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1. General Principles & Basic Science MCQs

Practice Set 287 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 5721

Topic: Surgical Anatomy & Approaches

A patient sustains a posterior shoulder dislocation and subsequently demonstrates weakness in shoulder external rotation and a sensory deficit over the lateral deltoid. The affected nerve exits the axilla through a space bordered superiorly by which of the following structures?

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

Correct Answer & Explanation

. Subscapularis

Explanation

The axillary nerve passes through the quadrangular space, which is bordered 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.

Question 5722

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach to the shoulder, the cephalic vein is typically retracted. Which of the following describes the correct internervous plane for this approach?

. Axillary nerve and Musculocutaneous nerve
. Axillary nerve and Pectoral nerves
. Musculocutaneous nerve and Radial nerve
. Suprascapular nerve and Axillary nerve
. Pectoral nerves and Thoracodorsal nerve

Correct Answer & Explanation

. Axillary nerve and Pectoral nerves

Explanation

The deltopectoral approach utilizes an internervous plane between the deltoid (axillary nerve) and pectoralis major (medial and lateral pectoral nerves). The cephalic vein marks this interval and is usually retracted laterally to preserve its primary venous drainage.

Question 5723

Topic: Surgical Anatomy & Approaches

A surgeon is performing an anterior (Smith-Petersen) approach to the hip. The superficial surgical interval is between the sartorius and the tensor fasciae latae. What is the internervous plane of this superficial interval?

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

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

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

Question 5724

Topic: Surgical Anatomy & Approaches

An orthopedic resident is dissecting the posterior shoulder. The quadrangular space transmits the axillary nerve and posterior circumflex humeral artery. Which of the following forms the superior border of this space in a normal anatomic specimen?

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

Correct Answer & Explanation

. Surgical neck of the humerus

Explanation

The quadrangular space is bordered superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the surgical neck of the humerus.

Question 5725

Topic: Surgical Anatomy & Approaches

The Thompson (posterolateral) approach to the proximal radius utilizes an internervous plane between which two muscles?

. Extensor carpi radialis brevis and Extensor digitorum communis
. Brachioradialis and Pronator teres
. Flexor carpi ulnaris and Flexor digitorum profundus
. Extensor digitorum communis and Extensor carpi ulnaris
. Anconeus and Extensor carpi ulnaris

Correct Answer & Explanation

. Extensor carpi radialis brevis and Extensor digitorum communis

Explanation

The Thompson approach utilizes the internervous plane between the extensor carpi radialis brevis (radial nerve) and the extensor digitorum communis (posterior interosseous nerve). It exposes the proximal and middle thirds of the radius while allowing the PIN to be protected within the supinator.

Question 5726

Topic: Surgical Anatomy & Approaches

An anterior approach to the humeral shaft utilizes the plane between the biceps brachii and brachialis. During deep dissection, the brachialis muscle is split longitudinally. Which aspect of the split brachialis is retracted laterally to protect the radial nerve?

. The medial third
. The lateral half
. The superficial layer
. The medial half
. The distal third

Correct Answer & Explanation

. The lateral half

Explanation

The brachialis has dual innervation; the medial portion is innervated by the musculocutaneous nerve, while the lateral portion is innervated by the radial nerve. Splitting the brachialis longitudinally and retracting the lateral half laterally cushions and protects the radial nerve.

Question 5727

Topic: Surgical Anatomy & Approaches

During the ilioinguinal approach for an anterior column acetabular fracture, the surgeon develops three surgical "windows." What anatomical structure forms the boundary between the lateral and middle windows?

. External iliac artery
. External iliac vein
. Iliopectineal fascia
. Symphysis pubis
. Spermatic cord

Correct Answer & Explanation

. Iliopectineal fascia

Explanation

The iliopectineal fascia divides the lateral and middle windows in the ilioinguinal approach. The middle window lies between this fascia (laterally) and the external iliac vessels (medially).

Question 5728

Topic: Surgical Anatomy & Approaches

A spine surgeon is performing a lateral transpsoas approach (LLIF) for an L4-L5 interbody fusion. Which of the following nerves emerges on the anterior surface of the psoas major muscle and runs longitudinally, making it particularly vulnerable to injury during initial retractor placement?

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

Correct Answer & Explanation

. Genitofemoral nerve

Explanation

The genitofemoral nerve pierces the anterior surface of the psoas major muscle and travels longitudinally down its anterior aspect. Due to this anterior course, it is highly vulnerable during the lateral transpsoas approach, with iatrogenic injury typically leading to groin and anterior thigh paresthesia.

Question 5729

Topic: 1. General Principles & Basic Science

Following a chevron bunionectomy performed through a dorsal approach, a patient has persistent numbness on the dorsal and medial aspect of the hallux. What nerve has most likely been injured?

. Lateral plantar nerve
. Deep peroneal nerve
. Dural nerve
. Medial plantar nerve
. Dorsomedial cutaneous nerve of the hallux

Correct Answer & Explanation

. Dorsomedial cutaneous nerve of the hallux

Explanation

The dorsomedial cutaneous nerve of the hallux, which is a distal branch of the superficial peroneal nerve, supplies sensation to the skin on the dorsal and medial half of the hallux and may be injured during a chevron bunionectomy. Injury to the nerve leads to particularly painful neuromas that directly impinge on the shoe. For this reason, direct medial approaches are typically preferred for access to the medial aspect of the metatarsophalangeal joint.

Question 5730

Topic: Surgical Anatomy & Approaches

The anterior (Smith-Petersen) approach to the hip utilizes a true internervous plane. Which two nerves supply the muscles that form the superficial boundary of this interval?

. Superior gluteal and femoral
. Superior gluteal and obturator
. Inferior gluteal and femoral
. Femoral and obturator
. Sciatic and superior gluteal

Correct Answer & Explanation

. Superior gluteal and femoral

Explanation

The superficial interval of the Smith-Petersen approach is between the tensor fasciae latae (supplied by the superior gluteal nerve) and the sartorius (supplied by the femoral nerve).

Question 5731

Topic: 1. General Principles & Basic Science

When performing a volar (Henry) approach to the proximal radius, the surgeon must mobilize the supinator. How should the supinator be managed to protect the posterior interosseous nerve (PIN)?

. Detach it from its ulnar insertion and reflect it radially
. Detach it from its radial insertion and reflect it ulnarly
. Split it longitudinally in its mid-substance
. Elevate it from distal to proximal as a single flap
. Detach it from its radial insertion and reflect it radially

Correct Answer & Explanation

. Detach it from its radial insertion and reflect it ulnarly

Explanation

To safely protect the PIN, the supinator should be detached from its insertion on the radius and reflected ulnarly. The nerve runs within the substance of the muscle belly.

Question 5732

Topic: Surgical Anatomy & Approaches

A patient develops posterior shoulder pain and weakness in external rotation following a direct blow to the posterior axilla. Compression in the quadrangular space is suspected. Which of the following structures pass through this space?

. Radial nerve and profunda brachii artery
. Axillary nerve and posterior circumflex humeral artery
. Suprascapular nerve and suprascapular artery
. Circumflex scapular artery and thoracodorsal nerve
. Lower subscapular nerve and axillary vein

Correct Answer & Explanation

. Axillary nerve and posterior circumflex humeral artery

Explanation

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

Question 5733

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the acetabulum, massive bleeding occurs upon dissection near the superior pubic ramus. This is most likely due to injury to the "corona mortis," which is an anastomosis between the:

. Internal iliac vein and external iliac vein
. External iliac artery (or inferior epigastric) and obturator artery
. Superior gluteal artery and inferior gluteal artery
. Pudendal artery and inferior epigastric artery
. External iliac artery and superior vesical artery

Correct Answer & Explanation

. External iliac artery (or inferior epigastric) and obturator artery

Explanation

The corona mortis is an arterial or venous anastomosis between the external iliac (or inferior epigastric) and the obturator vessels. It rests on the posterior aspect of the superior pubic ramus.

Question 5734

Topic: Surgical Anatomy & Approaches

When performing a lateral approach to the distal humerus, the radial nerve is identified as it pierces the lateral intermuscular septum. At what average distance proximal to the lateral epicondyle does this occur?

. 5 cm
. 10 cm
. 15 cm
. 20 cm
. 25 cm

Correct Answer & Explanation

. 10 cm

Explanation

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

Question 5735

Topic: Surgical Anatomy & Approaches

The anterior (volar) approach to the radius (Henry approach) proximally exploits the internervous plane between which two muscles?

. Brachioradialis and pronator teres
. Flexor carpi radialis and palmaris longus
. Brachioradialis and flexor carpi radialis
. Flexor digitorum superficialis and flexor carpi ulnaris
. Pronator teres and flexor carpi radialis

Correct Answer & Explanation

. Brachioradialis and pronator teres

Explanation

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

Question 5736

Topic: Surgical Anatomy & Approaches

A surgeon performs a direct anterior approach (Smith-Petersen) for a total hip arthroplasty. The superficial internervous plane is between the sartorius and tensor fasciae latae. What is the deep internervous plane?

. Rectus femoris and vastus lateralis
. Rectus femoris and gluteus medius
. Iliacus and psoas
. Pectineus and adductor longus
. Gluteus medius and minimus

Correct Answer & Explanation

. Rectus femoris and gluteus medius

Explanation

The deep internervous plane in the direct anterior approach to the hip is between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve).

Question 5737

Topic: Surgical Anatomy & Approaches

A 45-year-old male undergoes arthroscopic rotator cuff repair. During portal placement, the surgeon places a portal 5 cm distal to the lateral edge of the acromion. Which nerve is most at risk?

. Suprascapular nerve
. Axillary nerve
. Musculocutaneous nerve
. Radial nerve
. Accessory nerve

Correct Answer & Explanation

. Axillary nerve

Explanation

The axillary nerve courses circumferentially around the surgical neck of the humerus, approximately 5 cm distal to the lateral acromial edge. Portals placed too distally risk transecting its branches.

Question 5738

Topic: Infection, Pharmacology & VTE

The medial collateral ligament (MCL) of the knee has a superficial and deep component. The superficial MCL attaches distally to the medial aspect of the proximal tibia deep to which structure?

. Pes anserinus
. Semimembranosus tendon
. Medial patellofemoral ligament
. Popliteus tendon
. Iliotibial band

Correct Answer & Explanation

. Pes anserinus

Explanation

The superficial MCL inserts on the medial tibia approximately 4-5 cm distal to the joint line, situated deep to the pes anserinus tendons (sartorius, gracilis, and semitendinosus).

Question 5739

Topic: Surgical Anatomy & Approaches

The corona mortis is an anastomotic vascular connection at risk during the ilioinguinal approach to the acetabulum. It connects which two vessel systems?

. External iliac and internal iliac
. External iliac and obturator
. Internal pudendal and inferior gluteal
. Superior gluteal and internal iliac
. Femoral and deep external pudendal

Correct Answer & Explanation

. External iliac and obturator

Explanation

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

Question 5740

Topic: Surgical Anatomy & Approaches

A 30-year-old male sustains a Monteggia fracture-dislocation. During surgical fixation via a posterior (Boyd) approach, the surgeon elevates the supinator off the proximal radius. Which nerve lies within the substance of the supinator and is at risk?

. Anterior interosseous nerve
. Posterior interosseous nerve
. Superficial branch of the radial nerve
. Ulnar nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

The posterior interosseous nerve (PIN), a branch of the radial nerve, passes between the superficial and deep heads of the supinator muscle. It is at significant risk during posterior and lateral approaches to the proximal radius.

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