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Orthopedic Ob Basic Review | Dr Hutaif Basic Science Re -...

Orthopedic Anatomy Review | Dr Hutaif Basic Science Rev -...

17 Apr 2026 56 min read 128 Views
Orthopedic Imaging: Can you solve this question? It's a B-level quiz.

Key Takeaway

Learn more about ORTHOPEDIC MCQS 011 ANATOMY IMAGING and how to manage it. A stress or insufficiency fracture of the anterior calcaneus is the likely cause of persistent plantar and lateral foot pain, unresponsive to conservative treatment. MRI typically shows increased signal (edema) and abnormal trabecular patterns in the inferior anterior calcaneus. The accurate diagnosis question is a b in managing this condition effectively, particularly in overweight patients.

Orthopedic Anatomy Review | Dr Hutaif Basic Science Rev -...

Comprehensive 100-Question Exam


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Question 1

During a posterolateral corner reconstruction of the knee, understanding the exact anatomic footprint on the fibular head is crucial. What is the relationship of the lateral collateral ligament (LCL) footprint to the popliteofibular ligament (PFL) footprint on the fibular head?





Explanation

On the fibular head, the LCL inserts anteriorly and distally relative to the popliteofibular ligament (PFL) footprint. The PFL attaches to the posterior and medial aspect of the fibular styloid.

Question 2

A 45-year-old overhead athlete presents with posterior shoulder pain and selective weakness in external rotation. Abduction strength is intact. MRI reveals a paralabral cyst. In which anatomic location is the cyst most likely compressing the suprascapular nerve, and what are its borders?





Explanation

Isolated weakness in external rotation (infraspinatus) with preserved abduction (supraspinatus) implies compression of the suprascapular nerve at the spinoglenoid notch, which is located distal to the motor branch supplying the supraspinatus. The spinoglenoid ligament spans this notch.

Question 3

A patient sustains a deep laceration to the mid-palm, resulting in pulsatile bleeding from the deep palmar arch. Anatomically, the deep palmar arch is primarily formed by the terminal continuation of the radial artery. How does the radial artery anatomically enter the deep palm to form this arch?





Explanation

The radial artery passes dorsally through the anatomic snuffbox, dives between the two heads of the first dorsal interosseous muscle, and then passes between the two heads of the adductor pollicis to enter the deep palm. There, it forms the deep palmar arch by anastomosing with the deep branch of the ulnar artery.

Question 4

When performing a surgical dislocation of the hip, the medial femoral circumflex artery (MFCA) must be protected to prevent avascular necrosis of the femoral head. Which of the following best describes the anatomic course of the deep branch of the MFCA?





Explanation

The deep branch of the MFCA runs posteriorly, passing anterior (deep) to the quadratus femoris and posterior to the obturator externus tendon. It then crosses the superior gemellus to branch into the critical retinacular vessels that supply the femoral head.

Question 5

During a plantar approach to the midfoot for an excision of a plantar fibroma, the surgeon identifies the 'Master Knot of Henry'. Which of the following anatomic relationships correctly defines this surgical landmark?





Explanation

At the Master Knot of Henry, which is located in the plantar midfoot just posterior to the base of the first metatarsal, the flexor digitorum longus (FDL) tendon crosses plantar (superficial) to the flexor hallucis longus (FHL) tendon.

Question 6

A surgeon is planning a posterior C1-C2 fusion using transarticular screws. Preoperative CTA is obtained to evaluate the vertebral artery. Anatomically, the vertebral artery typically enters the transverse foramen at which cervical level, and what percentage of the population has an anomalous entry?





Explanation

The vertebral artery typically arises from the subclavian artery and enters the transverse foramen of C6 in about 90-95% of individuals. In 5-10% of people, it has an anomalous entry, most commonly entering higher up at C5, C4, or occasionally C7.

Question 7

A 30-year-old bodybuilder presents with poorly localized posterior shoulder pain and paresthesias over the lateral deltoid. He is diagnosed with quadrilateral space syndrome. Which vascular structure passes through this anatomical space alongside the axillary nerve?





Explanation

The quadrilateral space is bordered by the teres minor (superior), teres major (inferior), long head of the triceps (medial), and surgical neck of the humerus (lateral). It transmits the axillary nerve and the posterior circumflex humeral artery.

Question 8

During the anterior intrapelvic (modified Stoppa) approach for an acetabular fracture, an aberrant vascular anastomosis known as the 'corona mortis' is encountered draped over the superior pubic ramus. This vessel represents an anastomosis between the obturator vessels and which of the following?





Explanation

The corona mortis ('crown of death') is a vascular anastomosis between the external iliac system (specifically the deep inferior epigastric artery/vein or the external iliac itself) and the obturator system. It crosses over the superior pubic ramus and is highly susceptible to iatrogenic injury.

Question 9

A patient complains of medial knee and leg pain following a medial unicompartmental knee arthroplasty. Entrapment or iatrogenic injury of the saphenous nerve is suspected. Anatomically, how does the saphenous nerve exit the adductor (Hunter's) canal?





Explanation

The adductor canal contains the superficial femoral artery, femoral vein, saphenous nerve, and the nerve to the vastus medialis. The saphenous nerve exits the canal by piercing the vastoadductor membrane (the roof of the canal) beneath the sartorius muscle, rather than passing through the adductor hiatus with the femoral vessels.

Question 10

A surgeon is performing an anterior (Henry) approach to the proximal radius. To safely expose the proximal third of the radius, the supinator muscle must be elevated. The posterior interosseous nerve (PIN) runs through the supinator. The proximal fibrous edge of the superficial head of the supinator is anatomically known as:





Explanation

The Arcade of Frohse is the proximal fibrous arch of the superficial head of the supinator muscle. It is the most common site of compression of the posterior interosseous nerve (PIN) in radial tunnel syndrome and must be carefully released during proximal radius exposure.

Question 11

During a submuscular transposition of the ulnar nerve, the surgeon must ensure all potential sites of compression are released. Which of the following structures is NOT a recognized site of ulnar nerve compression around the elbow?





Explanation

The Ligament of Struthers is an anomalous band of tissue that extends from a supracondylar process of the humerus to the medial epicondyle and compresses the MEDIAN nerve. The Arcade of Struthers, medial intermuscular septum, Osborne's fascia, and the FCU aponeurosis are all potential compression sites for the ULNAR nerve.

Question 12

In evaluating a high ankle sprain, a surgeon assesses the tibiofibular syndesmosis. Which ligament is the primary restraint to anterior translation of the distal fibula relative to the tibia?





Explanation

The syndesmosis complex consists of the AITFL, PITFL, interosseous ligament, and the transverse tibiofibular ligament. The AITFL provides the primary restraint to anterior translation of the fibula and is the most common ligament injured in syndesmotic sprains.

Question 13

The high nonunion rate of proximal pole scaphoid fractures is largely due to its precarious blood supply. The major blood supply to the scaphoid is derived from the radial artery. Where do these primary vessels anatomically enter the scaphoid bone?





Explanation

The scaphoid receives its primary blood supply (70-80%) from branches of the radial artery that enter along the dorsal ridge, near the waist and distal pole of the bone. This blood supply courses retrograde to supply the proximal pole, explaining the high risk of avascular necrosis in proximal pole fractures.

Question 14

A 35-year-old male sustains a spiral fracture of the middle third of the humerus (Holstein-Lewis fracture). He presents with a wrist drop. The radial nerve is closely associated with the posterior humerus. Approximately how far proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum to enter the anterior compartment of the arm?





Explanation

The radial nerve runs in the spiral groove of the posterior humerus and pierces the lateral intermuscular septum to enter the anterior compartment approximately 10 cm (range, 10-12 cm) proximal to the lateral epicondyle. This anatomical landmark is crucial during surgical approaches to the humerus.

Question 15

A hand surgeon is treating a severe flexor tendon laceration in zone II. During the repair, it is essential to reconstruct the tendon sheath to prevent bowstringing. Which two annular pulleys are the most mechanically critical and must be preserved or reconstructed?





Explanation

The flexor tendon pulley system consists of 5 annular (A1-A5) and 3 cruciate (C1-C3) pulleys. The A2 pulley (located over the proximal phalanx) and the A4 pulley (located over the middle phalanx) are the most critical biomechanical pulleys for preventing bowstringing of the flexor tendons during digit flexion.

Question 16

When reconstructing the coracoclavicular (CC) ligaments for a chronic acromioclavicular (AC) joint dislocation, anatomic graft placement is crucial. Which of the following accurately describes the anatomic insertions of the native CC ligaments on the undersurface of the clavicle?





Explanation

The coracoclavicular (CC) ligament complex consists of the conoid and trapezoid ligaments. The conoid ligament inserts posteromedially on the conoid tubercle of the clavicle, whereas the trapezoid ligament inserts anterolaterally on the trapezoid line.

Question 17

The anterior cruciate ligament (ACL) is composed of the anteromedial (AM) and posterolateral (PL) bundles. During biomechanical testing, which of the following accurately describes the tensioning pattern of these bundles?





Explanation

The ACL has two distinct bundles named for their tibial insertion sites. The anteromedial (AM) bundle is tightest in knee flexion and provides the primary restraint to anterior tibial translation. The posterolateral (PL) bundle is tightest in extension and provides the primary restraint to rotatory loads.

Question 18

A patient presents with classic signs of piriformis syndrome, including buttock pain and sciatic radiculopathy that worsens with prolonged sitting. Anatomical variations in the relationship between the sciatic nerve and the piriformis muscle can predispose to this condition. According to Beaton and Anson classification, what is the most common variant (excluding the normal anatomy)?





Explanation

Normally (Type A, ~85%), the entire sciatic nerve exits the greater sciatic foramen inferior to the piriformis muscle. The most common variation (Type B, ~10%) occurs when the common peroneal nerve division pierces the piriformis muscle, while the tibial division passes inferior to it.

Question 19

A 24-year-old football player sustains a hyper-plantarflexion injury to his midfoot. Radiographs show widening of the space between the first and second metatarsals. The Lisfranc ligament is injured. Between which two osseous structures does the primary Lisfranc ligament span?





Explanation

The classic Lisfranc ligament is a strong interosseous ligament that spans from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. There is no direct intermetatarsal ligament between the first and second metatarsals, making the Lisfranc ligament essential for midfoot stability.

Question 20

A spine surgeon is performing a lateral lumbar interbody fusion (LLIF) at L4-L5. The retractor must be passed through the psoas major muscle. Which of the following best describes the anatomical location of the lumbar plexus, specifically the femoral nerve, within the psoas major at the L4-L5 disc space level?





Explanation

As the lumbar plexus descends, its nerves migrate from medial to lateral and from anterior to posterior within the psoas major muscle. At the L4-L5 disc space, the femoral nerve is generally located in the posterior third of the psoas major, making the anterior/middle aspect the safest zone for retractor placement during lateral transpsoas approaches.

Question 21

During a posterior approach to the shoulder (Judson approach) for the treatment of a posterior glenoid fracture, the surgeon develops the primary internervous plane. Which of the following defines the muscles and their respective innervations that form this boundary?





Explanation

The classic posterior approach to the shoulder utilizes the internervous plane between the infraspinatus (innervated by the suprascapular nerve) and the teres minor (innervated by the axillary nerve). Retracting the infraspinatus superiorly and the teres minor inferiorly provides excellent access to the posterior shoulder joint capsule while respecting distinct nerve supplies.

Question 22

In the ilioinguinal approach to the acetabulum, three distinct 'windows' are utilized for access. Which of the following anatomic structures must be incised to gain access to the true pelvis and strictly divides the lateral window from the middle window?





Explanation

The iliopectineal fascia separates the lateral window (containing the iliacus and the iliopsoas muscle with the femoral nerve) from the middle window (containing the external iliac vessels). Incising the iliopectineal fascia down to the pelvic brim is a critical step in the ilioinguinal approach to allow access to the true pelvis and the quadrilateral plate.

Question 23

When performing a direct lateral (Hardinge) approach to the hip, the anterior portion of the gluteus medius and minimus is split. To minimize the risk of denervating the remaining anterior portion of the gluteus medius, the proximal split should not extend beyond what distance from the tip of the greater trochanter?





Explanation

The superior gluteal nerve runs approximately 3 to 5 cm proximal to the tip of the greater trochanter. Extending the split of the gluteus medius more than 5 cm proximally puts the main trunk or its major branches at high risk, which can result in a devastating postoperative Trendelenburg gait.

Question 24

The deep palmar arch of the hand is a crucial collateral circulatory pathway. It is formed primarily by the terminal part of the radial artery. Which structure most commonly anastomoses with it to complete the arch?





Explanation

The deep palmar arch is primarily formed by the terminal continuation of the radial artery after it passes between the two heads of the first dorsal interosseous muscle. It completes the arch by anastomosing with the deep palmar branch of the ulnar artery. In contrast, the superficial palmar arch is primarily formed by the ulnar artery and anastomoses with the superficial branch of the radial artery.

Question 25

During a posterolateral approach (Kocher) to the radial head for an ORIF of a type III fracture, the surgeon dissects between two muscle bellies to reach the joint capsule. What is the correct internervous plane for this approach?





Explanation

The Kocher approach to the 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). The posterior interosseous nerve itself crosses within the supinator distally and anteriorly, so staying proximal and strictly within this plane protects the nerve.

Question 26

During surgical reconstruction of the posterolateral corner (PLC) of the knee, careful dissection must be carried out around the lateral collateral ligament (LCL). Which vascular structure courses horizontally and immediately deep to the LCL at the level of the joint line and must be protected?





Explanation

The inferior lateral genicular artery courses horizontally along the joint line, lying deep to the lateral collateral ligament (LCL) and superficial to the lateral meniscus. It must be carefully isolated and protected or ligated during lateral approaches to the knee, meniscus repairs, and PLC reconstructions.

Question 27

When tracing the path of the vertebral artery through the cervical spine, it typically ascends and enters the transverse foramen at which cervical vertebral level?





Explanation

The vertebral artery is the first branch of the subclavian artery. It typically enters the transverse foramen at the C6 vertebral level in approximately 90% of individuals. It rarely enters at C7, which is a key anatomic detail for cervical spine instrumentation and anterior cervical approaches.

Question 28

The adductor canal (Hunter's canal) serves as a passageway for structures moving from the anterior thigh to the popliteal fossa. Which nerve exits the canal by directly piercing its roof (the vastoadductor membrane)?





Explanation

The adductor canal contains the superficial femoral artery, the superficial femoral vein, the saphenous nerve, and the nerve to the vastus medialis. The saphenous nerve (along with the descending genicular artery) exits the adductor canal prematurely by piercing the vastoadductor membrane to become subcutaneous.

Question 29

An orthopedic surgeon is planning an anterolateral approach to the distal tibia for a pilon fracture. To protect the superficial peroneal nerve (SPN) during the superficial dissection, the surgeon must be aware of its anatomic course. On average, at what distance proximal to the lateral malleolus does the SPN pierce the crural fascia to become subcutaneous?





Explanation

The superficial peroneal nerve lies in the lateral compartment of the lower leg. It typically pierces the deep crural fascia to become a subcutaneous structure approximately 10-12 cm proximal to the tip of the lateral malleolus. Knowledge of this location is critical when placing incisions or percutaneous plates in the distal third of the leg.

Question 30

The posterior aspect of the shoulder contains several defined anatomic spaces through which neurovascular structures pass. Which structure passes through the triangular space?





Explanation

The triangular space is bounded by the teres minor superiorly, the teres major inferiorly, and the long head of the triceps laterally. It contains the circumflex scapular artery. This is distinct from the quadrilateral space, which contains the axillary nerve and posterior circumflex humeral artery.

Question 31

During a medial surgical approach to the midfoot, a dense fibrous connection is encountered on the plantar aspect beneath the navicular, known as the 'Master Knot of Henry'. Which two tendons cross at this specific anatomic landmark?





Explanation

The Master Knot of Henry is the anatomic location where the flexor digitorum longus (FDL) tendon crosses superficial (plantar) to the flexor hallucis longus (FHL) tendon in the plantar midfoot. Suturing the stumps of the tendons here is common during an FDL transfer to prevent FHL dysfunction.

Question 32

In the deep compartments of the hand, the deep palmar space is anatomically divided into the thenar space and the midpalmar space. Which structure physically separates these two deep fascial spaces?





Explanation

The midpalmar septum, classically described as the oblique septum of Legueu and Juvara, extends deep from the palmar aponeurosis to the fascia of the third metacarpal. It effectively divides the deep palmar potential space into the more lateral thenar space and the medial midpalmar space, limiting the spread of deep hand infections.

Question 33

When planning a lateral plate osteosynthesis for a distal third humerus fracture, the surgeon must identify the radial nerve as it transitions compartments. At what average distance proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum to enter the anterior compartment of the arm?





Explanation

The radial nerve spirals down the posterior humerus and pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment. This transition occurs predictably at an average of 10 cm (range roughly 9-11 cm) proximal to the lateral epicondyle.

Question 34

During preoperative planning for posterior spinal instrumentation in the lumbar spine, morphometric assessment of the pedicles is essential. In a typical patient, which lumbar vertebra possesses the largest transverse pedicle diameter?





Explanation

In the lumbar spine, the transverse (coronal) diameter of the pedicles gradually increases from L1 to L5. Therefore, L5 typically has the widest transverse pedicle diameter, which accommodates larger diameter pedicle screws, though it also has the highest degree of medial angulation (trajectory).

Question 35

A trauma surgeon is using the Stoppa approach for an acetabular fracture. To avoid catastrophic bleeding, the 'corona mortis' must be identified and ligated. This vascular anastomosis crosses the superior pubic ramus at what average distance laterally from the symphysis pubis?





Explanation

The corona mortis ('crown of death') is a vascular anastomosis between the external iliac (or deep inferior epigastric) vessels and the obturator vessels. It is draped over the superior pubic ramus, on average about 5-6 cm (range 4-8 cm) lateral to the symphysis pubis.

Question 36

A surgeon is performing a posteromedial exposure of the ankle for a medial malleolus fracture with significant comminution extending posteriorly. From anterior to posterior (starting immediately posterior to the medial malleolus), what is the correct anatomical order of the structures within the tarsal tunnel?





Explanation

The correct order of structures behind the medial malleolus from anterior to posterior is: Tibialis posterior tendon, Flexor digitorum longus tendon, Posterior tibial Artery, posterior tibial Vein, Tibial Nerve, and Flexor hallucis longus tendon. This is classically remembered by the mnemonic 'Tom, Dick, And Very Nervous Harry'.

Question 37

During a posterior approach to the hip (Moore/Southern) for an elective arthroplasty, preserving the deep branch of the medial circumflex femoral artery (MCFA) is critical if avoiding avascular necrosis is desired (e.g., in tumor or trauma, or preserving anatomy). Which of the following short external rotators anatomically protects the MCFA when left intact?





Explanation

The deep branch of the medial circumflex femoral artery (MCFA) represents the primary blood supply to the femoral head. It passes deep to the quadratus femoris and runs along the inferior border of the obturator externus. Thus, preserving the obturator externus tendon safely shields the MCFA from injury during the posterior approach.

Question 38

A patient is evaluated for weakness in making an 'OK' sign, demonstrating an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. The injured nerve is ultimately derived from which cord(s) of the brachial plexus?





Explanation

The clinical presentation is classic for Anterior Interosseous Nerve (AIN) syndrome. The AIN is a branch of the median nerve. The median nerve itself is formed by the union of the medial and lateral roots, which originate from the medial and lateral cords of the brachial plexus, respectively.

Question 39

The menisci of the knee have distinct attachments that dictate their mobility and susceptibility to injury. Which of the following ligaments connects the anterior horn of the medial meniscus directly to the anterior horn of the lateral meniscus?





Explanation

The transverse meniscal ligament (or transverse geniculate ligament) connects the anterior horns of the medial and lateral menisci. The ligaments of Wrisberg and Humphrey are the posterior meniscofemoral ligaments. Coronary ligaments connect the menisci to the tibial plateau.

Question 40

The posterior compartment of the forearm is divided into a superficial, a mobile wad, and a deep layer. Which of the following muscles is NOT found in the deep layer of the posterior forearm?





Explanation

The extensor carpi radialis brevis (ECRB) is part of the superficial layer (specifically the 'mobile wad of Henry' along with the brachioradialis and ECRL). The deep layer of the posterior forearm contains the Supinator, Abductor pollicis longus (APL), Extensor pollicis brevis (EPB), Extensor pollicis longus (EPL), and Extensor indicis proprius (EIP).

Question 41

During a total hip arthroplasty, a screw is inadvertently placed outside the safe zone in the anterosuperior quadrant of the acetabulum. Which of the following structures is at the highest risk of injury?





Explanation

According to Wasielewski's quadrants, the anterosuperior quadrant of the acetabulum places the external iliac artery and vein at high risk of injury from screw penetration. The anteroinferior quadrant endangers the obturator nerve and vessels. The posterosuperior quadrant is considered the 'safe zone,' while the posteroinferior quadrant endangers the sciatic nerve and internal pudendal vessels.

Question 42

A 28-year-old overhead athlete presents with posterior shoulder pain and deltoid weakness. MRI reveals a paralabral cyst compressing a nerve within the quadrangular space. Which vascular structure runs alongside the affected nerve in this space?





Explanation

The quadrangular space transmits the axillary nerve and the posterior humeral circumflex artery. The boundaries are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and surgical neck of the humerus (lateral). The circumflex scapular artery passes through the triangular space.

Question 43

The plantar calcaneonavicular ligament (spring ligament) is a crucial static stabilizer of the medial longitudinal arch. Which of the following structures is considered its primary medial dynamic augment?





Explanation

The tibialis posterior tendon is the primary dynamic stabilizer of the medial longitudinal arch and provides crucial support to the spring ligament complex. Dysfunction of the tibialis posterior is the primary driver of adult acquired flatfoot deformity, eventually leading to spring ligament failure.

Question 44

Which of the following structures is considered the primary restraint to external rotation of the tibia at 30 degrees of knee flexion?





Explanation

The posterolateral corner (PLC) consists primarily of the lateral collateral ligament (LCL), popliteus tendon, and popliteofibular ligament (PFL). The popliteofibular ligament and the popliteus complex serve as the primary restraint to external tibial rotation at 30 degrees of knee flexion.

Question 45

During a wide surgical release for an aggressive tendon sheath infection in the hand, multiple flexor pulleys are encountered. Which combination of pulleys is considered biomechanically most critical to prevent bowstringing of the flexor tendons and must be preserved?





Explanation

The A2 (located over the proximal phalanx) and A4 (located over the middle phalanx) are the most critical biomechanical pulleys in the finger. Preservation of these two is essential to prevent bowstringing of the flexor tendons and loss of mechanical advantage.

Question 46

When preparing the entry point for a thoracic pedicle screw, the standard anatomic landmark is best described as the intersection of the:





Explanation

The standard free-hand entry point for a thoracic pedicle screw is located at the intersection of the lateral border of the superior articular facet and a line bisecting the transverse process (midline of the transverse process).

Question 47

The Triangular Fibrocartilage Complex (TFCC) is the primary stabilizer of the distal radioulnar joint (DRUJ). Which specific component of the TFCC is the primary restraint to dorsal and volar translation of the radius relative to the ulna?





Explanation

The volar and dorsal radioulnar ligaments form the thickened margins of the articular disc of the TFCC. They are the primary stabilizers of the DRUJ, preventing dorsal and volar translation of the radius over the fixed ulna during pronation and supination.

Question 48

The distal tibiofibular syndesmosis relies on several ligaments for stability. Which of the following ligaments provides the greatest resistance to diastasis (accounts for the greatest percentage of syndesmotic strength)?





Explanation

The Posterior Inferior Tibiofibular Ligament (PITFL) provides the greatest strength and resistance to diastasis, contributing approximately 42% of syndesmotic strength. This is followed by the AITFL (35%) and the interosseous ligament (22%).

Question 49

The coracoclavicular (CC) ligaments are key stabilizers of the acromioclavicular joint. Which of the following best describes their anatomic orientation and primary biomechanical functions?





Explanation

The conoid ligament is posteromedial and is the primary restraint to superior translation of the clavicle. The trapezoid ligament is anterolateral and primarily resists horizontal (axial) compression towards the acromion.

Question 50

Following a scaphoid waist fracture, the proximal pole is at high risk for avascular necrosis due to its retrograde blood supply. Which vessel provides the primary intraosseous retrograde blood supply to the proximal scaphoid?





Explanation

The dorsal carpal branch of the radial artery provides the major blood supply (70-80%) to the scaphoid. It enters distally at the dorsal ridge and flows retrogradely to supply the proximal pole. The volar palmar carpal branch supplies only the distal 20-30%.

Question 51

A trauma patient undergoes a prophylactic four-compartment fasciotomy of the leg. During the release of the deep posterior compartment, which of the following muscle bellies will be directly encountered?





Explanation

The deep posterior compartment of the leg contains the Tibialis posterior, Flexor digitorum longus (FDL), and Flexor hallucis longus (FHL), along with the posterior tibial artery and tibial nerve. The gastrocnemius is in the superficial posterior compartment.

Question 52

The primary soft-tissue stabilizer of the posterior pelvic ring, providing the strongest resistance against vertical shear forces, is the:





Explanation

The interosseous sacroiliac ligament is the strongest ligament in the body. It bridges the irregular articular surfaces of the sacrum and ilium and is the primary stabilizer of the posterior pelvic ring, providing the major resistance to vertical shear forces.

Question 53

In Guyon's canal at the wrist, the ulnar nerve bifurcates into superficial and deep branches. Which of the following anatomic structures forms the primary floor of Guyon's canal?





Explanation

The floor of Guyon's canal is primarily formed by the transverse carpal ligament (flexor retinaculum) and the pisohamate ligament. The roof consists of the volar carpal ligament and palmaris brevis. The ulnar border is the pisiform, and the radial border is the hook of the hamate.

Question 54

During a posterior triceps-splitting approach to the humerus, the radial nerve is identified. In relation to the posterior humerus, at what approximate distance from the lateral epicondyle does the radial nerve typically cross the posterior midshaft?





Explanation

The radial nerve courses in the spiral groove and crosses the posterior aspect of the humerus approximately 14 cm proximal to the lateral epicondyle (and roughly 20 cm proximal to the medial epicondyle). Recognizing these landmarks is critical to avoid iatrogenic injury.

Question 55

The central band of the forearm interosseous membrane is critical for longitudinal stability of the radioulnar relationship. What is the predominant fiber orientation of this central band?





Explanation

The fibers of the central band of the interosseous membrane originate on the radius and course distally and obliquely (ulnarly) to insert on the ulna. This orientation is biomechanically suited to transmit axial loads applied to the distal radius proximally towards the ulna.

Question 56

In the adult hip, the predominant blood supply to the superior weight-bearing dome of the femoral head is derived from which of the following vessels?





Explanation

The medial femoral circumflex artery (MFCA), specifically through its lateral epiphyseal (posterosuperior) retinacular branches, provides the predominant blood supply to the femoral head, including the critical superior and anterior weight-bearing portions in adults.

Question 57

The vertebral artery typically enters the transverse foramen of the cervical spine at which vertebral level?





Explanation

The vertebral artery arises from the subclavian artery and typically bypasses C7 to enter the transverse foramen at the C6 level (in ~90% of individuals). The transverse foramen of C7 usually only transmits the accessory vertebral vein.

Question 58

The subscapularis muscle is unique among the rotator cuff muscles due to its dual innervation. Which of the following nerves provides innervation to the inferior portion of the subscapularis?





Explanation

The subscapularis is innervated by both the upper and lower subscapular nerves. The upper subscapular nerve innervates the superior portion, while the lower subscapular nerve innervates the inferior portion. The lower subscapular nerve also innervates the teres major.

Question 59

During a minimally invasive repair of an Achilles tendon rupture, care must be taken to avoid the sural nerve. At what approximate level does the sural nerve typically cross the lateral border of the Achilles tendon?





Explanation

The sural nerve courses distally in the posterior leg and typically crosses the lateral border of the Achilles tendon approximately 10 cm proximal to its calcaneal insertion. Sutures passed blindly laterally above this level place the nerve at significant risk.

Question 60

The medial and lateral menisci of the knee exhibit distinct anatomical differences. Which of the following statements regarding meniscal anatomy is correct?





Explanation

The medial meniscus is C-shaped (semi-circular) with widely separated anterior and posterior horns. The lateral meniscus is more circular (O-shaped) and covers a larger portion of its respective tibial plateau. The lateral meniscus is also more mobile, partly due to the popliteus hiatus disrupting its peripheral attachment.

Question 61

A 25-year-old male is undergoing an open Latarjet procedure. During the approach, the surgeon must identify and protect the musculocutaneous nerve. What is the classic anatomic relationship of the musculocutaneous nerve to the coracoid process?





Explanation

The musculocutaneous nerve typically enters the deep surface of the coracobrachialis muscle approximately 5 to 8 cm distal to the tip of the coracoid process. Retraction of the conjoined tendon medial to this point during anterior shoulder approaches places the nerve at significant risk.

Question 62

During a posterior approach to the hip for total hip arthroplasty, the surgeon must take care not to injure the primary blood supply to the femoral head. Anatomically, where does the deep branch of the medial femoral circumflex artery (MFCA) course in relation to the short external rotators?





Explanation

The deep branch of the MFCA courses posterior to the obturator externus tendon and anterior to the inferior gemellus and quadratus femoris. Protecting the obturator externus during a posterior approach helps shield this critical vessel from iatrogenic injury.

Question 63

A 34-year-old male sustains a distal humerus fracture requiring plate osteosynthesis via a posterior approach. The surgeon performs an olecranon osteotomy. When elevating the supinator muscle to expose the proximal radius, the posterior interosseous nerve (PIN) is at risk. Which anatomic structure marks the proximal edge of the superficial head of the supinator where the PIN commonly enters?





Explanation

The Arcade of Frohse is the proximal fibrous arch of the superficial head of the supinator muscle. The posterior interosseous nerve passes beneath this arch, making it a common site for PIN entrapment and a critical surgical landmark.

Question 64

A surgeon is performing an anterior cervical discectomy and fusion (ACDF) at C5-C6. During lateral decompression of the uncovertebral joint, there is a risk of injuring the vertebral artery. In the standard human anatomy, at which cervical level does the vertebral artery typically enter the transverse foramen?





Explanation

The vertebral artery typically enters the transverse foramen at the C6 vertebral level in over 90% of individuals. It does not pass through the C7 transverse foramen, which usually transmits only the vertebral vein.

Question 65

A 45-year-old patient presents with a displaced acetabular fracture requiring surgical fixation via an ilioinguinal approach. During the dissection, severe hemorrhage is encountered posterior to the superior pubic ramus. Which of the following anatomic variants is the most likely source of the bleeding?





Explanation

The corona mortis is a vascular anastomosis between the external iliac (or inferior epigastric) and obturator vessels. It courses over the superior pubic ramus and is highly susceptible to injury during the ilioinguinal approach.

Question 66

During a direct lateral (Hardinge) approach to the hip, the anterior third of the gluteus medius is split to gain access to the joint. Splitting the muscle too proximally risks denervating the remaining anterior portion of the muscle. What is the accepted safe zone for splitting the gluteus medius proximal to the tip of the greater trochanter to avoid injuring the superior gluteal nerve?





Explanation

The superior gluteal nerve courses approximately 3 to 5 cm proximal to the tip of the greater trochanter. Limiting the proximal split of the gluteus medius to less than 3 cm minimizes the risk of iatrogenic denervation.

Question 67

A 28-year-old athlete undergoes an open repair of a completely ruptured pectoralis major tendon. The surgeon notes that the tendon consists of two primary heads with a unique insertion pattern. Which of the following accurately describes the anatomic insertion of the pectoralis major tendon onto the humerus?





Explanation

The pectoralis major tendon twists on itself prior to insertion. The sternal head twists 180 degrees so that its inferior fibers insert superiorly and deep, while the clavicular head does not twist and inserts anteriorly (superficial) and distally.

Question 68

A patient with persistent medial midfoot pain is diagnosed with intersection syndrome of the foot (Master Knot of Henry). This anatomical site is critical for understanding tendon transfers in the midfoot. Which best describes the anatomic relationship at the Master Knot of Henry?





Explanation

At the Master Knot of Henry in the medial midfoot, the flexor hallucis longus (FHL) tendon crosses dorsal (deep) to the flexor digitorum longus (FDL) tendon. They are often tethered together here by a tendinous slip.

Question 69

A 22-year-old sustains a traumatic posterolateral elbow dislocation. During surgical reconstruction of the lateral ulnar collateral ligament (LUCL), accurate placement of the isometric origin and insertion points is essential. What are the true anatomical attachments of the LUCL?





Explanation

The lateral ulnar collateral ligament (LUCL) is the primary restraint to posterolateral rotatory instability (PLRI) of the elbow. It originates on the lateral epicondyle and inserts on the supinator crest of the proximal ulna.

Question 70

A patient is scheduled for an extreme lateral interbody fusion (XLIF) at L4-L5. The trans-psoas approach places specific nerves of the lumbar plexus at risk. Which nerve lies most anteriorly on the surface of the psoas major muscle and is highly vulnerable during initial psoas dilation?





Explanation

The genitofemoral nerve arises from L1-L2 and pierces the anterior surface of the psoas major muscle. Its superficial and anterior position makes it particularly vulnerable to injury during lateral trans-psoas approaches.

Question 71

A 19-year-old football player undergoes an anterior cruciate ligament (ACL) reconstruction. The surgeon wishes to replicate the native anatomy of the ACL bundles. Which statement correctly describes the femoral footprint of the ACL bundles with the knee in extension?





Explanation

On the lateral femoral condyle, the anteromedial (AM) bundle originates high (proximal) and posterior, whereas the posterolateral (PL) bundle originates lower (distal) and anterior. The bundles cross as the knee moves into flexion.

Question 72

A surgeon is repairing a ruptured Achilles tendon using a percutaneous technique. The sural nerve is at risk of being ensnared by the passing sutures. In relation to the lateral border of the Achilles tendon, at what approximate distance proximal to the calcaneal insertion does the sural nerve typically cross from lateral to medial?





Explanation

The sural nerve typically crosses the lateral border of the Achilles tendon approximately 9 to 12 cm proximal to its insertion on the calcaneus. Sutures placed proximal to this level laterally put the nerve at significant risk.

Question 73

A patient presents with inability to make an "OK" sign with their thumb and index finger following a penetrating forearm injury. Which of the following muscles are denervated in this patient's specific nerve palsy?





Explanation

Inability to make the "OK" sign indicates anterior interosseous nerve (AIN) palsy. The AIN exclusively innervates the flexor pollicis longus, flexor digitorum profundus to the index and middle fingers, and the pronator quadratus.

Question 74

A 30-year-old patient with intractable piriformis syndrome is undergoing surgical release. The surgeon considers the anatomic variations of the sciatic nerve in relation to the piriformis muscle. What is the most common anatomical variation (Beaton and Anson Type B) of the sciatic nerve?





Explanation

The normal anatomy (Type A, ~85%) has the sciatic nerve passing inferior to the piriformis. The most common variation (Type B, ~10%) features the common peroneal division piercing the piriformis while the tibial division passes inferiorly.

Question 75

A 55-year-old cyclist complains of numbness and tingling in his ring and small fingers, diagnosed as ulnar tunnel syndrome (Guyon's canal compression). When releasing Guyon's canal, the surgeon must understand its anatomic boundaries. What structure forms the floor of Guyon's canal?





Explanation

The floor of Guyon's canal is formed primarily by the transverse carpal ligament (flexor retinaculum) and the pisohamate ligament. The roof is formed by the volar carpal ligament.

Question 76

A 24-year-old presents with a scaphoid waist fracture. The surgeon opts for percutaneous screw fixation. A deep understanding of the scaphoid's blood supply is necessary to appreciate the risk of avascular necrosis. Which vessel provides the primary blood supply to the proximal pole of the scaphoid?





Explanation

The primary blood supply to the scaphoid is from the dorsal carpal branch of the radial artery, which enters distally and flows retrograde to supply the proximal pole. This retrograde flow is why proximal pole fractures have a high rate of avascular necrosis.

Question 77

During a volar approach to the forearm (Henry approach) for a middle-third radius fracture, the surgeon develops the internervous plane. Between which two muscles is the proximal interval of the Henry approach classically developed?





Explanation

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

Question 78

A 60-year-old female is undergoing an open carpal tunnel release. The surgeon is extending the incision proximally into the distal forearm. To avoid injury to the palmar cutaneous branch of the median nerve, where should the incision be placed relative to the palmaris longus tendon?





Explanation

The palmar cutaneous branch of the median nerve arises approximately 5 cm proximal to the wrist crease and courses superficially just radial to the palmaris longus tendon. Incisions for carpal tunnel release should remain ulnar to the palmaris longus to avoid this nerve.

Question 79

During closed reduction and percutaneous pinning of a supracondylar humerus fracture in a pediatric patient, a medial pin is placed. The patient subsequently exhibits weakness in spreading their fingers and numbness in the small digit. At what anatomical location does the affected nerve run in relation to the medial epicondyle?





Explanation

The ulnar nerve is at high risk during medial pinning of pediatric supracondylar humerus fractures. It courses strictly posterior to the medial epicondyle within the cubital tunnel before entering the forearm between the two heads of the flexor carpi ulnaris.

Question 80

A surgeon is exposing the distal fibula for an ankle fracture utilizing a lateral approach. To avoid injuring the superficial peroneal nerve as it transitions from the deep to the superficial compartment, the surgeon should be aware of its typical exit point. Where does the superficial peroneal nerve typically pierce the crural fascia in relation to the lateral malleolus?





Explanation

The superficial peroneal nerve typically pierces the crural fascia to become subcutaneous approximately 10 to 12 cm proximal to the tip of the lateral malleolus. It emerges between the peroneus brevis and extensor digitorum longus.

Question 81

A 25-year-old male sustains a posterior shoulder dislocation resulting in isolated weakness in external rotation and a sensory deficit over the lateral deltoid. Which of the following defines the borders of the anatomic space through which the injured nerve passes?





Explanation

The axillary nerve passes through the quadrilateral space. Its borders are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and surgical neck of the humerus (lateral).

Question 82

During surgical fixation of a talar neck fracture, preservation of the blood supply is paramount to prevent avascular necrosis. Which artery provides the predominant vascular supply to the body of the talus?





Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, supplies the majority of the talar body. It enters the talus inferiorly and courses in a retrograde fashion.

Question 83

When performing a posterior approach to the humerus for internal fixation, the radial nerve must be identified and protected. At approximately what distance proximal to the lateral epicondyle does the radial nerve cross the lateral intermuscular septum from posterior to anterior?





Explanation

The radial nerve pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment approximately 10 cm proximal to the lateral epicondyle. This is a critical anatomical landmark during the posterior approach to the humerus.

Question 84

An orthopedic surgeon utilizes the anterior (Smith-Petersen) approach for a core decompression of the hip. This approach utilizes a true internervous plane. Which two nerves supply the muscles that form the superficial boundary of this plane?





Explanation

The superficial internervous plane of the Smith-Petersen approach lies between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep plane is between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 85

A patient presents with medial thigh numbness and weakness in hip adduction following a high-energy pelvic ring fracture. The affected nerve originates from the lumbar plexus. Anatomically, how does this nerve normally emerge from the psoas major muscle?





Explanation

The obturator nerve controls hip adduction and provides sensation to the medial thigh. Anatomically, it emerges from the medial border of the psoas major muscle before traveling into the pelvis.

Question 86

During a volar approach to the proximal radius (Henry approach), the surgeon dissects between the brachioradialis and the pronator teres. Which of the following describes the innervation of these two muscles respectively?





Explanation

The proximal internervous plane of the Henry approach is between the brachioradialis, which is innervated by the radial nerve, and the pronator teres, which is innervated by the median nerve.

Question 87

A patient experiences an inability to extend the fingers at the metacarpophalangeal joints, but wrist extension is preserved with radial deviation. Entrapment of the responsible nerve most commonly occurs at the Arcade of Frohse. Which structure forms this arch?





Explanation

The posterior interosseous nerve (PIN) is most commonly compressed at the Arcade of Frohse. This is formed by the thickened proximal tendinous edge of the superficial head of the supinator muscle.

Question 88

Scaphoid fractures are prone to nonunion and avascular necrosis due to their unique blood supply. How does the predominant vascular supply enter the scaphoid?





Explanation

The primary blood supply to the scaphoid is via the dorsal carpal branch of the radial artery, which enters at the dorsal ridge and supplies the distal 80 percent of the scaphoid. The retrograde blood flow places proximal pole fractures at high risk for avascular necrosis.

Question 89

A surgeon is exposing the medial tibia to harvest hamstring tendons for ACL reconstruction. From anterior to posterior, what is the correct anatomic order of the pes anserinus tendon insertions?





Explanation

The tendons of the pes anserinus insert on the proximal medial tibia. From anterior to posterior, they are the Sartorius, Gracilis, and Semitendinosus (SGS).

Question 90

During a posterior spinal fusion in the lumbar spine, standard pedicle screws are placed. The ideal anatomical starting point for a lumbar pedicle screw is located at the intersection of which structures?





Explanation

The starting point for a lumbar pedicle screw is classically defined as the confluence of the pars interarticularis, the midline of the transverse process, and the lateral border of the superior articular facet.

Question 91

In Acromioclavicular (AC) joint reconstructions, reconstructing the coracoclavicular (CC) ligaments anatomically is vital. Which of the following accurately describes the anatomical orientation and footprint of the CC ligaments on the clavicle?





Explanation

The coracoclavicular ligaments consist of the conoid and trapezoid. The conoid ligament inserts posteromedially on the conoid tubercle, while the trapezoid ligament inserts anterolaterally on the trapezoid line.

Question 92

A patient requires open reduction internal fixation of a posterior wall acetabular fracture via the Kocher-Langenbeck approach. To protect the main blood supply to the femoral head, which structure should ideally be left intact or minimally disturbed?





Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the main blood supply to the femoral head. It courses anterior to the obturator externus, making preservation of the obturator externus critical to protect the artery.

Question 93

Extensor pollicis longus (EPL) tendon ruptures can occur following distal radius fractures. The EPL tendon typically passes around a bony prominence on the dorsal radius. This prominence acts as a pulley and separates which two extensor compartments?





Explanation

Lister's tubercle is a bony prominence on the dorsal distal radius. It separates the second extensor compartment (ECRL, ECRB) from the third extensor compartment (EPL), which uses the tubercle as a mechanical pulley.

Question 94

Anterolateral and anteromedial portals are standard in anterior ankle arthroscopy. Establishing the anterolateral portal places which of the following nerves at highest risk of iatrogenic injury?





Explanation

The anterolateral portal is established just lateral to the peroneus tertius tendon. This location places the terminal branches of the superficial peroneal nerve at high risk if not identified by transillumination.

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