Orthopedic Anatomy 2026 MCQs: Board Review Part 1

Question 1

A patient has right shoulder pain. Figure 1a shows a gadolinium-enhanced transverse MRI scan at the level of the coracoid. Figure 1b shows an arthroscopic view of the anterior structures from a posterior portal. These images reveal which of the following findings?

Explanation

1b The area shown in the arthroscopic view and MRI scan is referred to as a Buford complex and represents a normal labral variant. It consists of a thickened, cord-like middle glenohumeral ligament, a superior labral attachment of the middle glenohumeral ligament just anterior to the biceps tendon, and absence of the anterosuperior labrum. This combination of findings can be confusing and may simulate labral pathology. Mistaken repair of the lesion back to the glenoid rim can result in significant loss of external rotation. A Bankart lesion would be located at the inferior anterior glenoid rim. The subscapularis is seen anterior to the labrum. Normal variations that occur in the anterosuperior labrum can simulate pathology. Gusmer PB, Potter HG, Schatz JA, et al: Labral injuries: Accuracy of detection with unenhanced MR imaging of the shoulder. Radiology 1996;200:519-524. Griffin LY (ed): Orthopaedic Knowledge Update: Sports Medicine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 47-63.

Question 2

What muscle attaches to the site shown by the arrow in Figure 2?

Explanation

The latissimus dorsi inserts on the humerus metaphysis between the pectoralis major (posterior) and teres major (anterior). Teres minor inserts on the base of the greater tuberosity. Pectoralis minor does not insert on the humerus. Williams PL, Warwick R, Dyson M, Bannister LH: Neurology, in Gray's Anatomy, ed 37. Edinburgh, Scotland, Churchill Livingstone, 1989, pp 1131-1132.

Question 3

Figures 3a and 3b show the inversion stress radiographs of a patient's ankle. What is the most likely ligament injury pattern?

Explanation

3b The radiographic findings show 30 degrees of talar tilt (severe) and 10 mm of anterior translation that typically involves laxity of both of the major lateral ligaments of the ankle (anterior talofibular and calcaneofibular). There is no evidence of deltoid laxity. Harper MC: Stress radiographs in the diagnosis of lateral instability of the ankle and hindfoot. Foot Ankle 1992;13:435-438.

Question 4

Posterior sternoclavicular dislocations are most commonly associated with which of the following complications?

Explanation

Posterior sternoclavicular dislocations are commonly associated with tracheal compression, which can be a life-threatening condition requiring immediate reduction. The other listed complications are less common. Brooks AL, Henning GD: Injury to the proximal clavicular epiphysis, abstracted. J Bone Joint Surg Am 1972;54:1347-1348.

Question 5

An AP radiograph of the pelvis is shown in Figure 4. What muscle attaches to the avulsed fragment of bone identified by the arrow?

Explanation

The radiograph reveals an avulsion of the ischial apophysis, most likely the result of violent contraction of the attached hamstring tendons (semimembranosus, semitendinosus, and long head of the biceps femoris). The short head of the biceps femoris arises from the linea aspera on the posterior femur. The pectineus and adductor longus attach to the pubic portion of the pelvis. The piriformis runs from the sacrum to the femur. Woodburne RT (ed): Essentials of Human Anatomy. New York, NY, Oxford University Press, 1978, pp 542-545.

Question 6

A patient with an acromioclavicular dislocation has a very prominent distal clavicle. Examination reveals that the deformity increases rather than reduces with an isometric shoulder shrug. Which of the following structures is most likely intact?

Explanation

Severely displaced acromioclavicular injuries disrupt the deltotrapezial fascia and muscular origin in addition to the ligaments (acromioclavicular and coracoclavicular or trapezoid and conoid). When the deltoid is still attached to the clavicle, an isometric shoulder shrug will tend to reduce the displacement. When the deltoid is detached but the trapezius is attached, this manuever will increase the deformity and surgery may be indicated.

Question 7

Figures 5a and 5b show axial and coronal MRI images of the left ankle of a patient with lateral ankle pain. What is the most likely diagnosis?

Explanation

5b The figures show a longitudinal split within the peroneus brevis tendon as it courses posterior to the fibula. The peroneus longus tendon has been driven between the medial and lateral components of the peroneus brevis tendon. Peroneal split syndrome is a cause of lateral ankle pain but may be less asymptomatic in the elderly. It may be associated with tendon subluxation following a tear of the superior peroneal retinaculum.

Question 8

Which of the following anatomic structures is often difficult to visualize during elbow arthroscopy?

Explanation

The ulnar collateral ligament is often difficult to visualize during elbow arthroscopy. It can be seen clearly in only 10% to 30% of elbow arthroscopies. All of the other structures should be easily and thoroughly seen and palpated during elbow arthroscopy. Johnson LL: Arthroscopic Surgery: Principles and Practice. St Louis, MO, CV Mosby, 1988.

Question 9

The quadrilateral space in the shoulder contains which of the following structures?

Explanation

The quadrilateral or quadrangular space of the shoulder is formed laterally by the humerus, proximally by the subscapularis (and teres minor viewed from posterior), distally by the teres major, and medially by the long head of triceps. The posterior humeral circumflex artery and axillary nerve pass through it. The axillary artery is more proximal. The radial nerve and profunda brachii pass through a triangular space more inferior. The circumflex scapular artery passes through a triangular space more medial. Hollinshead WH: Textbook of Anatomy, ed 3. Hagerstown, MD, Harper and Row, 1974, pp 205-206.

Question 10

Based on the MRI scan shown in Figure 6, the abnormal signal is seen in what carpal bone?

Explanation

The MRI scan reveals an abnormal signal in the trapezoid, which lies adjacent to the capitate in the distal carpal row. The tumor is a giant cell tumor of bone. Cooney WP, Linscheid RL, Dobyns JH: The Wrist: Diagnosis and Operative Treatment. St Louis, MO, Mosby-Year Book, 1998, vol 1, pp 278-282. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, pp 2238-2240. bar based on these measurements is shown in Figure 54d. Initial treatment should consist of 1- bony bar resection and distal fibula epiphysiodesis. 2- bony bar resection and corrective osteotomy. 3- bony bar resection and physiodesis of the opposite distal tibial physis. 4- corrective osteotomy and a limb-lengthening procedure. 5- corrective osteotomy and physiodesis of the opposite distal tibial physis. 2 54a 54b 54c 54d Mapping of a physeal bar from biplane polytomography or CT helps to identify lesions that should be treated surgically and aids in planning the surgical approach and resection. Criteria for surgical excision are at least 2 years of longitudinal growth remaining and involvement of no more than 50% of the physis. Osteotomy is required if angular deformity is greater than 20 degrees. Although this physeal bar is large, it is slightly less than 50% of the total area of the physis. Limb lengthening in this case should be reserved for failure of bar resection. Physiodesis of the opposite distal tibia at this age would result in disproportionate shortening of both tibiae. Carlson WO, Wenger DR: A mapping method to prepare for surgical excision of a partial physeal arrest. J Pediatr Orthop 1984;4:232-238.

Question 11

The recurrent motor branch of the median nerve innervates which of the following muscles?

Explanation

The recurrent motor branch of the median nerve supplies the thenar muscles (abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis) that are primarily responsible for thumb opposition. The nerve can be injured in carpal tunnel release. A branch of the nerve also supplies the first lumbrical. The adductor pollicis and the interossei are supplied by the ulnar nerve. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, p 109.

Question 12

Which of the following nerves innervates the muscle that originates from the middle third of the dorsal surface of the lateral border of the scapula, as shown in Figure 7?

Explanation

Teres minor originates from the middle third of the dorsal surface of the lateral border of the scapula. It is supplied by the axillary nerve (C5). Williams PL, Warwick R, Dyson M, Bannister LH: Myology, in Gray's Anatomy, ed 37. Edinburgh, Scotland, Churchill Livingstone, 1989, pp 611-615.

Question 13

Based on the MR arthrogram of the elbow shown in Figure 8, which of the following structures is torn?

Explanation

Based on the MR arthrogram in which gadolinium (bright on T1-weighted images) was injected into the joint space prior to imaging, the study shows a tear of the anterior band of the ulnar collateral ligament (UCL). The disruption in the distal end of the UCL is outlined by contrast. A small collection of contrast extravasation into the flexor musculature further confirms the presence of a tear. The UCL has a broad-based attachment on the medial epicondyle and has a pointed or tapered attachment distally on the ulna. Most UCL tears occur distally at the ulnar (coronoid) attachment. MR arthrography provides improved sensitivity compared to conventional MRI, without contrast, for the detection of UCL pathology, particularly in the subacute or chronic setting. After the soft-tissue edema and joint fluid associated with the injury have resolved, the torn end of the ligament may lie in contact with its adjacent attachment and create a false-negative appearance. In this patient, a noncontrasted MR arthrogram showed no tear, yet the tear is apparent with intra-articular contrast and distention. MR arthrography of the elbow also may be useful in detecting intra-articular bodies or in evaluation for loose osteochondral fragments or flaps. Morrey BF: Acute and chronic instability of the elbow. J Am Acad Orthop Surg 1996;4:117-128.

Question 14

A 26-year-old man has recurrent right knee pain. Figures 9a and 9b show consecutive sagittal T2-weighted MRI scans, and Figure 9c shows a coronal T1-weighted MRI scan. What is the most likely diagnosis?

Explanation

9b 9c A discoid meniscus is a large disk-like meniscus. It is seen in the lateral meniscus in 3% of the population; a discoid medial meniscus is much less common. It can be identified on the coronal view by noting meniscal tissue extending into the tibial spine at the intercondylar notch. The average width of a normal meniscus is less than 11 mm. A bow-tie appearance should not be seen on more than two consecutive sagittal images because the conventional thickness of the sagittal slices is 3 mm and the interval between two consecutive slices is 1.5 mm. Two sagittal slices will cover a 9-mm thickness. A discoid meniscus can be diagnosed on the sagittal views by noting a bow-tie appearance on more than two consecutive images. Helms CA: MR image of the knee, in Fundamentals of Skeletal Radiology, ed 2. Philadelphia, PA, WB Saunders, 1995, pp 172-191.

Question 15

The gluteus maximus is innervated by which of the following nerves?

Explanation

The inferior gluteal nerve supplies the gluteus maximus muscle. The superior gluteal nerve supplies the gluteus medius, gluteus minimus, and tensor fascia lata muscles. The femoral nerve supplies the quadriceps, sartorius, and pectineus muscles. The pudendal nerve is primarily a sensory nerve.

Question 16

The dorsal (Thompson) approach to the proximal forearm uses which of the following intermuscular intervals?

Explanation

The Thompson posterior approach is used in treatment of fractures of the proximal radius. Dissection is carried out through the interval between the extensor carpi radialis brevis (radial nerve) and the extensor digitorum communis (posterior interosseous nerve). To identify this interval, the forearm is pronated and the mobile lateral wad of muscles (the ulnar-most belly is the extensor carpi radialis brevis) is grasped with the thumb and finger and pulled from the much less mobile mass of the extensor digitorum communis. The furrow created is marked with a skin marker for subsequent skin incision. The skin incision follows a line from the lateral epicondyle of the humerus to a point corresponding to the middle of the posterior aspect of the wrist. Distally, the intermuscular plane is between the extensor carpi radialis brevis and the extensor pollicis longus. Crenshaw AH Jr: Surgical techniques and approaches, in Canale ST (ed): Campbell's Operative Orthopaedics, ed 9. St Louis, MO, Mosby-Year Book, 1998, vol 1, pp 128-129. Hoppenfeld S, deBoer P: Posterior approach to the radius, in Surgical Exposures in Orthopaedics: The Anatomic Approach, ed 2. Philadelphia, PA, Lippincott-Raven, 1992, pp 136-146.

Question 17

A 45-year-old man who smokes reports the rapid onset of color changes and coolness in the fingers. Examination shows an abnormal Allen test. Plain radiographs of the hand and wrist are normal. Which of the following studies will best aid in diagnosis?

Explanation

The patient has symptoms typical of Raynaud's phenomenon secondary to underlying vascular disease. The next most appropriate step in the management of this patient should be to perform contrast angiography on the involved upper extremity to look for proximal or distal arterial lesions or insufficiencies. MRI and contrast CT are not as specific as angiography for the identification of vascular lesions of the upper extremity. Although patients with primary Raynaud's vasospastic disease can have normal angiographic findings, they typically are younger than age 40 years, are female, and have normal results on an Allen test. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, pp 2288-2290.

Question 18

A purulent flexor tenosynovitis of the thumb may communicate with the small finger flexor through which of the following structures?

Explanation

Only the flexor sheaths of the thumb and small finger are continuous from the digit through the carpal canal and into the distal forearm. If one of the sheaths ruptures from synovitis, it may contaminate the other sheath through Parona's space in the distal forearm. This potential space lies superficial to the pronator quadratus and deep to the flexor tendons. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, pp 1044-1045.

Question 19

Which of the following nerves travels with the deep palmar arch?

Explanation

The ulnar nerve divides alongside the pisiform, and the deep branch supplies the three hypothenar muscles and crosses the palm with the deep palmar arch to supply the two ulnar lumbricals, all interossei, and finally the adductor pollicis. The superficial branch supplies the ulnar digital branches to the small and ring fingers. The median nerve branches are more superficial in the palm near the superficial palmar arch. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, p 109.

Question 20

Figures 10a through 10c show the plain radiograph and MRI scans of a 41-year-old man who has right hip pain. What is the most likely diagnosis?

Explanation

10b 10c Transient osteoporosis is a self-limited painful but reversible disorder. Although first described in pregnant women, it is more common in young to middle-aged men. The radiograph shows loss of mineralization in the right hip relative to the left side. There is no osseous destruction or cortical expansion typical of metastasis or giant cell tumor. The process is confined to the femoral side of the joint unlike rheumatoid arthritis, which would be centered in the joint. Osteonecrosis is better defined with sharp but irregularly shaped margins, and there is no double-line sign. The MRI scans reveal diffuse edema in the femoral head and neck that is atypical for osteonecrosis. Transient osteoporosis may recur in the same or opposite hip.

Question 21

Figure 11 shows the anatomic dissection of the medial side of the knee joint after removal of the superficial fascia. The arrow is pointing to what structure?

Explanation

The semitendinosus and gracilis tendons lie beneath the superficial fascia and superficial to the medial collateral ligament. The semitendinosus is located more inferior to the gracilis tendon. The sartorius is more posterior and distal as is the medial collateral ligament. The semimembranosus is posterior. Pagnani MJ, Warner JJ, O'Brien SJ, Warren RF: Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565-571.

Question 22

Figure 12 shows a lateral radiograph of the elbow. What is the most likely diagnosis?

Explanation

The figure shows a supracondylar process, which is a normal anatomic variant. An osteochondroma tends to occur more toward the end of bones, and the medullary space of the underlying bone extends into the base of the osteochondroma. The presence of a supracondylar process is usually asymptomatic. However, the ligament of Struthers that always extends from the supracondylar process to the medial epicondyle can result in median nerve entrapment secondary to trauma. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, pp 132-133.

Question 23

Which of the following nerves is most likely responsible for symptoms associated with plantar fasciitis?

Explanation

The first branch of the lateral calcaneal nerve innervates the abductor digiti minimi. It is reported to be trapped at the interval between the abductor hallucis and the quadratus plantae muscles.

Question 24

A 16-year-old cheerleader reports an ache in the right shoulder and arm that is worse after activity. She denies any history of acute trauma. Examination reveals a positive sulcus sign and an AP glide test with a posterior and anterior apprehension sign. To confirm a diagnosis of multidirectional instability, which of the following imaging studies is most appropriate?

Explanation

Multidirectional instability is a common finding in young female athletes. The anatomic structures are all intact but are hypermobile; therefore, CT and bone scans and scapular Y-views are often normal. Obtaining a weighted or AP stress view while applying downward traction on the arm will document instability and hypermobility of the joint. MRI generally is not indicated in this condition. Ultrasound is used primarily for rotator cuff pathology. Neer CS II, Foster CR: Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder: A preliminary report. J Bone Joint Surg Am 1980;62:897-908.

Question 25

Which of the following findings is seen in the chest radiograph shown in Figure 13?

Explanation

Orthopaedic surgeons are often responsible for interpreting radiographs of general examinations such as the chest radiograph shown. For accurate interpretation, it is important to systematically review all of the information available on the radiograph. Using this approach, the fracture of the left proximal humerus is readily recognized. Linear air soft-tissue density at the lung periphery would suggest a pneumothorax, but this finding is not shown on the radiograph. The upper thoracic spine is well aligned. The sternoclavicular and distal clavicles are normal.

Question 26

A 25-year-old overhead throwing athlete presents with poorly localized posterior shoulder pain and weakness in external rotation. Examination reveals atrophy of the teres minor. MRI demonstrates an isolated paralabral cyst compressing a nerve within the quadrilateral space. Which of the following defines the superior border of this anatomic space?

Explanation

The quadrilateral space is bordered superiorly by the teres minor (posteriorly) and subscapularis (anteriorly). It is bordered inferiorly by the teres major, medially by the long head of the triceps, and laterally by the surgical neck of the humerus.

Question 27

A 45-year-old man presents with a right-sided paracentral disc herniation at the C5-C6 level causing severe radiculopathy. Which nerve root is most likely compressed, and where does it exit relative to the corresponding pedicle?

Explanation

In the cervical spine, nerve roots exit through the intervertebral foramina ABOVE their correspondingly named pedicles (e.g., the C6 root exits above the C6 pedicle at C5-C6). This contrasts with the lumbar spine, where roots exit below their corresponding pedicles.

Question 28

During an anterior intrapelvic approach (modified Stoppa) for an acetabular fracture, life-threatening hemorrhage occurs near the posterior aspect of the superior pubic ramus. This is most likely due to injury of the corona mortis, which is an anastomotic vessel connecting which two vascular systems?

Explanation

The corona mortis is a critical vascular anastomosis between the external iliac system (via the inferior epigastric vessels) and the internal iliac system (via the obturator vessels). It is classically located 5 to 6 cm from the pubic symphysis on the superior pubic ramus.

Question 29

A 22-year-old gymnast presents with chronic ulnar-sided wrist pain. MRI shows a tear of the triangular fibrocartilage complex (TFCC). Healing potential is highly dependent on the vascularity of the TFCC. Which portion of the TFCC receives the most robust blood supply?

Explanation

The peripheral 10% to 20% of the TFCC is highly vascularized, receiving supply from branches of the ulnar artery and interosseous arteries. Central and radial tears are largely avascular and typically require debridement, whereas peripheral tears can be repaired.

Question 30

A 24-year-old man sustains a scaphoid waist fracture after a fall on an outstretched hand. He is at high risk for avascular necrosis of the proximal pole due to its specific retrograde vascularity. What is the primary arterial supply to the proximal pole of the scaphoid?

Explanation

The predominant blood supply to the scaphoid (70-80%) comes from the dorsal carpal branch of the radial artery, which enters distally at the dorsal ridge. This establishes a retrograde blood flow, placing the proximal pole at high risk for ischemia following a fracture.

Question 31

A patient with an inability to extend the fingers at the metacarpophalangeal (MCP) joints without sensory loss is diagnosed with Posterior Interosseous Nerve (PIN) syndrome. The nerve is most commonly compressed by the Arcade of Frohse. This structure is a fibrous band associated with which of the following muscles?

Explanation

The Arcade of Frohse is the thickened proximal aponeurotic edge of the superficial head of the supinator muscle. It acts as the most frequent site of compression for the posterior interosseous nerve.

Question 32

When performing an anatomical reconstruction of the posterolateral corner (PLC) of the knee, identifying isometric graft attachment sites is crucial. Which of the following accurately describes the femoral attachment of the popliteus tendon relative to the origin of the lateral collateral ligament (LCL)?

Explanation

On the lateral femoral epicondyle, the popliteus tendon insertion is consistently located anterior and distal to the origin of the lateral collateral ligament (LCL). Respecting this anatomy is vital for restoring normal PLC kinematics.

Question 33

A 30-year-old runner suffers an inversion ankle sprain while her foot was locked in maximum dorsiflexion. Which of the following lateral ankle ligaments is the primary restraint to inversion in this specific foot position, and thus most likely to be injured?

Explanation

The calcaneofibular ligament (CFL) becomes taut in ankle dorsiflexion, making it the primary stabilizer against inversion in this position. Conversely, the ATFL is under maximum tension during plantarflexion.

Question 34

A 35-year-old male sustains a posterior shoulder dislocation and subsequently develops numbness over the lateral aspect of his deltoid. The affected nerve passes through an anatomical space in the posterior shoulder. Which of the following structures forms the inferior border of this space?

Explanation

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

Question 35

During a posterolateral corner (PLC) reconstruction of the knee, the surgeon must accurately restore the primary static stabilizer to varus stress at 30 degrees of knee flexion. What is the precise femoral attachment site of this structure relative to the lateral epicondyle?

Explanation

The fibular collateral ligament (LCL) is the primary static stabilizer to varus stress at 30 degrees of flexion. Its femoral footprint is located slightly proximal and posterior to the lateral epicondyle.

Question 36

A 28-year-old rock climber presents with a sudden "pop" in his ring finger followed by bowstringing of the flexor tendons on forced flexion. Rupture of which of the following annular pulleys is most responsible for this biomechanical failure?

Explanation

The A2 and A4 pulleys arise from the periosteum of the proximal and middle phalanges, respectively. They are the most biomechanically critical pulleys for preventing flexor tendon bowstringing.

Question 37

An orthopedic surgeon performing an anterior (ilioinguinal) approach for an acetabular fracture encounters severe hemorrhage while dissecting superior to the superior pubic ramus. This bleeding most likely originates from an anomalous anastomosis between the external iliac system and which other vascular system?

Explanation

The "corona mortis" is a vascular anastomosis between the obturator (internal iliac system) and external iliac/inferior epigastric systems. It courses over the superior pubic ramus and is at high risk during anterior pelvic approaches.

Question 38

When placing C1 lateral mass screws, a surgeon must understand the anomalous and typical courses of the vertebral artery to avoid catastrophic vascular injury. At which cervical level does the vertebral artery typically enter the transverse foramen?

Explanation

The vertebral artery typically enters the transverse foramen at C6 in about 90% of individuals. It rarely enters at C7.

Question 39

A patient undergoes surgical release of the tarsal tunnel for compressive neuropathy. From anterior to posterior, what is the correct anatomical order of structures passing behind the medial malleolus?

Explanation

The correct order of structures from anterior to posterior is remembered by the mnemonic 'Tom, Dick, AND Very Nervous Harry': Tibialis posterior, Flexor Digitorum longus, Artery, Vein, Nerve, Flexor Hallucis longus.

Question 40

A patient presents with an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger after a supracondylar humerus fracture. The affected nerve normally passes between the two heads of which muscle?

Explanation

The clinical presentation describes anterior interosseous nerve (AIN) palsy. The AIN is a branch of the median nerve, which enters the forearm by passing between the superficial and deep heads of the pronator teres.

Question 41

A 65-year-old female sustains a displaced femoral neck fracture. Which artery provides the predominant blood supply to the adult femoral head, placing it at high risk of avascular necrosis in this fracture pattern?

Explanation

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the adult femoral head. It branches into the lateral epiphyseal artery which enters the femoral head posterosuperiorly.

Question 42

During a four-compartment fasciotomy of the lower leg for compartment syndrome, the surgeon must ensure the deep posterior compartment is adequately decompressed. Which muscle serves as the critical landmark within this specific compartment?

Explanation

The deep posterior compartment contains the tibialis posterior, flexor digitorum longus, and flexor hallucis longus. The tibialis posterior is the key deep structure that must be decompressed to fully release this compartment.

Question 43

A 22-year-old male sustains a scaphoid waist fracture that progresses to a nonunion. The proximal pole of the scaphoid is highly susceptible to avascular necrosis because its major vascular supply enters the bone at the:

Explanation

The major blood supply to the scaphoid is a branch of the radial artery that enters at the dorsal ridge and supplies the proximal pole via retrograde flow.

Question 44

A collegiate baseball pitcher undergoes ulnar collateral ligament (UCL) reconstruction. The anterior bundle of the UCL is the primary restraint to valgus stress. Where is the precise anatomical footprint of this bundle on the ulna?

Explanation

The anterior bundle of the MUCL originates on the anteroinferior surface of the medial epicondyle and inserts on the sublime tubercle at the medial margin of the coronoid process.

Question 45

A 28-year-old volleyball player presents with isolated weakness in external rotation of the right shoulder. Atrophy of the infraspinatus is noted, but supraspinatus strength is normal. Entrapment of the affected nerve at which anatomical location is most likely?

Explanation

The suprascapular nerve supplies the supraspinatus and infraspinatus. Entrapment at the spinoglenoid notch affects only the infraspinatus, while entrapment at the suprascapular notch affects both muscles.

Question 46

In a severe high ankle sprain requiring surgical fixation, the surgeon aims to restore syndesmotic stability. Which ligament is anatomically considered the strongest and most substantial stabilizer of the distal tibiofibular syndesmosis?

Explanation

The posterior inferior tibiofibular ligament (PITFL) provides the greatest strength to the distal syndesmosis, contributing over 40% of the total syndesmotic stability.

Question 47

An orthopedic surgeon utilizes the direct anterior (Smith-Petersen) approach for a total hip arthroplasty. The superficial internervous plane lies between the sartorius and the tensor fasciae latae. These muscles are innervated, respectively, by which of the following nerves?

Explanation

The Smith-Petersen approach exploits a true internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve).

Question 48

Following a distal radius fracture, a patient develops spontaneous rupture of the extensor pollicis longus (EPL) tendon. The EPL tendon normally utilizes which bony landmark as a pulley before inserting on the distal phalanx of the thumb?

Explanation

The extensor pollicis longus (EPL) courses in the 3rd dorsal compartment and wraps around Lister's tubercle on the dorsal radius, changing its line of pull toward the thumb.

Question 49

A patient with advanced rheumatoid arthritis presents with myelopathic symptoms. Flexion-extension radiographs show significant atlantoaxial instability. Which ligament, primarily responsible for limiting axial rotation and lateral bending between the occiput and the axis, is most likely compromised?

Explanation

The alar ligaments connect the dens to the occipital condyles and are the primary restraints to axial rotation and lateral bending at the craniocervical junction.

Question 50

A trauma patient sustains a severe deep laceration over the volar-ulnar aspect of the wrist, transecting the ulnar artery. Anatomically, the superficial palmar arch receives its major contribution from the ulnar artery and is completed radially by which of the following structures?

Explanation

The superficial palmar arch is formed predominantly by the ulnar artery and is typically completed by the superficial palmar branch of the radial artery.

Question 51

A 19-year-old soccer player undergoes knee arthroscopy revealing a complex radial tear in the inner third of the medial meniscus. Why is simple debridement favored over repair for this specific meniscal zone?

Explanation

The inner third (white-white zone) of the meniscus is completely avascular. Healing requires a blood supply, rendering repairs in this zone highly prone to failure.

Question 52

A patient with severe, long-standing carpal tunnel syndrome presents with noticeable atrophy of the thenar eminence. Which intrinsic muscles of the hand, aside from the thenar group, are predominantly innervated by the affected nerve?

Explanation

The median nerve innervates the thenar muscles (LOAF: Lumbricals 1 and 2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis superficial head). The first and second lumbricals are median nerve innervated.

Question 53

A 55-year-old female presents with a progressive flatfoot deformity. MRI demonstrates severe tendinosis of the posterior tibial tendon. What primary static soft-tissue stabilizer of the medial longitudinal arch is most likely anatomically attenuated secondary to this tendon's failure?

Explanation

The plantar calcaneonavicular (spring) ligament is the primary static stabilizer of the medial longitudinal arch. It commonly fails or attenuates following posterior tibial tendon dysfunction.

Question 54

A surgeon is performing an open reduction of a proximal humerus fracture via a deltopectoral approach. To mobilize the proximal fragment, they dissect inferiorly along the capsule. Which of the following structures exits the quadrangular space and is at greatest risk during an inferior capsular release?

Explanation

The quadrangular space is bound by the teres minor, teres major, long head of triceps, and the humeral shaft. It contains the axillary nerve and posterior humeral circumflex artery, which are at risk during inferior capsular releases.

Question 55

During an anterior (Smith-Petersen) approach to the hip, an internervous plane is utilized to access the joint. Which of the following correctly describes the superficial internervous plane for this approach?

Explanation

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

Question 56

A spine surgeon is placing percutaneous pedicle screws in the thoracolumbar junction. A breach of the anterior vertebral body cortex places which major vascular structure at greatest risk on the left side at the T11-L1 levels?

Explanation

The aorta is located strictly left-sided and immediately anterior to the vertebral bodies at the T11-L1 levels. An anterior cortical breach by a left-sided pedicle screw in this region places the aorta at severe risk of injury.

Question 57

A baseball pitcher undergoes ulnar collateral ligament (UCL) reconstruction. The graft is secured anatomically to the sublime tubercle. On which specific anatomical structure is the sublime tubercle located?

Explanation

The anterior bundle of the UCL is the primary restraint to valgus stress at the elbow. It originates on the anterior undersurface of the medial epicondyle and inserts on the sublime tubercle of the anteromedial coronoid process.

Question 58

During a plantar approach to the midfoot for excision of a severe plantar fibroma, the surgeon must identify the "Master Knot of Henry" to protect the flexor tendons. Which of the following describes the correct anatomical relationship at this location?

Explanation

At the Master Knot of Henry in the plantar midfoot, the flexor hallucis longus (FHL) tendon crosses dorsal (deep) to the flexor digitorum longus (FDL) tendon. Both tendons are tethered here, facilitating combined digit flexion.

Question 59

A 28-year-old volleyball player presents with isolated weakness in external rotation of the shoulder. Forward elevation and abduction strength are normal. MRI reveals a paralabral cyst compressing a nerve. Where is the most likely location of the cyst?

Explanation

Isolated infraspinatus weakness (decreased external rotation) with normal supraspinatus function (abduction) suggests suprascapular nerve entrapment at the spinoglenoid notch. Entrapment at the suprascapular notch affects both the supraspinatus and infraspinatus muscles.

Question 60

A 35-year-old carpenter suffers a deep laceration to the volar palm, severing the flexor digitorum profundus (FDP) tendon to the index finger. Which lumbrical muscle originates from this specific tendon, and what is its normal innervation?

Explanation

The first and second lumbricals are unipennate, originate from the radial sides of the FDP tendons of the index and long fingers respectively, and are innervated by the median nerve. The third and fourth are bipennate and innervated by the ulnar nerve.

Question 61

During an ilioinguinal approach to the acetabulum, the surgeon must identify and ligate the "corona mortis" to prevent massive, difficult-to-control hemorrhage. This structure is a vascular anastomosis between which two systems?

Explanation

The corona mortis is a critical vascular anastomosis between the external iliac (or its inferior epigastric branch) and the obturator vessels (branch of the internal iliac). It typically crosses the superior pubic ramus.

Question 62

The posterolateral corner (PLC) of the knee provides critical rotatory stability. The popliteofibular ligament is a key structure in this complex. What are its precise origin and insertion?

Explanation

The popliteofibular ligament originates from the musculotendinous junction of the popliteus and inserts on the posteromedial aspect of the fibular styloid. It acts as a primary restraint to external rotation of the tibia.

Question 63

Nonunion and avascular necrosis are common complications following fractures of the scaphoid waist due to its retrograde blood supply. Which artery provides the primary blood supply to the proximal pole of the scaphoid?

Explanation

The dorsal carpal branch of the radial artery enters the scaphoid at its distal waist and provides 70-80% of its blood supply. This supply flows in a retrograde fashion, placing the proximal pole at high risk for ischemia following a waist fracture.

Question 64

The volar (Henry) approach to the radius utilizes an internervous plane that changes from the proximal to the distal forearm. What is the correct distal internervous plane for this approach?

Explanation

The distal internervous plane of the volar Henry approach is between the brachioradialis (radial nerve) and the flexor carpi radialis (median nerve). The proximal plane is between the brachioradialis and the pronator teres.

Question 65

During surgical reconstruction of the coracoclavicular (CC) ligaments for a high-grade acromioclavicular joint separation, anatomic placement of the drill holes is critical. Relative to the distal clavicle tip, what is the normal anatomic location of the CC ligament insertions?

Explanation

The trapezoid ligament inserts more laterally on the clavicle, approximately 25 mm from the distal clavicle tip. The conoid ligament inserts more medially, approximately 45 mm from the distal tip.

Question 66

A patient is undergoing an anterolateral approach to the distal tibia for plating of a pilon fracture. The superficial peroneal nerve (SPN) is at risk as it pierces the deep fascia. On average, at what distance proximal to the lateral malleolus does the SPN pierce the crural fascia?

Explanation

The superficial peroneal nerve pierces the deep crural fascia to become subcutaneous approximately 10 to 12 cm proximal to the tip of the lateral malleolus. It is highly vulnerable to iatrogenic injury during distal anterolateral approaches.

Question 67

The distal tibiofibular syndesmosis is primarily stabilized by three main ligaments. Which of the following ligaments provides the greatest mechanical resistance to diastasis of the syndesmosis?

Explanation

The Posterior inferior tibiofibular ligament (PITFL) provides the strongest restraint to syndesmotic widening. Biomechanical studies show it contributes approximately 42% of the overall strength of the syndesmotic complex.

Question 68

A 55-year-old patient presents with severe right arm pain, weakness in elbow flexion, and a diminished biceps reflex. MRI reveals a unilateral posterolateral disc herniation. Between which two vertebrae is the herniation most likely located, and which nerve root is affected?

Explanation

Weakness in elbow flexion (biceps) and a diminished biceps reflex indicate a C6 radiculopathy. In the cervical spine, the exiting nerve root is named for the lower vertebral segment, so the C6 root exits at the C5-C6 level.

Question 69

During a Smith-Petersen (anterior) approach to the hip, an internervous plane is utilized for the superficial dissection. Which of the following represents the correct internervous plane and their respective innervations?

Explanation

The superficial internervous plane for the Smith-Petersen approach is 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 70

A 45-year-old patient undergoes arthroscopic shoulder surgery. The surgeon identifies the rotator interval. Which of the following structures form the superior and inferior borders of the rotator interval, respectively?

Explanation

The rotator interval is a triangular anatomic space in the shoulder. Its borders are the supraspinatus tendon superiorly and the subscapularis tendon inferiorly, with the base formed by the coracoid process.

Question 71

During a posterior approach to the humeral shaft, the radial nerve is at greatest risk of iatrogenic injury as it crosses the posterior aspect of the humerus. On average, what is the distance from the point where the radial nerve pierces the lateral intermuscular septum to the lateral epicondyle?

Explanation

According to Gerwin et al., the radial nerve pierces the lateral intermuscular septum approximately 14.2 cm proximal to the lateral epicondyle. It crosses the posterior aspect of the humerus roughly 20 cm proximal to the medial epicondyle.

Question 72

A 22-year-old football player sustains a direct blow to the anteromedial aspect of his knee, resulting in a posterolateral corner (PLC) injury. Which of the following structures is the primary static restraint to varus opening at 30 degrees of knee flexion?

Explanation

The lateral collateral ligament (LCL) is the primary static restraint to varus stress at both 5 and 30 degrees of knee flexion. The popliteus complex (including the popliteofibular ligament) is the primary restraint to external rotation at 30 degrees.

Question 73

When placing lumbar pedicle screws, the identification of correct anatomic landmarks is crucial to avoid neurologic injury. The ideal starting point for a lumbar pedicle screw is located at the intersection of which of the following structures?

Explanation

In the lumbar spine, the anatomic starting point for a pedicle screw is the intersection of a horizontal line bisecting the transverse process and a vertical line tangential to the lateral border of the superior articular process.

Question 74

A patient presents with an isolated laceration to the recurrent motor branch of the median nerve at the wrist. Which of the following intrinsic thumb muscles will most likely retain normal function due to its sole innervation by the ulnar nerve?

Explanation

The adductor pollicis is solely innervated by the deep branch of the ulnar nerve. The abductor pollicis brevis, opponens pollicis, and the superficial head of the flexor pollicis brevis are typically innervated by the median nerve.

Question 75

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

Explanation

The corona mortis ('crown of death') is a vascular anastomosis located over the superior pubic ramus. It connects the obturator system (internal iliac) with the external iliac or inferior epigastric systems, putting it at high risk during anterior pelvic approaches.

Question 76

The 'Master Knot of Henry' is an important anatomic landmark in the plantar aspect of the midfoot. It is defined by the crossing of which two structures?

Explanation

The Master Knot of Henry is the location where the flexor hallucis longus (FHL) tendon crosses over (dorsal to) the flexor digitorum longus (FDL) tendon in the plantar midfoot. It is a critical landmark when harvesting the FDL tendon for transfer.

Question 77

A patient presents with an inability to make an 'OK' sign, demonstrating a pinched posture of the thumb interphalangeal joint and index distal interphalangeal joint. The affected nerve branch primarily innervates which of the following muscle combinations?

Explanation

The patient exhibits signs of anterior interosseous nerve (AIN) syndrome. The AIN innervates the flexor pollicis longus (FPL), the pronator quadratus, and the radial half of the flexor digitorum profundus (FDP to index and long fingers).

Question 78

A 28-year-old male sustains a severe rotational ankle injury resulting in a syndesmotic rupture. Which of the following ligaments provides the greatest resistance to diastasis and is considered the strongest component of the distal tibiofibular syndesmosis?

Explanation

The posterior inferior tibiofibular ligament (PITFL) is the strongest ligament of the syndesmosis complex. It contributes approximately 40-42% to the overall strength of the syndesmosis, preventing lateral displacement of the fibula.

Question 79

A 55-year-old patient undergoes a modified radical neck dissection for malignancy. Postoperatively, she is unable to actively elevate her arm above 90 degrees and demonstrates lateral winging of the scapula. Which nerve was most likely injured?

Explanation

Lateral winging of the scapula is caused by trapezius muscle paralysis due to spinal accessory nerve (CN XI) injury, a known complication of neck dissections. Medial winging is caused by serratus anterior weakness secondary to long thoracic nerve injury.

Question 80

During the volar (Henry) approach to the proximal third of the radius, the internervous plane lies between the brachioradialis and the pronator teres. What is the respective nerve supply of these two muscles?

Explanation

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

Question 81

During surgical excision of a soft tissue sarcoma involving the subsartorial (adductor) canal in the thigh, a sensory nerve running alongside the superficial femoral artery is at risk. Injury to this nerve will result in sensory loss over which area?

Explanation

The saphenous nerve travels within the adductor canal alongside the superficial femoral artery. It provides pure sensory innervation to the medial aspect of the leg and foot.

Question 82

Avascular necrosis of the scaphoid proximal pole is a well-known complication of scaphoid waist fractures. This occurs due to the retrograde intraosseous blood supply of the scaphoid, with the major blood vessels entering at which anatomic location?

Explanation

The major blood supply to the scaphoid comes from branches of the radial artery that enter the bone via the dorsal ridge in 70-80% of individuals. The vessels then course in a retrograde fashion to supply the proximal pole.

Question 83

A patient is evaluated for tarsal tunnel syndrome. The surgeon plans a release behind the medial malleolus. From anterior to posterior, what is the correct anatomic order of structures passing posterior to the medial malleolus?

Explanation

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

Question 84

A 25-year-old male sustains a traction injury to his brachial plexus. Clinical examination reveals profound weakness in shoulder extension and internal rotation, but intact rhomboid and serratus anterior function. Which of the following cords of the brachial plexus is most likely injured?

Explanation

The posterior cord gives rise to the thoracodorsal nerve (latissimus dorsi, shoulder extension) and upper/lower subscapular nerves (subscapularis, internal rotation). The rhomboids and serratus anterior are innervated by more proximal roots.

Question 85

During an anatomic reconstruction of the anterolateral ligament (ALL) of the knee, the surgeon must be mindful of its precise anatomic landmarks. What is the correct tibial insertion site of the ALL?

Explanation

The ALL originates proximal and posterior to the lateral epicondyle and inserts on the proximal tibia midway between Gerdy's tubercle and the anterior margin of the fibular head. It helps control anterolateral rotatory instability.

Question 86

An orthopedic surgeon is performing an anterior intrapelvic (modified Stoppa) approach for an acetabular fracture. Brisk bleeding is encountered from an anastomotic vessel located on the posterior aspect of the superior pubic ramus. This vessel typically connects which two vascular systems?

Explanation

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

Question 87

A patient presents with progressive adult-acquired flatfoot deformity. MRI demonstrates rupture of the primary static stabilizer of the medial longitudinal arch. This structure originates from the sustentaculum tali and inserts onto which of the following?

Explanation

The plantar calcaneonavicular (spring) ligament is the primary static stabilizer of the longitudinal arch. It connects the sustentaculum tali of the calcaneus to the plantar and medial aspect of the navicular.

Question 88

A 30-year-old carpenter suffers a deep laceration to the volar aspect of his hand, severing the deep branch of the ulnar nerve. Which of the following lumbrical muscles will most likely lose innervation?

Explanation

The third and fourth lumbricals are bipennate muscles innervated by the deep branch of the ulnar nerve. The first and second lumbricals are unipennate and innervated by the median nerve.

Question 89

During a transforaminal endoscopic lumbar discectomy, the surgeon accesses the disc space through Kambin's triangle. Which of the following defines the anterior and superior boundary of this safe zone?

Explanation

Kambin's triangle is bounded anteriorly and superiorly by the exiting nerve root, medially by the traversing nerve root and dura, and inferiorly by the superior endplate of the inferior vertebral body.

Question 90

When performing a surgical dislocation of the hip, the surgeon preserves the primary blood supply to the femoral head. The deep branch of this primary vessel passes between which two muscles?

Explanation

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head. Its deep branch consistently passes between the quadratus femoris and obturator externus muscles.

Question 91

A 28-year-old professional volleyball player presents with painless weakness of the shoulder. Examination reveals isolated atrophy of the infraspinatus with preserved supraspinatus bulk and strength. Where is the most likely site of nerve compression?

Explanation

Compression of the suprascapular nerve at the spinoglenoid notch affects only the infraspinatus muscle. Compression at the suprascapular notch would affect both the supraspinatus and infraspinatus.

Question 92

A patient develops compartment syndrome in the leg following a tibia fracture. A dual-incision fasciotomy is planned. Which of the following structures is located within the deep posterior compartment?

Explanation

The deep posterior compartment of the leg contains the tibialis posterior, flexor hallucis longus, flexor digitorum longus, posterior tibial artery, and the tibial nerve.

Question 93

A patient presents with weakness of finger and thumb extension but normal wrist extension (with radial deviation) and no sensory deficits. The affected nerve is most likely compressed by a fibrous arch located at the proximal edge of which muscle?

Explanation

Posterior interosseous nerve (PIN) syndrome causes weakness in digit extension while preserving wrist extension (ECRL is innervated before the PIN). The most common site of compression is the Arcade of Frohse at the proximal edge of the supinator muscle.

Question 94

The triangular fibrocartilage complex (TFCC) is crucial for distal radioulnar joint (DRUJ) stability. The primary bony attachment of the deep radioulnar ligaments (ligamentum subcruentum) is located at which structure?

Explanation

The deep radioulnar ligaments (ligamentum subcruentum) of the TFCC attach to the fovea at the base of the ulnar styloid. This deep foveal attachment is the primary stabilizer of the DRUJ.

Question 95

During percutaneous sacroiliac joint fixation, a screw directed too anteriorly through the sacral ala places which neurovascular structure at greatest iatrogenic risk?

Explanation

The L5 nerve root courses directly over the anterior aspect of the sacral ala. Screws or drills that penetrate the anterior cortex of the ala place the L5 nerve root at significant risk of injury.

Question 96

An ankle fracture involves disruption of the distal tibiofibular syndesmosis. The strongest ligamentous stabilizer of the syndesmotic complex is the:

Explanation

The posterior inferior tibiofibular ligament (PITFL) is the strongest and largest component of the syndesmotic complex. It provides approximately 40% of the resistance to lateral fibular displacement.

Question 97

A patient exhibits posterolateral rotatory instability (PLRI) of the elbow. Reconstruction of the primary deficient ligament is planned. What is the anatomic insertion of this key stabilizing ligament?

Explanation

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

Question 98

In performing an anterior (Smith-Petersen) approach to the hip, the internervous plane between the sartorius and tensor fasciae latae is utilized. In the deep dissection, the rectus femoris must be identified. Its reflected head originates from which of the following structures?

Explanation

The rectus femoris has two distinct origins. The direct head originates from the anterior inferior iliac spine (AIIS), while the reflected head originates from the supraacetabular groove and the anterior hip capsule.

Question 99

An anterior cervical discectomy and fusion (ACDF) is performed at the C6-C7 level via a left-sided approach. Which of the following fascial layers must be incised to access the interval between the carotid sheath and the midline visceral structures?

Explanation

The pretracheal fascia envelops the visceral structures (trachea, esophagus, thyroid). It must be divided to enter the avascular plane between the midline viscera and the laterally retracted carotid sheath.

Question 100

The intrinsic blood supply to the flexor tendons within the digital sheath is critical for healing after repair. The vinculum breve profundus (VBP) provides vascularity to the flexor digitorum profundus tendon at which location?

Explanation

The vincula provide essential segmental blood supply to the flexor tendons within the sheath. The vinculum breve profundus is located distally, supplying the FDP tendon near its insertion at the base of the distal phalanx.

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

Orthopedic Anatomy 2026 MCQs: Board Review Questions & Answers (Part 1)

Key Takeaway

Orthopedic Anatomy 2026 MCQs: Board Review Questions & Answers (Part 1)

Chapter Index