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 1641
Topic: Surgical Anatomy & Approaches
Which surgical approach to the hip carries the highest risk of sciatic nerve injury?
Correct Answer & Explanation
. Posterior (Moore) approach
Explanation
The posterior (Moore) approach to the hip involves dissecting through the short external rotators and often requires retraction of the sciatic nerve, placing it at the highest risk of injury compared to other approaches. The anterior, direct lateral, and anterolateral approaches generally pose a lower risk to the sciatic nerve as they are distant from its course.
Question 1642
Topic: Surgical Anatomy & Approaches
Which nerve is most commonly injured in a displaced midshaft humerus fracture?
Correct Answer & Explanation
. Radial nerve
Explanation
The radial nerve is intimately associated with the midshaft of the humerus as it courses through the spiral groove. Therefore, it is the most commonly injured nerve in midshaft humerus fractures. Injury to the radial nerve typically results in wrist drop and sensory deficits on the dorsum of the hand.
Question 1643
Topic: Surgical Anatomy & Approaches
A 25-year-old male driver involved in a head-on motor vehicle collision presents with severe hip pain. Radiographs reveal a posterior dislocation of the right hip. Prior to reduction, a detailed neurologic exam notes inability to extend the right great toe and decreased sensation over the dorsal first web space. The hip is successfully reduced via closed means under conscious sedation. Post-reduction, the neurologic deficit remains unchanged. What is the most appropriate management of the neurologic deficit?
Correct Answer & Explanation
. Observation and application of an ankle-foot orthosis (AFO)
Explanation
Sciatic nerve injury (most commonly the peroneal division) occurs in 10-20% of posterior hip dislocations. If the neurologic deficit is present BEFORE reduction and persists post-reduction, the standard of care is observation, as the injury is usually a neuropraxia from the initial stretch, and most patients recover spontaneously. An AFO helps prevent equinus contracture and assists with ambulation. Surgical exploration is indicated only if a new nerve palsy develops AFTER reduction (suggesting iatrogenic entrapment of the nerve or a bone fragment) or if an incarcerated fragment is seen on post-reduction CT.
Question 1644
Topic: Surgical Anatomy & Approaches
A 60-year-old male slips on ice and grabs a railing to break his fall, sustaining a forceful hyperabduction injury to his shoulder. He presents to the ER with his arm locked in 120 degrees of abduction and his elbow flexed, with his hand resting near his head. What is the most commonly associated nerve injury with this specific type of dislocation?
Correct Answer & Explanation
. Axillary nerve
Explanation
The clinical presentation (arm locked in extreme abduction/flexion) is pathognomonic for luxatio erecta (inferior shoulder dislocation). This severe injury has a high rate of associated complications. The axillary nerve is the most commonly injured nerve (up to 60% of cases) due to traction as the humeral head is forced inferiorly into the axilla. There is also a significant risk of axillary artery injury and massive rotator cuff tears.
Question 1645
Topic: Surgical Anatomy & Approaches
A 42-year-old male presents to the ED with his arm locked in 120 degrees of abduction and his forearm resting on his head following a fall. He reports numbness over the lateral aspect of his shoulder. Radiographs confirm luxatio erecta. Which neurovascular structure is most commonly injured in this type of dislocation?
Correct Answer & Explanation
. Axillary nerve
Explanation
Luxatio erecta is an inferior shoulder dislocation presenting with the arm locked in hyperabduction. The axillary nerve is the most commonly injured neurovascular structure due to the severe inferior displacement of the humeral head.
Question 1646
Topic: Surgical Anatomy & Approaches
When utilizing the volar approach (Henry approach) to the proximal third of the radius, the internervous plane developed during the superficial dissection lies between which two muscles?
Correct Answer & Explanation
. Brachioradialis and Pronator Teres
Explanation
The superficial internervous plane of the volar (Henry) approach to the forearm is between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve) proximally. In the distal third, the plane is between the brachioradialis and the flexor carpi radialis (median nerve). It is a true internervous approach throughout its length.
Question 1647
Topic: Surgical Anatomy & Approaches
During a volar approach to the forearm (Henry approach), the internervous plane in the proximal third of the forearm is developed between which of the following muscles?
Correct Answer & Explanation
. Brachioradialis and Pronator Teres
Explanation
The proximal 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). Distally, the plane shifts to run between the Brachioradialis and the Flexor Carpi Radialis (Median nerve).
Question 1648
Topic: Surgical Anatomy & Approaches
Following a closed humerus fracture, a patient develops a radial nerve palsy. Electromyography at 4 weeks shows active fibrillation potentials, and the nerve injury is determined to be a Sunderland Grade III. Which of the following neural connective tissue structures remains intact in this specific grade of injury?
Correct Answer & Explanation
. Perineurium
Explanation
In the Sunderland classification of nerve injury: Grade I = Neuropraxia (local myelin damage, no axon disruption). Grade II = Axonotmesis (axon disrupted, endoneurium intact). Grade III = Axon and endoneurium disrupted, perineurium intact. Grade IV = Axon, endoneurium, and perineurium disrupted, epineurium intact. Grade V = Neurotmesis (complete transection, epineurium disrupted). Thus, in Grade III, the perineurium remains intact.
Question 1649
Topic: Surgical Anatomy & Approaches
A surgeon utilizes the Smith-Petersen (anterior) approach for an open reduction of a developmental hip dysplasia. The superficial internervous plane lies between the sartorius and the tensor fasciae latae (TFL). What muscles define the deep internervous plane of this approach?
Correct Answer & Explanation
. Rectus femoris and gluteus minimus
Explanation
The Smith-Petersen (anterior) approach uses a true internervous plane superficially between the sartorius (femoral nerve) and TFL (superior gluteal nerve), and deeply between the rectus femoris (femoral nerve) and gluteus minimus (superior gluteal nerve).
Question 1650
Topic: Surgical Anatomy & Approaches
An orthopedic surgeon performing an ilioinguinal approach for open reduction of an anterior column acetabular fracture encounters brisk arterial bleeding while dissecting over the superior pubic ramus. This bleeding is most likely originating from the 'corona mortis', which is an anastomosis between which two vascular territories?
Correct Answer & Explanation
. External iliac and internal iliac systems
Explanation
The 'corona mortis' (crown of death) is a highly variable vascular anastomosis between the external iliac system (inferior epigastric artery/vein) and the internal iliac system (obturator artery/vein). It crosses over the superior pubic ramus and is highly susceptible to injury during anterior approaches to the pelvis and acetabulum.
Question 1651
Topic: Surgical Anatomy & Approaches
During the ilioinguinal approach to the pelvis, the surgeon must carefully identify and ligate the 'corona mortis' to prevent catastrophic hemorrhage. This structure typically represents an anastomosis between which two vascular systems?
Correct Answer & Explanation
. Inferior epigastric and obturator vessels
Explanation
The corona mortis ('crown of death') is a retropubic vascular anastomosis between the obturator vessels and the external iliac or inferior epigastric vessels. It is located over the superior pubic ramus and is at high risk of injury during anterior pelvic approaches.
Question 1652
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. The transferred coracoid brings with it the conjoined tendon. Which of the following nerves is at greatest risk of iatrogenic injury during the mobilization and inferior transfer of the conjoined tendon?
Correct Answer & Explanation
. Musculocutaneous nerve
Explanation
The musculocutaneous nerve enters the coracobrachialis muscle (which makes up part of the conjoined tendon along with the short head of the biceps) approximately 5 to 8 cm distal to the tip of the coracoid process. Aggressive inferior retraction or mobilization of the conjoined tendon puts this nerve at high risk for stretch or transection injuries.
Question 1653
Topic: Surgical Anatomy & Approaches
A 60-year-old woman with a long-standing history of rheumatoid arthritis presents with a progressive inability to actively extend her ring and small fingers at the MCP joints. Passive extension is full and intact, but the tenodesis effect is absent. What is the underlying pathophysiology of her condition?
Correct Answer & Explanation
. Attritional rupture of the extensor tendons over the distal ulna
Explanation
This is Vaughan-Jackson syndrome, which is characterized by the progressive attritional rupture of the digital extensor tendons in rheumatoid arthritis patients. It typically starts with the extensor digiti minimi and progresses radially to involve the EDC of the ring, long, and index fingers. It is most often caused by a dorsally prominent and subluxated distal ulna (caput ulnae syndrome) acting as a sharp fulcrum.
Question 1654
Topic: Surgical Anatomy & Approaches
During digital replantation following an acute traumatic amputation, successful revascularization and functional outcomes depend on a systematic surgical approach. Which anatomical structure should ideally be repaired or stabilized first to provide a foundation for the remainder of the microsurgical reconstruction?
Correct Answer & Explanation
. Bone
Explanation
The standard and universally accepted sequence for digital replantation starts with Bone (skeletal fixation). Stabilizing the bone first provides a rigid framework necessary to accurately repair and tension the remaining soft tissue structures. The typical sequence follows: Bone, Extensor tendons, Flexor tendons, Arteries, Nerves, and Veins.
Question 1655
Topic: Surgical Anatomy & Approaches
A surgeon is performing a primary THA using the Direct Anterior Approach (Smith-Petersen interval). Which of the following nerves is at the greatest risk of iatrogenic injury during the superficial dissection, and what is the corresponding sensory deficit?
The direct anterior approach to the hip utilizes the internervous plane between the sartorius (femoral nerve) and tensor fasciae latae (superior gluteal nerve). The lateral femoral cutaneous nerve (LFCN) typically crosses the anterior aspect of the thigh and branches in the proximal thigh. It is highly variable in its course but is at significant risk during the superficial dissection. Injury results in meralgia paresthetica, characterized by numbness, tingling, or burning pain over the anterolateral thigh.
Question 1656
Topic: Surgical Anatomy & Approaches
A surgeon is performing a primary total hip arthroplasty using the direct anterior approach. During the superficial dissection, which of the following nerve injuries is the most common complication?
Correct Answer & Explanation
. Lateral femoral cutaneous nerve
Explanation
The direct anterior approach uses the internervous plane between the tensor fasciae latae and sartorius. The lateral femoral cutaneous nerve is at high risk of neurapraxia during this superficial dissection.
Question 1657
Topic: Surgical Anatomy & Approaches
When utilizing the direct anterior approach for a primary total hip arthroplasty, the primary superficial internervous plane is developed between which two muscles?
Correct Answer & Explanation
. Sartorius and tensor fasciae latae
Explanation
The direct anterior (Smith-Petersen) approach exploits the true superficial internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve).
Question 1658
Topic: Surgical Anatomy & Approaches
When performing a Total Hip Arthroplasty (THA) via the direct anterior (Smith-Petersen) approach, the surgeon utilizes a true internervous plane. Which two muscles define this superficial surgical interval?
Correct Answer & Explanation
. Sartorius and Tensor fasciae latae (TFL)
Explanation
The direct anterior approach utilizes the internervous plane between the Sartorius (femoral nerve) and the Tensor Fasciae Latae (superior gluteal nerve) superficially. Deep, it passes between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).
Question 1659
Topic: Surgical Anatomy & Approaches
Which of the following approaches to the hip has historically been associated with the highest risk of postoperative dislocation if careful soft-tissue repair is not performed?
Correct Answer & Explanation
. Direct Anterior (Smith-Petersen)
Explanation
The posterior approach has historically carried the highest risk of posterior dislocation because it involves taking down the posterior capsule and short external rotators. A rigorous enhanced posterior soft-tissue repair significantly reduces this risk to levels comparable to other approaches.
Question 1660
Topic: Surgical Anatomy & Approaches
A 68-year-old man undergoes primary THA via a direct anterior approach. Postoperatively, he has weakness with active knee extension and diminished sensation over the anterior thigh. Which of the following structures was most likely injured during the surgical approach?
Correct Answer & Explanation
. Lateral femoral cutaneous nerve
Explanation
Weakness in knee extension and anterior thigh sensory loss indicate a femoral nerve injury. In the direct anterior approach, this can occur from excessive retraction medial to the tensor fasciae latae and sartorius interval.
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