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Surgical Anatomy & Approaches MCQs

Practice Set 99 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 1961

Topic: Surgical Anatomy & Approaches

During an anterior intrapelvic (modified Stoppa) approach for an acetabular fracture, the surgeon must identify and protect the 'corona mortis' to prevent catastrophic hemorrhage. This vascular structure typically represents an anastomosis between which two vessel systems?

. Internal pudendal and superior gluteal
. External iliac (or inferior epigastric) and obturator
. Internal iliac and inferior gluteal
. Femoral and deep circumflex iliac
. Median sacral and lateral sacral

Correct Answer & Explanation

. External iliac (or inferior epigastric) and obturator

Explanation

The corona mortis (crown of death) is a vascular anastomosis between the external iliac or inferior epigastric vessels and the obturator vessels. It is located over the superior pubic ramus, typically 4 to 9 cm from the pubic symphysis, and is at high risk of iatrogenic injury during anterior pelvic surgical approaches.

Question 1962

Topic: Surgical Anatomy & Approaches

A 24-year-old elite volleyball player presents with vague posterior shoulder pain and weakness in external rotation. MRI reveals isolated atrophy of the teres minor. Compression of the neurovascular bundle in the quadrilateral space is suspected. Which of the following forms the inferior boundary of this anatomical space?

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

Correct Answer & Explanation

. Teres minor

Explanation

The quadrilateral space is bordered superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the surgical neck of the humerus. It contains the axillary nerve and the posterior circumflex humeral artery. Compression here leads to quadrilateral space syndrome.

Question 1963

Topic: Surgical Anatomy & Approaches

During the proximal extension of the volar (Henry) approach to the forearm, the surgeon develops an internervous plane. Which of the following correctly identifies the muscles and their respective nerve supplies forming this proximal interval?

. Brachioradialis (Radial) and Flexor Carpi Radialis (Median)
. Brachioradialis (Radial) and Pronator Teres (Median)
. Flexor Carpi Ulnaris (Ulnar) and Flexor Digitorum Superficialis (Median)
. Extensor Carpi Radialis Brevis (Radial) and Extensor Digitorum Communis (PIN)
. Pronator Teres (Median) and Flexor Carpi Radialis (Median)

Correct Answer & Explanation

. Brachioradialis (Radial) and Pronator Teres (Median)

Explanation

The proximal portion of the volar (Henry) approach to the radius utilizes the true internervous plane between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve). Distally, the plane shifts between the brachioradialis and the flexor carpi radialis.

Question 1964

Topic: Surgical Anatomy & Approaches
Following a closed humerus fracture, a patient develops a radial nerve palsy. An EMG performed at 4 weeks shows fibrillation potentials but no motor unit action potentials. The nerve injury involves disruption of the axons and myelin sheath, but the endoneurium, perineurium, and epineurium remain intact. Which Sunderland grade corresponds to this injury?
. Grade I
. Grade II
. Grade III
. Grade IV
. Grade V

Correct Answer & Explanation

. Grade II

Explanation

A Sunderland Grade II injury corresponds to axonotmesis where the axon and myelin sheath are disrupted, but the endoneurial tubes, perineurium, and epineurium are intact. Recovery is generally complete as the intact endoneurium guides regenerating axons at a rate of 1 mm/day.

Question 1965

Topic: Surgical Anatomy & Approaches

Following a closed humerus fracture, a patient develops a radial nerve palsy. An EMG at 4 weeks shows fibrillation potentials, but the nerve remains anatomically continuous with disruption of axons and their myelin sheath, while the endoneurium, perineurium, and epineurium remain intact. This injury corresponds to which Sunderland grade?

. Grade 1
. Grade 2
. Grade 3
. Grade 4
. Grade 5

Correct Answer & Explanation

. Grade 2

Explanation

Sunderland Grade 2 (which corresponds to Seddon's axonotmesis) involves disruption of the axon and myelin sheath, but the surrounding connective tissue framework (endoneurium, perineurium, epineurium) is intact. Wallerian degeneration occurs distal to the injury, but the intact endoneurial tubes guide regenerating axons, leading to an excellent prognosis for recovery. Grade 1 is neurapraxia. Grades 3-5 involve progressive connective tissue disruption.

Question 1966

Topic: Surgical Anatomy & Approaches

A patient sustains a closed midshaft humerus fracture with an associated radial nerve palsy. According to Sunderland's classification, a 3rd-degree nerve injury involves the disruption of the axon and myelin sheath along with which of the following connective tissue layers?

. None; all connective tissues remain intact
. The endoneurium is disrupted, but the perineurium remains intact
. The perineurium is disrupted, but the epineurium remains intact
. The epineurium is disrupted, constituting complete transection
. The epimysium and surrounding fascia are disrupted

Correct Answer & Explanation

. The endoneurium is disrupted, but the perineurium remains intact

Explanation

A Sunderland 3rd-degree injury involves damage to the axon, myelin, and the endoneurium, while the perineurium remains intact. Because the endoneurial tubes are disrupted, axonal regeneration may be misdirected, leading to incomplete or aberrant functional recovery.

Question 1967

Topic: Surgical Anatomy & Approaches

A patient sustained a closed midshaft humerus fracture 4 months ago and has a persistent radial nerve palsy. Electromyography (EMG) shows fibrillation potentials in the brachioradialis. Surgical exploration reveals the radial nerve is in continuity but contains a dense, focal neuroma. Resection of the neuroma and nerve grafting is planned. This injury best corresponds to which of the following Sunderland classifications?

. First-degree
. Second-degree
. Third-degree
. Fourth-degree
. Fifth-degree

Correct Answer & Explanation

. Fourth-degree

Explanation

A Sunderland fourth-degree nerve injury involves disruption of the axon, endoneurium, and perineurium; only the epineurium remains intact. Clinically, the nerve is in continuity but contains dense scar tissue (a neuroma-in-continuity) that mechanically blocks axonal regeneration. Because spontaneous recovery will not occur across this scar, excision and grafting are required. First-degree is neuropraxia. Second-degree is axonotmesis (intact endoneurium). Third-degree involves loss of endoneurium with intact perineurium. Fifth-degree is complete nerve transection.

Question 1968

Topic: Surgical Anatomy & Approaches

The anterior (Smith-Petersen) approach to the hip utilizes a true internervous plane. This approach develops the interval between muscles innervated by which of the following pairs of nerves?

. Femoral and Superior Gluteal
. Femoral and Obturator
. Superior Gluteal and Inferior Gluteal
. Sciatic and Femoral
. Obturator and Sciatic

Correct Answer & Explanation

. Femoral and Superior Gluteal

Explanation

The Smith-Petersen approach exploits the true internervous plane between the femoral nerve and the superior gluteal nerve. Superficially, the plane is between the sartorius (femoral) and tensor fasciae latae (superior gluteal), and deeply between the rectus femoris (femoral) and gluteus medius (superior gluteal).

Question 1969

Topic: Surgical Anatomy & Approaches

When performing a direct anterior approach to the hip for a total hip arthroplasty, the internervous plane utilized superficially is between muscles supplied by which two nerves?

. Superior gluteal nerve and femoral nerve
. Femoral nerve and obturator nerve
. Inferior gluteal nerve and superior gluteal nerve
. Sciatic nerve and inferior gluteal nerve
. Obturator nerve and sciatic nerve

Correct Answer & Explanation

. Superior gluteal nerve and femoral nerve

Explanation

The direct anterior approach (Smith-Petersen) utilizes an internervous plane. Superficially, it runs between the Sartorius (femoral nerve) and the Tensor Fasciae Latae (superior gluteal nerve). Deeply, it separates the Rectus Femoris (femoral nerve) from the Gluteus Medius (superior gluteal nerve).

Question 1970

Topic: Surgical Anatomy & Approaches

During a Smith-Petersen (anterior) approach to the hip, the superficial internervous plane is developed. Which two nerves supply the specific muscles that define this superficial plane?

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

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The superficial plane of the Smith-Petersen approach lies between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). This establishes a true internervous corridor.

Question 1971

Topic: Surgical Anatomy & Approaches

Four weeks after sustaining a closed humeral shaft fracture, a patient exhibits complete radial nerve palsy. An electromyogram (EMG) reveals fibrillation potentials in the brachioradialis but no voluntary motor unit action potentials. According to Seddon's classification, this nerve injury is best termed:

. Neuropraxia
. Axonotmesis
. Neurotmesis
. A first-degree Sunderland injury
. Wallerian regeneration

Correct Answer & Explanation

. Axonotmesis

Explanation

Fibrillation potentials confirm denervation, ruling out neuropraxia (which has preserved distal conduction and no fibrillations). Given the intact nerve sheath typically seen in closed fractures (as opposed to full transection in neurotmesis), this represents axonotmesis undergoing Wallerian degeneration.

Question 1972

Topic: Surgical Anatomy & Approaches

While performing an ilioinguinal approach for an acetabular fracture, significant hemorrhage occurs posterior to the superior pubic ramus. This is most likely due to an injury to the "corona mortis," which is an anastomosis between which two vascular systems?

. External iliac and internal pudendal
. External iliac and obturator
. Internal iliac and superior gluteal
. Femoral and obturator
. Internal pudendal and obturator

Correct Answer & Explanation

. External iliac and obturator

Explanation

The corona mortis is a critical vascular anastomosis between the external iliac (or inferior epigastric) system and the obturator system. It is classically located 5 to 7 cm laterally from the pubic symphysis.

Question 1973

Topic: Surgical Anatomy & Approaches

A patient presents with a spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). Which nerve is most at risk of being entrapped in the fracture site, and what clinical deficit would be expected?

. Median nerve; inability to flex the IP joint of the thumb
. Ulnar nerve; numbness of the small finger
. Radial nerve; inability to extend the wrist
. Axillary nerve; weakness of shoulder abduction
. Musculocutaneous nerve; weakness of elbow flexion

Correct Answer & Explanation

. Radial nerve; inability to extend the wrist

Explanation

The Holstein-Lewis fracture involves the distal third of the humerus, placing the radial nerve at high risk as it passes through the lateral intermuscular septum. Injury causes radial nerve palsy, which presents clinically as a wrist drop.

Question 1974

Topic: Surgical Anatomy & Approaches

When performing a total hip arthroplasty via the direct anterior approach (Smith-Petersen), the superficial surgical internervous plane is located between muscles supplied by which two nerves?

. Superior gluteal and inferior gluteal nerves
. Femoral and superior gluteal nerves
. Femoral and sciatic nerves
. Obturator and femoral nerves
. Superior gluteal and sciatic nerves

Correct Answer & Explanation

. Femoral and superior gluteal nerves

Explanation

The direct anterior approach utilizes an internervous plane between the sartorius (femoral nerve) and tensor fasciae latae (superior gluteal nerve). The deep plane continues between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 1975

Topic: Surgical Anatomy & Approaches
A patient sustains an anteroposterior compression (APC III) pelvic ring injury. During the surgical approach to the pubic symphysis, significant retropubic hemorrhage is encountered due to injury of the "corona mortis". This represents an anastomosis between which two vessels?
. External iliac artery and internal pudendal artery
. Inferior epigastric artery and obturator artery
. Superior gluteal artery and inferior epigastric artery
. Internal iliac artery and femoral artery
. Obturator artery and superior vesical artery

Correct Answer & Explanation

. Inferior epigastric artery and obturator artery

Explanation

The corona mortis is a potentially lethal vascular anastomosis between the external iliac (or inferior epigastric) and the obturator systems. It typically crosses the superior pubic ramus and is highly susceptible to iatrogenic or traumatic injury.

Question 1976

Topic: Surgical Anatomy & Approaches

The direct anterior approach (Smith-Petersen) to the hip utilizes a true internervous plane. This plane is located between muscles innervated by which of the following nerve pairs?

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

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The superficial internervous plane of the direct anterior approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep plane is between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 1977

Topic: Surgical Anatomy & Approaches

Which of the following muscles of the posterior thigh is uniquely innervated by the common peroneal division of the sciatic nerve?

. Semimembranosus
. Short head of the biceps femoris
. Long head of the biceps femoris
. Semitendinosus
. Ischial portion of the adductor magnus

Correct Answer & Explanation

. Short head of the biceps femoris

Explanation

The short head of the biceps femoris is the only muscle in the posterior compartment of the thigh innervated by the common peroneal division of the sciatic nerve. All other hamstring muscles are innervated by the tibial division.

Question 1978

Topic: Surgical Anatomy & Approaches

A patient suffers a closed humerus fracture and subsequent radial nerve palsy. Electromyography at 4 weeks suggests an axonotmesis injury (Sunderland second-degree). Which of the following best describes the pathophysiology of this nerve injury?

. Loss of myelin with an intact axon
. Disruption of the axon with an intact endoneurium
. Disruption of the axon and endoneurium with an intact perineurium
. Disruption of the entire nerve trunk including the epineurium
. Ischemic neuropraxia without Wallerian degeneration

Correct Answer & Explanation

. Disruption of the axon with an intact endoneurium

Explanation

In an axonotmesis (Sunderland second-degree) injury, the axon is disrupted, leading to distal Wallerian degeneration, but the endoneurial tubes remain intact. These intact tubes guide the regenerating axons, allowing for a good prognosis for spontaneous recovery.

Question 1979

Topic: Surgical Anatomy & Approaches

A patient sustains a midshaft humerus fracture resulting in a radial nerve palsy. According to Seddon's classification, which type of injury is characterized by axonal disruption with an intact endoneurial tube?

. Neurapraxia
. Axonotmesis
. Neurotmesis
. Sunderland Grade I
. Sunderland Grade V

Correct Answer & Explanation

. Axonotmesis

Explanation

Axonotmesis involves the loss of axonal continuity and subsequent Wallerian degeneration, but the surrounding connective tissue framework (endoneurium) remains intact. This structure guides spontaneous, albeit slow, axonal regeneration.

Question 1980

Topic: Surgical Anatomy & Approaches

A patient sustains a proximal fibula fracture and subsequently presents with a foot drop. If the injury involves the common peroneal nerve at the fibular neck, which of the following muscles will remain fully functional?

. Tibialis anterior
. Extensor hallucis longus
. Peroneus brevis
. Tibialis posterior
. Extensor digitorum brevis

Correct Answer & Explanation

. Tibialis posterior

Explanation

The tibialis posterior is innervated by the tibial nerve, which is a branch of the sciatic nerve that courses through the posterior compartment. The common peroneal nerve innervates the anterior and lateral compartments, affecting the other listed muscles.

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