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Surgical Anatomy & Approaches MCQs

Practice Set 57 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 1121

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the pelvis for acetabular fracture fixation, significant hemorrhage occurs while dissecting over the superior pubic ramus. The bleeding is most likely from an anomalous anastomotic vessel connecting the external iliac system to the internal iliac system. This vessel, known as the 'corona mortis,' typically connects which of the following?

. External pudendal artery to the internal pudendal artery
. Inferior epigastric artery/vein to the obturator artery/vein
. Deep circumflex iliac artery to the superior gluteal artery
. Internal pudendal artery to the obturator artery
. Superior vesical artery to the inferior epigastric artery

Correct Answer & Explanation

. External pudendal artery to the internal pudendal artery

Explanation

The corona mortis ('crown of death') is a vascular anastomosis between the obturator artery or vein (internal iliac system) and the inferior epigastric artery or vein (external iliac system). It traverses over the superior pubic ramus at a distance of roughly 4-6 cm from the symphysis pubis and is highly susceptible to iatrogenic injury during anterior pelvic approaches such as the ilioinguinal or Stoppa approach.

Question 1122

Topic: Surgical Anatomy & Approaches

A 28-year-old male bodybuilder presents with right posterior shoulder pain, as well as distinct weakness in shoulder abduction and external rotation. An MRI of the shoulder reveals an isolated paralabral cyst compressing the structures within the quadrangular space. Which of the following neurovascular structures are most likely being compressed?

. Suprascapular nerve and suprascapular artery
. Axillary nerve and posterior circumflex humeral artery
. Radial nerve and profunda brachii artery
. Circumflex scapular artery and lower subscapular nerve
. Thoracodorsal nerve and thoracodorsal artery

Correct Answer & Explanation

. Suprascapular nerve and suprascapular artery

Explanation

The quadrangular space in the posterior shoulder transmits the axillary nerve and the posterior circumflex humeral artery. It is bounded by the teres minor (superiorly), teres major (inferiorly), long head of the triceps (medially), and the surgical neck of the humerus (laterally). Compression in this space leads to Quadrilateral Space Syndrome, causing dysfunction of the axillary nerve, which manifests as weakness of the deltoid (abduction) and teres minor (external rotation), along with posterior shoulder pain.

Question 1123

Topic: Surgical Anatomy & Approaches

A surgeon is utilizing the anterior (Smith-Petersen) approach to the hip for an open reduction of a displaced femoral neck fracture. Which of the following best describes the deep internervous plane of this surgical approach?

. Sartorius and Tensor fasciae latae
. Rectus femoris and Gluteus medius
. Pectineus and Adductor longus
. Gluteus medius and Gluteus minimus

Correct Answer & Explanation

. Sartorius and Tensor fasciae latae

Explanation

The anterior approach to the hip (Smith-Petersen) utilizes both a superficial and a deep internervous plane. The superficial plane is between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). The deep internervous plane lies between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve). Recognizing these planes prevents denervation of the surrounding hip musculature during deep dissection.

Question 1124

Topic: Surgical Anatomy & Approaches

A 35-year-old man requires open reduction and internal fixation of a middle-third humeral shaft fracture via a posterior approach. The surgeon must identify and protect the radial nerve as it passes through the intermuscular septum. At what average distance proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum?

. 10 cm
. 5 cm
. 15 cm
. 20 cm

Correct Answer & Explanation

. 10 cm

Explanation

The radial nerve spirals around the posterior humerus in the spiral groove and pieces the lateral intermuscular septum to enter the anterior compartment of the arm. On average, this crossing occurs approximately 10 cm (range, 7.5 to 12 cm) proximal to the lateral epicondyle. Knowledge of this landmark is highly critical to avoiding iatrogenic injury to the radial nerve during posterior and lateral approaches to the humerus.

Question 1125

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the pelvis for an anterior column acetabular fracture, severe hemorrhage is encountered superior to the superior pubic ramus while dissecting near the posterior aspect of the symphysis pubis. This bleeding is most likely originating from an anastomosis between which two vascular systems?

. Obturator and external iliac (or inferior epigastric) systems
. Internal pudendal and external iliac systems
. Superior gluteal and internal iliac systems
. Inferior epigastric and internal pudendal systems

Correct Answer & Explanation

. Obturator and external iliac (or inferior epigastric) systems

Explanation

The corona mortis ('crown of death') is a vascular anastomosis between the external iliac system (or its inferior epigastric branch) and the obturator system. It is found posterior to the superior pubic ramus at a variable distance (average 5-6 cm) from the symphysis pubis. Uncontrolled bleeding from this vascular ring can be life-threatening if it retracts into the true pelvis or external iliac system.

Question 1126

Topic: Surgical Anatomy & Approaches

A surgeon is plating a proximal radius fracture utilizing the volar (Henry) approach to the forearm. In the proximal portion of the incision, what is the primary internervous plane being developed?

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

Correct Answer & Explanation

. Brachioradialis and Flexor carpi radialis

Explanation

The proximal portion of the volar (Henry) approach to the forearm utilizes the internervous plane between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve). In the distal half of the forearm, the plane is between the brachioradialis and the flexor carpi radialis (which is also innervated by the median nerve).

Question 1127

Topic: Surgical Anatomy & Approaches

A 60-year-old man is undergoing an open reduction and internal fixation of a proximal humerus fracture using a minimally invasive deltoid-splitting approach. To avoid injury to the axillary nerve, the surgeon must be aware of its location. The axillary nerve typically crosses the humerus at what distance distal to the lateral edge of the acromion?

. 2 to 3 cm
. 9 to 11 cm
. 12 to 14 cm
. 5 to 7 cm

Correct Answer & Explanation

. 2 to 3 cm

Explanation

The axillary nerve runs transversely from posterior to anterior along the deep surface of the deltoid muscle. It crosses the proximal humerus at an average distance of 5 to 7 cm distal to the lateral edge of the acromion. Deltoid-splitting approaches must remain proximal to this landmark (commonly limiting the split to 3-5 cm) to prevent denervation of the anterior deltoid.

Question 1128

Topic: Surgical Anatomy & Approaches

During an anterior approach (Smith-Petersen) to the hip for a core decompression, the superficial internervous plane is developed between the sartorius and the tensor fasciae latae. What is the deep internervous plane utilized in this surgical approach?

. Between the gluteus medius and gluteus minimus
. Between the rectus femoris and the gluteus medius
. Between the iliacus and the psoas
. Between the pectineus and the adductor longus
. Between the rectus femoris and the vastus lateralis

Correct Answer & Explanation

. Between the gluteus medius and gluteus minimus

Explanation

The Smith-Petersen (anterior) approach uses a superficial internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). The deep internervous plane lies between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve). This strict internervous approach minimizes denervation to the hip musculature.

Question 1129

Topic: Surgical Anatomy & Approaches

A 45-year-old man undergoes open reduction and internal fixation of a diaphyseal radius fracture via a volar (Henry) approach. The surgeon begins the exposure in the proximal forearm. Which of the following describes the correct internervous plane for the proximal third of this approach?

. Brachioradialis and flexor carpi radialis
. Brachioradialis and pronator teres
. Flexor carpi ulnaris and flexor digitorum superficialis
. Flexor carpi radialis and palmaris longus
. Pronator teres and flexor carpi radialis

Correct Answer & Explanation

. Brachioradialis and flexor carpi radialis

Explanation

The volar approach to the radius (Henry approach) utilizes the plane between muscles innervated by the radial and median nerves. Proximally, this plane is between the brachioradialis (radial nerve) and the pronator teres (median nerve). Distally, the plane transitions to run between the brachioradialis and the flexor carpi radialis (median nerve).

Question 1130

Topic: Surgical Anatomy & Approaches

A 35-year-old male undergoes a modified Stoppa approach for a displaced acetabular fracture involving the anterior column. During the dissection along the pelvic brim, the surgeon carefully ligates a vascular structure known as the 'corona mortis'. This structure represents an anastomotic connection between which two vascular systems?

. Internal iliac and external iliac systems
. Internal iliac and inferior mesenteric systems
. External iliac and obturator systems
. External pudendal and deep femoral systems
. Femoral and saphenous systems

Correct Answer & Explanation

. Internal iliac and external iliac systems

Explanation

The corona mortis ('crown of death') is a significant vascular anastomosis between the external iliac vascular system (typically the inferior epigastric vessels) and the obturator vascular system (a branch of the internal iliac system). It is located over the superior pubic ramus and is highly susceptible to iatrogenic injury during anterior pelvic surgical approaches.

Question 1131

Topic: Surgical Anatomy & Approaches

During surgical exploration for a compressive neuropathy in the proximal forearm, the radial nerve is identified. The superficial branch of the radial nerve and the deep branch (posterior interosseous nerve, PIN) are visualized at their bifurcation. The PIN classically passes beneath the arcade of Frohse and dives between the two heads of which muscle?

. Pronator teres
. Supinator
. Flexor carpi ulnaris
. Brachioradialis
. Extensor carpi radialis brevis

Correct Answer & Explanation

. Pronator teres

Explanation

The posterior interosseous nerve (PIN), which is the deep motor branch of the radial nerve, passes between the superficial and deep heads of the supinator muscle. The proximal fibrous edge of the superficial head of the supinator is known as the arcade of Frohse, which is the most common site of PIN entrapment (radial tunnel syndrome).

Question 1132

Topic: Surgical Anatomy & Approaches

A 45-year-old man is undergoing an open reduction and internal fixation of an anterior column acetabular fracture via an ilioinguinal approach. During the deep dissection near the posterior aspect of the superior pubic ramus, brisk arterial bleeding is suddenly encountered. Which of the following vascular anastomoses was most likely injured in this location?

. External iliac artery and internal pudendal artery
. Internal iliac artery and inferior epigastric artery
. Superior gluteal artery and inferior gluteal artery
. Inferior epigastric artery and obturator artery
. Internal pudendal artery and obturator artery

Correct Answer & Explanation

. External iliac artery and internal pudendal artery

Explanation

The patient has sustained an injury to the corona mortis (crown of death), which is an anatomic variant anastomosis between the obturator system (internal iliac) and the external iliac or inferior epigastric system. It is situated on the posterior aspect of the superior pubic ramus, typically 4 to 7 cm lateral to the pubic symphysis. If lacerated and not properly addressed, it retracts into the pelvis, leading to catastrophic hemorrhage during anterior acetabular approaches (e.g., ilioinguinal or Stoppa approaches).

Question 1133

Topic: Surgical Anatomy & Approaches

A surgeon is performing a lateral lumbar interbody fusion (LLIF) at the L4-L5 level utilizing a transpsoas approach. Postoperatively, the patient reports significant new-onset weakness in hip flexion and knee extension, along with numbness over the anterior thigh. Injury to which of the following neural structures within the psoas major muscle is the most likely cause?

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

Correct Answer & Explanation

. Ilioinguinal nerve

Explanation

The transpsoas approach places the lumbar plexus at risk, particularly at the L4-L5 level where the plexus tends to migrate more anteriorly within the psoas muscle. The femoral nerve (L2-L4 roots) forms within the psoas major and supplies the major hip flexors (iliacus, pectineus) and knee extensors (quadriceps), while providing sensation to the anterior thigh. Weakness in hip flexion and knee extension following this procedure classicly indicates a femoral nerve injury. The lateral femoral cutaneous nerve causes strictly sensory deficits, and the obturator nerve innervates hip adductors.

Question 1134

Topic: Surgical Anatomy & Approaches

A 45-year-old man undergoes an open reduction and internal fixation of a femoral head fracture via a Smith-Petersen (anterior) approach to the hip. The superficial internervous plane used in this approach lies between muscles innervated by which of the following pairs of nerves?

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

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The Smith-Petersen (anterior) approach utilizes the internervous plane between the sartorius, which is innervated by the femoral nerve, and the tensor fasciae latae (TFL), which is innervated by the superior gluteal nerve. The lateral femoral cutaneous nerve is highly at risk during the superficial dissection of this approach.

Question 1135

Topic: Surgical Anatomy & Approaches

A surgeon is performing an open reduction and internal fixation of a severely displaced proximal humerus fracture. To identify and protect the axillary nerve, the surgeon explores the quadrangular space. Which of the following correctly describes the anatomical boundaries of this space?

. Superior: Teres minor; Inferior: Teres major; Medial: Long head of triceps; Lateral: Humeral shaft
. Superior: Teres major; Inferior: Latissimus dorsi; Medial: Humeral shaft; Lateral: Long head of triceps
. Superior: Infraspinatus; Inferior: Teres minor; Medial: Short head of biceps; Lateral: Humeral shaft
. Superior: Teres minor; Inferior: Teres major; Medial: Humeral shaft; Lateral: Long head of triceps
. Superior: Teres major; Inferior: Teres minor; Medial: Long head of triceps; Lateral: Humeral shaft

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 the posterior humeral circumflex artery. Its boundaries are the teres minor (superiorly), the teres major (inferiorly), the long head of the triceps brachii (medially), and the surgical neck of the humerus (laterally).

Question 1136

Topic: Surgical Anatomy & Approaches

An orthopedic surgeon is performing a modified Stoppa approach for an acetabular fracture. Which of the following vascular structures represents the 'corona mortis,' a significant potential source of hemorrhage during this dissection?

. An anastomosis between the external iliac artery and the internal iliac artery
. An anastomosis between the obturator artery and the external iliac or inferior epigastric artery
. An anastomosis between the internal pudendal artery and the inferior epigastric artery
. An anastomosis between the superior gluteal artery and the obturator artery
. An anastomosis between the deep circumflex iliac artery and the inferior epigastric artery

Correct Answer & Explanation

. An anastomosis between the external iliac artery and the internal iliac artery

Explanation

The corona mortis is a vascular anastomosis between the obturator vessels and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus and can be a source of significant, life-threatening hemorrhage during anterior approaches to the acetabulum, such as the ilioinguinal or modified Stoppa approaches.

Question 1137

Topic: Surgical Anatomy & Approaches

Which of the following statements best describes the anatomical relationship of the posterior interosseous nerve (PIN) as it relates to surgical approaches of the proximal radius?

. It runs superficial to the supinator muscle and exits between the two heads of the extensor carpi radialis brevis
. It runs between the superficial and deep heads of the supinator muscle
. It passes anterior to the radiocapitellar joint and pieces the brachioradialis
. It courses medial to the biceps tendon and enters the pronator teres
. It lies directly on the periosteum of the radial shaft in the distal third of the forearm

Correct Answer & Explanation

. It runs superficial to the supinator muscle and exits between the two heads of the extensor carpi radialis brevis

Explanation

The posterior interosseous nerve (PIN) originates from the radial nerve at the level of the radiocapitellar joint. It enters the arcade of Frohse and runs between the superficial and deep heads of the supinator muscle, wrapping around the radial neck and proximal shaft. Protection of the PIN by keeping the forearm in supination (to move the nerve away from the surgical field) is critical during volar approaches to the proximal radius (e.g., Henry approach).

Question 1138

Topic: Surgical Anatomy & Approaches

During the surgical exposure of the posterior column of the acetabulum via a Kocher-Langenbeck approach, the surgeon carefully identifies and protects the sciatic nerve. In what percentage of the general population does a portion of the sciatic nerve (usually the peroneal division) pass directly through the piriformis muscle?

. Less than 1%
. 10-15%
. 30-40%
. 50-60%
. Greater than 80%

Correct Answer & Explanation

. Less than 1%

Explanation

In the majority of the population (~85%), the entire sciatic nerve exits the greater sciatic foramen inferior to the piriformis muscle. However, in approximately 10% to 15% of people, the sciatic nerve bifurcates prematurely, and the common peroneal division passes directly through the belly of the piriformis muscle. Recognition of this anatomic variation is critical to avoid nerve laceration or excessive tension during retraction in posterior hip exposures.

Question 1139

Topic: Surgical Anatomy & Approaches

A 38-year-old man sustains an unstable anteroposterior compression (APC-III) pelvic ring injury. The surgeon proceeds with open reduction and internal fixation of the anterior ring via a modified Stoppa approach. During dissection along the superior pubic ramus, brisk arterial hemorrhage is encountered. This bleeding is most likely caused by injury to the 'corona mortis', which represents an anastomosis between the obturator artery and which of the following vascular systems?

. Superior gluteal artery
. Internal pudendal artery
. External iliac artery
. Internal iliac artery
. Inferior gluteal artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

The correct answer is the external iliac artery. The 'corona mortis' (crown of death) is a significant anatomical variant consisting of a vascular anastomosis between the obturator system (internal iliac) and the external iliac or inferior epigastric systems. It courses over the posterior aspect of the superior pubic ramus at a variable distance (average 4-6 cm) from the pubic symphysis. This structure is highly susceptible to iatrogenic injury during anterior pelvic ring approaches, such as the ilioinguinal or modified Stoppa approach. If lacerated, it can retract into the true pelvis or retroperitoneal space, causing severe and potentially life-threatening hemorrhage.

Question 1140

Topic: Surgical Anatomy & Approaches

A patient sustains a midshaft radius fracture, and a volar (Henry) approach is chosen for fixation. What is the internervous plane for the proximal third of this approach?

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

Correct Answer & Explanation

. Flexor carpi radialis and Palmaris longus

Explanation

The proximal portion of the Henry approach to the radius utilizes the internervous plane between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve).

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