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Surgical Anatomy & Approaches MCQs

Practice Set 79 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 1561

Topic: Surgical Anatomy & Approaches

Which of the following is an accepted indication for surgical exploration of the radial nerve in the context of a humeral shaft fracture?

. Primary radial nerve palsy with a closed humeral shaft fracture and no other surgical indications
. Incomplete radial nerve palsy that worsens after closed reduction
. Complete radial nerve palsy without recovery signs at 2 weeks post-injury
. Sensory loss in the radial nerve distribution only
. Radiographic evidence of nerve entrapment by a comminuted fragment

Correct Answer & Explanation

. Incomplete radial nerve palsy that worsens after closed reduction

Explanation

An incomplete radial nerve palsy that worsens after closed reduction (or any manipulation) is a strong indication for surgical exploration. This suggests potential iatrogenic injury, nerve entrapment by fracture fragments or scar tissue, or progressive compression. Primary radial nerve palsy with closed fracture typically warrants observation for 3-6 months unless other surgical indications exist. Two weeks is too early to assess recovery. Sensory loss alone is usually observed. Radiographic evidence of entrapment is an indication, but option B is a more common and explicit trigger for exploration.

Question 1562

Topic: Surgical Anatomy & Approaches

A 50-year-old male develops a foot drop immediately after primary total hip arthroplasty performed via a posterior approach. Clinical examination reveals weakness in ankle dorsiflexion and eversion, and sensory loss over the dorsum of the foot. What is the most likely injured nerve, and which factor is most commonly implicated in this type of injury?

. Femoral nerve; prolonged anterior retraction.
. Obturator nerve; excessive medial reaming.
. Sciatic nerve; limb lengthening exceeding 4 cm.
. Lateral femoral cutaneous nerve; direct compression from retractor blade.
. Peroneal nerve; direct trauma during wound closure.

Correct Answer & Explanation

. Sciatic nerve; limb lengthening exceeding 4 cm.

Explanation

Foot drop (weakness in ankle dorsiflexion and eversion) with sensory loss over the dorsum of the foot is the classic presentation of sciatic nerve palsy, specifically the peroneal division, which is more susceptible to stretch injury. The sciatic nerve (C) is at risk during a posterior approach due to direct trauma, thermal injury, or, most commonly, excessive limb lengthening. Limb lengthening exceeding 4 cm is a significant risk factor for sciatic nerve injury. The femoral nerve (A) is anterior. The obturator nerve (B) is medial. The lateral femoral cutaneous nerve (D) causes numbness in the lateral thigh (meralgia paresthetica). While the peroneal nerve (E) is affected, it's typically due to injury to its parent, the sciatic nerve, at the hip level, rather than isolated direct trauma during closure.

Question 1563

Topic: Surgical Anatomy & Approaches

A 70-year-old male with a history of Parkinson's disease undergoing primary THA via a direct anterior approach for severe osteoarthritis. Due to his underlying condition and a significant leg length discrepancy, the surgeon anticipates increased risk of neurological injury. Which of the following intraoperative neuromonitoring techniques would be most appropriate to mitigate this risk, specifically for the femoral nerve?

. Somatosensory evoked potentials (SSEPs).
. Motor evoked potentials (MEPs).
. Electromyography (EMG) of the vastus medialis and tibialis anterior.
. Transcranial motor evoked potentials (TcMEPs).
. Nerve conduction studies (NCS) postoperatively.

Correct Answer & Explanation

. Electromyography (EMG) of the vastus medialis and tibialis anterior.

Explanation

For monitoring the femoral nerve specifically, electromyography (EMG) of the muscles innervated by the femoral nerve (e.g., vastus medialis, quadriceps) provides real-time feedback on nerve irritation or impingement during surgery. The question asks to mitigate risk, so real-time intraoperative monitoring is required. Given the DA approach, the femoral nerve is at risk from retraction, not typically from limb lengthening as much as the sciatic nerve. SSEPs (A) primarily monitor sensory pathways. MEPs (B) and TcMEPs (D) monitor motor pathways but are more commonly used for spinal cord monitoring and may not provide specific peripheral nerve localization or real-time feedback for femoral nerve stretching during hip procedures. NCS (E) is a diagnostic tool used postoperatively, not for intraoperative risk mitigation. Therefore, EMG of the relevant muscles is the most appropriate.

Question 1564

Topic: Surgical Anatomy & Approaches

Following a primary THA via a posterior approach, a patient exhibits a foot drop and inability to extend the great toe, but plantar flexion is preserved. Which specific nerve division is most likely injured?

. Tibial division of the sciatic nerve
. Femoral nerve
. Common peroneal division of the sciatic nerve
. Superior gluteal nerve
. Obturator nerve

Correct Answer & Explanation

. Common peroneal division of the sciatic nerve

Explanation

The common peroneal division of the sciatic nerve is uniquely vulnerable to stretch injury during THA, particularly when lengthening the limb. Injury presents with weakness in ankle dorsiflexion and great toe extension, resulting in a clinical foot drop.

Question 1565

Topic: Surgical Anatomy & Approaches

A 24-year-old athlete sustains a traction injury to the shoulder, presenting with weakness in forward elevation and isolated sensory loss over the lateral aspect of the proximal arm. An MRI reveals a compressive lesion within the quadrangular space.

What anatomical structure forms the medial border of this space?

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

Correct Answer & Explanation

. Surgical neck of the humerus

Explanation

The quadrangular space transmits the axillary nerve and the posterior circumflex humeral artery. Its borders are: Superiorly - Teres minor; Inferiorly - Teres major; Medially - Long head of the triceps; Laterally - Surgical neck of the humerus. The patient's symptoms (deltoid weakness and lateral arm sensory loss) are classic for axillary nerve pathology.

Question 1566

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach to the shoulder for a hemiarthroplasty, the internervous plane is developed. Which of the following statements regarding the handling of the cephalic vein during this approach is anatomically correct?

. It should be retracted medially to preserve venous drainage of the deltoid.
. It should be retracted laterally to preserve venous drainage of the deltoid.
. It is a direct tributary to the external jugular vein.
. It runs in the internervous plane between the axillary and median nerves.
. It must be ligated routinely to expose the subscapularis.

Correct Answer & Explanation

. It should be retracted laterally to preserve venous drainage of the deltoid.

Explanation

The deltopectoral approach uses the internervous plane between the deltoid (axillary nerve) and pectoralis major (medial and lateral pectoral nerves). The cephalic vein lies in this interval. It is generally recommended to retract the cephalic vein laterally with the deltoid to preserve its primary venous tributaries, which originate from the deltoid muscle.

Question 1567

Topic: Surgical Anatomy & Approaches

The volar approach to the radius (Henry approach) utilizes two different internervous planes depending on the region of the forearm. Proximally, the plane is between the brachioradialis and the pronator teres. Which nerves supply these two muscles, respectively?

. Radial and Ulnar
. Median and Radial
. Radial and Median
. Musculocutaneous and Median
. Radial and Anterior Interosseous

Correct Answer & Explanation

. Median and Radial

Explanation

The proximal internervous plane of the volar Henry approach is between the Brachioradialis (innervated by the Radial nerve) and the Pronator Teres (innervated by the Median nerve). The distal internervous plane is between the Brachioradialis (Radial nerve) and the Flexor Carpi Radialis (Median nerve).

Question 1568

Topic: Surgical Anatomy & Approaches

When performing an anterior approach to the hip (Smith-Petersen), the internervous plane is between the sartorius and the tensor fasciae latae superficially. Which of the following structures is at greatest risk of iatrogenic injury during the superficial dissection?

. Femoral nerve
. Lateral femoral cutaneous nerve
. Superior gluteal nerve
. Medial femoral circumflex artery
. Ascending branch of the lateral femoral circumflex artery

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

During the anterior approach to the hip (Smith-Petersen), the superficial internervous plane is between the Sartorius (Femoral nerve) and the Tensor Fasciae Latae (Superior Gluteal nerve). The Lateral Femoral Cutaneous Nerve (LFCN) typically crosses over the sartorius 2-3 cm distal to the ASIS and is at high risk of injury during this superficial dissection.

Question 1569

Topic: Surgical Anatomy & Approaches

A trauma surgeon is applying a lateral plate to the humerus for a highly displaced midshaft fracture. To safely expose the bone distally, the path of the radial nerve must be meticulously protected. At what approximate distance proximal to the lateral epicondyle does the radial nerve typically pierce the lateral intermuscular septum to enter the anterior compartment of the arm?

. 2-3 cm
. 5-6 cm
. 10-12 cm
. 15-16 cm
. 18-20 cm

Correct Answer & Explanation

. 10-12 cm

Explanation

The radial nerve runs in the spiral groove of the posterior humerus and typically pierces the lateral intermuscular septum approximately 10 to 12 cm proximal to the lateral epicondyle to enter the anterior compartment of the arm. It then travels distally between the brachialis and brachioradialis muscles.

Question 1570

Topic: Surgical Anatomy & Approaches

During a Latarjet procedure for recurrent anterior shoulder instability with significant glenoid bone loss, the coracoid process is osteotomized and transferred to the anterior glenoid rim.

Which nerve is most at risk of injury due to overzealous medial retraction of the conjoint tendon?

. Axillary nerve
. Suprascapular nerve
. Musculocutaneous nerve
. Median nerve
. Radial nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The musculocutaneous nerve typically enters the coracobrachialis muscle 3 to 8 cm distal to the tip of the coracoid process. During the Latarjet procedure, aggressive medial retraction of the conjoint tendon can stretch or compress this nerve. The axillary nerve runs inferiorly but is more at risk during capsular release or inferior glenoid preparation.

Question 1571

Topic: Surgical Anatomy & Approaches

A 35-year-old overhead athlete complains of chronic, vague posterior shoulder pain and numbness over the lateral deltoid. Physical examination demonstrates point tenderness at the posterior aspect of the shoulder, inferior to the teres minor and lateral to the long head of the triceps. Which neurovascular bundle is most likely entrapped in this 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
. Dorsal scapular nerve and dorsal scapular artery

Correct Answer & Explanation

. Axillary nerve and posterior circumflex humeral artery

Explanation

The patient is describing Quadrilateral Space Syndrome. 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 humeral shaft. Entrapment of the axillary nerve and posterior circumflex humeral artery in this space (often by fibrous bands) leads to posterior shoulder pain and deltoid paresthesias.

Question 1572

Topic: Surgical Anatomy & Approaches

A 24-year-old rugby player undergoes a Latarjet procedure for recurrent anterior shoulder instability with 25% glenoid bone loss. Postoperatively, he exhibits profound weakness in elbow flexion and decreased sensation over the lateral aspect of his forearm. Which nerve was most likely injured during coracoid retraction?

. Axillary nerve
. Radial nerve
. Musculocutaneous nerve
. Median nerve
. Suprascapular nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The musculocutaneous nerve enters the coracobrachialis muscle 3 to 8 cm distal to the coracoid tip and is at high risk during inferior retraction of the conjoint tendon. Injury causes biceps and brachialis weakness as well as lateral antebrachial cutaneous sensory loss.

Question 1573

Topic: Surgical Anatomy & Approaches

A 45-year-old male sustains a pelvic ring injury and requires surgical fixation via an anterior intrapelvic (modified Stoppa) approach. During dissection along the superior pubic ramus, brisk arterial bleeding is encountered. This bleeding is most likely originating from the 'corona mortis'. Which of the following describes the most common anatomical configuration of this vascular structure?

. An anastomosis between the internal pudendal artery and the inferior gluteal artery
. An anastomosis between the obturator vessels and the external iliac or inferior epigastric vessels
. An anastomosis between the superior gluteal artery and the iliolumbar artery
. A terminal branch of the internal iliac artery directly supplying the pubic symphysis
. An aberrant branch of the femoral artery traversing the inguinal canal

Correct Answer & Explanation

. An anastomosis between the obturator vessels and the external iliac or inferior epigastric vessels

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 typically crosses the superior pubic ramus at an average distance of 5-6 cm from the pubic symphysis. Injury during ilioinguinal or Stoppa approaches can lead to significant, difficult-to-control hemorrhage.

Question 1574

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 1575

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 1576

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 1577

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 1578

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 1579

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 1580

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).

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