Menu

1. General Principles & Basic Science MCQs

Practice Set 206 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 4101

Topic: 1. General Principles & Basic Science

Recent quantitative anatomical studies have redefined the primary arterial supply to the proximal humeral head, altering historical teaching. Based on current evidence, which of the following vessels provides the majority of the extraosseous blood supply to the humeral head?

. Anterior circumflex humeral artery
. Posterior circumflex humeral artery
. Thoracoacromial artery
. Subscapular artery
. Suprascapular artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

Historically, the anterior circumflex humeral artery (via its anterolateral arcuate branch) was taught to be the primary blood supply to the humeral head. However, landmark modern quantitative studies (e.g., Hettrich et al.) demonstrated that the posterior circumflex humeral artery actually provides the majority (approximately 64%) of the extraosseous blood supply to the humeral head.

Question 4102

Topic: Infection, Pharmacology & VTE
A 2-year-old girl is diagnosed with septic arthritis of the knee. Synovial fluid PCR identifies Kingella kingae. Which of the following best describes the bacteriology of this organism?
. Gram-positive cocci in clusters
. Gram-negative coccobacillus
. Gram-positive spore-forming rod
. Acid-fast bacillus
. Spirochete

Correct Answer & Explanation

. Gram-negative coccobacillus

Explanation

Kingella kingae is a Gram-negative coccobacillus that is increasingly recognized as a leading cause of pediatric septic arthritis and osteomyelitis in children aged 6 months to 4 years. It is a fastidious organism that is often missed on standard solid agar cultures; thus, inoculation into BACTEC liquid blood culture vials or detection via PCR is required for reliable identification.

Question 4103

Topic: Surgical Anatomy & Approaches

During open reduction and internal fixation of a posterior wall acetabular fracture via a Kocher-Langenbeck approach, the surgeon places the patient's operative leg in a specific position to minimize tension on the sciatic nerve. Which position is most appropriate, and which division of the nerve is at highest risk of iatrogenic injury?

. Hip flexed, knee flexed; tibial division at highest risk
. Hip extended, knee extended; tibial division at highest risk
. Hip extended, knee flexed; peroneal division at highest risk
. Hip flexed, knee extended; peroneal division at highest risk
. Hip extended, knee flexed; femoral division at highest risk

Correct Answer & Explanation

. Hip flexed, knee flexed; tibial division at highest risk

Explanation

During the Kocher-Langenbeck approach, the sciatic nerve is at high risk of iatrogenic stretch injury from retractors. Extending the hip and flexing the knee maximally relaxes the sciatic nerve. The peroneal division is located more laterally, possesses less supportive perineural connective tissue, and is mechanically tethered distally at the fibular head, making it significantly more susceptible to stretch injuries than the tibial division.

Question 4104

Topic: Surgical Anatomy & Approaches

A 40-year-old male sustains a posterior wall acetabular fracture with a posterior hip dislocation. Post-reduction, he exhibits a foot drop and inability to actively extend his great toe. Which specific neural structure is most likely injured?

. Femoral nerve
. Tibial division of the sciatic nerve
. Peroneal division of the sciatic nerve
. Obturator nerve
. Superior gluteal nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

The sciatic nerve is at high risk during posterior hip dislocations and posterior wall acetabular fractures. The peroneal division is more lateral, tightly tethered, and has larger fascicles, making it significantly more susceptible to injury than the tibial division.

Question 4105

Topic: Surgical Anatomy & Approaches

The direct anterior (Smith-Petersen) approach for total hip arthroplasty utilizes a true internervous plane. Which of the following best describes the nerves supplying the muscles that form the superficial boundary of this interval?

. Superior gluteal nerve and inferior gluteal nerve
. Femoral nerve and superior gluteal nerve
. Femoral nerve and obturator nerve
. Sciatic nerve and inferior gluteal nerve
. Superior gluteal nerve and sciatic nerve

Correct Answer & Explanation

. Femoral nerve and superior gluteal nerve

Explanation

The direct anterior (Smith-Petersen) approach exploits a true internervous plane. Superficially, the interval is between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). Deeply, the interval is between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve).

Question 4106

Topic: 1. General Principles & Basic Science

A 40-year-old male sustains a bicondylar tibial plateau fracture with a large, displaced posteromedial shear fragment. The surgeon elects to use a posteromedial surgical approach. During this approach, which specific anatomical interval is utilized to access the posteromedial tibia?

. Between the medial head of the gastrocnemius and the pes anserinus
. Between the popliteus and the soleus
. Between the semitendinosus and semimembranosus
. Between the medial collateral ligament and the anterior tibialis
. Between the lateral head of the gastrocnemius and the biceps femoris

Correct Answer & Explanation

. Between the medial head of the gastrocnemius and the pes anserinus

Explanation

The posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted laterally/posteriorly along with the neurovascular bundle) and the pes anserinus/semimembranosus (which is retracted medially/anteriorly). This provides excellent visualization for buttress plating of posteromedial shear fragments.

Question 4107

Topic: 1. General Principles & Basic Science

A 28-year-old competitive weightlifter feels a sudden 'pop' in his anterior chest while performing a heavy bench press. Examination reveals a loss of the anterior axillary fold contour and weakness in active internal rotation. MRI confirms a complete rupture of the pectoralis major. In this specific demographic and mechanism, which portion of the muscle-tendon unit is most commonly injured?

. Sternal head avulsion at the muscle belly
. Clavicular head tear at the musculotendinous junction
. Sternal head avulsion at the humeral insertion
. Clavicular head avulsion at the clavicular origin
. Combined sternal and clavicular heads avulsion at the coracoid process

Correct Answer & Explanation

. Sternal head avulsion at the humeral insertion

Explanation

Pectoralis major ruptures almost exclusively occur in males, most commonly during the bench press exercise. The most common pattern of injury is an avulsion of the sternocostal (sternal) head from its insertion on the humerus. The sternal head is under maximal stretch when the humerus is extended, abducted, and externally rotated (the bottom of the bench press). The clavicular head usually remains intact.

Question 4108

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach for the fixation of an anterior column acetabular fracture, life-threatening hemorrhage occurs while dissecting over the superior pubic ramus near the symphysis. Which two vessels commonly anastomose in this region to form the 'corona mortis', the most likely source of this bleeding?

. Obturator artery and external iliac artery
. Obturator artery and internal pudendal artery
. Inferior epigastric artery and obturator artery
. Superior gluteal artery and internal iliac artery
. Deep circumflex iliac artery and femoral artery

Correct Answer & Explanation

. Inferior epigastric artery and obturator artery

Explanation

The corona mortis ('crown of death') is a highly variable vascular anastomosis between the obturator and external iliac systems. Most commonly, it is an anastomosis between the inferior epigastric artery (or vein) and the obturator artery (or vein). It courses over the superior pubic ramus at a distance of roughly 4-6 cm from the pubic symphysis and is at high risk of iatrogenic injury during the ilioinguinal or Stoppa approaches to the acetabulum and pelvic ring.

Question 4109

Topic: Surgical Anatomy & Approaches

A 72-year-old female undergoes a reverse total shoulder arthroplasty via a deltopectoral approach. During glenoid exposure, a retractor is placed inferiorly on the glenoid neck. Which nerve is at greatest risk of injury from this specific retractor placement?

. Musculocutaneous nerve
. Axillary nerve
. Suprascapular nerve
. Radial nerve
. Median nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

The axillary nerve courses inferior to the glenohumeral joint capsule and is highly vulnerable to compression or traction injury when retractors are placed inferiorly on the glenoid neck. Careful placement and avoiding excessive tension on the inferior retractor are critical to prevent neurapraxia.

Question 4110

Topic: Biology, Genetics & Bone Healing
In the pathogenesis of aseptic loosening secondary to ultra-high molecular weight polyethylene (UHMWPE) wear debris following a total hip arthroplasty, activated macrophages release inflammatory cytokines. Which specific receptor-ligand interaction is most directly responsible for driving the final common pathway of osteoclastogenesis and subsequent periprosthetic bone resorption?
. CD4 and MHC Class II
. RANK and RANKL
. BMP-2 and BMP Receptor Type IA
. Wnt and Frizzled receptor
. IL-6 and JAK-STAT

Correct Answer & Explanation

. RANK and RANKL

Explanation

Macrophage phagocytosis of UHMWPE wear particles results in the release of TNF-α, IL-1, and IL-6. These cytokines stimulate osteoblasts and fibroblasts to express Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL). The binding of RANKL to the RANK receptor on osteoclast precursors drives their differentiation into mature osteoclasts, which resorb periprosthetic bone, leading to osteolysis.

Question 4111

Topic: 1. General Principles & Basic Science

A 32-year-old male bodybuilder presents with acute pain, bruising, and a palpable defect in his anterior axilla after a heavy bench press. MRI confirms a complete rupture of the pectoralis major tendon. Based on normal anatomy, how does the sternocostal head of the pectoralis major typically insert onto the lateral lip of the bicipital groove relative to the clavicular head?

. Proximal and deep to the clavicular head
. Proximal and superficial to the clavicular head
. Distal and deep to the clavicular head
. Distal and superficial to the clavicular head
. Directly confluent with the short head of the biceps brachii

Correct Answer & Explanation

. Distal and deep to the clavicular head

Explanation

The pectoralis major tendon undergoes a 180-degree twist before its insertion on the lateral lip of the bicipital groove. Consequently, the inferior fibers (the sternocostal head) twist upward and insert proximal and deep relative to the superior fibers (the clavicular head). This complex arrangement places the sternocostal head at maximal tension during the eccentric phase of a bench press, making it the most common site of failure.

Question 4112

Topic: Surgical Anatomy & Approaches

A 45-year-old male sustains a complex acetabular fracture. CT imaging demonstrates a fracture of the anterior column with a posterior hemitransverse component, alongside a medially displaced quadrilateral plate. Which surgical approach provides the most direct and optimal access to reduce the quadrilateral plate and place an infrapectineal buttress plate?

. Kocher-Langenbeck approach
. Modified Stoppa (anterior intrapelvic) approach
. Extended iliofemoral approach
. Smith-Petersen approach
. Direct lateral (Hardinge) approach

Correct Answer & Explanation

. Modified Stoppa (anterior intrapelvic) approach

Explanation

The modified Stoppa approach, an anterior intrapelvic approach, provides excellent visualization of the true pelvis, quadrilateral plate, posterior column, and pelvic brim. It is highly advantageous for treating anterior column/posterior hemitransverse fractures with medial displacement of the quadrilateral plate, as it directly allows the placement of an infrapectineal buttress plate to counteract the medial displacement. The Kocher-Langenbeck is posterior and does not allow direct plating of the medial quadrilateral surface.

Question 4113

Topic: Surgical Anatomy & Approaches

The direct anterior approach (Smith-Petersen) to the hip is favored by many due to its utilization of a true internervous and intermuscular plane. Which two nerves supply the muscles that form the superficial boundary of this surgical interval?

. Femoral nerve and Superior gluteal nerve
. Superior gluteal nerve and Inferior gluteal nerve
. Femoral nerve and Obturator nerve
. Inferior gluteal nerve and Sciatic nerve
. Femoral nerve and Sciatic nerve

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The superficial interval of the direct anterior approach (Smith-Petersen) to the hip is between the sartorius and the tensor fasciae latae (TFL). The sartorius is innervated by the femoral nerve, and the TFL is innervated by the superior gluteal nerve, making it a true internervous plane. The deep interval is similarly internervous, between the rectus femoris (femoral nerve) and the gluteus medius/minimus (superior gluteal nerve).

Question 4114

Topic: Surgical Anatomy & Approaches

Following an open Latarjet procedure, the patient complains of an inability to actively flex the elbow and numbness along the lateral aspect of the forearm. Which nerve was most likely injured by excessive retraction of the conjoint tendon?

. Axillary nerve
. Radial nerve
. Median nerve
. Musculocutaneous nerve
. Suprascapular nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The musculocutaneous nerve enters the coracobrachialis 5-8 cm distal to the coracoid process. Excessive medial retraction of the conjoint tendon during a Latarjet can stretch this nerve, causing weak elbow flexion and lateral forearm numbness.

Question 4115

Topic: 1. General Principles & Basic Science

During a Zone II flexor tendon repair, which of the following biomechanical variables is most directly proportional to the ultimate tensile strength of the repair?

. Epitendinous suture caliber
. Number of core suture strands crossing the repair site
. Use of a locking rather than a grasping core technique
. Preservation of the A3 pulley
. Distance of the core knot from the repair interface

Correct Answer & Explanation

. Number of core suture strands crossing the repair site

Explanation

The ultimate tensile strength of a flexor tendon repair is most directly proportional to the number of core suture strands crossing the repair site. Increased strands provide greater strength but may increase bulk and gliding resistance.

Question 4116

Topic: 1. General Principles & Basic Science

During a Zone II flexor tendon repair, preservation or reconstruction of which specific annular pulleys is most critical to prevent mechanical bowstringing and maintain digital flexion excursion?

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

Correct Answer & Explanation

. A2 and A4

Explanation

The A2 and A4 pulleys arise directly from the periosteum of the proximal and middle phalanges, respectively. They are the primary mechanical constraints preventing bowstringing of the flexor tendons during digital flexion.

Question 4117

Topic: Surgical Anatomy & Approaches

A surgeon performs a total hip arthroplasty via the direct anterior approach. Which of the following internervous planes is utilized during the deep surgical dissection?

. Femoral nerve and Obturator nerve
. Superior gluteal nerve and Femoral nerve
. Superior gluteal nerve and Inferior gluteal nerve
. Sciatic nerve and Inferior gluteal nerve
. Femoral nerve and Sciatic nerve

Correct Answer & Explanation

. Superior gluteal nerve and Femoral nerve

Explanation

The direct anterior approach to the hip utilizes the internervous plane between the tensor fasciae latae (supplied by the superior gluteal nerve) and the sartorius/rectus femoris (supplied by the femoral nerve).

Question 4118

Topic: 1. General Principles & Basic Science

A 35-year-old male sustains a posterior hip dislocation in a motor vehicle accident. Which of the following clinical presentations is most characteristic of this injury?

. Shortened, abducted, and externally rotated lower extremity
. Shortened, adducted, and internally rotated lower extremity
. Lengthened, abducted, and externally rotated lower extremity
. Lengthened, adducted, and internally rotated lower extremity
. Shortened, adducted, and externally rotated lower extremity

Correct Answer & Explanation

. Shortened, adducted, and internally rotated lower extremity

Explanation

A posterior hip dislocation characteristically presents with the affected lower extremity in a shortened, adducted, and internally rotated position. Anterior dislocations present shortened, abducted, and externally rotated.

Question 4119

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the acetabulum, the surgeon encounters massive bleeding over the superior pubic ramus near the symphysis. This bleeding is most likely originating from an anastomosis between which two vascular systems?

. Internal iliac and external iliac systems
. Internal pudendal and inferior gluteal systems
. Femoral and superficial circumflex iliac systems
. Superior gluteal and inferior gluteal systems
. Obturator and internal pudendal systems

Correct Answer & Explanation

. Internal iliac and external iliac systems

Explanation

The 'corona mortis' is a critical vascular anastomosis between the external iliac system (inferior epigastric artery/vein) and the internal iliac system (obturator artery/vein), located approximately 5 cm from the pubic symphysis.

Question 4120

Topic: Surgical Anatomy & Approaches

A 24-year-old motorcyclist sustains a traumatic brachial plexus injury. Clinical examination reveals complete paralysis of the right upper extremity, an ipsilateral ptosis, and miosis. What does the presence of Horner's syndrome indicate regarding his nerve injury?

. A postganglionic injury of the upper trunk
. A preganglionic avulsion of the C8 and T1 nerve roots
. A rupture of the middle trunk
. An isolated axillary nerve avulsion
. A compressive hematoma in the scalene triangle

Correct Answer & Explanation

. A preganglionic avulsion of the C8 and T1 nerve roots

Explanation

Horner's syndrome (ptosis, miosis, anhidrosis) in the setting of a brachial plexus injury indicates disruption of the sympathetic chain. This is pathognomonic for a preganglionic avulsion of the lower roots (C8 and T1), which carries a poor prognosis for spontaneous recovery.

Test Yourself

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

On this Page