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1. General Principles & Basic Science MCQs

Practice Set 97 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1921

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 1922

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 1923

Topic: 1. General Principles & Basic Science

A 19-year-old male with a traumatic posterior sternoclavicular dislocation is undergoing closed reduction in the operating room. What is the recommended patient positioning and manipulative maneuver to facilitate this reduction?

. Supine with a sandbag between the scapulae, lateral traction, and arm extension
. Prone with downward force on the scapula
. Seated with overhead vertical traction
. Supine with extreme internal rotation and forward flexion
. Lateral decubitus with inferior traction on the humerus

Correct Answer & Explanation

. Supine with a sandbag between the scapulae, lateral traction, and arm extension

Explanation

Closed reduction of a posterior SC dislocation is optimally performed with the patient supine and a bump between the scapulae. The arm is abducted to 90 degrees, extended, and lateral traction is applied to pull the clavicle anteriorly.

Question 1924

Topic: 1. General Principles & Basic Science

A 33-year-old weightlifter feels a 'pop' in his anterior chest wall during a heavy bench press. Exam reveals a loss of the anterior axillary fold and weakness in internal rotation. Which specific portion of the pectoralis major is most commonly ruptured in this scenario?

. Clavicular head at the musculotendinous junction
. Sternal head at the humeral insertion
. Sternal head at the sternal origin
. Clavicular head at the clavicular origin
. Both heads at the mid-muscle belly

Correct Answer & Explanation

. Sternal head at the humeral insertion

Explanation

The sternal head of the pectoralis major is under maximal tension during the eccentric phase of a bench press when the arm is extended and externally rotated. It most commonly ruptures at or near its humeral insertion.

Question 1925

Topic: Infection, Pharmacology & VTE

A 45-year-old intravenous drug user presents with swelling, erythema, and severe pain over the sternoclavicular joint. Aspiration yields purulent fluid. What is the most common organism responsible for septic arthritis of the SC joint in this patient population?

. Streptococcus pneumoniae
. Neisseria gonorrhoeae
. Pseudomonas aeruginosa
. Staphylococcus aureus
. Salmonella species

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

While Pseudomonas aeruginosa is classically taught as being associated with IV drug use, Staphylococcus aureus is still the most common overall pathogen responsible for septic arthritis of the sternoclavicular joint in all patient demographics.

Question 1926

Topic: 1. General Principles & Basic Science

What is the primary anatomical restraint to both anterior and posterior translation of the sternoclavicular joint?

. Anterior sternoclavicular ligament
. Posterior sternoclavicular ligament
. Costoclavicular ligament
. Interclavicular ligament
. Intra-articular disk ligament

Correct Answer & Explanation

. Posterior sternoclavicular ligament

Explanation

Biomechanical studies demonstrate that the posterior sternoclavicular ligament is the most robust stabilizing structure, serving as the primary restraint against both anterior and posterior displacement of the medial clavicle.

Question 1927

Topic: 1. General Principles & Basic Science

A 'serendipity' radiographic view is requested to evaluate a patient for a suspected sternoclavicular joint dislocation. What is the proper positioning of the X-ray beam to obtain this image?

. 40 degrees cephalad tilt
. 40 degrees caudal tilt
. 20 degrees cephalad tilt
. 20 degrees caudal tilt
. Standard anteroposterior projection with neutral tilt

Correct Answer & Explanation

. 40 degrees cephalad tilt

Explanation

The serendipity view is obtained with the patient supine and the X-ray tube angled 40 degrees cephalad. This projects the clavicles away from the chest wall, allowing comparison of the medial clavicles to assess anterior or posterior displacement.

Question 1928

Topic: 1. General Principles & Basic Science

In the setting of a traumatic posterior sternoclavicular dislocation, which of the following vascular structures is most commonly at risk for compression or direct injury?

. Superior vena cava
. Subclavian artery
. Internal jugular vein
. Brachiocephalic (innominate) vein
. Aortic arch

Correct Answer & Explanation

. Brachiocephalic (innominate) vein

Explanation

The brachiocephalic (innominate) vein is located directly posterior to the sternoclavicular joint. Its immediate proximity makes it the most vulnerable and most frequently injured vascular structure during a posterior dislocation.

Question 1929

Topic: 1. General Principles & Basic Science

A 28-year-old male is undergoing ligamentous reconstruction for chronic posterior sternoclavicular instability. The surgeon plans a figure-of-8 reconstruction. Between which two osseous structures is the tendon graft typically routed?

. First rib and medial clavicle
. Sternum and medial clavicle
. Second rib and medial clavicle
. Lateral clavicle and coracoid process
. Sternum and first rib

Correct Answer & Explanation

. Sternum and medial clavicle

Explanation

A figure-of-8 reconstruction for the SC joint involves routing a free tendon graft (e.g., semitendinosus) through drill holes placed in the medial clavicle and the manubrium of the sternum to recreate the stabilizing ligaments.

Question 1930

Topic: 1. General Principles & Basic Science

Which of the following ligaments provides the primary restraint to both anterior and posterior translation of the sternoclavicular (SC) joint?

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

Correct Answer & Explanation

. Posterior sternoclavicular capsule

Explanation

Biomechanical studies have demonstrated that the posterior sternoclavicular capsule is the most important structure for providing anteroposterior stability to the SC joint. Sectioning of the posterior capsule leads to significant multidirectional instability.

Question 1931

Topic: 1. General Principles & Basic Science

When obtaining a "serendipity" radiographic view to evaluate a suspected sternoclavicular joint injury, how should the x-ray beam be directed?

. 40 degrees cephalad
. 40 degrees caudad
. 20 degrees cephalad
. 20 degrees caudad
. Strictly orthogonal to the chest wall

Correct Answer & Explanation

. 40 degrees cephalad

Explanation

The serendipity view is obtained with the patient supine and the x-ray beam angled 40 degrees cephalad. It allows side-by-side comparison of both medial clavicles to assess for anterior (superiorly displaced) or posterior (inferiorly displaced) translation.

Question 1932

Topic: 1. General Principles & Basic Science

A 22-year-old male sustains an acute, traumatic anterior sternoclavicular joint dislocation. There is no evidence of neurovascular compromise. What is the most appropriate initial management?

. Urgent open reduction and internal fixation with a plate
. Closed reduction under procedural sedation with a figure-of-eight brace
. Symptomatic treatment with a sling and observation
. Primary excision of the medial clavicle
. Sternoclavicular joint arthrodesis

Correct Answer & Explanation

. Symptomatic treatment with a sling and observation

Explanation

Acute anterior SC joint dislocations are notoriously unstable after closed reduction, but they typically result in excellent long-term functional outcomes despite residual deformity. Symptomatic treatment with a sling and gradual return to activity is the standard of care.

Question 1933

Topic: 1. General Principles & Basic Science

Which specific vascular structure is located immediately posterior to the sternoclavicular joint and is at greatest risk of injury in a posterior sternoclavicular dislocation?

. Subclavian artery
. Common carotid artery
. Brachiocephalic (innominate) vein
. Aortic arch
. Internal jugular vein

Correct Answer & Explanation

. Brachiocephalic (innominate) vein

Explanation

The brachiocephalic (innominate) veins converge to form the superior vena cava directly posterior to the sternoclavicular joints. They are the most immediate vascular structures at risk of compression or laceration during a posterior dislocation.

Question 1934

Topic: 1. General Principles & Basic Science

A 19-year-old gymnast presents with a long-standing history of spontaneous, painless anterior subluxation of her sternoclavicular joint when she raises her arm overhead. The joint reduces automatically when she lowers her arm. What is the recommended treatment?

. Activity modification, reassurance, and physical therapy
. Surgical reconstruction of the anterior sternoclavicular ligament
. Open reduction and plate fixation
. Medial clavicle resection
. Intra-articular corticosteroid injection

Correct Answer & Explanation

. Activity modification, reassurance, and physical therapy

Explanation

Atraumatic, spontaneous anterior SC joint subluxation is generally a painless condition seen in young patients with generalized ligamentous laxity. It is treated non-operatively with reassurance and physical therapy, as surgical intervention frequently fails or causes complications.

Question 1935

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 1936

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 1937

Topic: 1. General Principles & Basic Science

A 42-year-old orthopedic resident is performing a simulated internal fixation on a sawbone model. During screw insertion, they notice that bone debris is accumulating in the pilot hole, potentially hindering full screw seating. Referring to the provided image of screw anatomy, which labeled component is specifically designed to provide a route for the removal of such bone debris?

. A. Head
. B. Shank
. C. Thread
. D. Flutes
. E. Countersink

Correct Answer & Explanation

. D. Flutes

Explanation

Correct Answer: DExplanation:The teaching case explicitly states that "the flutes provide a route for removal of bone debris." Flutes are cutting channels typically found at the tip of self-tapping screws. As the screw advances, these channels collect and expel the bone material (debris) created during the tapping process, preventing it from compacting at the tip and hindering insertion or damaging the bone. The image clearly shows the 'Flutes' at the very tip of the screw's threaded portion.Why other options are incorrect:A. Head:The head provides a connection for a screwdriver and prevents sinking. It has no role in debris removal.B. Shank:The shank is the smooth, unthreaded portion. It does not participate in cutting or debris removal.C. Thread:The threads engage the bone for purchase, but their primary role is not to remove debris, although they do create the debris. The flutes are specifically designed for its evacuation.E. Countersink:The countersink is the undersurface of the head, designed to seat the screw head. It has no function in debris removal.

Question 1938

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 1939

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 1940

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.

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