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1. General Principles & Basic Science MCQs

Practice Set 507 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 10121

Topic: Biology, Genetics & Bone Healing

A 65-year-old female on long-term alendronate therapy for osteoporosis presents with atraumatic thigh pain. Radiographs demonstrate focal lateral cortical thickening of the subtrochanteric femur with a transverse radiolucent line. Which of the following is the primary pathophysiologic mechanism leading to this atypical femur fracture (AFF)?

. Excessive osteoblastic proliferation causing disorganized woven bone
. Severe suppression of targeted osteoclastic bone remodeling leading to accumulation of microdamage
. Depletion of uncarboxylated osteocalcin leading to brittle collagen cross-linking
. Spontaneous localized osteonecrosis of the lateral cortex
. Increased parathyroid hormone (PTH) activity secondary to bisphosphonate use

Correct Answer & Explanation

. Severe suppression of targeted osteoclastic bone remodeling leading to accumulation of microdamage

Explanation

Bisphosphonates profoundly suppress osteoclast function and apoptosis. Prolonged use (typically > 5 years) severely impairs targeted bone remodeling. Normally, microcracks from daily stress are repaired by basic multicellular units (BMUs). Suppressed remodeling allows these microcracks to accumulate, particularly on the tensile side of the femur (lateral cortex), eventually coalescing into an atypical femur fracture.

Question 10122

Topic: Surgical Anatomy & Approaches

During the anterior surgical approach (ilioinguinal or modified Stoppa) for an anterior column acetabulum fracture, massive hemorrhage is encountered when dissecting near the superior pubic ramus. Which of the following best describes the most likely source of this bleeding?

. Anastomosis between the external iliac artery and the obturator artery
. Anastomosis between the internal iliac artery and the superior gluteal artery
. Laceration of the deep circumflex iliac artery
. Avulsion of the internal pudendal artery
. Laceration of the inferior mesenteric artery

Correct Answer & Explanation

. Anastomosis between the external iliac artery and the obturator artery

Explanation

The 'corona mortis' (crown of death) is a vascular anastomosis between the external iliac (or deep inferior epigastric) and the obturator vessels (which branch from the internal iliac system). It traverses over the superior pubic ramus and is highly susceptible to injury during anterior approaches to the pelvis and acetabulum (such as the ilioinguinal or Stoppa approaches), potentially causing massive, difficult-to-control hemorrhage.

Question 10123

Topic: Surgical Anatomy & Approaches

A 68-year-old female sustains a Dubberley Type 3B fracture of the capitellum (a coronal shear fracture involving the capitellum and trochlea with posterior condylar comminution). If the surgeon elects to perform an Open Reduction and Internal Fixation (ORIF) via an extensile lateral approach (Kocher interval), between which two muscles is the dissection carried out?

. Brachioradialis and Extensor Carpi Radialis Longus
. Extensor Carpi Radialis Brevis and Extensor Digitorum Communis
. Extensor Digitorum Communis and Extensor Carpi Ulnaris
. Anconeus and Extensor Carpi Ulnaris
. Triceps and Anconeus

Correct Answer & Explanation

. Anconeus and Extensor Carpi Ulnaris

Explanation

The Kocher approach to the lateral elbow utilizes the internervous plane between the Extensor Carpi Ulnaris (ECU, innervated by the posterior interosseous nerve) and the Anconeus (innervated by the radial nerve). This provides excellent access to the capitellum and lateral joint space for addressing coronal shear fractures.

Question 10124

Topic: Infection, Pharmacology & VTE

A 19-year-old male suffers a gunshot wound to the right knee. Radiographs reveal a retained bullet lying entirely within the intra-articular space of the knee. The patient has no other systemic injuries, and the soft tissue wounds are small and clean. Which of the following is an absolute indication for the surgical retrieval of this bullet?

. Prevention of systemic lead toxicity and lead arthropathy
. Prevention of acute septic arthritis caused by the heat of the bullet
. High risk of migration into the popliteal artery
. Prevention of foreign-body induced osteosarcoma
. Improvement of the MRI compatibility of the limb

Correct Answer & Explanation

. Prevention of systemic lead toxicity and lead arthropathy

Explanation

A retained bullet within an intra-articular space (especially synovial joints like the knee or hip) is an absolute indication for surgical removal. Synovial fluid breaks down the lead bullet, which can lead to rapid, destructive mechanical joint wear (lead arthropathy) and systemic lead absorption causing systemic lead toxicity (plumbism). Acute septic arthritis is less directly correlated with the heat (bullets are actually sterilized by heat to some degree but carry skin flora in). Migration and malignancy are not the primary driving reasons.

Question 10125

Topic: Surgical Anatomy & Approaches

A 45-year-old male sustains a 3-part proximal humerus fracture and is scheduled for open reduction and internal fixation via a deltopectoral approach. During the superficial dissection, the cephalic vein is encountered. Which of the following best describes the internervous plane of this approach and the recommended management of the cephalic vein to preserve its major venous tributaries?

. Deltoid and Pectoralis minor; retract the vein medially
. Deltoid and Pectoralis major; retract the vein laterally
. Deltoid and Pectoralis major; retract the vein medially
. Coracobrachialis and Short head of biceps; retract the vein laterally
. Deltoid and Coracobrachialis; ligate the vein routinely

Correct Answer & Explanation

. Deltoid and Pectoralis major; retract the vein medially

Explanation

The deltopectoral approach utilizes the internervous plane between the deltoid (axillary nerve) and the pectoralis major (medial and lateral pectoral nerves). The cephalic vein is located within this interval. Standard orthopedic teaching recommends retracting the cephalic vein laterally with the deltoid muscle. This preserves the primary feeding veins which drain from the deltoid into the cephalic vein, thereby reducing postoperative deltoid swelling and venous congestion.

Question 10126

Topic: Surgical Anatomy & Approaches

A 32-year-old female undergoes a direct anterior (Smith-Petersen) approach to the hip for a peri-acetabular osteotomy. Which of the following describes the correct superficial internervous plane and the cutaneous nerve most at risk during this portion of the dissection?

. Sartorius and Rectus Femoris; Femoral branch of the genitofemoral nerve
. Sartorius and Tensor Fasciae Latae; Lateral femoral cutaneous nerve
. Tensor Fasciae Latae and Gluteus Medius; Lateral femoral cutaneous nerve
. Tensor Fasciae Latae and Gluteus Medius; Superior gluteal nerve
. Rectus Femoris and Vastus Lateralis; Saphenous nerve

Correct Answer & Explanation

. Sartorius and Tensor Fasciae Latae; Lateral femoral cutaneous nerve

Explanation

The Smith-Petersen (direct anterior) approach to the hip utilizes a superficial internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). The lateral femoral cutaneous nerve (LFCN) crosses over the sartorius approximately 2 cm distal to the ASIS and is at high risk of injury during the superficial dissection. Injury to the LFCN can result in meralgia paresthetica.

Question 10127

Topic: Surgical Anatomy & Approaches

An orthopedic surgeon is planning an approach to the radial head to perform an open reduction and internal fixation of a displaced fracture. The surgeon elects to use the Kocher approach. Between which two muscles is the internervous plane developed?

. Extensor carpi radialis brevis and Extensor digitorum communis
. Extensor carpi radialis longus and Brachioradialis
. Anconeus and Extensor carpi ulnaris
. Brachioradialis and Pronator teres
. Flexor carpi ulnaris and Extensor carpi ulnaris

Correct Answer & Explanation

. Anconeus and Extensor carpi ulnaris

Explanation

The Kocher approach to the elbow and radial head utilizes the internervous plane between the anconeus (innervated by the radial nerve) and the extensor carpi ulnaris (innervated by the posterior interosseous nerve). In contrast, the Kaplan approach is slightly more anterior and utilizes the plane between the extensor digitorum communis (PIN) and the extensor carpi radialis brevis (radial nerve proper). The Kocher approach is generally considered safer for the posterior interosseous nerve, which stays further anteriorly in the supinator.

Question 10128

Topic: Surgical Anatomy & Approaches

A surgeon performs the proximal portion of the volar (Henry) approach to the forearm to expose the proximal radius. The internervous plane at this level is between which of the following muscles?

. Pronator teres and Flexor carpi radialis
. Brachioradialis and Pronator teres
. Brachioradialis and Flexor carpi radialis
. Flexor carpi ulnaris and Flexor digitorum superficialis
. Extensor carpi radialis brevis and Extensor digitorum communis

Correct Answer & Explanation

. Brachioradialis and Pronator teres

Explanation

The volar (Henry) approach to the forearm provides extensile exposure to the radius. Proximally, the internervous plane is between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve). Distally, the plane shifts to become between the brachioradialis and the flexor carpi radialis (median nerve).

Question 10129

Topic: Surgical Anatomy & Approaches

A 28-year-old male presents with an anterior column acetabular fracture. An ilioinguinal approach is planned. Once the external oblique aponeurosis and inguinal canal are opened, the iliopectineal fascia is identified. The 'middle window' of this approach is defined laterally by the iliopsoas/iliopectineal fascia and medially by the external iliac vessels. Which of the following structures is found within this middle window?

. External iliac artery and vein
. Spermatic cord and genitofemoral nerve
. Iliopsoas muscle and femoral nerve
. Obturator nerve and artery
. Sciatic nerve and inferior gluteal artery

Correct Answer & Explanation

. Iliopsoas muscle and femoral nerve

Explanation

The ilioinguinal approach creates three surgical windows. The lateral window is lateral to the iliopsoas (contains the iliacus and lateral femoral cutaneous nerve). The middle window is between the iliopectineal fascia (lateral) and the external iliac vessels (medial); it contains the iliopsoas muscle and the femoral nerve. The medial window is medial to the external iliac vessels and provides access to the superior pubic ramus, the quadrilateral surface, and the retropubic space (Space of Retzius).

Question 10130

Topic: Surgical Anatomy & Approaches

During a modified Stoppa approach for a pelvic ring fracture, the surgeon elevates the peritoneum from the superior pubic ramus and quadrilateral plate. A significant vascular structure traversing vertically over the superior pubic ramus is encountered and must be ligated to prevent catastrophic hemorrhage. This structure is an anastomosis between which two vascular systems?

. Internal pudendal and External pudendal
. External iliac and Obturator
. Superior gluteal and Inferior gluteal
. Femoral and Deep femoral
. Internal iliac and Median sacral

Correct Answer & Explanation

. External iliac and Obturator

Explanation

The structure is the corona mortis (crown of death), which is an aberrant anastomosis between the external iliac system (specifically the inferior epigastric vessels) and the obturator system. It is present in approximately 30-40% of hemi-pelves and crosses over the superior pubic ramus at an average of 5-6 cm from the pubic symphysis. Ligation is critical during the modified Stoppa or ilioinguinal approach to prevent severe intrapelvic bleeding.

Question 10131

Topic: Surgical Anatomy & Approaches

A 40-year-old male sustains a midshaft humerus fracture requiring plate fixation. A posterior approach to the humerus is chosen. To safely identify and protect the radial nerve, the surgeon must know its reliable anatomical landmarks. The radial nerve typically crosses the posterior aspect of the humerus at approximately what distance proximal to the lateral and medial epicondyles respectively?

. 10 cm proximal to the lateral epicondyle; 15 cm proximal to the medial epicondyle
. 14 cm proximal to the lateral epicondyle; 20 cm proximal to the medial epicondyle
. 20 cm proximal to the lateral epicondyle; 14 cm proximal to the medial epicondyle
. 5 cm proximal to the lateral epicondyle; 10 cm proximal to the medial epicondyle
. 18 cm proximal to the lateral epicondyle; 18 cm proximal to the medial epicondyle

Correct Answer & Explanation

. 14 cm proximal to the lateral epicondyle; 20 cm proximal to the medial epicondyle

Explanation

The posterior approach to the humerus involves identifying the radial nerve as it passes through the spiral groove. A reliable anatomical landmark is that the radial nerve lies directly on the posterior aspect of the humerus approximately 14 cm proximal to the lateral epicondyle, and it crosses the medial intermuscular septum roughly 20 cm proximal to the medial epicondyle.

Question 10132

Topic: Surgical Anatomy & Approaches

Which of the following surgical approaches to the hip is accurately matched with its proper internervous plane?

. Watson-Jones : Tensor Fasciae Latae and Gluteus Medius
. Smith-Petersen : Sartorius and Rectus Femoris
. Kocher-Langenbeck : Gluteus Maximus and Gluteus Medius
. Hardinge : Gluteus Medius and Vastus Lateralis
. Smith-Petersen : Sartorius and Tensor Fasciae Latae

Correct Answer & Explanation

. Smith-Petersen : Sartorius and Tensor Fasciae Latae

Explanation

The Smith-Petersen approach uses a true internervous plane between the Sartorius (femoral n.) and the Tensor Fasciae Latae (superior gluteal n.). The Watson-Jones (anterolateral) approach utilizes the interval between the TFL and Gluteus Medius, which is not a true internervous plane since both are innervated by the superior gluteal nerve. The Hardinge approach involves a direct split of the Gluteus Medius and Vastus Lateralis, offering no internervous plane. The Kocher-Langenbeck splits the Gluteus Maximus.

Question 10133

Topic: Surgical Anatomy & Approaches

A surgeon is performing an open reduction and internal fixation of a distal tibia (pilon) fracture via a standard anterolateral approach. Which internervous plane is developed, and what nerve is directly at risk during the distal extent of this exposure?

. Tibialis anterior and Extensor hallucis longus; Deep peroneal nerve
. Extensor digitorum longus and Peroneus tertius; Superficial peroneal nerve
. Peroneus brevis and Peroneus tertius; Sural nerve
. Between the Tibia and Fibula (no true muscle plane); Superficial peroneal nerve
. Extensor hallucis longus and Extensor digitorum longus; Deep peroneal nerve

Correct Answer & Explanation

. Between the Tibia and Fibula (no true muscle plane); Superficial peroneal nerve

Explanation

The anterolateral approach to the distal tibia and ankle joint is truly an approach between the tibia and the fibula, without a strict internervous plane since both the extensor digitorum longus and the peroneus tertius are supplied by the deep peroneal nerve. During the superficial dissection, the superficial peroneal nerve (specifically its intermediate dorsal cutaneous branch) crosses the operative field from medial to lateral and is at high risk of injury.

Question 10134

Topic: Surgical Anatomy & Approaches

During a posterolateral approach to the tibia to bone graft an ununited fracture, an internervous plane is developed. Which of the following accurately describes the muscle interval and nerve supply for this approach?

. Flexor hallucis longus (Tibial n.) and Tibialis posterior (Tibial n.)
. Gastrocnemius/Soleus (Tibial n.) and Flexor digitorum longus (Tibial n.)
. Lateral head of Gastrocnemius (Tibial n.) and Peroneus longus/brevis (Superficial peroneal n.)
. Tibialis anterior (Deep peroneal n.) and Peroneus longus (Superficial peroneal n.)
. Soleus (Tibial n.) and Extensor digitorum longus (Deep peroneal n.)

Correct Answer & Explanation

. Lateral head of Gastrocnemius (Tibial n.) and Peroneus longus/brevis (Superficial peroneal n.)

Explanation

The posterolateral approach to the tibia utilizes the true internervous plane between the posterior compartment muscles (lateral head of gastrocnemius, soleus, and FHL), which are all innervated by the tibial nerve, and the lateral compartment muscles (peroneus longus and brevis), which are innervated by the superficial peroneal nerve.

Question 10135

Topic: Surgical Anatomy & Approaches

The classic posterior approach to the shoulder joint requires developing an internervous plane between the infraspinatus and teres minor. What are the respective nerve supplies to these muscles?

. Suprascapular nerve and Axillary nerve
. Axillary nerve and Suprascapular nerve
. Spinal accessory nerve and Dorsal scapular nerve
. Axillary nerve and Radial nerve
. Suprascapular nerve and Lower subscapular nerve

Correct Answer & Explanation

. Suprascapular nerve and Axillary nerve

Explanation

The posterior approach to the shoulder develops an internervous plane between the infraspinatus (innervated by the suprascapular nerve) and the teres minor (innervated by the axillary nerve). Care must be taken not to injure the axillary nerve, which exits the quadrangular space just inferior to the teres minor.

Question 10136

Topic: Surgical Anatomy & Approaches

When exposing the entire length of the radius via the volar (Henry) approach, the supinator must be detached to expose the proximal third of the radius. To safely detach the supinator without injuring the posterior interosseous nerve, how should the forearm be positioned during the detachment?

. Full pronation
. Full supination
. Neutral rotation
. 90 degrees of flexion and full pronation
. Forearm position has no effect on the nerve position

Correct Answer & Explanation

. Full supination

Explanation

During the proximal Henry approach, the supinator is elevated to expose the proximal radius. The posterior interosseous nerve (PIN) runs within the substance of the supinator. By fully supinating the forearm, the insertion of the supinator moves laterally and anteriorly, which safely rotates the PIN away from the surgical field. The muscle can then be safely elevated subperiosteally from medial to lateral.

Question 10137

Topic: Surgical Anatomy & Approaches

An anterolateral approach to the femur is performed for the treatment of a proximal third shaft fracture. The surgeon develops the plane between the rectus femoris and the vastus lateralis. Which structure crosses this surgical interval proximally and must be protected or ligated?

. Ascending branch of the lateral femoral circumflex artery
. Descending branch of the lateral femoral circumflex artery
. Transverse branch of the medial femoral circumflex artery
. Deep femoral artery
. Profunda femoris vein

Correct Answer & Explanation

. Descending branch of the lateral femoral circumflex artery

Explanation

The anterolateral approach to the femur utilizes the interval between the rectus femoris and the vastus lateralis (both innervated by the femoral nerve, so no true internervous plane). Proximally, the descending branch of the lateral femoral circumflex artery and vein cross this interval obliquely. They must be identified, isolated, and ligated to allow adequate retraction and to prevent significant bleeding.

Question 10138

Topic: Surgical Anatomy & Approaches

A surgeon is performing an anterolateral approach (Watson-Jones) to the hip for a femoral neck fracture.

What is the internervous plane for the superficial dissection of this approach?

. Tensor fasciae latae and Gluteus medius
. Sartorius and Tensor fasciae latae
. Gluteus medius and Gluteus minimus
. Tensor fasciae latae and Rectus femoris
. Gluteus maximus and Gluteus medius

Correct Answer & Explanation

. Tensor fasciae latae and Gluteus medius

Explanation

The Watson-Jones approach utilizes the plane between the Tensor fasciae latae (TFL) and Gluteus medius. Note that this is not a true internervous plane, as both muscles are innervated by the superior gluteal nerve.

Question 10139

Topic: Surgical Anatomy & Approaches

During a posterior approach to the shoulder, the internervous plane is developed between the infraspinatus and teres minor. Which of the following correctly pairs these muscles with their respective innervations?

. Infraspinatus (Suprascapular nerve) and Teres minor (Axillary nerve)
. Infraspinatus (Axillary nerve) and Teres minor (Suprascapular nerve)
. Infraspinatus (Suprascapular nerve) and Teres minor (Musculocutaneous nerve)
. Infraspinatus (Spinal accessory nerve) and Teres minor (Axillary nerve)
. Infraspinatus (Subscapular nerve) and Teres minor (Suprascapular nerve)

Correct Answer & Explanation

. Infraspinatus (Suprascapular nerve) and Teres minor (Axillary nerve)

Explanation

The posterior approach to the shoulder uses the true internervous plane between the infraspinatus (supplied by the suprascapular nerve) and teres minor (supplied by the axillary nerve).

Question 10140

Topic: Surgical Anatomy & Approaches

A surgeon utilizes the volar (Henry) approach to the forearm to plate a middle-third radial shaft fracture.

During the deep dissection in the proximal third of the forearm, the supinator muscle must be elevated from the radius. To minimize risk to the posterior interosseous nerve (PIN), how should the supinator be managed?

. It should be divided at its musculotendinous junction.
. It should be incised at its ulnar border and reflected radially.
. It should be detached from its radial insertion and reflected ulnarly.
. It should be split longitudinally in the midline.
. It should be detached from the lateral epicondyle.

Correct Answer & Explanation

. It should be detached from its radial insertion and reflected ulnarly.

Explanation

In the proximal third of the volar Henry approach, the posterior interosseous nerve (PIN) runs within the supinator. The muscle should be detached from its insertion on the radius and reflected ulnarly, carrying the PIN with it to protect it. Supination of the forearm moves the PIN further laterally, away from the surgical field.

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