Orthopedic Anatomy 2026 MCQs: Board Review Part 3

Question 1

A 41-year-old man who plays golf regularly has had ulnar-sided wrist pain for the past several days after striking a tree root with a golf club. Examination reveals significant pain with resisted flexion of the ring and small fingers and tenderness over the hook of the hamate. Which of the following radiographic views would be most helpful in identifying the pathology of this injury?

Explanation

The history and examination findings suggest an acute fracture of the hook of the hamate. The radiographic study considered most helpful in identifying this type of fracture is the carpal tunnel view. PA and lateral views of the wrist will not adequately visualize the hook of the hamate. Bruerton's view is intended for the assessment of the metacarpophalangeal joints. Pathology would not be suspected in the scaphoid, metacarpals, or the phalanges, so the scaphoid view and the PA, lateral, and oblique views of the hand would not be helpful. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, p 855.

Question 2

What is the primary limiting membrane and mechanical support for the periphery of the physis?

Explanation

The perichondrial fibrous ring of La Croix acts as a limiting membrane that provides mechanical support for the bone-cartilage junction of the growth plate. It is continuous with the ossification groove of Ranvier, which contributes chondrocytes for the increase in width of the growth plate. The zone of provisional calcification lies at the bottom of the hypertrophic zone and is the site of initial calcification of the matrix. It is quite weak and usually is the cleavage plane for fractures; therefore, it does not qualify as mechanical support. The last intact transverse septum separates the zone of provisional calcification from the primary spongiosa and provides no real support to the physis. The primary spongiosa is the part of the metaphysis nearest the physis. Netter FH: Growth plate, in Woodburne RT, Crelin ES, Kaplan FS, Dingle RV (eds): The Ciba Collection of Medical Illustrations. Summit, NJ, Ciba-Geigy Corporation, 1987, vol 8, pp 166-167.

Question 3

What normal tissue has a low signal intensity (appears black) on both T1- and T2-weighted images?

Explanation

Tendons, cortical bone, ligaments, menisci, and fibrous tissue will show low signal intensity (SI) on both T1- and T2-weighted images. Fat-containing tissues, such as subcutaneous fat and bone marrow, will show high SI on T1-weighted images and low SI on T2-weighted images. Tissues with high water content, such as joint fluid, intervertebral disk, and edema, will show low SI on T1-weighted images and high SI on T2-weighted images. Kasser JR (ed): Orthopaedic Knowledge Update 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 65-70.

Question 4

A positive Froment sign indicates weakness of which of the following muscles?

Explanation

Thumb adduction is powered by the adductor pollicis (ulnar nerve). Testing involves having the patient forcibly hold a piece of paper between the thumb and radial side of the index proximal phalanx. When this muscle is weak or nonfunctioning, the thumb interphalangeal joint flexes with this maneuver, resulting in a positive Froment sign. The paper is held by action of the thumb flexion (flexor pollicis longus and flexor pollicis brevis; median innervated).

Question 5

Figure 28 shows an AP radiograph of a 54-year-old woman who underwent lumbar laminectomy and fusion at the L4 and L5 levels with placement of a bone stimulator 8 years ago. She also underwent a left total hip arthroplasty 2 years ago; aspiration of that joint now reveals that it is infected with a gram-positive cocci organism. History is also significant for IV drug use and human immunodeficiency virus (HIV). The patient reports fever, chills, and left flank and abdominal pain. Examination reveals significant pain with resisted left hip flexion and passive hip extension. She also has lumbar hyperlordosis. Which of the following studies would best identify the underlying cause of her infection?

Explanation

The patient's clinical signs (fever and flank, hip, and abdominal pain) suggest a primary iliopsoas abscess. With an increased patient population who abuse drugs and/or who are HIV-positive, iliopsoas abscess may be more prevalent because of systemic bacterial seeding and may be potentially unrecognized. Diagnostic imaging studies provide a better understanding of the anatomic magnitude of the infection, give concrete confirmation of the diagnosis, and may suggest an underlying cause. Neither standard abdominal radiographs nor ultrasound studies are sensitive enough to be diagnostic of this disease process. CT has been established as the standard study for identifying the underlying cause of this abscess. The hip infection has most likely developed as a result of hematogenous spread from an infected skin lesion from the patient's IV drug use. Santaella RO, Fishman EK, Lipsett PA: Primary vs secondary iliopsoas abscess: Presentation, microbiology, and treatment. Arch Surg 1995;130:1309-1313.

Question 6

A 55-year-old woman who underwent a left total hip arthroplasty 8 months ago using a modified Hardinger approach reports a persistent painless limp. Examination reveals that when she is not using a cane, she lurches to the left during weight bearing on the left lower extremity. An AP radiograph is shown in Figure 29. Which of the following hip muscle groups should be strengthened to improve the gait abnormality?

Explanation

The modified Hardinger approach includes a partial anterior trochanteric osteotomy creating a trochanteric wafer (as seen on the radiograph) that is displaced anterior and medial in continuity with the gluteus medius and vastus lateralis. Failure of abductor reattachment, migration of the trochanter, nonunion of the osteotomy site, and excessive splitting of the gluteus medius muscle causing injury to the inferior branch of the superior gluteal nerve can result in weakness of the abductor mechanism. Abductor strength should be evaluated with the patient lying on the opposite side and elevating the affected limb. Although slight weakness may manifest itself as a limp only after prolonged muscular activity, significant weakness results in a constant limp without associated discomfort. Morrey BF (ed): Joint Replacement Arthroplasty. New York, NY, Churchill Livingstone, 1991, pp 512-526.

Question 7

Figure 30 shows an axial cross section of extensor tendon anatomy in zone 7 of the wrist. What letter best depicts the location of the posterior interosseous nerve?

Explanation

The posterior interosseous nerve in contained in the floor of the fourth dorsal compartment of the wrist, which is labelled C in this diagram. Tubiana R, McCullough CJ, Masquelet AC: An Atlas of Surgical Exposures of the Upper Extremity. Philadelphia, PA, JB Lippincott, 1990, p 224.

Question 8

Figures 31a and 31b show the T1- and T2-weighted MRI scans of a patient's knee joint. What is the most likely diagnosis?

Explanation

31b The scans show a lipohemarthrosis. There is the characteristic layering of a superior zone containing fat (high signal intensity), a central zone containing serum (low signal intensity), and an inferior zone that contains red blood cells (low signal intensity). The most common cause of a lipohemarthrosis is an intra-articular fracture with leakage of marrow fat into the joint. Resnick D, Kang HS: Synovial joints, in Resnick D, Kang HS (eds): Internal Derangements of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 49-53.

Question 9

A 15-year-old boy reports feeling a pop and notes sudden giving way of the left knee while playing basketball. He has immediate pain and swelling in the knee. An AP radiograph is shown in Figure 32. A small avulsion fragment from the lateral tibial margin is the only finding. What is the most likely diagnosis?

Explanation

An avulsion fracture from the lateral tibial margin carries the eponym Segond fracture and is pathognomonic for an anterior cruciate ligament (ACL) tear. The fragment is located posterior to Gerdy's tubercle and is superior and anterior to the fibular head. It represents an avulsion of the lateral capsular ligament of the knee and is caused by the same mechanism that causes the ACL tear. The pes anserinus is the insertion point of the medial hamstrings and would not be affected in a lateral avulsion injury. The posterior cruciate ligament may be seen on a lateral view if associated with an avulsion fragment, but a tear of the PCL generally cannot be diagnosed on an AP view. The insertion of the iliotibial band is broad and is unlikely to produce an avulsion injury such as that seen in the radiograph. This view is not consistent with the appearance of a lateral collateral ligament injury. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 533-557.

Question 10

What neurovascular structure is most at risk when performing an inside-out repair of the posterior horn of the medial meniscus?

Explanation

The saphenous nerve is located on the posterior medial aspect of the knee and must be protected when performing an inside-out repair of the medial meniscus. The peroneal nerve is most at risk with lateral meniscal repairs. The other structures usually are not at risk with meniscal repair. Cannon WD Jr, Morgan CD: Meniscal repair: Arthroscopic repair techniques. Instr Course Lect 1994;43:77-96.

Question 11

Figure 33 shows the AP and lateral radiographs of an obese 58-year-old man who underwent a cementless total hip arthroplasty 6 years ago. He reports no pain, and examination reveals a normal gait and painless hip range of motion. What is the most likely diagnosis?

Explanation

Osteolysis of an otherwise well-functioning total hip arthroplasty is a recognized complication, and its radiographic appearance is typical, as shown here. Distal osteolysis, such as that shown here, is more prevalent when there is noncircumferential sealing of the proximal femoral canal. Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 175-180.

Question 12

Which of the following muscles attaches to the coracoid process of the scapula?

Explanation

The insertion of the pectoralis minor is on the base of the coracoid process. The coracoid helps define the interval between the subscapularis and supraspinatus muscles but neither attaches to it. The coracobrachialis and short head of biceps attach to the tip of the coracoid but are not listed as options. The long head of the biceps attaches to the supraglenoid tubercle. The serratus arises from the vertebral border of the scapula. Jobe CM: Anatomy and surgical approaches, in Jobe FW (ed): Operative Techniques in Upper Extremity Sports Injuries. St Louis, MO, Mosby, 1996, pp 140-142.

Question 13

Turf toe typically involves injury to which of the following structures of the great toe?

Explanation

The term turf toe includes a range of injuries of the capsuloligamentous complex of the first metatarsophalangeal joint with or without osteochondral fracture of the first metatarsal head or one of the sesamoids. The mechanism of injury is hyperextension. Clanton TO, Butler JE, Eggert A: Injuries to the metatarsophalangeal joints in athletes. Foot Ankle 1986;7:162-176.

Question 14

Figures 34a through 34c show an axial proton density (spin echo long TR, short TE) image, a sagittal inversion recovery (STIR) image, and a sagittal T1-weighted (short TR, short TE) image of the left thigh. What is the most likely diagnosis?

Explanation

34b 34c The images reveal a region of increased signal within the rectus femoris muscle with mild, ill-defined surrounding edema. The presence of high intensity signal on the T1-weighted image favors acute blood, in this case associated with a rectus femoris muscle tear or fatty tissue. However, because of fat suppression, a fatty lesion or lipoma would be dark on STIR, rather than bright as in this image. Most foreign bodies are low intensity signal and if small, are difficult to evaluate with MRI. The lack of adjacent subcutaneous soft-tissue edema or surrounding fluid makes pyomyositis an unlikely diagnosis.

Question 15

The artery located within the substance of the coracoacromial ligament is a branch of what artery?

Explanation

The acromial branch of the thoracoacromial artery courses along the medial aspect of the coracoacromial ligament and may be encountered when performing an open or arthroscopic subacromial decompression. Bleeding can be controlled by ligation of its branch from the thoracoacromial artery. The other arteries may be injured in other surgical exposures of the shoulder. Esch JC, Baker CL: The shoulder and elbow, in Whipple TL (ed): Arthroscopic Surgery. Philadelphia, PA, JB Lippincott, 1993, pp 65-66.

Question 16

Figures 35a and 35b show the axial T2-weighted and coronal T1-weighted MRI scans of a patient who has enlargement of the right thigh. What is the most likely diagnosis?

Explanation

35b The images show a large, almost circumferential, mass surrounding the diaphysis of the femur. The intramedullary signal is normal with minimal cortical destruction, both findings that should be abnormal in conventional osteosarcoma and Ewing's sarcoma. There are very low-signal striations representing osteoid formation that would have a sunburst radiographic pattern. This indicates an osteogenic lesion. Myositis ossificans is not indicated because studies would reveal zonal ossification starting in the periphery rather than the more central pattern seen in this patient. This appearance is typical for periosteal osteosarcoma.

Question 17

Figures 36a and 36b show the MRI scans of a patient who has shoulder weakness. What is the most likely diagnosis?

Explanation

36b The sagittal image reveals increased signal and decreased size of the supraspinatus and infraspinatus muscles, indicating muscle atrophy. The rotator cuff tendon signal is normal. The subscapularis and teres minor muscles are unaffected. Muscular dystrophy and thoracic outlet syndrome would be expected to have a more global effect. Although muscular atrophy can occur in the setting of a rotator cuff tear, the coronal image shows an intact supraspinatus. The suprascapular nerve supplies the supraspinatus and infraspinatus muscles. Therefore, suprascapular nerve entrapment would result in atrophy of these muscles with sparing of the surrounding musculature. Any lesion within the suprascapular notch, including neoplastic disease, a venous varix, or neuroma, can place pressure on the suprascapular nerve. Suprascapular nerve entrapment most commonly results from extension of a paralabral cyst or ganglion, often with associated labral pathology. Spinal accessory nerve disruption would show trapezius muscle atrophy. Resnick D, Kang HS (eds): Internal Derangement of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 308-317.

Question 18

Figure 37 shows the T2-weighted MRI scan of the hip joint. What structure is labeled A?

Explanation

The obturator internus originates on the obturator membrane and adjacent bone, including the quadrilateral plate, and exits the lesser sciatic notch to insert on the posterior medial greater trochanter. The structure labeled C is the pectineus, B is the sartorius, and D is the gluteus medius. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, pp 145-150, 324.

Question 19

The great medullary artery, also known as the Adamkiewicz artery, originates from which of the following arteries?

Explanation

The great medullary artery originates as a direct or indirect branch of the left posterior intercostal artery, usually between T8 and T12. It becomes intradural and crosses over one to three disk spaces before turning to the midline where it anastomoses with the anterior spinal artery. Injury to this artery can result in devastating ischemia of the lower spinal cord. Lu J, Ebraheim NA, Biyani A, Brown JA, Yeasting RA: Vulnerability of great medullary artery. Spine 1996;21:1852-1855.

Question 20

A patient who underwent total knee arthroplasty now reports a loss of sensation in the area circled in Figure 38. This area is innervated by which of the following nerves?

Explanation

The saphenous nerve follows the saphenous vein, giving off the infrapatellar branch that crosses the knee anteriorly to supply the peripatellar skin. A longitudinal incision can interrupt the nerve, leaving the terminal distribution without sensation.

Question 21

During an anterior approach to the shoulder, excessive traction on the conjoined tendon is most likely to result in loss of

Explanation

The musculocutaneous nerve travels through the conjoined tendon approximately 8 cm distal to the tip of the acromion. The musculocutaneous nerve innervates the biceps muscle and the bracialis muscle, both of which are responsible for elbow flexion. Shoulder flexion is facilitated by the anterior fibers of the deltoid muscle (axillary nerve) and the supraspinatus muscle (suprascapular nerve). The subscapular muscle facilitates internal rotation of the shoulder (upper and lower subscapularis nerve). Shoulder abduction is performed by the deltoid muscle (axillary nerve), and forearm pronation is facilitated by the pronator teres (median nerve). Hollinshead WH: Anatomy for Surgeons: The Back and Limbs, ed 3. Philadelphia, PA, Harper and Row, 1982, pp 391-393.

Question 22

Figure 39 shows the sagittal T1-weighted MRI scan of a 27-year-old man who twisted his knee 2 weeks ago. The arrow is pointing to

Explanation

The arrow identifies a transverse dark line that represents primary trabeculae of the physeal scar. A similar finding is seen in the proximal tibia. These lines may persist indefinitely. They do not represent ongoing growth, an abnormally open physeal plate, a stress fracture, or Looser's line (fatigue fracture in osteomalacia).

Question 23

Figure 40 shows the AP radiograph of a 55-year-old man who reports left knee pain. Which of the following conditions is least likely to produce this radiographic presentation?

Explanation

The radiograph reveals densities within the articular cartilage of the knee commonly referred to as chondrocalcinosis. The term chondrocalcinosis refers to the presence of calcium-containing crystals detected as radiodensities in cartilage. Calcium-containing crystals other than calcium pyrophosphate dihydrate may also deposit in articular cartilage and menisci, producing both radiographically detectable densities in cartilage and joint inflammation or degeneration. Hemochromatosis, alkaptonuria (ochronosis), and Wilson's disease are characterized by cellular deposition of iron, calcium, and copper ions, respectively, into various tissues including articular cartilage and can give this appearance. Septic arthritis does not usually cause chondrocalcinosis. Klippel JH (ed): Primer on the Rheumatic Diseases, ed 11. Atlanta, GA, Arthritis Foundation, 1997, pp 226-229 and 328-331.

Question 24

Figure 41 shows the MRI scan of a 39-year-old man who has severe left groin and anterior thigh pain. What is the most likely diagnosis?

Explanation

The MRI scan shows near complete involvement of the femoral head with bone marrow changes and some collapse of the necrotic segment. This is most suggestive of osteonecrosis.

Question 25

Iliosacral screws placed for stabilization of posterior pelvic ring injuries (eg, sacroiliac dislocation) that exit the sacrum anteriorly are most likely to injure which of the following structures?

Explanation

Iliosacral screws have gained popularity for posterior stabilization of pelvic ring disruptions, but complications attributed to incorrect placement are a clinical problem. The L5 nerve root is at greatest risk and is in closest proximity to a malpositioned screw (exiting the sacrum). The L4 root is more anterior at this level. The S1 root is still intraosseous at this level and is at risk but not from the screw exiting anteriorly at this level. The arteries are at risk but are more anterior and are at less risk than the L5 nerve root.

Question 26

A 26-year-old professional baseball pitcher presents with isolated, painless weakness in external rotation of his throwing shoulder. Magnetic resonance imaging demonstrates isolated atrophy of the infraspinatus muscle. At which of the following anatomical locations is the affected nerve most likely compressed?

Explanation

Compression of the suprascapular nerve at the spinoglenoid notch affects only the infraspinatus, presenting with painless weakness in external rotation. Compression at the suprascapular notch would affect both the supraspinatus and infraspinatus.

Question 27

During an ilioinguinal approach to the acetabulum, significant hemorrhage is encountered behind the superior pubic ramus near the symphysis. This bleeding is most likely originating from the corona mortis, which is an anastomotic connection between the obturator vessels and which of the following?

Explanation

The corona mortis is a vascular anastomosis between the external iliac or inferior epigastric vessels and the obturator vessels. It is located posterior to the superior pubic ramus at a variable distance from the symphysis pubica.

Question 28

A 45-year-old patient sustains a displaced talar neck fracture. Which of the following arteries provides the primary blood supply to the body of the talus and is at greatest risk of disruption in this injury?

Explanation

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

Question 29

When performing an anterior (Smith-Petersen) approach to the hip, the superficial internervous plane is utilized. Which of the following accurately describes the innervation of the muscles defining this plane?

Explanation

The superficial plane of the Smith-Petersen approach utilizes the interval 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 30

A patient sustains a midfoot sprain. Radiographs are suspicious for a subtle Lisfranc injury. The primary stabilizing ligament of this joint complex connects which of the following osseous structures?

Explanation

The Lisfranc ligament is an interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is critical for the primary stability of the tarsometatarsal joint complex.

Question 31

A 35-year-old mechanic presents with an inability to extend his thumb and fingers at the MCP joints, but retains normal wrist extension and normal sensation in the hand. The nerve responsible for this deficit is most commonly compressed by the proximal edge of the superficial layer of which muscle?

Explanation

The patient has Posterior Interosseous Nerve (PIN) syndrome. The most common site of PIN compression is the Arcade of Frohse, which is a fibrous band at the proximal edge of the superficial head of the supinator muscle.

Question 32

During an anterolateral approach to the distal humerus, the surgeon develops an internervous plane to access the humeral shaft. Which of the following describes the innervation of the muscles defining this plane?

Explanation

The anterolateral approach to the distal humerus utilizes the internervous plane between the brachialis (musculocutaneous nerve) and the brachioradialis (radial nerve).

Question 33

A 28-year-old man sustains a displaced talar neck fracture. Disruption of which of the following vessels puts him at highest risk for avascular necrosis of the talar body?

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, provides the dominant blood supply to the talar body. Disruption of this vessel in talar neck fractures significantly increases the risk of avascular necrosis.

Question 34

A 34-year-old professional volleyball player presents with insidious onset of right shoulder weakness. Examination reveals isolated atrophy of the infraspinatus with normal supraspinatus bulk and strength. Where is the most likely site of nerve compression?

Explanation

Compression of the suprascapular nerve at the spinoglenoid notch results in isolated infraspinatus weakness and atrophy. Compression at the suprascapular notch would affect both the supraspinatus and infraspinatus.

Question 35

During an ilioinguinal approach for an acetabular fracture, significant hemorrhage occurs while dissecting over the superior pubic ramus. This bleeding is most likely originating from an anastomosis between the obturator vessels and which of the following?

Explanation

The corona mortis is a vascular anastomosis between the obturator system and the external iliac or inferior epigastric vessels, located on the posterior aspect of the superior pubic ramus. It is at high risk of iatrogenic injury during anterior pelvic approaches.

Question 36

A 25-year-old man sustains a severe traction injury to his shoulder, resulting in a disruption of the posterior cord of the brachial plexus. Which of the following muscles will most likely demonstrate profound weakness on clinical examination?

Explanation

The latissimus dorsi is innervated by the thoracodorsal nerve, which arises from the posterior cord. The pectoralis major (medial/lateral cords), biceps (lateral cord), flexor carpi ulnaris (medial cord), and supraspinatus (upper trunk) do not receive primary innervation from the posterior cord.

Question 37

A 28-year-old elite volleyball player presents with isolated weakness of external rotation in his dominant shoulder. MRI reveals a paralabral cyst in the spinoglenoid notch. Which nerve is compressed, and which muscle(s) will demonstrate denervation changes?

Explanation

The suprascapular nerve passes through the suprascapular notch to innervate the supraspinatus, then travels through the spinoglenoid notch to innervate the infraspinatus. Compression at the spinoglenoid notch causes isolated infraspinatus weakness.

Question 38

A 72-year-old woman sustains a displaced femoral neck fracture. To understand the risk of avascular necrosis, an orthopedic resident reviews the blood supply to the adult femoral head. Which vessel provides the majority of the blood supply to the weight-bearing portion of the femoral head?

Explanation

The medial femoral circumflex artery (MFCA) is the primary blood supply to the weight-bearing portion of the adult femoral head. Its lateral epiphyseal branches enter the capsule posteriorly to perfuse the head.

Question 39

A 25-year-old baseball pitcher presents with vague posterior shoulder pain and deltoid weakness. Examination shows atrophy of the teres minor. Which anatomical boundaries define the space where the affected neurovascular bundle is likely compressed?

Explanation

Quadrangular space syndrome involves compression of the axillary nerve and posterior circumflex humeral artery. The boundaries are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and humeral shaft (lateral).

Question 40

A 30-year-old rock climber felt a "pop" in his right ring finger while bearing weight on a crimp hold. On examination, there is noticeable bowstringing of the flexor tendons upon resisted finger flexion. Which pulleys are biomechanically most critical to prevent this bowstringing and are most commonly injured in this scenario?

Explanation

The A2 and A4 pulleys are the most biomechanically critical pulleys in the flexor tendon sheath to prevent bowstringing. They are frequently injured in rock climbers due to high eccentric loads.

Question 41

A 22-year-old football player sustains a direct blow to the anteromedial tibia. Clinical examination demonstrates asymmetric varus laxity at 30 degrees of knee flexion, but symmetrical stability at 0 degrees. Which of the following structures is the primary restraint to varus opening at 30 degrees of flexion?

Explanation

The lateral collateral ligament (LCL) is the primary restraint to varus stress at 30 degrees of knee flexion. At full extension (0 degrees), the posterior cruciate ligament and posterolateral capsule act as secondary restraints, masking an isolated LCL injury.

Question 42

A 45-year-old marathon runner presents with burning pain and tingling in the plantar aspect of her foot. Tinel's sign is positive posterior to the medial malleolus. In the tarsal tunnel, what is the anatomical relationship of the structures from anterior to posterior?

Explanation

The structures in the tarsal tunnel from anterior to posterior follow the mnemonic "Tom, Dick, AND Very Nervous Harry": Tibialis posterior, flexor Digitorum longus, posterior tibial Artery, Tibial Nerve, and flexor Hallucis longus.

Question 43

A 35-year-old man sustains a midshaft humerus fracture. During open reduction and internal fixation via an anterolateral approach, the surgeon must identify and protect the radial nerve. At approximately what distance proximal to the lateral epicondyle does the radial nerve typically pierce the lateral intermuscular septum?

Explanation

The radial nerve travels in the spiral groove and pieces the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle to enter the anterior compartment of the arm.

Question 44

A 40-year-old mother of a newborn undergoes surgical release for refractory De Quervain's tenosynovitis. Which tendons are released, and what is the most common anatomical variation that can lead to surgical failure if unrecognized?

Explanation

De Quervain's affects the first dorsal compartment, containing the abductor pollicis longus (APL) and extensor pollicis brevis (EPB). Multiple slips of the APL and a separate intracompartmental septum for the EPB are common causes of failed conservative or surgical treatment.

Question 45

A 6-year-old boy sustains a displaced supracondylar humerus fracture. Post-reduction, he is unable to form an "OK" sign with his thumb and index finger. The affected nerve innervates which of the following muscle groups?

Explanation

The inability to form the "OK" sign indicates an Anterior Interosseous Nerve (AIN) palsy. The AIN is a motor branch of the median nerve that innervates the flexor pollicis longus, the radial half of the flexor digitorum profundus, and the pronator quadratus.

Question 46

A 21-year-old soccer player injures his knee. Radiographs reveal a small avulsion fracture of the lateral tibial plateau, known as a Segond fracture. This pathognomonic sign represents an avulsion of which anatomical structure?

Explanation

The Segond fracture is a cortical avulsion fracture off the lateral tibial plateau, representing an avulsion of the anterolateral ligament (ALL) and lateral capsular structures. It is highly correlated with anterior cruciate ligament (ACL) tears.

Question 47

Following a retroperitoneal hematoma, a patient presents with weak knee extension, weak hip flexion, and an absent patellar reflex. Sensation is decreased over the anterior thigh and medial lower leg. Which nerve is affected, and from which nerve roots does it arise?

Explanation

The femoral nerve innervates the anterior compartment of the thigh (hip flexors and knee extensors) and provides sensation via the saphenous nerve. It originates from the posterior divisions of the ventral rami of L2, L3, and L4.

Question 48

During a lateral surgical approach for an Achilles tendon repair, the surgeon carefully dissects to avoid nerve injury. The sural nerve is typically formed by the convergence of the medial sural cutaneous nerve and a communicating branch from which nerve?

Explanation

The sural nerve is formed by the union of the medial sural cutaneous nerve (a branch of the tibial nerve) and the sural communicating branch of the lateral sural cutaneous nerve (a branch of the common peroneal nerve).

Question 49

In a patient with adult-acquired flatfoot deformity secondary to posterior tibial tendon dysfunction, the spring ligament complex gradually fails. This critical static stabilizer of the longitudinal arch connects which two bones?

Explanation

The spring ligament is properly termed the plantar calcaneonavicular ligament. It connects the calcaneus to the navicular and provides a sling-like support for the head of the talus, maintaining the medial longitudinal arch.

Question 50

A patient with subacromial impingement syndrome is scheduled for an arthroscopic subacromial decompression. The coracoacromial ligament is a key structure in the roof of the subacromial space. Which of the following is true regarding its anatomy?

Explanation

The coracoacromial ligament forms the coracoacromial arch over the humeral head. Uniquely, it connects two parts of the same bone (the coracoid process and the acromion of the scapula) rather than bridging a joint.

Question 51

During a posterior approach to the hip for a total hip arthroplasty, identifying the sciatic nerve is critical. What is the most common anatomical relationship of the sciatic nerve to the piriformis muscle in the general population?

Explanation

In roughly 85% of individuals, the entire sciatic nerve exits the greater sciatic foramen passing directly inferior to the piriformis muscle. Variations include the common peroneal division piercing or passing superior to the piriformis.

Question 52

A 34-year-old male sustains a distal third humeral shaft fracture (Holstein-Lewis) and presents with a wrist drop. The nerve at risk pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment of the arm. Approximately how far proximal to the lateral epicondyle does this anatomic transition occur?

Explanation

The radial nerve pierces the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle. This predictable anatomic location puts it at high risk of tethering and injury in distal third humeral shaft fractures.

Question 53

A patient presents with the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger, but has normal upper extremity sensation. Which of the following muscles will likely also exhibit weakness on examination?

Explanation

The patient has an anterior interosseous nerve (AIN) palsy, presenting with weakness of the FPL and FDP to the index finger. The AIN also innervates the pronator quadratus, which can be tested by resisting forearm pronation with the elbow fully flexed.

Question 54

During a posterolateral corner (PLC) reconstruction of the knee, the surgeon must anatomically restore the femoral footprints of the lateral collateral ligament (LCL) and the popliteus tendon. What is the spatial relationship of the LCL origin relative to the popliteus origin on the lateral femoral condyle?

Explanation

On the lateral femoral condyle, the origin of the LCL is situated proximal and posterior to the popliteus insertion. Recognizing this relationship is critical for isometric graft placement during PLC reconstruction.

Question 55

A 25-year-old athlete sustains a severe ankle syndesmosis injury. Which of the following anatomic structures provides the greatest resistance against lateral displacement of the fibula relative to the tibia?

Explanation

The posterior inferior tibiofibular ligament (PITFL) is the strongest component of the syndesmotic complex. Biomechanical studies show it provides approximately 40% of the resistance to syndesmotic diastasis.

Question 56

A surgeon utilizes the volar (Henry) approach to internally fix a distal radius fracture. During the deep dissection in the distal third of the forearm, the interval is developed between the brachioradialis and the flexor carpi radialis (FCR). Where should the radial artery be safely retracted?

Explanation

In the distal third of the Henry approach, the radial artery runs just deep and ulnar to the brachioradialis. It must be carefully mobilized and retracted medially along with the FCR tendon to protect it.

Question 57

During the anterior (Smith-Petersen) approach to the hip, the superficial interval is between the sartorius and the tensor fasciae latae. In the deep interval, a muscle is retracted medially. Which nerve provides the primary innervation to this medially retracted muscle?

Explanation

The deep interval of the Smith-Petersen approach is between the rectus femoris (medial) and the gluteus medius (lateral). The rectus femoris is innervated by the femoral nerve.

Question 58

A 28-year-old volleyball player presents with isolated weakness in external rotation of the shoulder with the arm at the side, but has normal abduction strength and no sensory deficits. An MRI reveals a paralabral cyst in the spinoglenoid notch. From which structural level of the brachial plexus does the affected nerve originate?

Explanation

The suprascapular nerve originates from the upper trunk of the brachial plexus (C5, C6). Compression at the spinoglenoid notch affects only the infraspinatus muscle, leading to isolated external rotation weakness.

Question 59

When performing a deltoid-splitting approach to the proximal humerus, the surgeon must be mindful of the axillary nerve traversing the deep surface of the muscle. What is the generally accepted safe distance from the lateral tip of the acromion to avoid injury to the axillary nerve?

Explanation

The axillary nerve runs transversely across the deep surface of the deltoid approximately 5 to 7 cm distal to the lateral edge of the acromion. A split extending further distally puts the nerve at significant risk.

Question 60

During an ilioinguinal approach for an acetabular fracture, significant hemorrhage occurs while dissecting the posterior aspect of the superior pubic ramus. This is most likely due to an injury of the 'corona mortis', which is an anastomosis between the obturator vessels and which of the following?

Explanation

The corona mortis is an important vascular anastomosis between the external iliac system (usually via the deep inferior epigastric artery) and the obturator system. It crosses the superior pubic ramus and is highly vulnerable during anterior pelvic surgery.

Question 61

A surgeon is performing a medial approach to the midfoot and dissects near the Master Knot of Henry. Which of the following statements correctly describes the anatomical relationship of the tendons at this location?

Explanation

At the Master Knot of Henry, the flexor digitorum longus (FDL) crosses over the flexor hallucis longus (FHL) from medial to lateral. Therefore, the FHL lies deep (dorsal) to the FDL at this intersection.

Question 62

A spinal deformity surgeon is planning a long posterior fusion. To minimize the risk of anterior spinal artery syndrome, the surgeon must consider the Artery of Adamkiewicz. Which of the following is the most common anatomical location for the entrance of this artery into the spinal canal?

Explanation

The Artery of Adamkiewicz is the largest anterior segmental medullary artery. It most commonly enters the spinal canal on the left side between the T8 and L1 levels.

Question 63

During an in situ ulnar nerve decompression at the elbow, the surgeon releases the roof of the cubital tunnel. The primary fascial structure forming this roof (Osborne's ligament) connects which of the following bony landmarks?

Explanation

Osborne's ligament (the cubital tunnel retinaculum) forms the roof of the cubital tunnel. It spans from the medial epicondyle to the olecranon, connecting the two heads of the flexor carpi ulnaris.

Question 64

A 30-year-old male sustains a displaced talar neck fracture. Which artery provides the predominant blood supply to the body of the talus and is at highest risk of disruption in this injury pattern?

Explanation

The artery of the tarsal canal provides the majority of the blood supply to the talar body. It is a direct branch of the posterior tibial artery and enters the talus inferiorly.

Question 65

A plastic surgeon harvests a vascularized free fibula flap using a direct lateral approach. The internervous plane developed for this exposure lies between the peroneal muscles and the soleus. Which two nerves supply the muscles defining this plane?

Explanation

The lateral approach to the fibula exploits the internervous plane between the peroneus brevis (supplied by the superficial peroneal nerve) and the soleus (supplied by the tibial nerve).

Question 66

During ligamentous reconstruction for early basilar thumb arthritis, the anterior oblique ligament (beak ligament) is targeted to restore stability against dorsal subluxation. Where is the primary metacarpal attachment site of this ligament?

Explanation

The anterior oblique ligament is the primary static stabilizer of the trapeziometacarpal joint. It attaches to the volar palmar beak of the first metacarpal and prevents dorsal, radial, and proximal translation.

Question 67

A collegiate baseball pitcher undergoes a Tommy John procedure (ulnar collateral ligament reconstruction). To correctly reconstruct the primary restraint to valgus stress, the graft must be anchored to the anatomical insertion of the anterior bundle of the MCL. What is this ulnar insertion site?

Explanation

The anterior bundle of the medial collateral ligament is the primary restraint to valgus stress at the elbow. It originates on the anterior-inferior aspect of the medial epicondyle and inserts on the sublime tubercle of the ulna.

Question 68

A 22-year-old male presents with a proximal pole scaphoid nonunion. The vulnerability of the proximal pole to avascular necrosis is due to its retrograde blood supply. The principal vessel supplying the proximal pole enters the scaphoid at which of the following anatomic locations?

Explanation

The dorsal carpal branch of the radial artery provides the dominant blood supply to the scaphoid (proximal 80%). It enters through foramina along the dorsal ridge at the waist and distal pole, flowing retrogradely to the proximal pole.

Question 69

In patients diagnosed with piriformis syndrome, variations in the relationship between the sciatic nerve and the piriformis muscle are often noted. According to the Beaton and Anson classification, what is the most common anatomical variant (Type B)?

Explanation

In normal anatomy, the entire sciatic nerve exits below the piriformis. The most common variant (seen in 10-15% of people) occurs when the common peroneal division pierces the piriformis while the tibial division passes inferiorly.

Question 70

During the anterior (Henry) approach to the proximal radius, which internervous plane is utilized?

Explanation

The proximal anterior approach to the radius (Henry) utilizes the internervous plane between the brachioradialis (radial nerve) and the pronator teres (median nerve). This safely exposes the proximal radius without crossing nerve territories.

Question 71

When performing an extensile lateral approach for an intra-articular calcaneus fracture, what structure is at greatest risk of injury at the distal limb of the incision?

Explanation

The sural nerve crosses the lateral aspect of the foot and is at greatest risk of injury during the horizontal limb of the extensile lateral approach to the calcaneus. Careful full-thickness flap elevation is critical to protect it.

Question 72

In the Smith-Petersen approach to the hip, what represents the true internervous plane?

Explanation

The Smith-Petersen (anterior) approach utilizes the internervous plane between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). This allows excellent access to the anterior hip joint and pelvis.

Question 73

Which ligament provides the greatest mechanical contribution to the stability of the ankle syndesmosis?

Explanation

The posterior inferior tibiofibular ligament (PITFL) provides approximately 42% of the strength of the syndesmosis, making it the strongest single ligamentous stabilizer. The anterior inferior tibiofibular ligament provides roughly 35%.

Question 74

A posterior approach to the shoulder is performed. To avoid injury to the axillary nerve, the surgeon must be aware of its course through the quadrangular space. Which of the following forms the inferior border of this space?

Explanation

The quadrangular space is bordered superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the humeral shaft. It contains the axillary nerve and posterior circumflex humeral artery.

Question 75

A 28-year-old man sustains a talar neck fracture. Which artery provides the predominant blood supply to the body of the talus, placing it at high risk for avascular necrosis?

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, is the most consistent and predominant blood supply to the body of the talus. It enters through the inferior surface of the talar neck.

Question 76

When performing an endoscopic carpal tunnel release, the surgeon must stay radial to the hook of the hamate to avoid entering Guyon's canal. Which structures form the anatomic roof of Guyon's canal?

Explanation

The roof of Guyon's canal is formed by the palmar carpal ligament and the palmaris brevis muscle. The floor is formed by the flexor retinaculum (transverse carpal ligament) and the pisohamate ligament.

Question 77

During a transforaminal lumbar interbody fusion (TLIF) at L4-L5, the surgeon utilizes Kambin's triangle to access the disc space safely. Which structure constitutes the anterior/hypotenuse border of Kambin's triangle?

Explanation

Kambin's triangle is an anatomic corridor for safe access to the lumbar disc. It is bounded anteriorly (hypotenuse) by the exiting nerve root, inferiorly (base) by the superior endplate of the lower vertebral body, and posteriorly by the superior articular process.

Question 78

A patient presents with scapular winging and inability to efficiently retract the scapula. EMG reveals a lesion isolated to the dorsal scapular nerve. Which of the following muscles are primarily affected?

Explanation

The dorsal scapular nerve arises from the C5 root of the brachial plexus and innervates the rhomboid major, rhomboid minor, and the levator scapulae. Denervation leads to weakness in scapular retraction and elevation.

Question 79

A 22-year-old athlete sustains a scaphoid waist fracture. What is the primary source of the retrograde blood supply to the proximal pole of the scaphoid?

Explanation

The proximal pole of the scaphoid relies entirely on retrograde blood flow provided by the dorsal carpal branch of the radial artery. It enters the bone along the dorsal ridge at the waist and distal pole.

Question 80

During a posterolateral corner (PLC) reconstruction of the knee, anatomic femoral tunnels must be created. What is the correct position of the popliteus tendon femoral insertion relative to the lateral collateral ligament (LCL) origin?

Explanation

The popliteus tendon originates on the lateral femoral epicondyle an average of 18.5 mm anterior and inferior to the origin of the lateral collateral ligament (LCL). Recognizing this relationship is crucial for anatomic PLC reconstructions.

Question 81

A 35-year-old typist complains of proximal anterior forearm pain and paresthesias in the radial three-and-a-half digits. Examination shows reproduction of symptoms with resisted forearm pronation and elbow flexion. Compression of the median nerve by the lacertus fibrosus is suspected. From which muscle does the lacertus fibrosus originate?

Explanation

The lacertus fibrosus, or bicipital aponeurosis, is a fascial band originating from the biceps brachii tendon and crossing medially over the median nerve and brachial artery. It is a recognized site of proximal median nerve compression.

Question 82

In a skeletally mature patient, an intracapsular femoral neck fracture significantly compromises the blood supply to the femoral head. Which vessel supplies the majority of blood to the adult femoral head?

Explanation

The medial femoral circumflex artery (MFCA), specifically its lateral epiphyseal branch, provides the predominant blood supply to the femoral head in adults. It courses posteriorly and is highly vulnerable in displaced femoral neck fractures.

Question 83

During a modified Weaver-Dunn procedure for acromioclavicular joint separation, the coracoacromial (CA) ligament is transferred to the distal clavicle. Which anatomic structure attaches to the medial border of the coracoid process?

Explanation

The pectoralis minor inserts on the medial border and superior surface of the coracoid process. The conjoined tendon inserts at the tip, while the coracoclavicular ligaments attach to the base.

Question 84

A patient suffers an isolated ulnar nerve injury at the wrist. Which of the following intrinsic hand muscles will lose its innervation?

Explanation

The deep branch of the ulnar nerve innervates the adductor pollicis, all interossei, the third and fourth lumbricals, and the deep head of the flexor pollicis brevis. The median nerve supplies the LOAF muscles (Lumbricals 1-2, Opponens pollicis, Abductor pollicis brevis, superficial Flexor pollicis brevis).

Question 85

When performing open reduction and internal fixation of a calcaneus fracture via a medial approach, the surgeon visualizes a prominent bony shelf, the sustentaculum tali. Which tendon runs immediately inferior to this structure?

Explanation

The flexor hallucis longus (FHL) tendon passes through a groove located immediately inferior to the sustentaculum tali. The flexor digitorum longus and tibialis posterior lie superior/medial to it.

Question 86

A 24-year-old marathon runner is diagnosed with exertional compartment syndrome of the deep posterior compartment of the leg. Which nerve is located within this specific compartment?

Explanation

The deep posterior compartment of the lower leg contains the tibialis posterior, flexor hallucis longus, flexor digitorum longus, and the posterior tibial artery and tibial nerve. Fasciotomy must decompress this compartment adequately.

Question 87

During a direct lateral approach (Hardinge) to the hip, the gluteus medius is split. What is the precise anatomic footprint of the gluteus medius tendon insertion on the greater trochanter?

Explanation

The gluteus medius inserts broadly onto the lateral and superoposterior facets of the greater trochanter. The gluteus minimus inserts anteriorly on the anterior facet.

Question 88

When evaluating a patient for meniscal repair, the vascular zone of the meniscus is critical. Which vessels provide the primary blood supply to the peripheral genicular capsular attachments of the menisci?

Explanation

The peripheral 10% to 30% of the menisci receives its vascular supply primarily from the perimeniscal capillary plexus, which is fed by the medial and lateral inferior genicular arteries. The central portions remain avascular.

Question 89

A 28-year-old professional baseball pitcher presents with vague right posterior shoulder pain and progressive weakness in external rotation. MRI reveals isolated atrophy of the teres minor muscle with a paralabral cyst in the anatomic space transmitting the axillary nerve. Which of the following structures forms the superior border of this specific anatomic space?

Explanation

The axillary nerve and posterior circumflex humeral artery pass through the quadrangular space. The borders of the quadrangular space are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and the humeral shaft (lateral).

Question 90

A 22-year-old man sustains a scaphoid waist fracture. Because of the unique vascular anatomy of the scaphoid, he is at high risk for avascular necrosis of the proximal pole. The primary blood supply to the proximal pole of the scaphoid is delivered in a retrograde fashion from which of the following vessels?

Explanation

The dorsal carpal branch of the radial artery enters the scaphoid at the distal pole and along the dorsal ridge, supplying 70-80% of the bone including the proximal pole via retrograde flow. Disruption of this intraosseous retrograde blood supply leads to proximal pole avascular necrosis.

Question 91

During the ilioinguinal approach for open reduction and internal fixation of an anterior column acetabular fracture, brisk arterial bleeding is encountered superior to the superior pubic ramus. This hemorrhage is most likely originating from an anatomic variant vascular connection between the obturator vessels and which of the following?

Explanation

The "corona mortis" is a vascular anastomosis between the external iliac system (or inferior epigastric vessels) and the obturator vessels. It is located roughly 5 cm from the symphysis pubis overlying the superior pubic ramus and is highly susceptible to injury during pelvic surgery.

Question 92

A 35-year-old patient requires reconstruction of the posterolateral corner of the knee following a multiligamentous knee injury. Accurate anatomical tunnel placement is critical to restore proper joint kinematics. Relative to the lateral epicondyle, where is the normal anatomic femoral attachment of the fibular collateral ligament (FCL) located?

Explanation

The anatomic femoral attachment of the fibular collateral ligament (FCL) is located slightly proximal and posterior to the lateral epicondyle. Placing the femoral tunnel incorrectly alters tensioning across the flexion-extension arc.

Question 93

A spine surgeon is utilizing a lateral transpsoas approach to perform an interbody fusion at L4-L5. Postoperatively, the patient has profound weakness in hip flexion and knee extension, alongside anterior thigh numbness. Which neural structure was most likely injured or compressed during retraction of the posterior third of the psoas muscle?

Explanation

The femoral nerve (L2-L4) descends through the posterior third of the psoas muscle and is at highest risk during lateral transpsoas approaches at the L4-L5 level. Injury results in weak hip flexion/knee extension and anterior thigh numbness.

Question 94

A 40-year-old man undergoes percutaneous repair of an acute Achilles tendon rupture. Postoperatively, he complains of numbness and paresthesias along the lateral aspect of his foot. The injured nerve is most vulnerable as it crosses from the lateral aspect of the leg to the lateral border of the Achilles tendon. At what approximate distance proximal to the calcaneal insertion does this crossing occur?

Explanation

The sural nerve crosses the lateral border of the Achilles tendon at an average of 9.8 cm (approximately 10 cm) proximal to the calcaneal insertion. Percutaneous sutures placed in the proximal stump must be passed carefully to avoid capturing this nerve.

Question 95

A 31-year-old mechanic complains of an inability to extend his digits at the metacarpophalangeal joints. Examination reveals intact wrist extension with radial deviation, and no sensory deficits. The diagnosis of Posterior Interosseous Nerve (PIN) syndrome is confirmed. The most common site of compression is the Arcade of Frohse, which is formed by the tendinous proximal border of which muscle?

Explanation

The Arcade of Frohse is a fibrous arch formed by the proximal edge of the superficial head of the supinator muscle. It is the most common site of compression for the Posterior Interosseous Nerve, leading to finger and thumb drop with preserved wrist extension.

Question 96

A surgeon is performing a posterior approach to the hip for a total hip arthroplasty. To prevent iatrogenic avascular necrosis of the native femoral head in a joint-preserving procedure, the deep branch of the medial femoral circumflex artery (MFCA) must be protected. This critical vessel passes between which two anatomic structures?

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) courses posterior to the obturator externus and anterior to the quadratus femoris. Sparing the obturator externus tendon during the posterior approach helps protect the primary blood supply to the femoral head.

Question 97

During a Latarjet procedure for recurrent anterior shoulder instability, the conjoined tendon is mobilized and retracted to gain exposure to the anterior glenoid. The surgeon must be mindful of the musculocutaneous nerve entering the coracobrachialis muscle. What is the typical distance from the tip of the coracoid process to the point where this nerve enters the muscle?

Explanation

The musculocutaneous nerve typically enters the coracobrachialis muscle 5 to 8 cm distal to the tip of the coracoid process. Vigorous retraction of the conjoined tendon past this limit can cause a stretch injury to the nerve.

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

Orthopedic Anatomy 2026 MCQs: Board Review Questions & Answers (Part 3)

Key Takeaway

Orthopedic Anatomy 2026 MCQs: Board Review Questions & Answers (Part 3)

Chapter Index