AAOS Orthopedic Anatomy MCQs (Set 5): Musculoskeletal & Regional Review

You are interested in learning a new technique for minimally invasive total knee arthroplasty. The Keyhole Genuflex system seems appealing to you because the instrumentation comes with wireless controls. Which of the following represents an acceptable arrangement?

During the proximal extension of the volar (Henry) approach to the forearm, the surgeon elevates the supinator muscle to expose the proximal radius. Which nerve lies within the substance of the supinator and is at highest risk of iatrogenic injury if the muscle is elevated aggressively or incorrectly?

During a deltopectoral approach to the shoulder, the conjoint tendon is identified and retracted medially to access the subscapularis. Excessive medial retraction of the conjoint tendon places which of the following nerves at greatest risk of neuropraxia?

A surgeon is performing a posterior (Moore) approach to the hip. The short external rotators are detached near their trochanteric insertions and reflected posteriorly. Which muscle is intentionally left intact to protect the medial circumflex femoral artery (MFCA) from iatrogenic injury?

The anterior (Smith-Petersen) approach to the hip utilizes both superficial and deep internervous planes. Which of the following describes the deep internervous plane for this approach?

During a direct lateral (Hardinge) approach to the hip, the gluteus medius and vastus lateralis are split. The proximal split of the gluteus medius must not extend beyond 3 to 5 cm from the tip of the greater trochanter to avoid denervating the anterior portion of the muscle. Which nerve is at risk?

While performing a modified Stoppa approach for an anterior column acetabular fracture, the surgeon encounters severe hemorrhage when dissecting over the superior pubic ramus. This bleeding is most likely originating from the corona mortis, an anastomosis between which two vascular systems?

During an anterior approach to the ankle for arthrodesis, the surgeon develops the interval between the extensor hallucis longus (EHL) and the extensor digitorum longus (EDL). Which neurovascular bundle lies deep within this interval and must be mobilized and protected?

When performing an anterolateral approach to the distal half of the humerus, the radial nerve must be identified and protected. In this distal region, the primary internervous plane is developed between which two muscles?

The posteromedial approach to the knee is often utilized for repairing tibial avulsions of the posterior cruciate ligament (PCL) or accessing the posterior horn of the medial meniscus. This approach develops an interval between which of the following muscle bellies?

During an open in-situ ulnar nerve decompression at the cubital tunnel, the skin incision is made just posterior to the medial epicondyle. To avoid painful neuroma formation, the surgeon must carefully identify and protect a sensory nerve branch that crosses the proximal forearm transversely. Which nerve is this?

To safely execute a standard open carpal tunnel release while minimizing the risk of injuring the palmar cutaneous branch of the median nerve, the surgeon should align the longitudinal incision with which anatomical landmark?

During a tarsal tunnel release, the surgeon sequentially identifies structures from anteromedial to posterolateral behind the medial malleolus. Which structure lies immediately posterior to the flexor digitorum longus (FDL) tendon?

The Wiltse paraspinal approach to the lumbar spine is frequently used for minimally invasive pedicle screw placement or far-lateral disc excisions. This approach relies on a natural avascular cleavage plane between which two muscle groups?

A surgeon is performing a posterior approach to the upper cervical spine to treat an atlantoaxial subluxation. Deep dissection exposes the suboccipital triangle. Which critical structure lies within the borders of this triangle?

When harvesting an autogenous structural bone graft from the medial distal tibia, a longitudinal incision is typically made over the medial aspect of the medial malleolus. Which structure is most susceptible to iatrogenic injury during the superficial exposure in this region?

During a posterior approach to the humeral shaft for open reduction internal fixation of a spiral midshaft fracture, the radial nerve is identified within the spiral groove. Which blood vessel accompanies the radial nerve in this anatomic location?

When establishing a posterolateral portal during knee arthroscopy, the surgeon makes an incision posterior to the fibular collateral ligament. The incision must remain strictly anterior to the biceps femoris tendon and superior to the fibular head to prevent injury to which structure?

During diagnostic shoulder arthroscopy, an anterior portal is created using an outside-in technique. The portal should be placed just lateral to the coracoid process. Misplacement of this portal too far medially significantly increases the risk of injuring which neurovascular bundle as it enters the conjoint tendon?

A patient undergoes a minimally invasive percutaneous repair of an acute Achilles tendon rupture using a specialized passing jig. Following surgery, the patient reports severe lateral foot numbness and radiating pain. Entrapment of which nerve by a proximolateral locking suture most likely occurred?

During a posterior approach to the shoulder, the surgeon identifies the teres minor, teres major, long head of the triceps, and the humeral shaft. Which of the following neurovascular structures traverses this specific anatomic space?

A 28-year-old volleyball player presents with isolated weakness in external rotation of the shoulder. MRI reveals a paralabral cyst. Compression of the involved nerve at the spinoglenoid notch will selectively denervate which of the following muscles?

When performing a lateral approach to the distal humerus, the surgeon must protect the radial nerve. On average, at what distance proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum to enter the anterior compartment?

A patient exhibits an inability to actively extend the metacarpophalangeal joints of the fingers and thumb, but maintains normal wrist extension with radial deviation. Which of the following anatomic structures is the most common site of compression for the affected nerve?

Electrodiagnostic testing of a patient reveals an anomalous median-to-ulnar nerve communication in the forearm. This anomaly most commonly involves crossing motor fibers that eventually innervate which of the following muscles?

During an ilioinguinal approach to the acetabulum, severe hemorrhage occurs over the posterior aspect of 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?

A direct anterior (Smith-Petersen) approach to the hip utilizes an internervous plane between the sartorius and tensor fasciae latae. Which of the following structures is most at risk of injury in the superficial dissection of this approach?

During a direct lateral (Hardinge) approach to the hip, proximal splitting of the gluteus medius must be limited to prevent denervation of its anterior portion and the tensor fasciae latae. What is the generally accepted maximal safe distance for this split proximal to the tip of the greater trochanter?

In the normal anatomic variant, the sciatic nerve exits the pelvis through the greater sciatic foramen. What is its relationship to the piriformis muscle in the vast majority of the general population?

A patient is undergoing reconstruction of the posterolateral corner (PLC) of the knee. Which of the following structures constitutes the primary static stabilizer to external tibial rotation at 30 degrees of knee flexion?

During a lateral approach to the fibula for a distal third fracture, the surgeon identifies the intermuscular septum between the lateral and anterior compartments. Which nerve resides immediately deep to the fascia in the anterior compartment, traveling with the anterior tibial artery?

To avoid iatrogenic injury during placement of the anterolateral portal for ankle arthroscopy, the surgeon must be aware of the path of the superficial peroneal nerve. On average, where does this nerve pierce the deep crural fascia to become subcutaneous?

During a deltopectoral approach to the shoulder, the cephalic vein is typically identified and retracted laterally to protect its tributaries. The cephalic vein marks the internervous plane between muscles innervated by which of the following pairs of nerves?

During a Kocher-Langenbeck approach for a posterior wall acetabular fracture, a blunt retractor is placed over the anterior rim of the acetabulum to assist with exposure. Which of the following structures is most at risk of iatrogenic injury due to improper placement of this anterior retractor?

When performing an extensile lateral approach for an intra-articular calcaneus fracture, the peroneal tendons must be mobilized in the full-thickness flap. At the level of the fibular tubercle (trochlea) on the lateral calcaneus, what is the anatomical relationship of the peroneal tendons?

A surgeon utilizes the anterior Henry approach to the proximal radius to treat a radial head fracture. The dissection proceeds between the brachioradialis and pronator teres. Which nerve provides motor innervation to the muscle forming the lateral border of this interval?

In the modified Stoppa approach to the anterior pelvic ring, the surgeon must identify and often ligate the "corona mortis" to prevent massive hemorrhage. This structure is typically an anastomosis between which two vascular systems?

A patient presents with isolated weakness of external rotation of the shoulder following a posterior labral repair. Abduction is full and symmetric to the contralateral side. Which of the following anatomical locations is the most likely site of neural compression or injury?

During a direct lateral (Hardinge) approach to the hip for arthroplasty, the gluteus medius is split longitudinally. To avoid denervating the anterior portion of the gluteus medius and tensor fasciae latae, the split should not extend proximally beyond the tip of the greater trochanter by more than what distance?

The deltopectoral approach utilizes a true internervous plane. Which two nerves supply the muscles defining this surgical interval?

During an anterolateral approach to the distal tibia, the extensor retinaculum is incised. To safely expose the bone, a specific neurovascular bundle must be identified and mobilized medially. Which structures compose this bundle?

A patient requires a surgical release for tarsal tunnel syndrome. The flexor retinaculum is divided. What is the correct anterior-to-posterior (medial-to-lateral) order of the structures passing behind the medial malleolus?

When repairing a distal biceps tendon rupture via a two-incision technique, the surgeon must avoid placing retractors forcefully against the radial neck. Which structure is most at risk of injury in this region?

In the Smith-Petersen (anterior) approach to the hip, an internervous plane is utilized both superficially and deep. What are the innervating nerves of the muscles comprising the superficial interval?

A surgeon is executing a posterior approach to the shoulder. The superficial dissection interval is between the deltoid and the teres minor. The deep internervous plane separates which two muscles?

When splitting the brachialis muscle during an anterolateral approach to the humeral shaft, the muscle is divided longitudinally. Why is this split considered safe, and what is the underlying innervation pattern?

During a right anterior cervical discectomy and fusion (ACDF) at C6-C7, the recurrent laryngeal nerve is at greater risk than on the left side. Which anatomical characteristic explains this increased vulnerability?

During a Kocher-Langenbeck approach for an acetabular fracture, the surgeon extends the split in the gluteus maximus proximally. Which structure is at greatest risk of iatrogenic injury if the split extends more than 5 cm proximal to the tip of the greater trochanter?

When performing a two-incision four-compartment fasciotomy of the leg, the lateral incision is used to release the anterior and lateral compartments. The surgeon must identify and protect the superficial peroneal nerve. What is the anatomic course of this nerve relative to the muscular compartments?

A 25-year-old sustains a laceration over the volar middle phalanx of the index finger, transecting both the FDS and FDP tendons. Regarding the intrinsic hand musculature, the first lumbrical associated with the index finger originates from which of the following structures?

A 30-year-old baseball pitcher presents with vague posterior shoulder pain and deltoid weakness. MRI reveals isolated atrophy of the teres minor. Which of the following anatomic boundaries defines the quadrilateral space through which the affected nerve passes?

During an ulnar nerve transposition at the elbow, the surgeon must carefully identify and mobilize the first motor branch of the ulnar nerve to prevent tethering. Which muscle does this specific branch typically supply?

When placing thoracic pedicle screws at the T6 level, understanding the local morphometry is critical for safe instrumentation. Compared to the lumbar spine, which of the following best describes the typical anatomic characteristics of the mid-thoracic pedicle?

A patient undergoes surgical reconstruction of the posterolateral corner (PLC) of the knee. The surgeon reconstructs the popliteofibular ligament, which originates from the popliteus musculotendinous junction and inserts onto the fibular styloid. What is its primary biomechanical role?

During open reduction and internal fixation of a calcaneus fracture via an extensile lateral approach, screws are targeted into the "constant" fragment. Which anatomical structure represents this fragment and serves as a roof for the flexor hallucis longus (FHL) tendon?

During an ilioinguinal approach for an anterior column acetabular fracture, massive hemorrhage occurs near the superior pubic ramus. The bleeding is most likely originating from the "corona mortis", which is an anastomosis between which two vascular systems?

An orthopedic surgeon is performing a posterior approach to the humerus. The radial nerve is identified in the spiral groove. At what approximate distance proximal to the radiocapitellar joint does the radial nerve typically pierce the lateral intermuscular septum to enter the anterior compartment?

During a volar (Henry) approach to the proximal radius, the surgeon supinates the forearm to protect the posterior interosseous nerve (PIN). Supination achieves this protection by displacing the PIN in which direction relative to the surgical plane?

A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. In evaluating the pathogenesis of avascular necrosis in this age group, which of the following arteries provides the predominant blood supply to the capital femoral epiphysis?

A surgeon is performing a complex microvascular reconstruction of the hand. The deep palmar arch is primary formed by the terminal continuation of the radial artery and completes an anastomosis with which of the following vessels?

A patient presents with intractable heel pain and a positive Tinel's sign posterior to the medial malleolus. The surgeon elects to release the tarsal tunnel. The first branch of the lateral plantar nerve (Baxter's nerve) typically passes between which two muscles in the foot?

When planning for C1-C2 transarticular screw placement, preoperative imaging is reviewed to assess the vertebral artery course. In standard cervical anatomy, the vertebral artery arises from the subclavian artery and enters the transverse foramen at which cervical level?

A 22-year-old athlete requires an anatomic repair of a completely avulsed superficial medial collateral ligament (sMCL). The femoral origin is on the medial epicondyle. Where is the normal anatomic insertion of the sMCL on the proximal tibia?

A 45-year-old patient presents postoperatively with profound isolated weakness in shoulder external rotation following a massive rotator cuff repair. Electromyography reveals denervation of the infraspinatus with normal supraspinatus function. At what anatomical site is the suprascapular nerve most likely entrapped?

During a direct anterior (Smith-Petersen) approach to the hip, an internervous plane is utilized to minimize muscle denervation. Which of the following best describes the nerves supplying the muscles that define this superficial internervous plane?

A 28-year-old overhead athlete presents with vague posterior shoulder pain and deltoid weakness. MRI reveals isolated atrophy of the teres minor. Compression in the quadrilateral space is suspected. What are the correct anatomical boundaries of this space?

A patient has isolated weakness in external rotation of the shoulder but demonstrates normal active abduction. An MRI reveals a paralabral cyst. In which anatomical location is the cyst most likely compressing the affected nerve?

During an ilioinguinal approach for an anterior column acetabular fracture, significant hemorrhage occurs while dissecting the posterior aspect of the superior pubic ramus. This is most likely due to iatrogenic injury to an anastomosis between which two vascular systems?

While utilizing a lateral approach to the distal humerus, the surgeon must identify the radial nerve as it pierces the lateral intermuscular septum. At what average distance proximal to the radiocapitellar joint does the radial nerve cross this septum?

A surgeon is performing a direct lateral (Hardinge) approach to the hip for arthroplasty. To prevent denervation of the anterior portion of the gluteus medius, the proximal split of the muscle should not extend beyond what maximum distance from the tip of the greater trochanter?

During a medial displacement calcaneal osteotomy for an adult-acquired flatfoot deformity, excessive medial and superior translation of the posterior tuberosity fragment puts which of the following nerves at the highest risk of injury?

An anterolateral approach to the ankle is chosen for open reduction and internal fixation of a juvenile Tillaux fracture. Which nerve must be carefully identified and protected as it crosses the ankle joint in this surgical interval?

A patient sustains a high-energy posterior knee dislocation. An angiogram shows an intimal tear of the popliteal artery. The artery is tightly tethered and particularly vulnerable to injury at which proximal and distal anatomical boundaries?

During an anterior cervical discectomy and fusion (ACDF), aggressive lateral dissection over the uncinate process risks iatrogenic injury to the vertebral artery. At which cervical level does the vertebral artery most commonly enter the transverse foramen?

While performing an open carpal tunnel release, the surgeon notes an aberrant nerve branch piercing directly through the transverse carpal ligament to innervate the thenar musculature. This corresponds to which Lanz classification of the recurrent motor branch of the median nerve?

The dorsal (Thompson) approach to the proximal radius is often used to treat proximal third radius fractures. This approach exploits an internervous plane between which two muscles?

A patient presents with a symptomatic right-sided far lateral (extraforaminal) disc herniation at the L4-L5 level. Which nerve root is most likely compressed by this specific herniation?

A medial approach is used to buttress a posteromedial tibial plateau fracture. The surgeon must dissect meticulously near the pes anserinus. From anterior/superior to posterior/inferior, what is the correct arrangement of the tendinous insertions of the pes anserinus?

A competitive cyclist presents with isolated weakness of finger abduction and adduction but normal sensation over the volar hypothenar eminence and small finger. Entrapment of the ulnar nerve is suspected at Guyon's canal. Which zone of Guyon's canal is most likely affected?

During a four-compartment fasciotomy for acute compartment syndrome of the leg, the deep posterior compartment must be adequately released. Which of the following muscles is NOT contained within the deep posterior compartment?

A surgeon is reconstructing the posterolateral corner of the knee. The fibular collateral ligament (FCL) and the popliteus tendon (PT) both insert on the lateral femoral epicondyle. What is the spatial relationship of the FCL footprint relative to the PT footprint on the femur?

During an anterior intrapelvic (modified Stoppa) approach to the acetabulum, the obturator nerve is visualized before it exits the pelvis. In relation to the deep pelvic musculature, what is the expected path of the obturator nerve as it heads toward the obturator canal?

During a Smith-Petersen (anterior) approach to the hip, the superficial internervous plane is utilized. Between which two muscles is this plane, and what are their respective innervations?

A 28-year-old overhead throwing athlete presents with posterior shoulder pain and teres minor atrophy on MRI. Entrapment of the axillary nerve in the quadrilateral space is suspected. What are the boundaries of this anatomical space?

During an ilioinguinal approach for an anterior column acetabular fracture, significant hemorrhage is encountered while dissecting over the superior pubic ramus. This bleeding is most likely originating from an anastomosis between which two vascular systems?

An extensile lateral approach is planned for a displaced intra-articular calcaneus fracture. The full-thickness flap must be carefully elevated directly off the periosteum to protect vascular supply. Which artery provides the primary blood supply to the apex of this lateral flap?

A surgeon is reconstructing the medial patellofemoral ligament (MPFL) for recurrent patellar instability. Anatomically, the femoral origin of the native MPFL is located in a saddle-like depression between which two osseous landmarks?

A 32-year-old volleyball player presents with isolated weakness in external rotation of the shoulder. MRI reveals a paralabral cyst compressing a nerve at the spinoglenoid notch. Which physical examination finding corresponds to this specific level of entrapment?

A patient undergoes an anterior cervical discectomy and fusion (ACDF) for a right-sided C5-C6 paracentral disc herniation. Which nerve root is most likely compressed by this disc herniation?

During a direct lateral (Hardinge) approach to the hip, the anterior portion of the gluteus medius and vastus lateralis are split. Proximal propagation of the split in the gluteus medius is typically limited to 3-5 cm superior to the greater trochanter to prevent injury to which nerve?

The posterolateral corner (PLC) of the knee provides primary restraint to varus stress and posterolateral rotation. Which of the following structures is considered one of the three major static stabilizers of the PLC?

A 45-year-old female presents with burning pain in the plantar foot consistent with tarsal tunnel syndrome. Which of the following represents the correct anatomical order of structures within the tarsal tunnel from anterior/medial to posterior/lateral?

A 30-year-old male presents with elbow clicking and apprehension when pushing up from a chair. Posterolateral rotatory instability (PLRI) is diagnosed. The primary deficient structure originates on the lateral epicondyle and inserts on which of the following structures?

Dissection for a distal radius fracture utilizes the volar approach of Henry. The superficial surgical interval is developed between the flexor carpi radialis (FCR) and the brachioradialis. Which structure runs immediately deep to the brachioradialis and must be protected and retracted laterally during this exposure?

A surgeon is performing a complex wrist reconstruction requiring mobilization of the arterial supply. The deep palmar arch provides critical collateral flow to the hand. It is primarily formed by the anastomosis of the deep branch of the ulnar artery with the terminal continuation of which vessel?

A patient with rheumatoid arthritis presents with an inability to actively extend their thumb interphalangeal joint. Rupture of the extensor pollicis longus (EPL) tendon is suspected. The EPL tendon normally routes around Lister's tubercle, separating which two dorsal extensor compartments?