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1. General Principles & Basic Science MCQs

Practice Set 386 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 7701

Topic: 1. General Principles & Basic Science

A 42-year-old marathon runner undergoes surgical exploration of the plantar aspect of the midfoot for chronic tendinopathy. The surgeon identifies the 'Master Knot of Henry.' Which of the following accurately describes the tendinous anatomic relationships at this precise anatomic node?

. The flexor hallucis longus tendon crosses dorsal (deep) to the flexor digitorum longus tendon
. The flexor digitorum longus tendon crosses dorsal (deep) to the flexor hallucis longus tendon
. The tibialis posterior tendon crosses superficial to the flexor digitorum longus tendon
. The peroneus longus tendon crosses dorsal to the peroneus brevis tendon
. The flexor hallucis longus tendon crosses superficial to the tibialis anterior tendon

Correct Answer & Explanation

. The flexor hallucis longus tendon crosses dorsal (deep) to the flexor digitorum longus tendon

Explanation

The Master Knot of Henry is an anatomic landmark located in the plantar aspect of the midfoot at the level of the navicular bone. Here, the flexor hallucis longus (FHL) tendon crosses the flexor digitorum longus (FDL) tendon. The anatomically critical relationship is that the FHL courses dorsal (deep, closer to the osseous structures) to the FDL tendon. Fibrous slip connections between the two tendons are frequently found at this intersection.

Question 7702

Topic: Surgical Anatomy & Approaches

A surgeon is performing a lateral lumbar interbody fusion (LLIF) at the L4-L5 level utilizing a transpsoas approach. Postoperatively, the patient reports significant new-onset weakness in hip flexion and knee extension, along with numbness over the anterior thigh. Injury to which of the following neural structures within the psoas major muscle is the most likely cause?

. Ilioinguinal nerve
. Genitofemoral nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Obturator nerve

Correct Answer & Explanation

. Ilioinguinal nerve

Explanation

The transpsoas approach places the lumbar plexus at risk, particularly at the L4-L5 level where the plexus tends to migrate more anteriorly within the psoas muscle. The femoral nerve (L2-L4 roots) forms within the psoas major and supplies the major hip flexors (iliacus, pectineus) and knee extensors (quadriceps), while providing sensation to the anterior thigh. Weakness in hip flexion and knee extension following this procedure classicly indicates a femoral nerve injury. The lateral femoral cutaneous nerve causes strictly sensory deficits, and the obturator nerve innervates hip adductors.

Question 7703

Topic: 1. General Principles & Basic Science

A 35-year-old carpenter sustained a zone III volar forearm laceration that resulted in a complete transaction of his flexor digitorum profundus (FDP) tendons, which were subsequently repaired. Several weeks later, when he forcefully attempts to make a fist, he demonstrates paradoxical extension of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints of the affected digits instead of flexion. What is the anatomic basis for this specific paradoxical movement?

. Adhesions between the FDP and flexor digitorum superficialis (FDS) tendons
. Denervation of the interosseous muscles
. Proximal migration of the FDP tendon pulling on the lumbrical origin
. Injury to the central slip of the extensor apparatus
. Scarring of the sagittal bands over the metacarpophalangeal joints

Correct Answer & Explanation

. Adhesions between the FDP and flexor digitorum superficialis (FDS) tendons

Explanation

The patient is demonstrating the 'lumbrical plus' phenomenon. The lumbrical muscles uniquely originate from the flexor digitorum profundus (FDP) tendons in the palm and insert into the lateral bands of the extensor hood mechanism. If the FDP tendon is severed distal to the lumbrical origin, or if a tendon graft is too long, the proximal muscular pull of the FDP is transmitted directly through the lumbricals. This results in paradoxical extension of the PIP and DIP joints through the extensor mechanism when the patient actively attempts to flex the digits.

Question 7704

Topic: Surgical Anatomy & Approaches

A 45-year-old man undergoes an open reduction and internal fixation of a femoral head fracture via a Smith-Petersen (anterior) approach to the hip. The superficial internervous plane used in this approach lies between muscles innervated by which of the following pairs of nerves?

. Femoral nerve and Superior gluteal nerve
. Femoral nerve and Obturator nerve
. Superior gluteal nerve and Inferior gluteal nerve
. Obturator nerve and Sciatic nerve
. Femoral nerve and Sciatic nerve

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The Smith-Petersen (anterior) approach utilizes the internervous plane between the sartorius, which is innervated by the femoral nerve, and the tensor fasciae latae (TFL), which is innervated by the superior gluteal nerve. The lateral femoral cutaneous nerve is highly at risk during the superficial dissection of this approach.

Question 7705

Topic: Surgical Anatomy & Approaches

A surgeon is performing an open reduction and internal fixation of a severely displaced proximal humerus fracture. To identify and protect the axillary nerve, the surgeon explores the quadrangular space. Which of the following correctly describes the anatomical boundaries of this space?

. Superior: Teres minor; Inferior: Teres major; Medial: Long head of triceps; Lateral: Humeral shaft
. Superior: Teres major; Inferior: Latissimus dorsi; Medial: Humeral shaft; Lateral: Long head of triceps
. Superior: Infraspinatus; Inferior: Teres minor; Medial: Short head of biceps; Lateral: Humeral shaft
. Superior: Teres minor; Inferior: Teres major; Medial: Humeral shaft; Lateral: Long head of triceps
. Superior: Teres major; Inferior: Teres minor; Medial: Long head of triceps; Lateral: Humeral shaft

Correct Answer & Explanation

. Superior: Teres minor; Inferior: Teres major; Medial: Long head of triceps; Lateral: Humeral shaft

Explanation

The quadrangular space transmits the axillary nerve and the posterior humeral circumflex artery. Its boundaries are the teres minor (superiorly), the teres major (inferiorly), the long head of the triceps brachii (medially), and the surgical neck of the humerus (laterally).

Question 7706

Topic: Surgical Anatomy & Approaches

An orthopedic surgeon is performing a modified Stoppa approach for an acetabular fracture. Which of the following vascular structures represents the 'corona mortis,' a significant potential source of hemorrhage during this dissection?

. An anastomosis between the external iliac artery and the internal iliac artery
. An anastomosis between the obturator artery and the external iliac or inferior epigastric artery
. An anastomosis between the internal pudendal artery and the inferior epigastric artery
. An anastomosis between the superior gluteal artery and the obturator artery
. An anastomosis between the deep circumflex iliac artery and the inferior epigastric artery

Correct Answer & Explanation

. An anastomosis between the external iliac artery and the internal iliac artery

Explanation

The corona mortis is a vascular anastomosis between the obturator vessels and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus and can be a source of significant, life-threatening hemorrhage during anterior approaches to the acetabulum, such as the ilioinguinal or modified Stoppa approaches.

Question 7707

Topic: 1. General Principles & Basic Science

During a posteromedial approach to the knee for open reduction and internal fixation of a medial tibial plateau fracture, the dissection involves the interval between the medial head of the gastrocnemius and the pes anserinus. Which of the following nerves is at greatest risk of iatrogenic injury during the superficial dissection?

. Saphenous nerve
. Sural nerve
. Tibial nerve
. Deep peroneal nerve
. Obturator nerve

Correct Answer & Explanation

. Saphenous nerve

Explanation

The saphenous nerve is the largest cutaneous branch of the femoral nerve. It exits the adductor canal and courses distally along the posteromedial aspect of the knee, posterior to the sartorius muscle, before giving off the infrapatellar branch and continuing down the medial leg. It is highly susceptible to injury during the superficial dissection of the posteromedial approach to the knee.

Question 7708

Topic: Surgical Anatomy & Approaches

Which of the following statements best describes the anatomical relationship of the posterior interosseous nerve (PIN) as it relates to surgical approaches of the proximal radius?

. It runs superficial to the supinator muscle and exits between the two heads of the extensor carpi radialis brevis
. It runs between the superficial and deep heads of the supinator muscle
. It passes anterior to the radiocapitellar joint and pieces the brachioradialis
. It courses medial to the biceps tendon and enters the pronator teres
. It lies directly on the periosteum of the radial shaft in the distal third of the forearm

Correct Answer & Explanation

. It runs superficial to the supinator muscle and exits between the two heads of the extensor carpi radialis brevis

Explanation

The posterior interosseous nerve (PIN) originates from the radial nerve at the level of the radiocapitellar joint. It enters the arcade of Frohse and runs between the superficial and deep heads of the supinator muscle, wrapping around the radial neck and proximal shaft. Protection of the PIN by keeping the forearm in supination (to move the nerve away from the surgical field) is critical during volar approaches to the proximal radius (e.g., Henry approach).

Question 7709

Topic: Surgical Anatomy & Approaches

During the surgical exposure of the posterior column of the acetabulum via a Kocher-Langenbeck approach, the surgeon carefully identifies and protects the sciatic nerve. In what percentage of the general population does a portion of the sciatic nerve (usually the peroneal division) pass directly through the piriformis muscle?

. Less than 1%
. 10-15%
. 30-40%
. 50-60%
. Greater than 80%

Correct Answer & Explanation

. Less than 1%

Explanation

In the majority of the population (~85%), the entire sciatic nerve exits the greater sciatic foramen inferior to the piriformis muscle. However, in approximately 10% to 15% of people, the sciatic nerve bifurcates prematurely, and the common peroneal division passes directly through the belly of the piriformis muscle. Recognition of this anatomic variation is critical to avoid nerve laceration or excessive tension during retraction in posterior hip exposures.

Question 7710

Topic: Surgical Anatomy & Approaches

A 38-year-old man sustains an unstable anteroposterior compression (APC-III) pelvic ring injury. The surgeon proceeds with open reduction and internal fixation of the anterior ring via a modified Stoppa approach. During dissection along the superior pubic ramus, brisk arterial hemorrhage is encountered. This bleeding is most likely caused by injury to the 'corona mortis', which represents an anastomosis between the obturator artery and which of the following vascular systems?

. Superior gluteal artery
. Internal pudendal artery
. External iliac artery
. Internal iliac artery
. Inferior gluteal artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

The correct answer is the external iliac artery. The 'corona mortis' (crown of death) is a significant anatomical variant consisting of a vascular anastomosis between the obturator system (internal iliac) and the external iliac or inferior epigastric systems. It courses over the posterior aspect of the superior pubic ramus at a variable distance (average 4-6 cm) from the pubic symphysis. This structure is highly susceptible to iatrogenic injury during anterior pelvic ring approaches, such as the ilioinguinal or modified Stoppa approach. If lacerated, it can retract into the true pelvis or retroperitoneal space, causing severe and potentially life-threatening hemorrhage.

Question 7711

Topic: 1. General Principles & Basic Science

During a surgical dislocation of the hip, the surgeon must protect the deep branch of the medial femoral circumflex artery (MFCA). What is the anatomical path of this vessel as it courses toward the femoral head?

. Anterior to the pectineus and lateral to the iliopsoas tendon
. Through the obturator foramen and along the ligamentum teres
. Between the quadratus femoris and the inferior gemellus, then posterior to the obturator externus
. Pierces the vastus lateralis and travels superiorly along the anterior femoral neck
. Branches from the internal iliac and courses anterior to the piriformis

Correct Answer & Explanation

. Anterior to the pectineus and lateral to the iliopsoas tendon

Explanation

The deep branch of the MFCA is the predominant blood supply to the femoral head. It consistently courses between the quadratus femoris and the inferior gemellus, passing anterior to the conjoined tendon.

Question 7712

Topic: Surgical Anatomy & Approaches

A patient sustains a midshaft radius fracture, and a volar (Henry) approach is chosen for fixation. What is the internervous plane for the proximal third of this approach?

. Flexor carpi radialis and Palmaris longus
. Brachioradialis and Flexor carpi radialis
. Flexor carpi ulnaris and Extensor carpi ulnaris
. Brachioradialis and Pronator teres
. Extensor digitorum communis and Extensor carpi radialis brevis

Correct Answer & Explanation

. Flexor carpi radialis and Palmaris longus

Explanation

The proximal portion of the Henry approach to the radius utilizes the internervous plane between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve).

Question 7713

Topic: Surgical Anatomy & Approaches

A surgeon is performing an open Latarjet procedure. Which nerve is most at risk during the coracoid osteotomy and subsequent mobilization of the conjoined tendon?

. Axillary nerve
. Musculocutaneous nerve
. Median nerve
. Suprascapular nerve
. Radial nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

The musculocutaneous nerve typically penetrates the coracobrachialis muscle 2 to 8 cm distal to the tip of the coracoid process. Aggressive distal retraction can cause neurapraxia or permanent injury.

Question 7714

Topic: Surgical Anatomy & Approaches

A patient presents with weakness in elbow flexion and forearm supination, but normal shoulder abduction and normal wrist extension. Which neural structure is most likely injured?

. Axillary nerve
. Radial nerve
. Musculocutaneous nerve
. Upper trunk of the brachial plexus
. Lateral cord of the brachial plexus

Correct Answer & Explanation

. Axillary nerve

Explanation

The musculocutaneous nerve innervates the biceps brachii and brachialis, driving elbow flexion and aiding in supination. Normal shoulder abduction rules out an upper trunk injury.

Question 7715

Topic: Surgical Anatomy & Approaches

A 45-year-old man undergoes an open reduction and internal fixation of a midshaft clavicle fracture. Postoperatively, he notes numbness over the anterolateral aspect of his shoulder. Which nerve was most likely injured during the procedure?

. Axillary nerve
. Supraclavicular nerve
. Lateral pectoral nerve
. Musculocutaneous nerve
. Suprascapular nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

The supraclavicular nerves (C3-C4) provide sensation over the anterior shoulder and clavicle. They are frequently injured during surgical approaches to the clavicle, leading to postoperative numbness.

Question 7716

Topic: Surgical Anatomy & Approaches

When utilizing the standard anterolateral (Watson-Jones) approach to the hip, what is the intermuscular internervous interval?

. Superior gluteal nerve and inferior gluteal nerve
. Femoral nerve and superior gluteal nerve
. Femoral nerve and sciatic nerve
. Superior gluteal nerve and obturator nerve
. There is no true internervous plane

Correct Answer & Explanation

. Superior gluteal nerve and inferior gluteal nerve

Explanation

The Watson-Jones approach utilizes the interval between the tensor fasciae latae and the gluteus medius. Both muscles are innervated by the superior gluteal nerve, making this a non-true internervous plane.

Question 7717

Topic: Surgical Anatomy & Approaches

A patient sustains a posterior shoulder dislocation, and MRI reveals an isolated tear of the teres minor. During a posterior surgical approach, the surgeon must identify the quadrangular space. Which of the following best describes the inferior boundary of this space?

. Teres minor
. Teres major
. Long head of the triceps
. Surgical neck of the humerus
. Latissimus dorsi

Correct Answer & Explanation

. Teres minor

Explanation

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

Question 7718

Topic: 1. General Principles & Basic Science

During a pectoralis major tendon repair following a weightlifting injury, the surgeon must recreate its anatomic insertion. Which of the following best describes the insertion of the sternal head of the pectoralis major?

. It inserts superficial and distal to the clavicular head on the lateral lip of the bicipital groove.
. It inserts deep and proximal to the clavicular head on the lateral lip of the bicipital groove.
. It inserts deep and proximal to the clavicular head on the medial lip of the bicipital groove.
. It inserts superficial and proximal to the clavicular head on the lateral lip of the bicipital groove.
. It inserts on the coracoid process, deep to the short head of the biceps.

Correct Answer & Explanation

. It inserts superficial and distal to the clavicular head on the lateral lip of the bicipital groove.

Explanation

The pectoralis major tendon twists 90 degrees before its insertion. The sternocostal (inferior) head inserts deep and proximal to the clavicular (superior) head on the lateral lip of the intertubercular groove.

Question 7719

Topic: Surgical Anatomy & Approaches

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

. Superior gluteal nerve and femoral nerve
. Femoral nerve and obturator nerve
. Superior gluteal nerve and sciatic nerve
. Inferior gluteal nerve and femoral nerve
. Femoral nerve and inferior gluteal nerve

Correct Answer & Explanation

. Superior gluteal nerve and femoral nerve

Explanation

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

Question 7720

Topic: Surgical Anatomy & Approaches

While performing an ilioinguinal approach for an anterior column acetabular fracture, significant hemorrhage is encountered posterior to the superior pubic ramus. This is most likely due to an injury to the "corona mortis", which is an anastomosis between which two vessel systems?

. Internal pudendal artery and obturator artery
. External iliac (or inferior epigastric) vessels and obturator vessels
. Internal iliac artery and superior gluteal artery
. Femoral artery and medial circumflex femoral artery
. Inferior epigastric artery and internal pudendal artery

Correct Answer & Explanation

. Internal pudendal artery and obturator artery

Explanation

The corona mortis is a vascular anastomosis between the external iliac system (specifically the inferior epigastric vessels) and the obturator system. It rests on the posterior aspect of the superior pubic ramus and is highly vulnerable during anterior pelvic exposures.

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