Orthopedic Anatomy Board Review MCQs 2026 (Part 4)

Question 1

Portions of which of the following normal structures help compose the spiral cord seen in Dupuytren's contracture?

Explanation

The normal fascial components that become diseased and compose the spiral cord include the pretendinous band, spiral band, lateral digital sheet, and Grayson's ligament. Cleland's ligament lies dorsal and is not involved with spiral cord formation. The intrinsic muscle and tendon, the natatory ligament, and the intermetacarpal ligament are well proximal to the digit and are not involved in spiral cord formation. McGrouther D: Dupuytren's contracture, in Green DP, Hotchkiss RN, Pederson WC (eds): Green's Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, vol 1, pp 565-569.

Question 2

Figure 43 shows an arthroscopic view of the posteromedial compartment of a patient's left knee using a 70-degree arthroscope placed through the intercondylar notch. The arrow is pointing to what structure?

Explanation

Passing the 70-degree arthroscope through the intercondylar notch provides excellent visualization of the posteromedial corner of the knee. This view should be part of every knee arthroscopy because these structures are often not well visualized from the anterior portals. If this view is omitted, tears of the peripheral posterior horn of the medial meniscus can be overlooked. The arrow points to the peripheral aspect of the posterior horn of the medial meniscus. With an intact medial meniscus, the medial tibial plateau should not be seen from this view. The semimembranosus and gastrocnemius tendons are extra-articular and not visualized. Miller MD: Basic arthroscopic principles, in DeLee JC, Drez D Jr, Miller MD (eds): Orthopaedic Sports Medicine, ed 2. Philadelphia, PA, Saunders, 2003, pp 224-237.

Question 3

Which of the following statements best describes the location of the nerve that is at risk in a direct posterior approach to the Achilles tendon?

Explanation

The sural nerve lies lateral to the Achilles tendon at the level of the foot but follows an oblique course proximally to lie directly over the tendon as it heads to the popliteal fossa. It is at risk with any proximal dissection from a direct posterior approach and in particular with procedures done at the musculotendinous junction. The nerve crosses over the lateral border of the Achilles tendon at an average of 9.8 cm above its insertion. Webb J, Moorjani N, Radford M: Anatomy of the sural nerve and its relation to the Achilles tendon. Foot Ankle Int 2000;21:475-477.

Question 4

A 46-year-old woman has bilateral groin pain, with more severe pain on the left side than on the right side. Figures 44a and 44b show a radiograph and a T1-weighted MRI scan. What is the most likely diagnosis?

Explanation

44b The radiograph reveals bilateral patchy sclerosis of the femoral heads without evidence of collapse. The MRI scan shows bilateral head involvement with a common serpentine-like low-intensity signal of the superior femoral head that is common to osteonecrosis. Changes confined to the femoral head effectively exclude rheumatoid arthritis and osteoarthritis. Resnick D (ed): Diagnosis of Bone and Joint Disorders, ed 4. Philadelphia, PA, WB Saunders, 2002, vol 4, pp 3160-3162.

Question 5

Figures 45a through 45c show the radiograph, CT scan, and MRI scan of a 15-year-old boy who has lateral ankle pain. What is the most likely diagnosis?

Explanation

45b 45c The elongated anterior process of the calcaneus reaching distally toward the navicular is an abnormal finding. Instead of viewing the rounded, blunt distal anterior process of the calcaneus, a bridge extends to the navicular, albeit incomplete. These findings are consistent with a fibrous coalition. CT can reveal a stress fracture of the calcaneus, arthritis of the subtalar joint with subchondral cysts, or an os peroneal bone disruption in the peroneus longus, but those entities are not shown here. The plantar fascia is intact. Richardson EG: Sesamoids and accessory bones of the foot, in Coughlin MJ, Mann RA (eds): Surgery of the Foot and Ankle, ed 7. St Louis, MO, Mosby, 1999, pp 702-732.

Question 6

A 5-year-old girl has had a low-grade fever, right hip and buttock pain, and a right-sided limp for the past 5 days. Examination shows diffuse tenderness and extreme pain on range of motion of the hip. Laboratory studies show a peripheral WBC count of 13,500/mm3 and an erythrocyte sedimentation rate of 55 mm/h. A radiograph is shown in Figure 46a, and an axial postgadolinium T1-weighted MRI scan with fat suppression and an axial T2-weighted fast spin echo MRI scan are shown in Figures 46b and 46c. What is the most likely diagnosis?

Explanation

46b 46c MRI findings of acute osteomyelitis include a decrease in the normally high signal intensity of bone marrow on T1-weighted imaging; however, a postgadolinium T1-weighted image with fat suppression will show osteomyelitis as a bright marrow signal compared to the surrounding fat. Osteomyelitis is also brighter than normal fat on T2-weighted imaging. There is no rim-enhancing lesion suggesting an abscess, although myositis is seen in the obturator internus and short external rotators. The clinical scenario and imaging studies do not support the diagnosis of septic hip, eosinophilic granuloma, or pelvic fracture. Dormans JP, Drummond DS: Pediatric hematogenous osteomyelitis: New trends in presentation, diagnosis and treatment. J Am Acad Orthop Surg 1994;2:333-341.

Question 7

The palmar cutaneous branch of the median nerve (PCBMN) originates from the

Explanation

The PCBMN originates from the median nerve proper between 3 and 21 cm proximal to the wrist with moderate variation. It virtually always originates from the radial side of the nerve and travels distally with the median nerve, radial to the palmaris longus, and ulnar to the flexor carpi radialis. Hobbs RA, Magnussen PA, Tonkin MA: Palmar cutaneous branch of the median nerve. J Hand Surg Am 1990;15:38-43.

Question 8

The blood supply to the anterior cruciate ligament is primarily derived from what artery?

Explanation

Microvascular studies have shown that the majority of the blood supply to the cruciate ligaments comes from the middle geniculate artery, although there is collateral flow through the other geniculates and from bone. Arnoczky SP: Blood supply to the anterior cruciate ligament and supporting structures. Orthop Clin North Am 1985;16:15-28.

Question 9

Figures 47a and 47b show the CT scans of a patient who reports persistent pain in the sinus tarsi following a fall. The avulsion fracture fragment remains attached to what ligament?

Explanation

47b The bifurcate ligament bifurcates to connect the dorsal aspect of the anterior process of the calcaneus to both the cuboid and the navicular. Inversion injuries on the side of the foot can result in avulsion fractures (arrow) of the anterior process of the calcaneus. Sarrafian SK: Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional, ed 2. New York, NY, Lippincott, 1993, p 192.

Question 10

Figure 48 shows an MRI scan of the knee. The arrow is pointing to what structure?

Explanation

The arrow points to the biceps femoris, which is inserted onto the fibula. The biceps femoris lies at the posterolateral aspect of the thigh. The semimembranosus and the semitendinous lie at the posterior medial aspect of the thigh. Gray H: Anatomy of the Human Body. Philadelphia, PA, Lea and Febiger, 1918, 2000.

Question 11

In Figure 49, line AB connects the anterior arch of C1 to the posterior margin of the foramen magnum. Line CD connects the anterior margin of the foramen magnum to the posterior arch of C1. What is the normal ratio of displacement from CD to AB (Power's ratio)?

Explanation

The ratio of displacement from CD to AB normally equals 1.0. If the ratio is greater than 1.0, an anterior atlanto-occipital dislocation may exist. Ratios slightly less than 1.0 are normal except in posterior dislocations, fractures of the odontoid process or ring of the atlas, or congenital abnormalities of the foramen magnum. In these conditions, the ratio may approach 0.7. Powers B, Miller MD, Kramer RS, et al: Traumatic anterior atlanto-occipital dislocation. Neurosurgery 1979;4:12-17.

Question 12

Figure 50 shows the AP radiograph of an asymptomatic 82-year-old woman who underwent total hip arthroplasty 16 years ago. What is the most likely diagnosis?

Explanation

Pelvic osteolysis in the presence of a well-fixed porous-coated socket is a recognized complication in total hip arthroplasty. The radiograph shows large lytic lesions superiorly adjacent to an acetabular screw and inferiorly extending into the ischium. It also reveals eccentricity of the femoral head with respect to the acetabular component, consistent with polyethylene wear. Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 440.

Question 13

The MRI findings shown in Figure 51 would most likely create which of the following signs and symptoms?

Explanation

The MRI scan shows a far lateral disk herniation. With the L4-5 disk, a far lateral herniation abuts the left L4 nerve root. The findings would be consistent with those of a left L4 radiculopathy and would include pain or a sensory deficit on the anteromedial aspect of the knee, diminished patellar tendon reflex, and quadriceps weakness, perhaps making it difficult to walk up and down stairs. Fardin DF, Garfin SR (eds): Orthopaedic Knowledge Update: Spine 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 329.

Question 14

Figure 52 shows the MRI scan of a 28-year-old baseball pitcher. Examination will most likely reveal which of the following findings?

Explanation

A ganglion cyst compressing the suprascapular nerve results in poorly localized pain in the shoulder girdle. Sensation is intact, with weakness of external rotation and abduction. Supraspinatus and infraspinatus atrophy is often noted when viewed from behind. These cysts are typically associated with labral tears. Deltoid weakness is associated with an axillary nerve injury, and scapular winging results from injury to the long thoracic nerve. Piatt BE, Hawkins RJ, Fritz RC, et al: Clinical evaluation and treatment of spinoglenoid notch ganglion cysts. J Shoulder Elbow Surg 2002;11:600-604.

Question 15

A 23-year-old man has had heel pain and fullness for the past several months. He reports that initially the pain was present only with activity, but more recently the pain has become constant. Figures 53a through 53d show a radiograph, a bone scan, and T2-weighted and gadolinium MRI scans. What is the most likely diagnosis?

Explanation

53b 53c 53d The imaging studies reveal an expansile lesion with the classic soap bubble appearance that involves most of the calcaneus. The bone scan reveals a very active lesion with intense uptake, and the MRI scans show the classic, loculated appearance of the lesion with multiple fluid-fluid levels. While it is important to rule out telangiectatic osteosarcoma, the most likely diagnosis is an aneurysmal bone cyst. While giant cell tumor might have a similar appearance, the multiple fluid levels in a expansile lesion strongly favor an aneurysmal bone cyst. Parsons TW: Benign bone tumors, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1027-1035.

Question 16

A 77-year-old woman who underwent total knee arthroplasty 16 years ago now reports pain, swelling, and notable crepitation with range of motion. AP, lateral, and Merchant radiographs are shown in Figures 54a through 54c. What is the most likely diagnosis?

Explanation

54b 54c The Merchant radiograph shows a lateral patellar shift with total polyethylene failure, resulting in a metal-on-metal bearing. This problem is associated with metal-backed patellar components. Component fixation appears solid, and no osteolysis is evident. Poss R (ed): Orthopaedic Knowledge Update 3. Park Ridge, IL, American Academy of Orthopaedic Surgeons, 1990, pp 590-593. Leopold SS, Berger RA, Patterson L, et al: Serum titanium level for diagnosis of a failed metal-backed patellar component. J Arthroplasty 2000;15:938-943.

Question 17

A 65-year-old woman who works as a florist has had pain in her right elbow for the past 6 months after lifting a flowerpot. MRI scans are shown in Figures 55a and 55b. The area of increased signal intensity seen in Figure 55b most likely represents which of the following findings?

Explanation

55b The MRI scans reveal a chronic distal biceps tendinitis. The T1-weighted scan shows the anatomic detail of the biceps tendon, and the T2-weighted scan shows increased signal caused by edema surrounding the tendon. The T1-weighted scan is not consistent with an antecubital lipoma. The chronicity of the lesion makes hematoma unlikely. An aneurysm usually appears with blood flow through the region and is dark on T1- and T2-weighted scans. Morrey BF: Tendon injuries about the elbow, in Morrey BF (ed): The Elbow and Its Disorders, ed 2. Philadelphia, PA, WB Saunders, 1993, pp 492-504.

Question 18

The carpal tunnel canal is narrowest (smallest cross-sectional area) at what level?

Explanation

The carpal tunnel canal has an hourglass shape in the coronal plane and is narrowest at the level of the hook of the hamate. Cobb TK, Dalley BK, Posteraro RH, et al: Anatomy of the flexor retinaculum. J Hand Surg Am 1993;18:91-99.

Question 19

When harvesting iliac crest bone graft during a posterior spinal decompression and fusion, injury to which of the following nerves may result in painful neuromas or numbness over the skin of the buttocks?

Explanation

The superior cluneal nerves (L1, L2, and L3) are at greatest risk when harvesting iliac crest bone graft during a posterior decompression and fusion. The nerves pierce the lumbodorsal fascia and cross the posterior iliac crest beginning at 8 cm lateral to the posterior superior iliac spine. The ilioinguinal and iliohypogastric nerves innervate anterior structures, and the lateral femoral cutaneous nerve lies in proximity to the anterior superior iliac spine and is at risk with anterior iliac crest bone graft harvesting. The superior gluteal nerve courses through the sciatic notch and supplies motor branches to the gluteus medius, minimus, and tensor fascia lata muscles. An HS: Principles and Techniques of Spine Surgery. Baltimore, MD, Williams and Wilkins, 1998, pp 770-773.

Question 20

The injury seen in the CT scan shown in Figure 56 is related to or associated with injury to which of the following structures?

Explanation

The right syndesmosis appears disrupted on the CT scan when compared to the normal left side. CT can be helpful in determining injury to the syndesmosis, especially with occult clinical findings. Ebraheim NA, Lu J, Yang H, et al: The fibular incisure of the tibia on CT scan: A cadaver study. Foot Ankle Int 1998;19:318-321. Ebraheim NA, Lu J, Yang H, et al: Radiographic and CT evaluation of tibiofibular syndesmotic diastasis: A cadaver study. Foot Ankle Int 1997;18:693-698.

Question 21

A 3-year-old girl has had wrist pain, a fever, and has refused to move her right wrist for the past 10 days. She has an oral temperature of 102 degrees F (38.7 degree C). Laboratory studies show an erythrocyte sedimentation rate of 50 mm/h, a WBC count of 11,000/mm3, and a left shift. AP and lateral radiographs are shown in Figures 57a and 57b. What is the most likely diagnosis?

Explanation

57b The most likely diagnosis is acute osteomyelitis. She may also have a septic wrist; however, the lytic lesion in the distal radius has the typical presentation and radiographic appearance of metaphyseal osteomyelitis. In this area of sluggish vascular flow, low oxygen tension, and low pH, bacterial seeding is common and is the usual origin of metaphyseal osteomyelitis. Leukemia and Ewing's sarcoma can present as a lytic lesion with an elevated erythrocyte sedimentation rate, but they are much less common than osteomyelitis and are less focal and more destructive in appearance. Nonossifying fibroma is typically metaphyseal and eccentric; however, it is well circumscribed and uncommon in the upper extremity. Eosinophilic granuloma does not typically present with inflammatory indicies. Dormans JP, Drummond DS: Pediatric hematogenous osteomyelitis: New trends in presentation, diagnosis and treatment. J Am Acad Orthop Surg 1994;2:333-341.

Question 22

Which of the following is considered the preferred approach to resect a lesion in the posterior one third of the proximal humerus?

Explanation

At least 8 cm of the posterior aspect of the proximal region of the humeral diaphyseal cortex can be exposed through the interval between the lateral head of the triceps and the deltoid muscle. No nerves or blood vessels need to be exposed in the dissection. The deltoid muscle is innervated by the axillary nerve and the triceps muscle by the radial nerve. This is a true internervous plane.

Question 23

The main blood supply to the lateral two thirds of the talar body is provided by the

Explanation

The main blood supply to the lateral two thirds of the talar body is derived from the artery of the tarsal canal, a branch of the posterior tibial artery. The peroneal artery helps form a vascular plexis over the posterior tubercle and combines with other arteries to form the artery of the sinus tarsi, which is the principal blood supply of the intrasinus structures of the talus. The anterior tibial arteries send branches to the superior surface of the talar head and give rise to the anterolateral malleolar artery, which may anastomose with other vessels to form the artery of the tarsal sinus. Sanders R: Fractures and fracture-dislocations of the talus, in Coughlin MJ, Mann RA (eds): Surgery of the Foot and Ankle, ed 7. St Louis, MO, Mosby, 1999, pp 1465-1518.

Question 24

When performing an arthroscopic subacromial decompression, bleeding can be encountered when dividing the coracoacromial ligament because of injury to what artery?

Explanation

The acromial branch of the thoracoacromial trunk courses along the coracoacromial ligament. This artery enters the ligament approximately 5 mm below the acromial edge. Division of the ligament at its insertion on the acromion minimizes the risk of bleeding. Esch JC, Baker CL: Arthroscopic anatomy and normal variations, in Whipple TL (ed): Surgical Arthroscopy: The Shoulder and Elbow. Philadelphia, PA, JB Lippincott, 1993, pp 63-76.

Question 25

Following its exit from the sciatic notch, the sciatic nerve passes between what two muscles?

Explanation

Though anatomic variations exist, both divisions of the sciatic nerve most commonly pass between the piriformis and superior gemellus. This anatomic consideration is relevant during the posterior approach to the hip, where careful retraction of the rotators avoids sciatic nerve injury. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 335-348.

Question 26

During a surgical reconstruction of the posterolateral corner of the knee, a surgeon identifies the precise fibular attachments. Which of the following correctly describes the anatomical insertion of the popliteofibular ligament?

Explanation

The popliteofibular ligament originates from the musculotendinous junction of the popliteus and inserts on the posteromedial aspect of the fibular styloid. It lies deep and posterior to the fibular collateral ligament insertion.

Question 27

A 45-year-old runner presents with medial heel pain and paresthesias radiating to the plantar foot. Symptoms are reproduced with percussion posterior to the medial malleolus. During surgical decompression of the affected structure, what is the anatomical order of the structures encountered deep to the flexor retinaculum, from anterior to posterior?

Explanation

The structures in the tarsal tunnel from anterior to posterior (Tom, Dick, AND Very Nervous Harry) are the Tibialis posterior tendon, Flexor digitorum longus tendon, Posterior tibial Artery, Vein, Tibial Nerve, and Flexor hallucis longus tendon.

Question 28

A cyclist presents with isolated weakness of the dorsal interossei and adductor pollicis, with completely normal sensation in the small and ring fingers. A lesion in which anatomical zone of Guyon's canal is most likely responsible?

Explanation

Zone 1 contains the mixed ulnar nerve before its bifurcation. Zone 2 contains only the deep motor branch, which innervates the interossei and adductor pollicis; compression here causes isolated motor deficits.

Question 29

A 28-year-old overhead athlete undergoes arthroscopic bursectomy for refractory snapping scapula syndrome. Which of the following bursae is most commonly implicated and located between the serratus anterior and the subscapularis?

Explanation

The supraserratus bursa is located between the deep surface of the subscapularis and the superficial surface of the serratus anterior. Inflammation of this bursa or the infraserratus bursa is a primary cause of snapping scapula syndrome.

Question 30

During an anterior surgical approach to the proximal radius (Henry approach), the surgeon must protect the posterior interosseous nerve (PIN). The PIN enters the supinator muscle beneath a fibrous arch. Which muscle's fascial edge forms the Arcade of Frohse?

Explanation

The Arcade of Frohse is formed by the thickened proximal fascial edge of the superficial head of the supinator muscle. It is the most common site of compression for the posterior interosseous nerve.

Question 31

During an ilioinguinal approach for an acetabular fracture, significant hemorrhage occurs while dissecting near the superior pubic ramus. The injured vessel represents an anastomosis between which two vascular systems?

Explanation

The corona mortis is a vascular anastomosis between the obturator vessels (internal iliac system) and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus and is highly vulnerable during pelvic surgery.

Question 32

During medial patellofemoral ligament (MPFL) reconstruction, anatomic placement of the femoral tunnel is critical to prevent graft anisometry. According to Schöttle's radiographic point, where should the femoral footprint be located on a strict lateral radiograph?

Explanation

Schöttle's point defines the radiographic femoral footprint of the MPFL. It is located 1 mm anterior to the posterior femoral cortex line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to Blumensaat's line.

Question 33

A rock climber feels a pop in his ring finger followed by bowstringing of the flexor tendons. Biomechanically, which two pulleys of the flexor tendon sheath are most critical to prevent bowstringing and must be preserved or reconstructed?

Explanation

The A2 and A4 pulleys are located over the proximal and middle phalanges, respectively. They are biomechanically the most critical pulleys for preventing flexor tendon bowstringing and maintaining functional excursion.

Question 34

A patient with thoracic outlet syndrome experiences compression of the lower trunk of the brachial plexus. This compression typically occurs in the interscalene triangle. What are the anatomical borders of the interscalene triangle?

Explanation

The interscalene triangle is bordered anteriorly by the anterior scalene muscle, posteriorly by the middle scalene muscle, and inferiorly by the first rib. The brachial plexus roots and trunks, along with the subclavian artery, pass through this space.

Question 35

In the lumbar spine, a surgeon is placing pedicle screws at the L4 level. If the screw inadvertently breaches the medial and inferior cortex of the L4 pedicle, which exiting nerve root is at the greatest risk of injury?

Explanation

In the lumbar spine, the exiting nerve root travels just inferomedial to the pedicle of the same numerical designation. Therefore, an inferomedial breach of the L4 pedicle endangers the L4 nerve root.

Question 36

Which component of the medial collateral (deltoid) ligament of the ankle is the primary restraint to valgus tilting of the talus within the ankle mortise?

Explanation

The deep posterior tibiotalar ligament is the strongest component of the deltoid ligament complex. It serves as the primary restraint to valgus tilting and external rotation of the talus.

Question 37

A patient sustains a displaced fracture of the surgical neck of the humerus. Which neurovascular bundle is at the highest risk of injury due to its location in the quadrangular space?

Explanation

The quadrangular space transmits the axillary nerve and the posterior circumflex humeral artery. These structures wrap around the surgical neck of the humerus, making them highly susceptible to injury in proximal humerus fractures.

Question 38

The Segond fracture is a pathognomonic sign of an anterior cruciate ligament (ACL) tear. This avulsion fracture from the anterolateral proximal tibia involves the insertion of which capsuloligamentous structure?

Explanation

The Segond fracture is a bony avulsion of the anterolateral ligament (ALL) and the meniscotibial attachment of the lateral capsule from the proximal anterolateral tibia. It is highly correlated with ACL ruptures.

Question 39

During a posterior approach to the upper cervical spine, dissecting too far laterally in the suboccipital triangle risks injuring the vertebral artery. Which structures form the borders of the suboccipital triangle?

Explanation

The suboccipital triangle is bordered by the rectus capitis posterior major (superomedial), obliquus capitis superior (superolateral), and obliquus capitis inferior (inferolateral). The vertebral artery and suboccipital nerve lie within this triangle.

Question 40

A patient sustains a Hawkins Type III talar neck fracture. The high rate of avascular necrosis in this injury is primarily due to the disruption of the major blood supply to the talar body. Which artery is the dominant blood supply to the talar body?

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, is the dominant blood supply to the talar body. It forms an anastomotic sling with the artery of the tarsal sinus to supply the bulk of the talus.

Question 41

A patient presents with median nerve compression symptoms proximal to the elbow. Imaging reveals a supracondylar process of the humerus. Which anatomical structure typically connects this process to the medial epicondyle and compresses the median nerve?

Explanation

The ligament of Struthers connects an anomalous supracondylar process to the medial epicondyle. It can compress the median nerve and the brachial artery, which pass deep to this ligament.

Question 42

The lumbrical muscles of the hand are crucial for coordinating finger flexion and extension. Which of the following accurately describes their origin and insertion?

Explanation

The lumbricals originate from the tendons of the flexor digitorum profundus and insert onto the radial side of the lateral bands of the extensor expansion. This unique anatomy allows them to flex the MCP joints and extend the IP joints.

Question 43

During a zone II flexor tendon repair, preservation of the pulley system is critical to prevent tendon bowstringing. Which two pulleys are considered the most biomechanically essential to preserve or reconstruct?

Explanation

The A2 and A4 pulleys arise from the periosteum of the proximal and middle phalanges, respectively. They are the most crucial for preventing bowstringing and preserving the mechanical advantage of the flexor tendons.

Question 44

A surgeon is performing an ilioinguinal approach for an anterior pelvic ring fracture. Severe hemorrhage is encountered while dissecting over the superior pubic ramus. This bleeding is most likely originating from an anomalous vascular connection between which two vessels?

Explanation

The corona mortis is a vascular anastomosis between the external iliac (or inferior epigastric) and obturator systems. It is located on the posterior aspect of the superior pubic ramus and is highly vulnerable during pelvic surgery.

Question 45

A 45-year-old male presents with severe right leg pain. MRI reveals a far lateral (extraforaminal) disc herniation at the L4-L5 level. Which nerve root is most likely compressed by this specific herniation?

Explanation

In the lumbar spine, a far lateral (extraforaminal) disc herniation compresses the exiting nerve root at the same level. Therefore, an L4-L5 far lateral herniation impinges the L4 nerve root.

Question 46

When utilizing the anterior approach (Henry) to the proximal radius, the posterior interosseous nerve (PIN) is at risk. The nerve typically enters the supinator muscle through which of the following anatomic structures?

Explanation

The posterior interosseous nerve (PIN) enters the supinator muscle at its proximal edge beneath a fibrous arch known as the Arcade of Frohse. Supination of the forearm helps move the PIN away from the surgical field during the Henry approach.

Question 47

A medial approach to the midfoot requires dissection near the Master Knot of Henry. Which two tendons cross at this specific anatomic landmark?

Explanation

The Master Knot of Henry is located in the plantar midfoot, where the flexor hallucis longus (FHL) tendon crosses dorsal to the flexor digitorum longus (FDL) tendon. It is a key landmark when harvesting or transferring these tendons.

Question 48

A 28-year-old overhead athlete is diagnosed with a ganglion cyst causing nerve compression strictly at the spinoglenoid notch. Physical examination is most likely to reveal weakness in which of the following muscles?

Explanation

The suprascapular nerve innervates the supraspinatus prior to passing through the spinoglenoid notch. Compression at the spinoglenoid notch isolatedly affects the innervation to the infraspinatus, causing isolated external rotation weakness.

Question 49

The medial circumflex femoral artery (MCFA) provides the primary blood supply to the adult femoral head. During its normal anatomical course, the MCFA typically passes between which two muscles?

Explanation

The medial circumflex femoral artery originates from the profunda femoris and courses posteriorly. It typically passes between the iliopsoas and pectineus muscles before running superior to the adductor brevis.

Question 50

A patient sustains a scaphoid waist fracture. The proximal pole is highly susceptible to avascular necrosis due to its retrograde blood supply. Which vessel is the primary source of arterial inflow to the proximal pole?

Explanation

The scaphoid is predominantly supplied by the dorsal carpal branch of the radial artery, which enters the bone distally at the dorsal ridge. The blood then flows retrogradely to supply the proximal pole.

Question 51

During a posterolateral corner (PLC) reconstruction of the knee, anatomic femoral tunnel placement is critical. Where is the normal femoral attachment of the fibular collateral ligament (FCL)?

Explanation

The fibular collateral ligament (FCL) attaches to the lateral femur proximal and posterior to the lateral epicondyle. It is also situated proximal and posterior to the femoral insertion of the popliteus tendon.

Question 52

When performing a direct posterior approach for Achilles tendon repair, the sural nerve is at risk of iatrogenic injury. At approximately what distance proximal to the calcaneal insertion does the sural nerve typically cross the lateral border of the Achilles tendon?

Explanation

The sural nerve crosses from the midline of the calf to the lateral border of the Achilles tendon approximately 9 to 10 cm proximal to the calcaneal insertion. Incisions and percutaneous sutures in this area must be carefully placed.

Question 53

A patient presents with a deep space infection of the forearm requiring surgical drainage of Parona's space. What are the volar (roof) and dorsal (floor) boundaries of this anatomic space?

Explanation

Parona's space is a potential deep fascial space in the distal forearm. It is located dorsal to the flexor digitorum profundus tendons (roof) and volar to the pronator quadratus muscle (floor).

Question 54

During a direct lateral approach to the hip (Hardinge), proximal splitting of the gluteus medius must be limited to avoid denervation of the muscle. What is the generally accepted safe limit for proximal dissection 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. Dissection is typically limited to a maximum of 5 cm to prevent denervation of the anterior gluteus medius and minimus.

Question 55

Biomechanically, the anterior cruciate ligament (ACL) is divided into the anteromedial (AM) and posterolateral (PL) bundles. Which of the following best describes the function and tension pattern of the AM bundle?

Explanation

The AM bundle of the ACL is relatively tight in flexion and provides the primary restraint to anterior tibial translation. The PL bundle is tight in extension and is the primary restraint to rotatory loads.

Question 56

A surgeon is repairing a massive rotator cuff tear involving the teres minor and encounters bleeding near the quadrilateral space. What are the anatomic borders of this space?

Explanation

The quadrilateral space is bounded superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the surgical neck of the humerus. It contains the axillary nerve and posterior circumflex humeral artery.

Question 57

A 22-year-old gymnast requires arthroscopic repair of a triangular fibrocartilage complex (TFCC) tear. Healing potential is closely related to the local vascularity. Which portion of the TFCC possesses the most robust blood supply?

Explanation

The TFCC receives its blood supply exclusively at its periphery, predominantly at the ulnar attachment (the peripheral 10-20%). The central portion is avascular and generally requires debridement rather than repair if torn.

Question 58

During open reduction and internal fixation of a midshaft humerus fracture via a posterior approach, the radial nerve must be identified. At what approximate distance proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum?

Explanation

The radial nerve pierces the lateral intermuscular septum to pass from the posterior compartment to the anterior compartment approximately 10 cm proximal to the lateral epicondyle of the humerus.

Question 59

A patient sustains a hyperplantarflexion injury to the midfoot resulting in a Lisfranc fracture-dislocation. The primary ligamentous stabilizer of the Lisfranc joint complex connects which two bones?

Explanation

The Lisfranc ligament is a strong plantar interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the primary stabilizer of the tarsometatarsal articulation.

Question 60

During an anatomic reconstruction of the coracoclavicular (CC) ligaments for an acromioclavicular joint separation, the surgeon must replicate the natural orientation of the conoid and trapezoid ligaments. What is the spatial relationship of the conoid ligament relative to the trapezoid ligament?

Explanation

The coracoclavicular ligaments consist of the conoid and trapezoid. The conoid ligament is positioned posteromedial to the trapezoid ligament and provides the primary restraint to superior clavicular translation.

Question 61

The posterior horn of the lateral meniscus is stabilized by two meniscofemoral ligaments. Which of the following describes the anatomical course of the Ligament of Wrisberg?

Explanation

The meniscofemoral ligaments connect the posterior horn of the lateral meniscus to the medial femoral condyle. The Ligament of Humphrey passes anterior to the PCL, while the Ligament of Wrisberg passes posterior to the PCL.

Question 62

When performing a volar release for de Quervain's tenosynovitis, care must be taken to avoid injury to sensory nerve branches. Which nerve is most at risk during the surgical release of the first dorsal compartment?

Explanation

The superficial sensory branch of the radial nerve courses over the first dorsal compartment (containing APL and EPB). It is highly susceptible to injury during surgical release for de Quervain's tenosynovitis.

Question 63

During the ilioinguinal approach to the acetabulum, the "corona mortis" poses a significant bleeding risk. This vascular structure is an anastomosis between which two systems?

Explanation

The corona mortis is a vascular anastomosis between the external iliac system (typically via the inferior epigastric artery/vein) and the internal iliac system (obturator artery/vein). It crosses the superior pubic ramus and is at risk during the ilioinguinal approach.

Question 64

The internervous plane for the distal extension of the anterolateral approach to the humerus lies between which two muscles?

Explanation

The distal internervous plane of the anterolateral humeral approach lies between the brachialis (musculocutaneous and radial nerves) and the brachioradialis (radial nerve). This plane safely exploits the dual innervation of the brachialis.

Question 65

During a posterior (Kocher-Langenbeck) approach to the hip, which structure provides the primary protection to the medial femoral circumflex artery (MFCA) during the capsulotomy?

Explanation

The deep branch of the MFCA runs superficial to the obturator externus but deep to the quadratus femoris. Preserving the obturator externus tendon protects the major blood supply to the femoral head during a posterior approach.

Question 66

A 28-year-old volleyball player presents with isolated weakness in external rotation of the shoulder. Abduction strength is 5/5. MRI reveals a paralabral cyst compressing a nerve. At which anatomical location is the cyst most likely located?

Explanation

A cyst at the spinoglenoid notch compresses the suprascapular nerve after it has already innervated the supraspinatus, leading to isolated infraspinatus weakness (defective external rotation). Compression at the suprascapular notch would affect both abduction and external rotation.

Question 67

When performing a lateral extensile approach for a calcaneus fracture, the sural nerve must be protected. Which of the following accurately describes the typical course of the sural nerve at the level of the lateral malleolus?

Explanation

The sural nerve travels down the posterior aspect of the leg, passing posterior to the lateral malleolus and lateral to the Achilles tendon. It typically travels alongside the small saphenous vein.

Question 68

The major blood supply to the proximal pole of the scaphoid enters the bone at which specific anatomical location?

Explanation

The major blood supply to the scaphoid comes from the dorsal carpal branch of the radial artery, which enters the bone distally at the dorsal ridge. It supplies the proximal 80% of the bone via retrograde flow.

Question 69

Which of the following structures is located immediately posterior/lateral to the posterior tibial artery within the tarsal tunnel?

Explanation

The mnemonic "Tom, Dick, And Very Nervous Harry" dictates the medial-to-lateral (or anterior-to-posterior) order: Tibialis posterior, Flexor Digitorum longus, Artery, Vein, Nerve (Tibial), Flexor Hallucis longus. Thus, the tibial nerve lies immediately posterior to the vascular bundle.

Question 70

During a posterior approach to the humerus, the radial nerve is identified. Approximately how far proximal to the lateral epicondyle does the radial nerve typically pierce the lateral intermuscular septum to enter the anterior compartment?

Explanation

The radial nerve pierces the lateral intermuscular septum to move from the posterior to the anterior compartment approximately 10 cm proximal to the radiocapitellar joint (or lateral epicondyle). This is a critical anatomical landmark during internal fixation of humeral shaft fractures.

Question 71

Which structure acts as the primary static restraint to valgus stress of the knee when tested at 30 degrees of flexion?

Explanation

The superficial medial collateral ligament (sMCL) is the primary restraint to valgus load at all angles of knee flexion, but its role is most isolated and prominent at 30 degrees. The posterior oblique ligament provides more resistance near full extension.

Question 72

A patient suffers a laceration to the recurrent motor branch of the median nerve at the wrist. Which of the following muscles will subsequently lose its innervation?

Explanation

The recurrent motor branch of the median nerve innervates the thenar muscles: Opponens pollicis, Abductor pollicis brevis, and the superficial head of the Flexor pollicis brevis (OAF). The adductor pollicis and deep head of the FPB are ulnar nerve supplied.

Question 73

The quadrangular space of the shoulder is bound by the teres minor, teres major, long head of the triceps, and surgical neck of the humerus. Which two structures pass through this space?

Explanation

The axillary nerve and the posterior humeral circumflex artery pass through the quadrangular space to supply the deltoid and teres minor. The radial nerve passes through the triangular interval.

Question 74

When performing an anterior approach to the lower cervical spine (e.g., C5-C6), the recurrent laryngeal nerve is at risk. Which of the following statements correctly describes its anatomy?

Explanation

The right recurrent laryngeal nerve loops under the right subclavian artery and ascends in a variable, oblique path toward the tracheoesophageal groove. Because of this variability, it is generally considered at higher risk of iatrogenic injury during right-sided cervical approaches.

Question 75

During a Smith-Petersen approach to the hip, the internervous plane is developed to access the anterior joint capsule. This plane is defined by muscles innervated by which of the following pairs of nerves?

Explanation

The Smith-Petersen (anterior) approach utilizes the internervous plane between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). Deep dissection passes between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 76

In reconstructing the posterolateral corner of the knee, anatomic placement of the femoral tunnels is critical to restore proper biomechanics. Which of the following best describes the femoral attachment of the popliteus tendon relative to the femoral attachment of the lateral collateral ligament (LCL)?

Explanation

On the lateral femoral condyle, the popliteus tendon inserts in the popliteal sulcus, which is located distal and anterior to the femoral attachment of the lateral collateral ligament. Accurate reproduction of this relationship is key to preventing postoperative stiffness and laxity.

Question 77

A 28-year-old volleyball player presents with isolated weakness of the infraspinatus and vague posterior shoulder pain. An MRI reveals a paralabral cyst. Where is the most likely location of the cyst and which nerve is affected?

Explanation

A cyst at the spinoglenoid notch typically compresses the suprascapular nerve after it has given off its motor branches to the supraspinatus. This distal entrapment results in isolated infraspinatus weakness with sparing of the supraspinatus.

Question 78

During an ilioinguinal approach for open reduction of an anterior column acetabular fracture, severe hemorrhage is encountered upon dissection just posterior to the superior pubic ramus. This bleeding is most likely originating from an anastomotic connection between which two vascular systems?

Explanation

The corona mortis is a vascular anastomosis between the external iliac system (usually via the inferior epigastric artery) and the internal iliac system (obturator artery). It crosses the superior pubic ramus approximately 5 cm from the pubic symphysis.

Question 79

When performing a posterior cervical fusion with instrumentation, the surgeon must be cognizant of the course of the vertebral artery. At which cervical level does the vertebral artery typically first enter the transverse foramen?

Explanation

The vertebral artery typically arises from the subclavian artery and enters the transverse foramen at the C6 level in approximately 90% of individuals. It then travels superiorly through the successive transverse foramina from C6 to C1.

Question 80

Which of the following anatomical landmarks best approximates the origin of the recurrent motor branch of the median nerve in the palm, serving as a safe zone reference during limited open carpal tunnel release?

Explanation

The recurrent motor branch of the median nerve generally arises near the intersection of Kaplan's cardinal line and a longitudinal line extending from the radial border of the middle finger. It curves radially to innervate the thenar musculature.

Question 81

During a volar (Henry) approach to the proximal third of the radius, adequate exposure of the supinator muscle requires mobilization of the mobile wad. What specific vascular structure must be ligated and divided to allow full lateral retraction of these muscles?

Explanation

The radial recurrent artery and its accompanying veins (the 'leash of Henry') cross the operative field transversely in the proximal volar approach to the radius. They must be ligated to allow lateral retraction of the brachioradialis and exposure of the supinator insertion.

Question 82

An extensile lateral approach is planned for the open reduction and internal fixation of a displaced intra-articular calcaneus fracture. The vertical limb of the incision is placed midway between the posterior aspect of the fibula and the Achilles tendon. What nerve is at greatest risk during the creation of the full-thickness subperiosteal flap?

Explanation

The sural nerve courses distally posterior to the lateral malleolus, closely associated with the small saphenous vein, making it highly vulnerable during lateral hindfoot incisions. Creating a full-thickness subperiosteal flap helps protect the nerve within the reflected soft tissue.

Question 83

During a lateral deltoid-splitting approach for fixation of a proximal humerus fracture, the axillary nerve is at risk of iatrogenic injury. Approximately how far distal to the lateral edge of the acromion does the axillary nerve typically course on the deep surface of the deltoid?

Explanation

The axillary nerve courses circumferentially from posterior to anterior on the deep surface of the deltoid, typically about 5 to 7 cm distal to the lateral tip of the acromion. Splitting the deltoid distal to this 'safe zone' risks denervating the anterior aspect of the muscle.

Question 84

Anatomical variations in the relationship between the sciatic nerve and the piriformis muscle can theoretically contribute to piriformis syndrome. In the most common normal anatomical arrangement, how does the sciatic nerve traverse the greater sciatic foramen relative to the piriformis?

Explanation

In over 80% of individuals, the sciatic nerve passes undivided through the greater sciatic foramen strictly inferior to the piriformis muscle. The most common variation involves the common peroneal nerve piercing the piriformis muscle belly.

Question 85

A 22-year-old male sustains a displaced fracture of the scaphoid waist. Avascular necrosis of the proximal pole is a known major complication. What is the primary arterial supply to the proximal pole of the scaphoid that dictates this risk pattern?

Explanation

The primary blood supply to the scaphoid is retrograde, originating predominantly from the dorsal carpal branch of the radial artery. This vessel enters the scaphoid distally at the dorsal ridge, making proximal pole fractures highly susceptible to avascular necrosis.

Question 86

Which specific branch of the medial circumflex femoral artery (MCFA) provides the primary blood supply to the weight-bearing dome of the femoral head in an adult, making it critical to protect during posterior approaches to the hip?

Explanation

The deep branch of the medial circumflex femoral artery travels posteriorly and superiorly along the femoral neck beneath the quadratus femoris. It gives rise to the lateral epiphyseal arteries, which supply the majority of the weight-bearing portion of the adult femoral head.

Question 87

In the setting of an Essex-Lopresti injury, longitudinal stability of the forearm is compromised due to a radial head fracture and disruption of the interosseous membrane (IOM). Which anatomical component of the IOM provides the greatest resistance to proximal migration of the radius?

Explanation

The central band is the thickest and most biomechanically robust component of the interosseous membrane. It originates on the radius and inserts distally on the ulna (running in a distal-ulnarward direction), acting as the primary soft-tissue restraint to longitudinal radioulnar translation.

Question 88

A 25-year-old athlete sustains an isolated grade III injury to the superficial medial collateral ligament (sMCL) of the knee, requiring anatomical reconstruction. What is the precise anatomic location of the femoral attachment of the sMCL?

Explanation

The femoral footprint of the superficial MCL is located approximately 3.2 mm proximal and 4.8 mm posterior to the medial epicondyle. It lies distinctly anterior to the insertion of the medial patellofemoral ligament (MPFL).

Question 89

During a lateral transpsoas approach (LLIF) to the lumbar spine at the L4-L5 disc space, the surgeon must carefully navigate the lumbar plexus to avoid neurologic injury. Which nerve pierces the anterior surface of the psoas major muscle and is highly vulnerable during initial psoas muscle splitting and retraction?

Explanation

The genitofemoral nerve uniquely emerges on the anterior aspect of the psoas major muscle belly and descends longitudinally. It is at significant risk of stretch or transection during the initial splitting and retraction of the psoas in lateral lumbar interbody fusion.

Question 90

During the volar (Henry) approach to the proximal radius, supination of the forearm protects the posterior interosseous nerve (PIN). The anatomic basis for this maneuver is that the PIN passes between the two heads of which of the following muscles?

Explanation

The PIN enters the forearm by passing between the superficial and deep heads of the supinator muscle. Supinating the forearm winds the PIN laterally and posteriorly, safely away from the volar surgical field.

Question 91

A 28-year-old overhead athlete presents with chronic posterior shoulder pain and teres minor atrophy. MRI confirms nerve compression within the quadrilateral space. Which of the following structures defines the superior boundary of this anatomic space?

Explanation

The quadrilateral space is bounded superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the surgical neck of the humerus. It contains the axillary nerve and the posterior humeral circumflex artery.

Question 92

During an ilioinguinal approach for an anterior column acetabular fracture, massive hemorrhage occurs posterior to the superior pubic ramus. This is most likely due to an iatrogenic injury to the corona mortis, which represents an anastomosis between the obturator vessels and branches of which artery?

Explanation

The corona mortis is an arterial or venous anastomosis between the external iliac (or its branch, the inferior epigastric) and the obturator vessels. It is located roughly 5 cm from the pubic symphysis along the superior pubic ramus and is highly vulnerable during anterior pelvic exposures.

Question 93

To prevent avascular necrosis during surgical dislocation of the hip, the surgeon must carefully protect the main blood supply to the femoral head, the medial circumflex femoral artery (MCFA). The deep branch of the MCFA consistently traverses between which two muscles?

Explanation

The deep branch of the MCFA provides the main arterial supply to the femoral head. It runs posterior to the obturator externus and anterior to the quadratus femoris, making preservation of the obturator externus critical during posterior hip approaches.

Question 94

A surgeon is performing an extensile lateral approach to the calcaneus for a displaced intra-articular fracture. To minimize the risk of iatrogenic injury to the sural nerve, the surgeon must recognize its typical anatomic location relative to the lateral malleolus. Where is the sural nerve located at this level?

Explanation

At the level of the lateral malleolus, the sural nerve is consistently found 10 to 15 mm posterior to the tip. Understanding this proximity is crucial when creating the full-thickness flap for the extensile lateral approach to the calcaneus.

Question 95

Anatomic reconstruction of the posterolateral corner (PLC) of the knee requires precise tunnel placement. The femoral footprint of the fibular collateral ligament (FCL) is situated in what position relative to the popliteus tendon insertion on the lateral femoral condyle?

Explanation

The FCL femoral footprint is located roughly 18.5 mm proximal and posterior to the popliteus tendon insertion on the lateral femoral condyle. Proper anatomic recognition of this relationship is essential to restore physiologic knee kinematics during PLC reconstructions.

Question 96

During the placement of pedicle screws at L4, the surgeon breaches the inferior cortex of the L4 pedicle. Which neural structure is at the greatest risk of direct mechanical injury?

Explanation

In the lumbar spine, the exiting nerve root travels immediately inferior to the pedicle of the same number. Therefore, an inferior breach of the L4 pedicle directly endangers the L4 exiting nerve root.

Question 97

During minimally invasive plate osteosynthesis (MIPO) for a distal third fibular fracture, the superficial peroneal nerve (SPN) is at risk during percutaneous screw placement. On average, the SPN pierces the deep crural fascia to become subcutaneous at what distance proximal to the tip of the lateral malleolus?

Explanation

The superficial peroneal nerve typically transitions from the lateral compartment to the subcutaneous tissue by piercing the deep fascia approximately 10 to 12 cm proximal to the tip of the lateral malleolus. It is highly susceptible to iatrogenic injury in this zone during lateral leg approaches.

Question 98

A rock climber sustains an acute closed rupture of the A2 pulley in his middle finger. Based on flexor tendon pulley anatomy, the normal A2 pulley originates from the periosteum of which structure?

Explanation

The A2 and A4 pulleys are the major biomechanical stabilizers of the flexor tendons and arise directly from bone. The A2 pulley originates from the periosteum of the proximal half of the proximal phalanx.

Question 99

A patient undergoes an in-situ decompression of the ulnar nerve at the elbow. The surgeon identifies and releases a distinct fascial band that bridges the humeral and ulnar heads of the flexor carpi ulnaris (FCU). This anatomic structure is known as:

Explanation

Osborne's ligament (the cubital tunnel retinaculum) forms the roof of the cubital tunnel, bridging the two heads of the FCU. The arcade of Struthers is a distinct structure located approximately 8 cm proximal to the medial epicondyle.

Question 100

A 34-year-old weightlifter presents with isolated infraspinatus atrophy and weakness, with completely preserved supraspinatus strength and bulk. An MRI is most likely to reveal a paralabral ganglion cyst compressing the suprascapular nerve at which of the following anatomic locations?

Explanation

Compression of the suprascapular nerve at the spinoglenoid notch affects only the infraspinatus muscle. In contrast, compression at the suprascapular notch (proximal to the spinoglenoid notch) denervates both the supraspinatus and infraspinatus.

AAOS & ABOS Basic Science MCQs (Set 3): Bone Biology, Biomechanics & Anatomy Review

Orthopedic Anatomy 2026 MCQs: Board Review Questions & Answers (Part 4)

Key Takeaway

Orthopedic Anatomy 2026 MCQs: Board Review Questions & Answers (Part 4)

Chapter Index