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Surgical Anatomy & Approaches MCQs

Practice Set 84 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 1661

Topic: Surgical Anatomy & Approaches

A 6-year-old boy sustains a completely displaced posteromedial supracondylar humerus fracture. Which nerve is at the highest risk of injury secondary to this specific direction of fracture displacement?

. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

In a posteromedial displacement, the proximal fracture fragment is driven anterolaterally, impaling the lateral structures and placing the radial nerve at highest risk. Conversely, posterolateral displacement places the anterior interosseous nerve at highest risk.

Question 1662

Topic: Surgical Anatomy & Approaches

During an anterior intrapelvic approach (ilioinguinal or modified Stoppa) for an acetabular fracture, significant hemorrhage occurs while dissecting over the posterior aspect of the superior pubic ramus. The injured vessel typically represents an anastomosis between which two vascular systems?

. Internal pudendal and external pudendal
. Obturator and external iliac
. Superior gluteal and internal iliac
. Inferior epigastric and internal pudendal
. External iliac and femoral

Correct Answer & Explanation

. Internal pudendal and external pudendal

Explanation

The corona mortis (crown of death) is a vascular anastomosis between the obturator system (internal iliac) and the external iliac or inferior epigastric system. It is located on the posterior aspect of the superior pubic ramus, typically 4 to 9 cm from the pubic symphysis, and must be identified and ligated during anterior intrapelvic approaches.

Question 1663

Topic: Surgical Anatomy & Approaches

A patient suffers from quadrilateral space syndrome, leading to localized shoulder weakness and paresthesia. Which nerve and vessel pass through this specific anatomic space?

. Suprascapular nerve and suprascapular artery
. Axillary nerve and posterior circumflex humeral artery
. Radial nerve and profunda brachii artery
. Musculocutaneous nerve and anterior circumflex humeral artery
. Lower subscapular nerve and subscapular artery

Correct Answer & Explanation

. Suprascapular nerve and suprascapular artery

Explanation

The quadrangular (quadrilateral) space is bounded 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 humeral circumflex artery.

Question 1664

Topic: Surgical Anatomy & Approaches

During a lateral approach to the distal humerus, the radial nerve is identified. At what approximate landmark does the radial nerve pierce the lateral intermuscular septum to pass from the posterior to the anterior compartment of the arm?

. 5 cm proximal to the lateral epicondyle
. 10 cm proximal to the lateral epicondyle
. 15 cm proximal to the lateral epicondyle
. At the level of the radial tuberosity
. At the mid-diaphysis of the humerus

Correct Answer & Explanation

. 5 cm proximal to the lateral epicondyle

Explanation

The radial nerve runs in the spiral groove and pierces the lateral intermuscular septum approximately 10 cm (range 7.5-12 cm) proximal to the lateral epicondyle to enter the anterior compartment of the arm. Knowing this anatomy is critical for surgical approaches and safe placement of external fixator half-pins.

Question 1665

Topic: Surgical Anatomy & Approaches

The posterior interosseous nerve (PIN) is at risk during a volar approach (Henry) to the proximal radius. Through which specific structure does the PIN pass as it enters the posterior compartment of the forearm?

. Between the two heads of the pronator teres
. Deep to the fibrous arch of the flexor digitorum superficialis
. Under the Arcade of Frohse
. Through the interosseous membrane at the mid-diaphysis
. Through the quadrilateral space

Correct Answer & Explanation

. Between the two heads of the pronator teres

Explanation

The posterior interosseous nerve (PIN), 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.

Question 1666

Topic: Surgical Anatomy & Approaches

The femoral nerve is the largest branch of the lumbar plexus. It descends through the pelvis to enter the anterior thigh. What is its anatomical relationship to the psoas major muscle within the retroperitoneum?

. Emerges from the medial border of the psoas major
. Emerges from the lateral border of the psoas major
. Pierces the anterior surface of the psoas major
. Runs strictly posterior to the quadratus lumborum
. Emerges through the greater sciatic foramen

Correct Answer & Explanation

. Emerges from the medial border of the psoas major

Explanation

The femoral nerve (roots L2-L4) emerges from the lateral border of the psoas major muscle, descending in the anatomic groove between the psoas and iliacus muscles before passing under the inguinal ligament. The obturator nerve emerges from the medial border, and the genitofemoral nerve pierces the anterior surface of the psoas major.

Question 1667

Topic: Surgical Anatomy & Approaches

A surgeon is performing a posterolateral approach to the distal tibia for a pilon fracture. What is the internervous plane utilized in this approach?

. Between Flexor hallucis longus and Peroneus brevis
. Between Tibialis posterior and Flexor digitorum longus
. Between Gastrocnemius and Soleus
. Between Peroneus brevis and Extensor digitorum longus
. Between Tibialis anterior and Extensor hallucis longus

Correct Answer & Explanation

. Between Flexor hallucis longus and Peroneus brevis

Explanation

The posterolateral approach to the tibia utilizes the internervous plane between the lateral compartment (superficial peroneal nerve) and the deep posterior compartment (tibial nerve). Specifically, the muscular interval developed is between the peroneus brevis anteriorly and the flexor hallucis longus posteriorly.

Question 1668

Topic: Surgical Anatomy & Approaches

During the ilioinguinal approach for an acetabular fracture, the surgeon develops the middle window. Which of the following structures forms the medial border of this middle window?

. Iliopectineal fascia
. External iliac vessels
. Iliopsoas muscle
. Spermatic cord
. Femoral nerve

Correct Answer & Explanation

. Iliopectineal fascia

Explanation

The ilioinguinal approach creates three distinct surgical windows. The medial window is between the rectus abdominis and the external iliac vessels. The middle window is bordered medially by the external iliac vessels and laterally by the iliopsoas muscle. The lateral window lies lateral to the iliopsoas.

Question 1669

Topic: Surgical Anatomy & Approaches

A 45-year-old male sustains a midshaft humerus fracture and is treated with open reduction and internal fixation via an anterolateral approach. Which of the following describes the correct internervous plane for the distal extent of this approach?

. Between Biceps brachii and Triceps brachii
. Between Brachialis and Brachioradialis
. Between Brachialis and Triceps brachii
. Between Brachioradialis and Extensor carpi radialis longus
. Between Pronator teres and Brachioradialis

Correct Answer & Explanation

. Between Biceps brachii and Triceps brachii

Explanation

Proximally, the anterolateral approach to the humerus goes between the deltoid (axillary n.) and pectoralis major (pectoral nerves). Distally, the true internervous plane is between the brachialis (musculocutaneous n.) and the brachioradialis (radial n.). Splitting the brachialis longitudinally in its lateral third is also a common variation to protect the radial nerve.

Question 1670

Topic: Surgical Anatomy & Approaches

Which of the following muscles of the lower extremity is exclusively innervated by the common peroneal division of the sciatic nerve?

. Semimembranosus
. Long head of the biceps femoris
. Short head of the biceps femoris
. Semitendinosus
. Adductor magnus (hamstring part)

Correct Answer & Explanation

. Semimembranosus

Explanation

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

Question 1671

Topic: Surgical Anatomy & Approaches

A patient is undergoing a volar (Henry) approach to the forearm for fixation of a proximal radial shaft fracture. In the proximal third of the forearm, the internervous plane is between which of the following two muscles?

. Flexor carpi radialis and Palmaris longus
. Brachioradialis and Pronator teres
. Brachioradialis and Flexor carpi radialis
. Pronator teres and Flexor carpi radialis
. Flexor digitorum superficialis and Flexor carpi ulnaris

Correct Answer & Explanation

. Flexor carpi radialis and Palmaris longus

Explanation

The volar (Henry) approach to the radius exploits the internervous plane between the brachioradialis (radial nerve) and the pronator teres (median nerve) in the proximal forearm. In the distal forearm, the plane is between the brachioradialis and the flexor carpi radialis.

Question 1672

Topic: Surgical Anatomy & Approaches

A surgeon is evaluating a patient with axillary nerve entrapment. Which of the following neurovascular structures pass together through the quadrangular space of the shoulder?

. Radial nerve and profunda brachii artery
. Suprascapular nerve and suprascapular artery
. Axillary nerve and posterior circumflex humeral artery
. Circumflex scapular artery and axillary nerve
. Musculocutaneous nerve and anterior circumflex humeral artery

Correct Answer & Explanation

. Radial nerve and profunda brachii artery

Explanation

The quadrangular space is defined 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 serves as the exit for the axillary nerve and the posterior circumflex humeral artery.

Question 1673

Topic: Surgical Anatomy & Approaches

The deep branch of the radial nerve (posterior interosseous nerve) is at risk during surgical approaches to the proximal radius. Underneath which anatomical structure does the posterior interosseous nerve typically enter the supinator muscle?

. Lacertus fibrosus
. Arcade of Struthers
. Arcade of Frohse
. Ligament of Struthers
. Osborne's ligament

Correct Answer & Explanation

. Lacertus fibrosus

Explanation

The posterior interosseous nerve (PIN) passes under the thick fibrous proximal edge of the superficial head of the supinator muscle, known as the Arcade of Frohse. This is the most common site for PIN entrapment (radial tunnel syndrome).

Question 1674

Topic: Surgical Anatomy & Approaches

An orthopaedic surgeon is using the posterior (Kocher-Langenbeck) approach to the acetabulum. The sciatic nerve must be carefully identified and protected. In what percentage of the general population does the common peroneal division of the sciatic nerve pierce the piriformis muscle (Beaton and Anson type B)?

. 1%
. 10-15%
. 30-40%
. 50%
. 75%

Correct Answer & Explanation

. 1%

Explanation

Anatomical variations exist in the relationship between the sciatic nerve and the piriformis muscle. In approximately 85% of people, the entire nerve exits below the piriformis. In about 10-15% of the population, the common peroneal division pierces the piriformis while the tibial division passes below it.

Question 1675

Topic: Surgical Anatomy & Approaches

A surgeon is performing a lateral approach to the proximal humerus. To avoid iatrogenic injury to the axillary nerve, the deltoid split should not extend distal to what landmark?

. 1 cm distal to the lateral edge of the acromion
. 3 cm distal to the lateral edge of the acromion
. 5 cm distal to the lateral edge of the acromion
. 7 cm distal to the lateral edge of the acromion
. 9 cm distal to the lateral edge of the acromion

Correct Answer & Explanation

. 1 cm distal to the lateral edge of the acromion

Explanation

The axillary nerve crosses the humerus approximately 5 to 7 cm distal to the lateral edge of the acromion. Extending a deltoid split beyond 5 cm places the nerve at significant risk of transection.

Question 1676

Topic: Surgical Anatomy & Approaches

The volar (Henry) approach to the radius utilizes a distinct internervous plane. Proximally, this plane is developed between which two muscles?

. Brachioradialis and Pronator Teres
. Brachioradialis and Flexor Carpi Radialis
. Flexor Carpi Radialis and Palmaris Longus
. Pronator Teres and Flexor Carpi Radialis
. Extensor Carpi Radialis Longus and Brachioradialis

Correct Answer & Explanation

. Brachioradialis and Pronator Teres

Explanation

The proximal internervous plane of the volar Henry approach is between the brachioradialis (radial nerve) and the pronator teres (median nerve). Distally, the plane transitions between the brachioradialis and the flexor carpi radialis.

Question 1677

Topic: Surgical Anatomy & Approaches

During a posterolateral (Kocher) approach to the radial head for a comminuted fracture, the internervous plane is developed between the anconeus and which other muscle?

. Extensor digitorum communis
. Extensor carpi ulnaris
. Flexor carpi ulnaris
. Brachioradialis
. Supinator

Correct Answer & Explanation

. Extensor digitorum communis

Explanation

The Kocher approach utilizes an internervous plane between the anconeus (innervated by the radial nerve) and the extensor carpi ulnaris (innervated by the posterior interosseous nerve).

Question 1678

Topic: Surgical Anatomy & Approaches

The anterolateral (Watson-Jones) approach to the hip exploits the plane between the tensor fasciae latae (TFL) and the gluteus medius. Which nerve innervates both of these muscles?

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

Correct Answer & Explanation

. Superior gluteal nerve

Explanation

Both the TFL and gluteus medius are innervated by the superior gluteal nerve. Therefore, the Watson-Jones approach utilizes an intermuscular, rather than a true internervous, plane.

Question 1679

Topic: Surgical Anatomy & Approaches

In the most common anatomical variant of the sciatic nerve's relationship to the piriformis muscle, where do the common peroneal and tibial nerve divisions exit the pelvis?

. Both pass inferior to the piriformis
. Both pass through the piriformis
. Peroneal passes through and tibial passes inferior
. Peroneal passes superior and tibial passes inferior
. Both pass superior to the piriformis

Correct Answer & Explanation

. Both pass inferior to the piriformis

Explanation

In over 80% of individuals, the undivided sciatic nerve passes completely inferior to the piriformis muscle through the greater sciatic foramen. Variations involving the peroneal division piercing or passing above the piriformis are less common.

Question 1680

Topic: Surgical Anatomy & Approaches

A patient suffers a midshaft humeral fracture. During a lateral approach to the humerus, the radial nerve is identified piercing the lateral intermuscular septum. At what approximate distance proximal to the lateral epicondyle does this transition occur?

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

Correct Answer & Explanation

. 2 cm

Explanation

The radial nerve pierces the lateral intermuscular septum, transitioning from the posterior compartment to the anterior compartment, approximately 10 cm proximal to the lateral epicondyle.

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