous nerve
. Ulnar nerve
. Radial artery and superficial radial nerve
. Median nerve
. Anterior interosseous nerve

Correct Answer & Explanation

. Radial artery and superficial radial nerve

Explanation

Correct Answer: CThe Henry (anterior) approach for the radial shaft involves dissecting between the brachioradialis and the flexor carpi radialis (or pronator teres, depending on the level). The radial artery and the superficial radial nerve (a sensory branch of the radial nerve) run immediately deep to the brachioradialis muscle. They are thus directly in the surgical field and are at high risk of injury if not carefully identified, mobilized, and retracted, typically ulnarward. The posterior interosseous nerve (PIN) is at risk with dorsal approaches to the radius. The ulnar and median nerves are located more medially in the forearm and are generally not directly in the field of the Henry approach for a mid-diaphyseal radial fracture. The anterior interosseous nerve (AIN) is a deeper structure, lying on the interosseous membrane, and while it can be at risk with very deep or extensive dissection, the radial artery and superficial radial nerve are more superficially and directly vulnerable.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page