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 1701
Topic: Surgical Anatomy & Approaches
A 6-year-old child sustains an extension-type supracondylar humerus fracture with posterolateral displacement. Which of the following neurologic structures is at greatest risk of injury?
Correct Answer & Explanation
. Ulnar nerve
Explanation
In an extension-type supracondylar humerus fracture with posterolateral displacement of the distal fragment, the proximal fragment is directed anteromedially. This anteromedial spike places the median nerve (specifically the anterior interosseous nerve branch) and the brachial artery at the greatest risk of injury. Conversely, posteromedial displacement of the distal fragment drives the proximal fragment anterolaterally, risking the radial nerve.
Question 1702
Topic: Surgical Anatomy & Approaches
A 35-year-old male sustained a closed mid-shaft humerus fracture resulting in an immediate complete radial nerve palsy. Four months post-injury, there is no clinical or electromyographic (EMG) evidence of recovery. If surgical exploration confirms a Sunderland Grade III nerve injury, what is the precise microanatomic state of the affected nerve?
Correct Answer & Explanation
. Axonal and endoneurial disruption with an intact perineurium
Explanation
In the Sunderland classification: Grade I (Neuropraxia) = local myelin damage; Grade II (Axonotmesis) = axonal disruption with intact endoneurium (excellent recovery potential); Grade III = axonal and endoneurial disruption with intact perineurium (unpredictable recovery due to intraneural scarring); Grade IV = disruption of axon, endoneurium, and perineurium, leaving only the epineurium intact; Grade V = complete nerve transection (Neurotmesis).
Question 1703
Topic: Surgical Anatomy & Approaches
A 62-year-old female undergoes a ligament reconstruction and tendon interposition (LRTI) using the flexor carpi radialis (FCR) tendon for advanced Eaton-Littler Stage III thumb CMC arthritis. During the surgical approach to the CMC joint, which of the following nerves is at greatest risk of iatrogenic injury?
Correct Answer & Explanation
. Superficial radial nerve
Explanation
The surgical approach to the thumb carpometacarpal (CMC) joint often involves a dorsal or dorsoradial incision. The terminal sensory branches of the superficial radial nerve run directly over this area and are at highest risk of injury, which can lead to painful neuromas. Careful blunt dissection and retraction are required to protect them.
Question 1704
Topic: Surgical Anatomy & Approaches
A 62-year-old woman undergoes a ligament reconstruction and tendon interposition (LRTI) using the flexor carpi radialis (FCR) tendon for advanced thumb carpometacarpal (CMC) arthritis. Postoperatively, she complains of new-onset numbness and tingling over the dorsal-radial aspect of the hand. Injury to which of the following nerves most likely occurred during the surgical approach?
Correct Answer & Explanation
. Palmar cutaneous branch of the median nerve
Explanation
The superficial branch of the radial nerve (SBRN) is highly vulnerable to injury or traction during the dorsal-radial surgical approaches to the thumb CMC joint, such as those used for LRTI. Injury results in numbness or painful neuromas over the dorsal-radial hand.
Question 1705
Topic: Surgical Anatomy & Approaches
You are reviewing an axial cross-section of the shoulder during a pre-operative imaging review for a posterior approach.
What structure forms the superior boundary of the quadrangular space, and what is its primary innervation?
Correct Answer & Explanation
. Teres major; Lower subscapular nerve
Explanation
The quadrangular space is a critical anatomic space in the posterior shoulder. Its boundaries are: superiorly the teres minor (innervated by the axillary nerve), inferiorly the teres major, medially the long head of the triceps, and laterally the surgical neck of the humerus. It contains the axillary nerve and the posterior circumflex humeral artery.
Question 1706
Topic: Surgical Anatomy & Approaches
A surgeon plans a volar (Henry) approach to the proximal radius for open reduction internal fixation of a diaphyseal fracture.
What are the innervations of the muscles defining the proximal internervous plane in this approach?
Correct Answer & Explanation
. Radial nerve and Median nerve
Explanation
The proximal internervous plane of the volar (Henry) approach to the forearm utilizes the interval between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve). Distally, the plane is between the brachioradialis and the flexor carpi radialis (median nerve).
Question 1707
Topic: Surgical Anatomy & Approaches
During a posterior (Kocher-Langenbeck) approach to the hip, protecting the primary blood supply to the adult femoral head is paramount. In this region, where is the deep branch of the medial femoral circumflex artery (MFCA) consistently found?
Correct Answer & Explanation
. Superior to the piriformis tendon
Explanation
The medial femoral circumflex artery (MFCA) is the primary blood supply to the adult femoral head. The deep branch of the MFCA runs anterior to the quadratus femoris and posterior to the obturator externus. To protect it during a posterior approach, the surgeon must avoid releasing the obturator externus and should not divide the quadratus femoris too medially.
Question 1708
Topic: Surgical Anatomy & Approaches
During a midfoot surgical approach, the surgeon identifies the 'Master Knot of Henry' on the plantar aspect of the foot. At this location, what is the specific anatomical relationship between the traversing long flexor tendons?
Correct Answer & Explanation
. The flexor hallucis longus (FHL) crosses dorsal (deep) to the flexor digitorum longus (FDL)
Explanation
The Master Knot of Henry is an important anatomic landmark located on the plantar aspect of the midfoot at the level of the navicular. Here, the flexor hallucis longus (FHL) tendon crosses dorsal (deep) to the flexor digitorum longus (FDL) tendon. It is a critical site of potential tendon tethering or tenosynovitis.
Question 1709
Topic: Surgical Anatomy & Approaches
A saphenous nerve block is planned within the adductor (Hunter's) canal for post-operative analgesia following knee surgery. Besides the superficial femoral artery and vein, what other structures travel through the adductor canal?
Correct Answer & Explanation
. Femoral nerve and nerve to vastus intermedius
Explanation
The adductor canal (Hunter's canal) begins at the apex of the femoral triangle and ends at the adductor hiatus. Its contents include the superficial femoral artery, superficial femoral vein, the saphenous nerve, and the nerve to the vastus medialis. The main femoral nerve has already arborized proximally in the femoral triangle.
Question 1710
Topic: Surgical Anatomy & Approaches
During a standard ilioinguinal approach for an anterior column acetabular fracture, the surgeon is working in the middle window. Which of the following neurovascular structures is primarily found in this window?
Correct Answer & Explanation
. Femoral nerve and iliopsoas
Explanation
The ilioinguinal approach has three windows. The middle window, located between the iliopectineal fascia and the conjoint tendon, contains the external iliac artery and vein.
Question 1711
Topic: Surgical Anatomy & Approaches
A 35-year-old male sustains a midshaft humerus fracture and develops a secondary radial nerve palsy after closed reduction. If the surgeon decides to explore the nerve via a posterior approach, between which two muscle bellies does the radial nerve most reliably emerge from the spiral groove?
Correct Answer & Explanation
. Long head and lateral head of the triceps
Explanation
In the posterior approach to the humerus, the radial nerve is found in the spiral groove between the lateral and medial heads of the triceps. The long head is medial to the nerve.
Question 1712
Topic: Surgical Anatomy & Approaches
While performing an extended volar approach to the radiocarpal joint (Henry approach), the surgeon retracts the flexor carpi radialis (FCR) tendon. To minimize the risk of injury to the palmar cutaneous branch of the median nerve (PCBMN), in which direction should the FCR tendon be retracted and where does the PCBMN typically lie?
Correct Answer & Explanation
. FCR retracted radially; PCBMN lies radial to the FCR
Explanation
The PCBMN typically arises 5 cm proximal to the wrist crease and travels on the ulnar side of the FCR. Retracting the FCR ulnarly protects the nerve during the volar approach.
Question 1713
Topic: Surgical Anatomy & Approaches
A surgeon is utilizing the Smith-Petersen approach to the hip. This approach exploits an internervous plane between which of the following muscles superficially?
The superficial internervous plane in the anterior (Smith-Petersen) approach to the hip lies between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve).
Question 1714
Topic: Surgical Anatomy & Approaches
While executing a deltopectoral approach for a total shoulder arthroplasty, the coracobrachialis is retracted.
To avoid iatrogenic injury, the surgeon must remember that the musculocutaneous nerve typically enters the coracobrachialis at what average distance distal to the coracoid process?
Correct Answer & Explanation
. 1 to 3 cm
Explanation
The musculocutaneous nerve typically penetrates the coracobrachialis muscle at an average distance of 5 to 8 cm distal to the tip of the coracoid process. Aggressive distal retraction of the conjoined tendon can cause neuropraxia.
Question 1715
Topic: Surgical Anatomy & Approaches
When planning an anterolateral approach to the distal humerus, an MRI shows the radial nerve piercing the lateral intermuscular septum. At what average distance proximal to the lateral epicondyle does this anatomically occur?
Correct Answer & Explanation
. 3 cm
Explanation
The radial nerve pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment of the arm at approximately 10 cm proximal to the lateral epicondyle.
Question 1716
Topic: Surgical Anatomy & Approaches
In a coronal MRI of the brachial plexus evaluating a traction injury, the posterior cord is visualized. Which of the following is a direct terminal branch of the posterior cord?
Correct Answer & Explanation
. Musculocutaneous nerve
Explanation
The posterior cord of the brachial plexus gives rise to the upper subscapular, thoracodorsal, and lower subscapular nerves, before bifurcating into its terminal branches: the axillary and radial nerves.
Question 1717
Topic: Surgical Anatomy & Approaches
During a modified Stoppa approach for an acetabular fracture, an aberrant vascular anastomosis termed the 'corona mortis' is encountered over the superior pubic ramus. This structure connects which two vascular systems?
Correct Answer & Explanation
. Internal iliac (obturator) and external iliac (inferior epigastric)
Explanation
The corona mortis ('crown of death') is an anastomosis between the obturator vessels (internal iliac system) and the inferior epigastric vessels (external iliac system). It is vulnerable to severe bleeding during intrapelvic approaches if not properly identified and ligated.
Question 1718
Topic: Surgical Anatomy & Approaches
The Kocher-Langenbeck approach to the acetabulum does not utilize a true internervous plane. What is the primary innervation of the gluteus maximus muscle, which is split during the superficial dissection of this approach?
Correct Answer & Explanation
. Superior gluteal nerve
Explanation
The gluteus maximus is innervated by the inferior gluteal nerve. The Kocher-Langenbeck approach utilizes a muscle-splitting incision through the gluteus maximus rather than a true internervous plane.
Question 1719
Topic: Surgical Anatomy & Approaches
When performing a posterior approach to the humerus, the radial nerve must be identified and protected. Approximately how far proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum?
Correct Answer & Explanation
. 5 cm
Explanation
The radial nerve passes from the posterior compartment to the anterior compartment by piercing the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle. This is a critical landmark during the posterior approach.
Question 1720
Topic: Surgical Anatomy & Approaches
In the anterior approach to the hip (Smith-Petersen), the superficial internervous plane lies between two muscles. What are the respective innervations of these two muscles?
Correct Answer & Explanation
. Femoral nerve and superior gluteal nerve
Explanation
The superficial plane of the Smith-Petersen approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). This provides a safe, true internervous plane.
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