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Surgical Anatomy & Approaches MCQs

Practice Set 77 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 1521

Topic: Surgical Anatomy & Approaches

A surgeon is performing a primary total hip arthroplasty utilizing the direct anterior approach. The superficial internervous plane is developed between the tensor fasciae latae and the sartorius. During this superficial dissection, which of the following nerves is at greatest risk of iatrogenic injury, and what is its primary sensory distribution?

. Femoral nerve; anterior thigh
. Lateral femoral cutaneous nerve; anterolateral thigh
. Superior gluteal nerve; gluteus medius and minimus
. Ilioinguinal nerve; medial thigh and scrotum/labia
. Obturator nerve; medial thigh

Correct Answer & Explanation

. Lateral femoral cutaneous nerve; anterolateral thigh

Explanation

Correct Answer: Lateral femoral cutaneous nerve; anterolateral thighThe direct anterior approach to the hip utilizes the superficial internervous plane between the tensor fasciae latae (superior gluteal nerve) and the sartorius (femoral nerve). The deep plane is between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve). The lateral femoral cutaneous nerve (LFCN) exits the pelvis medial to the anterior superior iliac spine (ASIS) and courses distally over the sartorius muscle. It is at high risk of stretch or transection during the superficial dissection and retraction of the direct anterior approach. Injury to the LFCN results in numbness, paresthesias, or meralgia paresthetica in the anterolateral thigh. The femoral nerve is located more medially in the femoral triangle and is rarely injured unless retractors are placed carelessly medial to the psoas.

Question 1522

Topic: Surgical Anatomy & Approaches

A 55-year-old female is undergoing a total hip arthroplasty via the direct anterior approach. The surgeon develops the internervous plane between the tensor fasciae latae and the sartorius. During the superficial dissection, a nerve is at risk of iatrogenic injury. Which of the following describes the typical anatomic course of the nerve most at risk?

. It exits the pelvis through the greater sciatic foramen superior to the piriformis.
. It passes deep to the inguinal ligament, approximately 1 to 2 cm medial to the anterior superior iliac spine.
. It travels within the substance of the psoas major muscle and exits lateral to the femoral artery.
. It exits the pelvis through the obturator canal to innervate the medial thigh compartment.
. It passes posterior to the hip joint and is at risk during excessive internal rotation.

Correct Answer & Explanation

. It passes deep to the inguinal ligament, approximately 1 to 2 cm medial to the anterior superior iliac spine.

Explanation

Correct Answer: It passes deep to the inguinal ligament, approximately 1 to 2 cm medial to the anterior superior iliac spine.The direct anterior approach utilizes the internervous plane between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The nerve most at risk during the superficial dissection is the lateral femoral cutaneous nerve (LFCN). The LFCN typically passes deep to the inguinal ligament, about 1 to 2 cm medial to the anterior superior iliac spine (ASIS), and courses distally over the sartorius muscle. Injury to this nerve results in meralgia paresthetica (numbness/dysesthesia over the anterolateral thigh). The superior gluteal nerve exits superior to the piriformis. The femoral nerve travels between the psoas and iliacus. The obturator nerve exits through the obturator canal. The sciatic nerve passes posterior to the hip joint.

Question 1523

Topic: Surgical Anatomy & Approaches

A surgeon is performing a primary total hip arthroplasty via the direct anterior (Smith-Petersen) approach. The internervous plane utilized for the superficial dissection is between muscles innervated by which of the following nerves?

. Superior gluteal nerve and femoral nerve
. Superior gluteal nerve and inferior gluteal nerve
. Femoral nerve and obturator nerve
. Inferior gluteal nerve and sciatic nerve
. Superior gluteal nerve and sciatic nerve

Correct Answer & Explanation

. Superior gluteal nerve and femoral nerve

Explanation

Correct Answer: Superior gluteal nerve and femoral nerveThe direct anterior approach to the hip utilizes a true internervous and intermuscular plane. The superficial dissection is between the tensor fasciae latae (TFL), which is innervated by the superior gluteal nerve, and the sartorius, which is innervated by the femoral nerve. The deep dissection utilizes the plane between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve). This approach avoids detaching any muscles from the pelvis or femur, which is theorized to allow for a faster early recovery.

Question 1524

Topic: Surgical Anatomy & Approaches

Following a primary right total hip arthroplasty, a patient demonstrates a profound foot drop. She is unable to actively dorsiflex or evert her foot, but plantar flexion and inversion remain completely intact. Which specific nerve structure is most commonly injured in this scenario and what anatomic feature accounts for this susceptibility?

. Tibial division of the sciatic nerve due to its lateral position
. Tibial division of the sciatic nerve due to its larger fascicles
. Peroneal division of the sciatic nerve due to its firm tethering at the fibular head
. Peroneal division of the sciatic nerve due to its lateral position and lesser amount of protective connective tissue
. Femoral nerve due to inappropriate anterior retractor placement

Correct Answer & Explanation

. Peroneal division of the sciatic nerve due to its lateral position and lesser amount of protective connective tissue

Explanation

The common peroneal division of the sciatic nerve is significantly more susceptible to injury during THA (from stretch or compression) because of its lateral anatomic position and its relative lack of protective epineural connective tissue compared to the tibial division.

Question 1525

Topic: Surgical Anatomy & Approaches

A 64-year-old female undergoes a THA via the direct anterior approach utilizing the internervous plane between the sartorius and the tensor fasciae latae. Postoperatively, she reports a burning sensation and significant numbness over the anterolateral aspect of her thigh, but her motor function is intact. Injury to which of the following structures is the most likely cause?

. Femoral nerve
. Sciatic nerve
. Ilioinguinal nerve
. Lateral femoral cutaneous nerve
. Obturator nerve

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

The lateral femoral cutaneous nerve (LFCN) is a purely sensory nerve supplying the anterolateral thigh. It is at high risk of neuropraxia or transection during the superficial dissection of the direct anterior approach due to its proximity to the surgical interval.

Question 1526

Topic: Surgical Anatomy & Approaches

A 6-year-old non-ambulatory boy with SMA Type II is noted to have progressive right hip subluxation on routine surveillance radiographs. He is currently asymptomatic. What is the primary driving force behind this hip instability?

. Primary acetabular dysplasia inherent to the genetic defect.
. Ligamentous laxity of the iliofemoral ligament.
. Muscle imbalance with relatively stronger iliopsoas and adductors compared to abductors.
. Spasticity of the hip adductors and flexors.
. Avascular necrosis of the femoral head due to recurrent microtrauma.

Correct Answer & Explanation

. Muscle imbalance with relatively stronger iliopsoas and adductors compared to abductors.

Explanation

Correct Answer: CHip subluxation and dislocation are common orthopedic complications in non-ambulatory patients with SMA. The primary etiology is a muscle imbalance around the hip joint. Specifically, the hip flexors (iliopsoas) and adductors remain relatively stronger than the hip abductors and extensors. This imbalance gradually pulls the femoral head out of the acetabulum. Because SMA is a lower motor neuron disease, spasticity (an upper motor neuron sign) is absent. While ligamentous laxity and lack of weight-bearing contribute, the primary deforming force is the muscle imbalance.

Question 1527

Topic: Surgical Anatomy & Approaches

A 2-week-old neonate presents with pseudoparalysis of the right leg. Ultrasound shows a large hip effusion, and aspiration yields frank pus.

What is the most appropriate surgical approach for emergency drainage of this joint?

. Anterior (Smith-Petersen) approach
. Anterolateral (Watson-Jones) approach
. Lateral (Hardinge) approach
. Posterior (Kocher-Langenbeck) approach
. Medial (Ludloff) approach

Correct Answer & Explanation

. Anterior (Smith-Petersen) approach

Explanation

The anterior (Smith-Petersen) approach is the standard for pediatric hip arthrotomy to drain septic arthritis. It provides direct, safe access to the joint capsule while avoiding damage to the critical lateral epiphyseal vessels.

Question 1528

Topic: Surgical Anatomy & Approaches

Based on the imaging provided of a patient with Dysplasia Epiphysealis Hemimelica, the mass is protruding from the distal femoral epiphysis into the popliteal fossa. Which of the following structures is at highest risk of compression from this specific lesion?



. Femoral nerve
. Popliteal artery
. Common peroneal nerve at the fibular head
. Anterior tibial artery
. Saphenous nerve

Correct Answer & Explanation

. Popliteal artery

Explanation

Correct Answer: Popliteal arteryThe MRI slide in the sagittal plane shows a protruding bone mass from the distal femoral epiphysis extending directly into the popliteal fossa. The popliteal fossa contains the popliteal artery, popliteal vein, and tibial nerve. A large space-occupying lesion in this area places these neurovascular structures, particularly the popliteal artery, at risk of compression.

Question 1529

Topic: Surgical Anatomy & Approaches

A 68-year-old female sustains a displaced four-part proximal humerus fracture after a fall. The primary blood supply to the articular segment is severely compromised, placing her at high risk for avascular necrosis. The critical vessel providing this predominant blood supply typically traverses which of the following anatomic spaces?

. Triangular space
. Quadrangular space
. Triangular interval
. Rotator interval
. Subacromial space

Correct Answer & Explanation

. Quadrangular space

Explanation

Correct Answer: B (Quadrangular space)The primary blood supply to the articular segment of the humeral head is the posterior humeral circumflex artery (specifically its arcuate branch), which provides the majority of the intraosseous vascularity. The posterior humeral circumflex artery travels through the quadrangular space along with the axillary nerve. The boundaries of the quadrangular space are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and the surgical neck of the humerus (lateral). Disruption of this vessel in displaced 3- and 4-part fractures significantly increases the risk of avascular necrosis (AVN). The triangular space contains the circumflex scapular artery. The triangular interval contains the radial nerve and profunda brachii artery. The rotator interval contains the coracohumeral ligament, superior glenohumeral ligament, and long head of the biceps tendon.

Question 1530

Topic: Surgical Anatomy & Approaches

A 24-year-old male sustains an anterior shoulder dislocation during a wrestling match. Following a successful closed reduction, neurological examination reveals an isolated axillary nerve palsy, characterized by decreased sensation over the lateral deltoid and weakness in shoulder abduction. The axillary nerve, along with the posterior humeral circumflex artery, exits the axilla to innervate the deltoid by passing through the quadrilateral space. Which of the following anatomical structures forms the superior border of this space?

. Teres major.
. Teres minor.
. Long head of the triceps.
. Surgical neck of the humerus.
. Subscapularis.

Correct Answer & Explanation

. Teres minor.

Explanation

Correct Answer: Teres minor.The axillary nerve is the most commonly injured nerve during an anterior glenohumeral dislocation due to traction as it courses inferiorly to the joint capsule. It exits the axilla to reach the posterior shoulder and innervate the deltoid and teres minor by passing through the quadrilateral space. A thorough understanding of this anatomy is crucial for both diagnosis and surgical approaches (e.g., posterior approach to the shoulder). The borders of the quadrilateral space are: Superiorly: Teres minor (and the inferior margin of the subscapularis/capsule more anteriorly); Inferiorly: Teres major; Medially: Long head of the triceps brachii; Laterally: Surgical neck of the humerus. Therefore, the teres minor forms the superior border.

Question 1531

Topic: Surgical Anatomy & Approaches

When assessing a patient with a suspected first-time shoulder dislocation, what is the significance of palpating the lateral border of the deltoid muscle?

. To assess for rotator cuff integrity
. To evaluate for an associated AC joint injury
. To test for axillary nerve sensation
. To check for biceps tendon pathology
. To locate the subacromial bursa

Correct Answer & Explanation

. To test for axillary nerve sensation

Explanation

The axillary nerve (C5-C6) provides sensory innervation to the skin over the lateral deltoid (sometimes called the 'regimental badge area'). Assessing sensation in this region is crucial for detecting axillary nerve neuropraxia or injury, which is the most common nerve injury associated with shoulder dislocations. It does not directly assess rotator cuff, AC joint, biceps, or bursa.

Question 1532

Topic: Surgical Anatomy & Approaches

A patient with a dislocated shoulder presents with wrist drop. Which nerve is most likely injured?

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

Correct Answer & Explanation

. Radial nerve

Explanation

Wrist drop, characterized by the inability to extend the wrist and fingers, is a classic sign of radial nerve palsy. While other nerves can be injured in severe shoulder trauma or brachial plexus injuries, radial nerve compression or stretch is the most direct cause of wrist drop. This is a less common injury with isolated shoulder dislocation but can occur with associated humeral shaft fractures or severe traction.

Question 1533

Topic: Surgical Anatomy & Approaches

A 55-year-old patient with an anterior shoulder dislocation complains of a new onset 'pins and needles' sensation in the lateral forearm. Which nerve injury is MOST likely responsible?

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

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The musculocutaneous nerve provides sensory innervation to the lateral forearm via its terminal branch, the lateral antebrachial cutaneous nerve. While less common than axillary nerve injury, a musculocutaneous nerve injury could occur with shoulder dislocation, especially with traction or compression. Axillary nerve injury affects the lateral deltoid sensation. Radial nerve affects posterior arm/forearm and dorsum of hand. Ulnar nerve affects medial forearm and hand. Median nerve affects volar hand and fingertips.

Question 1534

Topic: Surgical Anatomy & Approaches

A 35-year-old male sustains a high-energy trauma, resulting in a complex acetabular fracture involving both columns with posterior wall comminution and impaction of the femoral head. A post-reduction CT scan shows persistent articular incongruity of 3 mm and a displaced posterior wall fragment. The patient is neurologically intact. What is the single most critical factor influencing the long-term prognosis after surgical fixation of this injury?

. The timing of surgery (within 24 hours vs. delayed)
. The type of surgical approach used (e.g., ilioinguinal vs. Kocher-Langenbeck)
. The restoration of anatomical articular congruence
. The presence of associated ipsilateral lower extremity fractures
. The need for a blood transfusion during surgery

Correct Answer & Explanation

. The restoration of anatomical articular congruence

Explanation

For acetabular fractures, the most critical determinant of long-term prognosis and prevention of post-traumatic osteoarthritis is the achievement of anatomical reduction and stable fixation, particularly the restoration of articular congruence. Residual articular displacement greater than 1-2 mm significantly increases the risk of developing early degenerative changes and subsequent total hip arthroplasty. While timing, approach, and associated injuries are important, articular congruence directly impacts joint health and survival.

Question 1535

Topic: Surgical Anatomy & Approaches

A 40-year-old male sustains a complete avulsion of the C5-C6 nerve roots from the spinal cord following a motorcycle accident, resulting in a flail shoulder and absent biceps function. He presents 6 months post-injury. What is the most appropriate surgical strategy to restore elbow flexion in this patient?

. Direct nerve repair
. Neurolysis and nerve grafting
. Intercostal nerve transfer to the musculocutaneous nerve
. Triceps motor branch transfer to the anterior division of the axillary nerve
. Tendon transfer (e.g., Steindler flexorplasty)

Correct Answer & Explanation

. Intercostal nerve transfer to the musculocutaneous nerve

Explanation

In cases of complete nerve root avulsion from the spinal cord (a preganglionic injury), direct nerve repair or grafting is impossible due to the lack of a distal stump for the root. Nerve transfers are the reconstructive option of choice. To restore elbow flexion (mediated by the musculocutaneous nerve, which innervates the biceps), a common and effective strategy is to transfer intercostal nerves (typically 3rd and 4th) to the musculocutaneous nerve. The triceps motor branch to axillary nerve transfer is used to restore shoulder abduction/external rotation. Tendon transfers like Steindler flexorplasty are salvage procedures, often considered after nerve repair/transfer failure or when nerve options are exhausted.

Question 1536

Topic: Surgical Anatomy & Approaches

In proximal tibia fractures, antegrade IM nailing has specific biomechanical challenges. Which of the following is most accurately described as a biomechanical risk for this approach?

. High risk of superior gluteal artery injury.
. Difficulty achieving sufficient purchase in the proximal metaphysis, leading to varus/valgus malalignment.
. Increased risk of radial nerve palsy.
. High incidence of implant migration into the knee joint.
. Inability to achieve rotational stability.

Correct Answer & Explanation

. Difficulty achieving sufficient purchase in the proximal metaphysis, leading to varus/valgus malalignment.

Explanation

Antegrade nailing of proximal tibia fractures is challenging. The wide proximal medullary canal, combined with often comminuted metaphyseal bone and the natural valgus angulation of the proximal tibia, makes it difficult to achieve stable fixation of the proximal fragment. This can lead to loss of reduction, particularly in the coronal plane, resulting in varus or valgus malalignment. Modern nails for this indication often feature multi-planar proximal locking options, blade configurations, or expanded proximal diameters to address this biomechanical challenge. Gluteal artery and radial nerve injuries are not risks for tibial nailing. Implant migration into the knee is a risk if the nail is too long, but not the primary challenge of proximal fragment stability.

Question 1537

Topic: Surgical Anatomy & Approaches

A 25-year-old male undergoes antegrade intramedullary nailing for a mid-shaft femoral fracture. Two weeks post-operatively, he develops a foot drop and diminished sensation over the dorsum of the foot. Which nerve is most likely injured?

. A. Sciatic nerve.
. B. Femoral nerve.
. C. Common peroneal nerve.
. D. Tibial nerve.
. E. Obturator nerve.

Correct Answer & Explanation

. C. Common peroneal nerve.

Explanation

A foot drop (weakness in dorsiflexion and eversion of the foot) and sensory deficit over the dorsum of the foot are classic signs of common peroneal nerve injury. While sciatic nerve injury (A) can also cause foot drop, the common peroneal nerve (a branch of the sciatic nerve) is more susceptible to injury around the knee, often due to positioning on the fracture table or direct compression, or traction during manipulation. Femoral (B), tibial (D), and obturator (E) nerve injuries present with different motor and sensory deficits.

Question 1538

Topic: Surgical Anatomy & Approaches

A 45-year-old male sustains a posterior column and posterior wall acetabular fracture in a motor vehicle accident. CT scan confirms significant displacement and a large posterior wall fragment. The ideal surgical approach for this specific fracture pattern, considering the need for direct visualization and reduction, is typically:

. Ilioinguinal approach
. Kocher-Langenbeck approach
. Modified Stoppa approach
. Extended iliofemoral approach
. Trochanteric flip osteotomy approach

Correct Answer & Explanation

. Kocher-Langenbeck approach

Explanation

The Kocher-Langenbeck approach provides excellent exposure to the posterior column and posterior wall of the acetabulum, making it the workhorse approach for fractures involving these components. The ilioinguinal and modified Stoppa approaches are anterior approaches used for anterior column, anterior wall, or transverse fractures. The extended iliofemoral approach is a more extensive approach for complex bicompartmental fractures but carries higher morbidity. A trochanteric flip osteotomy is typically used for surgical hip dislocation for femoral head or central acetabular pathology, not primarily for posterior column/wall fractures.

Question 1539

Topic: Surgical Anatomy & Approaches

A 28-year-old male sustains a complete avulsion of the C5 and C6 nerve roots from the spinal cord following a high-energy motorcycle accident. Six months post-injury, he has no voluntary contraction in his deltoid, biceps, or wrist extensors. Electromyography confirms no reinnervation across the C5-C6 territory. For restoration of elbow flexion, which of the following nerve transfer options is generally considered the most effective for a patient with C5-C6 avulsion?

. Intercostal nerve to musculocutaneous nerve transfer.
. Accessory nerve to suprascapular nerve transfer.
. Ulnar fascicle of the median nerve to musculocutaneous nerve (Oberlin transfer).
. Pectoralis major motor branch to musculocutaneous nerve transfer.
. Phrenic nerve to musculocutaneous nerve transfer.

Correct Answer & Explanation

. Ulnar fascicle of the median nerve to musculocutaneous nerve (Oberlin transfer).

Explanation

For complete C5-C6 root avulsion, where no proximal nerve stumps are available for grafting, nerve transfers are the treatment of choice to restore function, particularly elbow flexion. The Oberlin transfer (transfer of a fascicle from the ulnar nerve to the biceps branch of the musculocutaneous nerve) is a highly effective and commonly utilized procedure for restoring elbow flexion, as it provides a strong, reliable donor with minimal donor site morbidity. Intercostal nerves can be used but provide less robust power. Accessory to suprascapular is for shoulder abduction/external rotation. Pectoralis major motor branch is an option but less commonly used than Oberlin for isolated C5-C6. Phrenic nerve transfer is considered a last resort due to potential respiratory compromise.

Question 1540

Topic: Surgical Anatomy & Approaches

During an anterior intrapelvic (modified Stoppa) approach for an acetabular fracture, significant hemorrhage is encountered from a vascular anastomosis over the superior pubic ramus. This structure represents an anastomosis between which two vascular systems?

. External iliac artery and internal iliac artery
. External iliac artery and superior gluteal artery
. Internal pudendal artery and obturator artery
. Inferior epigastric artery and obturator artery
. Superior gluteal artery and obturator 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 connects the inferior epigastric artery or vein (branches of the external iliac system) to the obturator artery or vein (branches of the internal iliac system). It is typically located 5-6 cm from the pubic symphysis along the superior pubic ramus.

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