Orthopedic Anatomy MCQs 2026: Board Review Part 4

Question 1

Figure 42 is a transverse MRI scan of the left shoulder. The arrow points to which of the following structures?

Explanation

The figure shows an axial image of the shoulder immediately inferior to the coracoid process. The subscapularis tendon, which can be traced from the myotendinous junction, is torn and detached from its lesser tuberosity attachment on the humerus. Lateral to the lesser tuberosity, the bicipital groove is empty. The arrow points to the subluxated biceps tendon. Superficial fibers of the subscapularis tendon are contiguous with the biceps retinaculum, which covers the bicipital groove and hold the biceps tendon in place. The vast majority of subscapularis tendon tears result in disruption of the biceps retinaculum with resultant subluxation of the tendon. Resnick D, Kang HS (eds): Internal Derangement of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 308-317.

Question 2

Within the menisci, the majority of the large collagen fiber bundles are oriented in what configuration?

Explanation

The majority of large collagen fibers within the menisci are oriented circumferentially. It is these fibers that develop the hoop stress with compressive loading of the menisci. Most meniscal tears are longitudinal and occur between these circumferential fibers. Mow VC, et al: Structure and function relationships of the menisci of the knee, in Mow VC, Arnoczky SP, Jackson DW (eds): Knee Meniscus: Basic and Clinical Foundations. New York, NY, Raven Press, 1992, pp 37-57.

Question 3

For halo traction, what is the preferred site for anterior pin placement?

Explanation

The safe zone for anterior halo pin insertion is marked laterally by the anterior border of the temporalis muscle (to avoid penetration of this muscle and relative thin cortex of the skull). Medially, the pin should be placed 4.5 cm lateral to the midline to avoid injury to the supraorbital nerve or the frontal sinus. The safe area is marked superiorly by the head equator to avoid cephalad migration of the pin and inferiorly by the supraorbital ridge to prevent displacement or penetration into the orbit.

Question 4

A 12-year-old boy has had progressive pain and flatfeet for the past year. Pain is increased with weight-bearing activities. Examination reveals that subtalar motion is absent. On standing, the patient has obvious hindfoot valgus and loss of the normal arch bilaterally. Plain radiographs are shown in Figures 43a through 43c, and a CT scan is shown in Figure 43d. What is the most likely diagnosis?

Explanation

43b 43c 43d The axial views show fusion of the talus and calcaneus at the medial facet (talocalcaneal coalition). Peroneal spastic flatfoot is a descriptive term applying to the symptoms of painful flatfoot associated with apparent peroneal spasm and is sometimes caused by tarsal coalition; however, this is not the most appropriate diagnosis for this patient. Flexible flatfoot with a short Achilles tendon often causes symptoms similar to the ones listed above, but subtalar motion should be normal. A diagnosis of calcaneonavicular coalition can be made based on plain oblique views of the foot but is not seen in these views. Posterior tibial tendon dysfunction in the absence of other pathology is uncommon in children. Vincent KA: Tarsal coalition and painful flatfoot. J Am Acad Orthop Surg 1998;6:274-281.

Question 5

When performing ankle arthroscopy through the anterolateral portal, what anatomic structure is at greatest risk?

Explanation

The superficial branch of the peroneal nerve travels subcutaneously anterior to the lateral malleolus at the ankle. It can be easily damaged by deep penetration of the knife blade when making this portal or when passing shavers in and out of the portal. Anesthesia or dysesthesia from laceration or neuroma formation can cause significant postoperative morbidity. The anterior tibialis tendon, anterior tibial artery, and the deep peroneal nerve are located much more anterior and central on the ankle. The sural nerve is posterior lateral to the ankle and is not at risk from this portal. Ferkel RD, Heath DD, Guhl JF: Neurological complications of ankle arthroscopy. Arthroscopy 1996;12:200-208.

Question 6

Figure 44 shows the AP radiograph of the hip of a patient who underwent screw fixation of the acetabulum. Which of the following structures is at least risk for injury during screw placement in the acetabular component?

Explanation

Acetabular screws are inserted to supplement fixation. The acetabular component can be divided into four quadrants. Anatomic studies have shown that screws placed in the anterior superior and anterior inferior quadrants of the cup may injure the external iliac vein and obturator artery, respectively. Posterior superior and posterior inferior placement (in screws greater than 25 mm) may injure the sciatic nerve or the superior gluteal artery. The common iliac artery is proximal to the acetabulum and is at least risk for injury from acetabular screw placement.

Question 7

Figure 45 shows the lateral radiograph of a 19-year-old swimmer who has had back pain for the past 2 months. What is the most likely diagnosis?

Explanation

The patient has a pars interarticularis defect of L5 without apparent listhesis. The other diagnoses are not present. Papanicolaou N, Wilkinson RH, Emmans JB, Treves S, Micheli LJ: Bone scintigraphy and radiography in young athletes with low back pain. Am J Roentgenol 1985;145:1039-1044.

Question 8

Figure 46 shows the AP radiograph of a patient with right shoulder pain. What is the most likely diagnosis?

Explanation

Posttraumatic osteolysis of the distal portion of the clavicle is a condition that can be a complication of acute or repetitive trauma. The distal end of the clavicle is frayed and resorbed. Resorption may occur after weeks or months. The end of the clavicle may reconstitute over a period of months, or the acromioclavicular joint may remain widened. The differential diagnosis for distal clavicular erosion also includes rheumatoid arthritis, hyperparathyroidism, neoplastic destruction, cleidocranial dysplasia, and pyknodysostosis. Acutely, a type 2 acromioclavicular joint injury does not result in erosion or resorption of the clavicle. Periosteal sleeve injuries radiographically mimic acromioclavicular joint dislocation. Rickets occurs only in childhood.

Question 9

The main arterial supply to the humeral head is provided by which of the following arteries?

Explanation

The main arterial supply to the humeral head is provided by the ascending branch of the anterior humeral circumflex artery and its intraosseous continuation, the arcuate artery. There are significant intraosseous anastomoses between the arcuate artery, the posterior humeral circumflex artery through vessels entering the posteromedial aspect of the proximal humerus, the metaphyseal vessels, and the vessels of the greater and lesser tuberosities. Four-part fractures and dissection during exposure affect perfusion of the humeral head. Brooks CH, Revell WJ, Heatley FW: Vascularity of the humeral head after proximal humeral fractures: An anatomical cadaver study. J Bone Joint Surg Br 1993;75:132-136.

Question 10

Figure 47 shows a transverse MRI scan of a patient's left shoulder. The findings reveal which of the following abnormalities?

Explanation

The MRI scan shows a defect in the posterior aspect of the humeral head, commonly referred to as a Hill-Sachs lesion. This is an impaction fracture of the humeral head that occurs during anterior shoulder dislocation. The abnormality on this image is an irregularity of the posterior humeral head; the humeral head otherwise has a homogenous appearance. The coracoid, subscapularis, and posterior labrum are normal. Griffin LY (ed): Orthopaedic Knowledge Update: Sports Medicine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 47-63.

Question 11

An 18-year-old man sustains an injury to the right brachial plexus after falling off his bicycle. Examination reveals no rhomboideus major or minor muscle function. This finding most likely indicates a preganglionic injury to which of the following nerve roots?

Explanation

The rhomboideus major and minor muscles are innervated by the dorsal scapular nerve, which is supplied entirely by the C5 nerve root. The dorsal scapular nerve arises just distal to the dorsal root ganglion of the C5 nerve root. A functioning rhomboid muscle indicates that an injury involving C5 nerve root fibers must be postganglionic or distal to the C5 dorsal root ganglion. Woodburne RT, Crelin ES, Kaplan FS, Dingle RV (eds): The Ciba Collection of Medical Illustrations. Summit, NJ, Ciba-Geigy Corporation, 1987, vol 8, pp 23-28.

Question 12

A 53-year-old man with a history of severe left hip pain has a significant limp that is the result of a 5-cm limb-length discrepancy. An AP radiograph is shown in Figure 48. The underlying etiology is most likely related to a history of

Explanation

Radiographic abnormalities such as coxa magna, coxa breva secondary to growth arrest, and coxa plana and acetabular deformities are associated with healed Legg-Calve-Perthes disease. Femoral heads that were flat yet congruent with the acetabulum are at risk for disabling arthritis in the sixth decade of life in 50% of these untreated patients. As the normal ball-and-socket joint deforms to a flattened cylinder, the hip loses abduction and rotation capability, while retaining flexion and extension potential. If the femoral head is flat and is not concentric with the acetabulum, early severe arthritis occurs. Hinge abduction and anterior impingement are known sequelae of a flat, incongruent femoral head.

Question 13

Where does the median nerve pass in the proximal forearm?

Explanation

The median nerve passes through the pronator teres and deep to the flexor digitorum superficialis. The ulnar artery passes deep to both. Anderson JE (ed): Grant's Atlas of Anatomy, ed 7. Baltimore, MD, Williams and Wilkins, 1978, pp 6-55.

Question 14

The vascularity of the digital flexor tendons is significantly richer in what cross-sectional region?

Explanation

The vascularity of the dorsal portion of the digital flexor tendons is considerably richer than the volar portion. The other regions are not preferentially more vascular. Hunter JM, Scheider LH, Makin EJ (eds): Tendon Surgery in the Hand. St Louis, MO, Mosby, 1987, pp 91-99.

Question 15

Figures 49a and 49b show MRI scans of the shoulder. What is the most likely diagnosis?

Explanation

49b The supraspinatus tendon shows clear detachment and retraction from its greater tuberosity attachment by the absence of the normal dark subacromial signal extending to the attachment on the greater tuberosity. There is no anterior inferior glenoid labral detachment that usually is seen in a Bankart lesion. The acromioclavicular joint shows no evidence of separation. The humeral head is migrated cranially, indicating a chronic rotator cuff tear. Iannotti JP, Zlatkin MB, Esterhai JL, Kressel HY, Dalinka MK, Spindler KP: Magnetic resonance imaging of the shoulder: Sensitivity, specificity, and predictive value. J Bone Joint Surg Am 1991;73:17-29. Seeger LL, Gold RH, Bassett LW, Ellman H: Shoulder impingement syndrome: MR findings in 53 shoulders. Am J Roentgenol 1988;150:343-347.

Question 16

A fracture of the radial head is surgically exposed using a posterolateral approach to the elbow. Once the radial head is exposed, how should the arm be positioned to best protect the posterior interosseous nerve from injury?

Explanation

As long as the dissection stays proximal to the annular ligament, the posterior interosseous nerve is not at risk for injury. However, to ensure that the nerve is as far removed from the surgical field as possible, the forearm should be placed in pronation. Forearm supination of any degree will bring the nerve toward the surgical field. A neutral position of the forearm or elbow extension with wrist extension will not protect the posterior interosseous nerve. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach, ed 2. Philadelphia, PA, Lippincott-Raven, 1992, p 100.

Question 17

Figure 50 shows the MRI scan of a 20-year-old female college soccer player with knee pain. What is the most likely diagnosis?

Explanation

The MRI scan shows an acute complete tear of the posterior cruciate ligament. No evidence is seen of a quadriceps tendon rupture, a tibia fracture, or a bone contusion. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 533-557.

Question 18

The tibiofibular overlap used to diagnose syndesmotic diastasis on an AP view is most commonly measured between the

Explanation

The tibiofibular overlap is measured between the medial border of the fibula and the lateral border of the anterior tibial tubercle. Plain radiographic assessment of the distal tibiofibular syndesmosis requires AP and mortise views. The following criteria have been used as the normal limits in adults: a talocrural angle of + or - 83 degrees with up to 5 degrees of normal difference between both sides, a medial clear space of less than 4 mm, a talar tilt of less than 2 mm, a tibiofibular clear space of less than 5 mm, a tibiofibular overlap of greater than or equal to 0 mm, and a talar subluxation that is a subjective assessment of congruity of the tibial articular surface and the talar dome; any incongruity is abnormal. It has been recommended to obtain the first three measurements on the mortise view and the other three on the AP view. Wuest TK: Injuries to the distal lower extremity syndesmosis. J Am Acad Orthop Surg 1997;5:172-181.

Question 19

Figures 51a and 51b show subluxation of the

Explanation

51b The extensor carpi ulnaris tendon is shown subluxated from its tunnel at the ulnar head; this requires disruption of the tendon's subsheath. Rowland SA: Acute traumatic subluxation of the extensor carpi ulnaris tendon at the wrist. J Hand Surg Am 1986;11:809-811.

Question 20

The so-called high ankle sprain from an external rotation mechanism of injury typically involves injury to which of the following structures?

Explanation

Ankle sprains most commonly involve injury to the lateral collateral ligaments of the ankle (anterior talofibular, posterior talofibular, and calcaneofibular) from an inversion mechanism of injury. A different entity has been more recently described that involves an external rotation mechanism of injury that widens the ankle mortise and disrupts the anterior inferior tibiofibular ligament. Deltoid ligament and extensor retinaculum injuries do occur, although infrequently, and involve eversion and extreme plantar flexion mechanisms, respectively. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, p 182. Kaye RA: Stabilization of ankle syndesmosis injuries with a syndesmosis screw. Foot Ankle 1989;9:290-293. Baxter DE: The Foot and Ankle in Sports. St Louis, MO, Mosby-Year Book, 1995, p 30.

Question 21

In the first dorsal compartment of the wrist, what tendon most frequently contains multiple slips?

Explanation

The first extensor compartment of the wrist typically contains a single extensor pollicis brevis tendon and the abductor pollicis longus tendon that nearly always has multiple tendon slips. The extensor pollicis brevis tendon is frequently found to be separated from the slips of the abductor pollicis longus tendon by an intracompartmental septum. During surgery, this septum must be divided to complete the release of the compartment. Jackson WT, Viegas SF, Coon TM, Stimpson KD, Frogameni AD, Simpson JM: Anatomical variations in the first extensor compartment of the wrist: A clinical and anatomical study. J Bone Joint Surg Am 1986;68:923-926.

Question 22

The preferred surgical approach to the elbow of a child with an irreducible type III supracondylar distal humerus fracture and pulseless extremity is through which of the following muscle intervals?

Explanation

In a type III supracondylar distal humerus fracture of the elbow, the brachial artery can become incarcerated, yielding a pulseless extremity. In this situation, closed reduction may not be effective; therefore, open management is often necessary. The preferred surgical approach to the brachial artery and to this fracture is the anterior approach to the cubital fossa. The lacertus fibrosis is incised, and the dissection is carried out between the brachialis (musculocutaneous nerve) and the pronator teres (median nerve), mobilizing the brachial artery. Once the brachial artery is mobilized, the anterior elbow joint capsule may be exposed. The interval between the brachialis and the biceps describes the anterolateral approach to the elbow more commonly used for exposure of the proximal aspect of the posterior interosseous nerve. The dissection interval between the brachioradialis and the pronator teres describes the proximal extent of the anterior approach to the radius. Tubiana R, McCullough CJ, Masquelet AC: An Atlas of Surgical Exposures of the Upper Extremity. Philadelphia, PA, JB Lippincott, 1990, p 115.

Question 23

A 48-year-old man has recurrent right knee pain. Figure 52a shows the sagittal proton density T2-weighted MRI scan, and Figure 52b shows the sagittal T2-weighted MRI scan at the same level. The arrow is pointing to a

Explanation

52b Meniscal tears have many configurations and locations. The normal medial meniscus has a bow-tie configuration on the two most medial consecutive sagittal views. Toward the center of the joint the anterior and posterior horns have a triangular shape. These images show an abnormal intra-articular low-signal structure located anterior to the intact posterior cruciate ligament. This most likely represents a torn and displaced posterior horn of the medial meniscus, sometimes called "double PCL sign". A popliteal cyst and ligaments of Wrisberg and Humphry are not visible on these figures. Helms CA: MR image of the knee, in Fundamentals of Skeletal Radiology, ed 2. Philadelphia, PA, WB Saunders, 1995, pp 172-191.

Question 24

Figure 53 shows a thoracolumbar specimen as viewed from posterior to anterior following removal of all posterior elements. Which of the following structures does the red string pass under?

Explanation

The string passes under the ligamentum flavum as it runs from the posterior aspect of the vertebra above to the inferior aspect of the vertebra below in the sagittal midline. This is an important structure in diskectomy and in posterior approaches to the thoracolumbar spine and neural elements. It is rarely visualized in its entirety because typical exposures provide only a limited view.

Question 25

A 5-year-old girl sustained a comminuted Salter-Harris type IV fracture of the left distal tibia 2 years ago. The AP radiograph shown in Figure 54a reveals a growth arrest and a 1.4-cm limb-length discrepancy. The ankle is in approximately 20 degrees of varus. Figure 54b shows a coronal reconstruction image of the distal tibial physis, and Figure 54c shows a sagittal reconstruction image of the same area. On the sagittal reconstruction image, the bar extends from the 9-mm mark to the 24-mm mark in 3-mm increments. On the coronal image, the bar extends from the 9-mm mark to the 24-mm mark, also in 3-mm increments. A map of the physeal bar based on these measurements is shown in Figure 54d. Initial treatment should consist of

Explanation

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 26

A 45-year-old male presents with an inability to extend his thumb and digits at the metacarpophalangeal joints. Wrist extension is preserved but deviates radially. He has no sensory deficits. The most likely site of nerve compression is:

Explanation

This is a classic presentation of posterior interosseous nerve (PIN) syndrome. The PIN is most commonly compressed at the Arcade of Frohse, the proximal tendinous edge of the supinator muscle.

Question 27

What is the primary blood supply to the body of the talus?

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, is the major blood supply to the body of the talus. It forms an essential vascular sling with the artery of the tarsal sinus.

Question 28

During a posterior approach to the hip, preserving the insertion of which of the following muscles protects the deep branch of the medial femoral circumflex artery (MFCA)?

Explanation

The deep branch of the MFCA courses posteriorly between the quadratus femoris and obturator externus. Maintaining the obturator externus tendon intact protects the artery from iatrogenic injury during a posterior approach.

Question 29

A 24-year-old man sustains a scaphoid waist fracture. He is at high risk for avascular necrosis of the proximal pole. The primary blood supply to the proximal pole of the scaphoid is derived from which of the following arteries?

Explanation

The dorsal carpal branch of the radial artery provides 70-80% of the scaphoid's blood supply, entering distally and flowing retrograde. This retrograde flow makes the proximal pole highly susceptible to avascular necrosis after a waist fracture.

Question 30

A 28-year-old pitcher presents with vague posterior shoulder pain and isolated atrophy of the teres minor. An MRI demonstrates a paralabral cyst in the quadrilateral space. Which of the following borders the quadrilateral space superiorly?

Explanation

The quadrilateral 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 humeral circumflex artery.

Question 31

A 32-year-old volleyball player has weakness in external rotation of the shoulder. Examination reveals isolated atrophy of the infraspinatus without supraspinatus involvement. Entrapment of the suprascapular nerve at the spinoglenoid notch is typically associated with which of the following?

Explanation

Entrapment at the spinoglenoid notch affects only the motor branch to the infraspinatus, leading to isolated external rotation weakness. It is most commonly caused by a ganglion cyst associated with a posterior labral tear.

Question 32

A 45-year-old woman presents with vague forearm pain, weakness of the flexor pollicis longus, and numbness in the radial three and a half digits. Radiographs show a bony spur on the anteromedial distal humerus. Which structure is compressed as it passes under the Ligament of Struthers?

Explanation

The Ligament of Struthers connects a supracondylar process to the medial epicondyle. The median nerve and brachial artery pass deep to this ligament, and compression leads to proximal median nerve neuropathy.

Question 33

A spine surgeon is performing a posterior cervical foraminotomy at C6-C7. Understanding the vascular anatomy of the cervical spine is critical to prevent iatrogenic injury. Which of the following is true regarding the transverse foramen of the C7 vertebra?

Explanation

The vertebral artery typically enters the transverse foramen at C6 and travels proximally. The C7 transverse foramen usually contains only the vertebral vein and sympathetic nerves.

Question 34

A 20-year-old collegiate baseball pitcher reports medial elbow pain during the late cocking phase of throwing. He is diagnosed with a UCL injury. Which bundle of the ulnar collateral ligament is the primary restraint to valgus stress between 30 and 120 degrees of flexion?

Explanation

The anterior bundle of the UCL is the primary restraint to valgus stress at the elbow between 30 and 120 degrees of flexion. It originates from the anteroinferior medial epicondyle and inserts on the sublime tubercle.

Question 35

A 30-year-old man falls from a height and sustains a displaced talar neck fracture (Hawkins Type III). He is at high risk for osteonecrosis. The major blood supply to the body of the talus is provided by the artery of the tarsal canal, which is a branch of which artery?

Explanation

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

Question 36

A 42-year-old bodybuilder hears a "pop" in his antecubital fossa while performing heavy deadlifts. He has a reverse Popeye sign and weakness in forearm supination. The distal biceps tendon inserts onto which of the following structures?

Explanation

The distal biceps tendon inserts primarily on the posterior aspect of the radial tuberosity. This anatomical position allows the biceps to act as a powerful supinator of the forearm.

Question 37

A 55-year-old diabetic woman presents with burning pain and tingling in the plantar aspect of her foot, which worsens at night. Tinel's sign is positive posterior to the medial malleolus. The structure responsible for compressing the nerve in this syndrome is the:

Explanation

Tarsal tunnel syndrome is caused by entrapment of the tibial nerve under the flexor retinaculum (laciniate ligament) posterior to the medial malleolus. It results in neuropathic pain in the plantar foot.

Question 38

A 60-year-old woman presents with a progressive flatfoot deformity. Examination reveals a loss of the medial longitudinal arch and a positive too-many-toes sign. Which ligament is considered the primary static stabilizer of the talonavicular joint and medial longitudinal arch?

Explanation

The plantar calcaneonavicular (spring) ligament originates on the sustentaculum tali and inserts on the navicular. It supports the talar head and is a critical static stabilizer of the medial longitudinal arch.

Question 39

A 22-year-old football player sustains a non-contact pivoting injury to his knee. Radiographs reveal an avulsion fracture of the lateral tibial plateau (Segond fracture). This radiographic finding is considered pathognomonic for an anterior cruciate ligament tear and represents an avulsion of which structure?

Explanation

A Segond fracture is an avulsion of the anterolateral ligament (ALL) and capsular tissue from the lateral tibial plateau. It is highly associated with ACL tears and indicates severe rotational instability.

Question 40

A surgeon is performing a lateral compartment fasciotomy for chronic exertional compartment syndrome. To avoid injuring the superficial peroneal nerve, the surgeon must be aware that the nerve typically pierces the deep fascia to become subcutaneous at what location?

Explanation

The superficial peroneal nerve exits the lateral compartment by piercing the deep crural fascia approximately 10-12 cm proximal to the lateral malleolus. An anterolateral portal or incision in this area puts the nerve at risk.

Question 41

A 72-year-old woman sustains a displaced femoral neck fracture. She is counseled on the high risk of avascular necrosis and nonunion. The primary blood supply to the adult femoral head comes from the:

Explanation

The medial femoral circumflex artery (MFCA) provides the dominant blood supply to the adult femoral head via the lateral epiphyseal artery. Injury to these vessels during a displaced neck fracture leads to avascular necrosis.

Question 42

A 35-year-old man sustains a spiral fracture of the distal third of the humeral shaft. On presentation, he is unable to extend his wrist or fingers. Which structure is at highest risk of entrapment or injury in this specific fracture pattern?

Explanation

A Holstein-Lewis fracture is a spiral fracture of the distal third of the humerus, which carries a high risk (up to 22%) of radial nerve entrapment or palsy. The nerve is tethered as it passes through the lateral intermuscular septum.

Question 43

A 45-year-old woman with rheumatoid arthritis presents with an inability to extend her thumb. She is diagnosed with a ruptured extensor pollicis longus (EPL) tendon. The EPL tendon travels through which extensor compartment of the wrist, and what bony landmark serves as a pulley for it?

Explanation

The extensor pollicis longus (EPL) is the sole occupant of the third dorsal extensor compartment. It travels ulnar to Lister's tubercle, which acts as a bony fulcrum to redirect the tendon toward the thumb.

Question 44

A surgeon is utilizing the volar (Henry) approach to the proximal radius for open reduction and internal fixation of a radius fracture. Supination of the forearm during this approach protects which nerve by moving it radially and away from the surgical field?

Explanation

Supinating the forearm during the proximal Henry approach wraps the supinator muscle around the radius, moving the posterior interosseous nerve (PIN) laterally and safely away from the surgical dissection.

Question 45

A 30-year-old swimmer undergoes shoulder arthroscopy for instability. The surgeon evaluates the rotator interval, an anatomical space in the anterior shoulder. Which of the following tendons forms the inferior border of the rotator interval?

Explanation

The rotator interval is a triangular space bordered superiorly by the anterior margin of the supraspinatus and inferiorly by the superior margin of the subscapularis. It contains the coracohumeral ligament, superior glenohumeral ligament, and biceps tendon.

Question 46

During a volar (Henry) approach to the proximal radius, what structure marks the proximal edge of the superficial layer of the supinator muscle where the posterior interosseous nerve enters?

Explanation

The Arcade of Frohse is a fibrous arch at the proximal edge of the superficial head of the supinator muscle. It is the most common site of compression for the posterior interosseous nerve (PIN) and must be protected during the Henry approach.

Question 47

In percutaneous or minimally invasive repairs of the Achilles tendon, sutures passed through the proximal-lateral aspect of the tendon are most likely to injure which nerve?

Explanation

The sural nerve courses distally on the posterolateral aspect of the calf, crossing in close proximity to the lateral border of the Achilles tendon in its proximal and mid-substance regions, making it highly vulnerable during percutaneous repair.

Question 48

During an arthroscopic procedure for adhesive capsulitis, the surgeon releases the structures within the rotator interval. Which of the following anatomic structures forms the superior border of this interval?

Explanation

The rotator interval is a triangular anatomic space in the anterosuperior shoulder. It is bordered superiorly by the anterior margin of the supraspinatus tendon, inferiorly by the superior margin of the subscapularis tendon, and medially by the base of the coracoid process.

Question 49

During a lateral approach to the humerus, the radial nerve is at risk as it pierces the lateral intermuscular septum. At approximately what distance proximal to the lateral epicondyle does this occur?

Explanation

The radial nerve pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment approximately 10 cm proximal to the lateral epicondyle. Knowledge of this landmark is critical during lateral and anterolateral approaches to the distal humerus.

Question 50

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the adult femoral head. The deep branch of the MFCA typically courses between which two muscles?

Explanation

The deep branch of the MFCA runs posteriorly between the pectineus and iliopsoas, then courses posteriorly between the obturator externus and the quadratus femoris. It crosses posterior to the obturator externus tendon to reach the femoral neck.

Question 51

A patient presents with an isolated compression neuropathy of the posterior interosseous nerve (PIN). The most common site of compression is the arcade of Frohse, which is formed by the proximal tendinous edge of which muscle?

Explanation

The arcade of Frohse is a fibrous band formed by the proximal margin of the superficial head of the supinator muscle. It is the most common anatomical structure responsible for PIN entrapment (radial tunnel syndrome).

Question 52

During knee flexion, what is the normal biomechanical tension pattern of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL)?

Explanation

The ACL is composed of two distinct bundles. During knee flexion, the anteromedial (AM) bundle tightens while the posterolateral (PL) bundle becomes lax, whereas in extension the PL bundle is tight.

Question 53

A surgeon is performing an Achilles tendon repair and wishes to avoid injury to the sural nerve. The sural nerve typically crosses the lateral border of the Achilles tendon at approximately what distance proximal to the calcaneal insertion?

Explanation

The sural nerve generally crosses from the central posterior aspect of the calf to the lateral border of the Achilles tendon roughly 10 cm (range 9-12 cm) proximal to its calcaneal insertion. Incisions in this region should be carefully planned to avoid iatrogenic injury.

Question 54

Within the medial retromalleolar space (tarsal tunnel), the posterior tibial artery and tibial nerve are located between the tendons of which two muscles?

Explanation

The anatomical order of structures in the tarsal tunnel from anterior to posterior is Tibialis posterior, Flexor Digitorum Longus, Posterior tibial Artery, Tibial Nerve, and Flexor Hallucis Longus (Tom, Dick, AND Very Nervous Harry). The neurovascular bundle runs between the FDL and FHL.

Question 55

Which component of the deltoid ligament complex is considered the strongest and serves as the primary restraint to external rotation and anterolateral displacement of the talus?

Explanation

The deep posterior tibiotalar ligament is the strongest and thickest component of the deltoid ligament. It is the primary restraint preventing outward translation and external rotation of the talus within the mortise.

Question 56

The proximal pole of the scaphoid is highly susceptible to avascular necrosis following a fracture due to its retrograde blood supply. The primary vascular contribution enters the scaphoid at which of the following locations?

Explanation

The primary blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery, which enters the bone at the dorsal ridge of the scaphoid waist. The blood flows in a retrograde fashion to supply the proximal pole.

Question 57

During a lateral approach to the fibula for ORIF of an ankle fracture, the superficial peroneal nerve must be protected. This nerve typically pierces the deep fascia to become subcutaneous at what distance proximal to the tip of the lateral malleolus?

Explanation

The superficial peroneal nerve typically transitions from the lateral compartment deep to the fascia to become subcutaneous approximately 10 to 12 cm proximal to the tip of the lateral malleolus. It is highly vulnerable to injury during lateral surgical approaches in this zone.

Question 58

When performing an anterior cervical discectomy and fusion (ACDF), knowledge of the vertebral artery's course is crucial. Moving from proximal to distal, the vertebral artery typically first enters the foramen transversarium at which cervical level?

Explanation

The vertebral artery normally branches off the subclavian artery and enters the foramen transversarium at the level of C6. It rarely enters at C7, making the C7 transverse foramen often vacant of the main artery.

Question 59

A patient presents with median nerve compression symptoms above the elbow. Imaging reveals a supracondylar process. The ligament of Struthers connects this process to which anatomical structure?

Explanation

The ligament of Struthers is a fibrous band that extends from an anomalous supracondylar process on the anteromedial humerus to the medial epicondyle. It can compress the median nerve and brachial artery.

Question 60

To prevent neurapraxia on a fracture table, the perineal post must be adequately padded to protect the pudendal nerve. The pudendal nerve exits the pelvis through the greater sciatic foramen and re-enters the perineum through the lesser sciatic foramen by wrapping around the:

Explanation

The pudendal nerve exits the greater sciatic foramen, crosses posterior to the sacrospinous ligament, and hooks tightly around the ischial spine to re-enter the pelvis via the lesser sciatic foramen. This tethering makes it vulnerable to traction injuries from a perineal post.

Question 61

The popliteal artery is at high risk of stretch injury or transection during high-energy knee dislocations. It is particularly vulnerable due to firm tethering proximally at the adductor hiatus and distally at the:

Explanation

The popliteal artery is firmly fixed distally by the tendinous arch of the soleus muscle, and proximally by the adductor hiatus. These rigid tethering points prevent the artery from accommodating extreme translational forces during knee dislocations.

Question 62

The ligaments of Humphry and Wrisberg are accessory meniscofemoral ligaments. The ligament of Wrisberg is characterized anatomically as running from the:

Explanation

The meniscofemoral ligaments originate from the posterior horn of the lateral meniscus and insert onto the medial femoral condyle. Humphry passes Anterior to the PCL, while Wrisberg passes Posterior to the PCL (mnemonic: 'Humphry is High/Ahead, Wrisberg is in the Wake/Behind').

Question 63

During the Latarjet procedure for recurrent anterior shoulder instability, the musculocutaneous nerve is at risk. It typically pierces the coracobrachialis muscle at what average distance distal to the tip of the coracoid process?

Explanation

The musculocutaneous nerve typically enters the coracobrachialis muscle approximately 5-8 cm distal to the coracoid process. Care must be taken during anterior shoulder approaches and coracoid osteotomy down to this level.

Question 64

When preparing for pedicle screw instrumentation in the lumbar spine, understanding the transverse pedicle angulation is critical. How does the medial pedicle angulation in the transverse plane typically change from L1 to L5?

Explanation

The medial angulation of the lumbar pedicles in the transverse (axial) plane increases progressively from approximately 10 degrees at L1 to 25-30 degrees at L5. This requires an increasingly medial trajectory for screw insertion moving caudally.

Question 65

A patient presents with posterior shoulder pain and selective weakness of external rotation. MRI reveals a large paralabral ganglion cyst isolated to the spinoglenoid notch. Which muscle will exhibit denervation changes?

Explanation

Compression of the suprascapular nerve at the spinoglenoid notch affects only the terminal motor branch to the infraspinatus. Compression at the more proximal suprascapular notch would affect both the supraspinatus and infraspinatus.

Question 66

The quadrangular space transmits the axillary nerve and posterior circumflex humeral artery. Which muscle forms the inferior anatomical border of this space?

Explanation

The borders of the quadrangular space are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and surgical neck of the humerus (lateral).

Question 67

The pes anserinus insertion on the proximal medial tibia consists of three tendon insertions. From anterior to posterior, what is the correct anatomical order of these tendons?

Explanation

The tendons of the pes anserinus insert on the anteromedial proximal tibia. From anterior to posterior, the order is Sartorius, Gracilis, and Semitendinosus (mnemonic: 'Say Grace before Tea').

Question 68

During the ilioinguinal approach to the acetabulum, severe hemorrhage can occur if the corona mortis is inadvertently transected. This vascular structure is an anastomosis between the:

Explanation

The corona mortis ('crown of death') is an anatomical vascular anastomosis between the external iliac system (usually the inferior epigastric artery or vein) and the obturator vessels. It is located on the posterior aspect of the superior pubic ramus.

Question 69

During a volar (Henry) approach to the radius, the surgeon develops the proximal internervous plane. Which of the following describes the correct muscles and their respective innervations for this plane?

Explanation

The proximal internervous plane for the volar (Henry) approach to the forearm is between the brachioradialis (supplied by the radial nerve) and the pronator teres (supplied by the median nerve). This true internervous plane allows for safe exposure of the proximal radius.

Question 70

The deltopectoral approach to the shoulder utilizes a true internervous plane. Between which two muscles is this plane located?

Explanation

The deltopectoral approach utilizes the internervous plane between the deltoid (axillary nerve) and the pectoralis major (medial and lateral pectoral nerves). The cephalic vein is a key landmark that usually lies within this interval.

Question 71

In an adult patient, which of the following vessels provides the predominant blood supply to the femoral head?

Explanation

The medial femoral circumflex artery, specifically its lateral epiphyseal branch, provides the majority of the blood supply to the adult femoral head. The artery of the ligamentum teres (from the obturator artery) provides a negligible supply in adults.

Question 72

The meniscofemoral ligaments of the knee are anatomically associated with the posterior cruciate ligament (PCL). What is the specific anatomic course of the ligament of Wrisberg?

Explanation

The ligament of Wrisberg passes posterior to the posterior cruciate ligament (PCL). The ligament of Humphry passes anterior to the PCL.

Question 73

The anterior cruciate ligament (ACL) consists of two distinct functional bundles. Which bundle provides the primary restraint to anterior tibial translation when the knee is in 90 degrees of flexion?

Explanation

The anteromedial (AM) bundle of the ACL tightens in flexion, making it the primary restraint to anterior translation at 90 degrees. The posterolateral (PL) bundle is tightest in extension and provides rotational stability.

Question 74

A surgeon is performing a posterior approach to the popliteal fossa. Which of the following structures is located most deeply (closest to the joint capsule)?

Explanation

From superficial to deep, the structures in the popliteal fossa are the tibial nerve, popliteal vein, and popliteal artery. The popliteal artery lies deepest, resting directly against the posterior aspect of the femur and knee joint capsule.

Question 75

Which of the following describes the correct anatomical pathway of the pudendal nerve as it navigates the pelvis?

Explanation

The pudendal nerve exits the pelvis through the greater sciatic foramen (inferior to the piriformis), hooks around the sacrospinous ligament, and re-enters the perineum through the lesser sciatic foramen to enter Alcock's canal.

Question 76

During posterior cervical spine surgery, the suboccipital triangle must be carefully navigated. Which structures are primarily contained within this anatomical boundary?

Explanation

The suboccipital triangle is bounded by the rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior. It contains the vertebral artery and the suboccipital nerve (dorsal ramus of C1).

Question 77

In the anatomical layout of the tarsal tunnel at the medial malleolus, which of the following structures is positioned most posteriorly?

Explanation

The mnemonic "Tom, Dick, And Very Nervous Harry" dictates the order from anterior to posterior: Tibialis posterior, flexor Digitorum longus, Artery, Vein, Nerve, and flexor Hallucis longus. The FHL is the most posterior structure.

Question 78

The rotator interval is a triangular anatomical space in the anterior shoulder. Which of the following sets of structures is contained within this interval?

Explanation

The rotator interval is bordered by the supraspinatus superiorly, subscapularis inferiorly, and the coracoid base medially. It contains the long head of the biceps tendon, the coracohumeral ligament, and the superior glenohumeral ligament.

Question 79

When decompressing the ulnar nerve at the wrist in Guyon's canal, a precise understanding of the boundaries is essential. Which of the following accurately describes a boundary of Guyon's canal?

Explanation

Guyon's canal is bordered radially by the hook of the hamate and ulnarly by the pisiform. The roof is the volar carpal ligament, and the floor is the transverse carpal ligament.

Question 80

The radial nerve is highly susceptible to injury as it passes through the spiral groove of the humerus. Which vascular structure accompanies the radial nerve in this groove?

Explanation

The radial nerve travels in the spiral (radial) groove of the posterior humerus accompanied by the profunda brachii (deep brachial) artery. This close relationship puts both structures at risk during midshaft humeral fractures.

Question 81

In evaluating a brachial plexus injury, knowledge of the cord formations is critical. The posterior cord is formed by the union of which of the following?

Explanation

The posterior cord of the brachial plexus is formed by the posterior divisions of the superior, middle, and inferior trunks. It subsequently gives rise to the radial and axillary nerves.

Question 82

The lateral collateral ligament (LCL) of the knee is a critical structure for stability. What is its primary biomechanical function?

Explanation

The LCL originates on the lateral femoral epicondyle and inserts on the fibular head. It serves as the primary static restraint to varus stress at 30 degrees of knee flexion.

Question 83

Which of the following defines the correct origins of the femoral nerve within the lumbar plexus?

Explanation

The femoral nerve is formed by the dorsal divisions of the ventral rami of L2, L3, and L4. Conversely, the obturator nerve is formed by the ventral divisions of the same roots.

Question 84

During surgical approach to the medial elbow, the flexor-pronator mass is encountered originating from the medial epicondyle. Which muscle has the most proximal and lateral origin on the medial epicondyle?

Explanation

The pronator teres is the most proximal and lateral muscle of the superficial flexor-pronator mass originating from the medial epicondyle. It forms the medial border of the cubital fossa.

Question 85

Avascular necrosis of the scaphoid after fracture is highly dependent on its specific arterial supply. Which statement accurately describes the primary blood supply to the scaphoid?

Explanation

The primary blood supply to the scaphoid is from the dorsal carpal branch of the radial artery, which enters the distal pole and provides retrograde flow proximally. This retrograde supply accounts for the high rate of proximal pole nonunions and AVN.

Question 86

In the setting of an ankle syndesmotic injury, which ligament provides the greatest resistance to lateral displacement of the fibula?

Explanation

Biomechanical studies have shown that the posterior inferior tibiofibular ligament (PITFL) provides the largest contribution (approximately 42%) of the syndesmotic resistance to fibular displacement. The interosseous ligament provides about 22%, and the AITFL provides about 35%.

Question 87

The sciatic nerve typically divides into the tibial and common peroneal nerves in the distal thigh. Which of the following describes the embryologic origins of these two divisions from the sacral plexus?

Explanation

The tibial nerve is formed by the ventral branches of the ventral rami of L4-S3. The common peroneal nerve is formed by the dorsal branches of the ventral rami of L4-S2.

Question 88

When utilizing the extensile lateral approach for open reduction internal fixation of a calcaneus fracture, where should the corner of the L-shaped incision be placed to minimize the risk of flap necrosis?

Explanation

The incision should be made at the junction of the glabrous (plantar) and non-glabrous (lateral) skin to preserve the lateral calcaneal artery, which is the primary vascular supply to the full-thickness soft tissue flap.

Question 89

Which of the following accurately describes the primary blood supply to the scaphoid, predisposing its proximal pole to avascular necrosis following a fracture?

Explanation

The primary blood supply to the scaphoid is retrograde, originating from the radial artery and entering the dorsal ridge distally. This retrograde vascular flow puts the proximal pole at high risk for avascular necrosis following a fracture.

Question 90

When placing a pedicle screw in the lumbar spine, violating the medial cortex of the pedicle places which of the following structures at greatest immediate risk?

Explanation

The medial wall of the lumbar pedicle borders the spinal canal. A medial breach of the pedicle risks direct injury to the dural sac (cauda equina) or the traversing nerve root, which exits at the level below.

Question 91

A patient presents with groin pain exacerbated by resisted hip flexion following a total hip arthroplasty. If an oversized acetabular component is impinging on a soft tissue structure anteriorly, which structure is most likely involved?

Explanation

Anterior overhang of an acetabular cup can cause direct impingement and secondary tendinitis of the iliopsoas tendon. This typically presents as groin pain that is reproducibly exacerbated by active, resisted hip flexion.

Question 92

During surgical reconstruction of the posterolateral corner of the knee, a surgeon isolates the fibular collateral ligament (FCL). What is the anatomic relationship of the FCL femoral attachment relative to the popliteus tendon femoral attachment?

Explanation

On the lateral femoral epicondyle, the attachment of the fibular collateral ligament (FCL) is located proximal and posterior to the attachment of the popliteus tendon. Identifying this relationship is crucial for anatomic reconstruction of the posterolateral corner.

Question 93

A 28-year-old overhead athlete presents with insidious onset of posterior shoulder pain and weakness in external rotation. An MRI reveals isolated atrophy of the teres minor. Compression of which nerve in the quadrilateral space is most likely responsible?

Explanation

The axillary nerve and posterior circumflex humeral artery pass through the quadrilateral space. Compression here (quadrilateral space syndrome) typically causes isolated teres minor atrophy and weakness in external rotation, while the deltoid may be spared.

Question 94

In a patient with acquired adult flatfoot deformity, progressive failure of the posterior tibial tendon often leads to attenuation of the plantar calcaneonavicular (spring) ligament. Which of the following is the primary attachment site of the superomedial bundle of the spring ligament?

Explanation

The superomedial bundle of the spring ligament originates on the sustentaculum tali and inserts on the navicular tuberosity. It is a critical static stabilizer of the medial longitudinal arch, supporting the talar head.

Question 95

During a distal biceps tendon repair, the surgeon must reattach the tendon to its anatomical footprint on the radial tuberosity. In which portion of the radial tuberosity does the distal biceps predominantly insert?

Explanation

The distal biceps tendon inserts on the ulnar and posterior aspect of the radial tuberosity. This eccentric, posterior insertion maximizes its mechanical advantage as a powerful supinator of the forearm.

Question 96

During an anterior intrapelvic (modified Stoppa) approach to the acetabulum, brisk arterial bleeding is encountered near the superior pubic ramus. This is most likely due to injury to an anastomosis between which two vascular systems?

Explanation

The corona mortis is a venous or arterial anastomosis between the obturator (internal iliac system) and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus and is highly susceptible to injury during anterior intrapelvic approaches.

Question 97

A rock climber presents with a "bowstringing" deformity of the ring finger flexor tendons following a sudden snap during a dynamic climbing move. Which two annular pulleys are biomechanically most critical to prevent this bowstringing?

Explanation

The A2 (located over the proximal phalanx) and A4 (located over the middle phalanx) are the most important biomechanical pulleys in the hand. Rupture of these specific pulleys leads to significant flexor tendon bowstringing and loss of mechanical advantage.

Question 98

Resection of a large soft tissue sarcoma in the popliteal fossa requires sacrifice of the tibial nerve. What specific post-operative functional deficit will this patient most likely demonstrate?

Explanation

The tibial nerve innervates the posterior compartment of the leg (gastrocnemius, soleus, posterior tibialis) and provides sensation to the plantar surface of the foot. Sacrifice results in a loss of active plantarflexion and an insensate sole.

Question 99

During posterior cervical instrumentation, the surgeon must be mindful of the vertebral artery. At which cervical level does the vertebral artery typically enter the transverse foramen?

Explanation

The vertebral artery typically arises from the subclavian artery and enters the transverse foramen at the level of C6 in about 90% of individuals. It runs cephalad through the transverse foramina up to C1 before entering the foramen magnum.

Question 100

To avoid injury to the medial femoral circumflex artery (MFCA) during a posterior approach to the hip, an essential anatomical landmark is the superior border of which muscle?

Explanation

The ascending branch of the MFCA courses posteriorly between the superior border of the quadratus femoris and the inferior gemellus. Preserving the superior portion of the quadratus femoris tendon during a posterior approach helps protect this critical blood supply to the femoral head.

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

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

Key Takeaway

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

Chapter Index