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1. General Principles & Basic Science MCQs

Practice Set 614 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 12261

Topic: 1. General Principles & Basic Science

A patient is diagnosed with Anterior Interosseous Nerve (AIN) syndrome. Surgical exploration reveals compression by Gantzer's muscle. Which of the following accurately describes Gantzer's muscle?

. An accessory head of the flexor digitorum profundus
. An accessory head of the flexor pollicis longus
. An anomalous muscle belly of the pronator teres
. An accessory slip of the brachioradialis
. A fibrous band arising from the supinator

Correct Answer & Explanation

. An accessory head of the flexor digitorum profundus

Explanation

Gantzer's muscle is an accessory head of the flexor pollicis longus (FPL). It is the most common anomalous muscle in the forearm and is a well-documented site of compression of the anterior interosseous nerve (AIN).

Question 12262

Topic: 1. General Principles & Basic Science

During a medial approach to the midfoot for a complex reconstruction, the surgeon identifies the 'Master Knot of Henry'. Which anatomical relationship characterizes this structure?

. The flexor hallucis longus crosses volar (superficial) to the flexor digitorum longus
. The flexor hallucis longus crosses dorsal (deep) to the flexor digitorum longus
. The tibialis posterior crosses volar to the flexor hallucis longus
. The flexor digitorum longus crosses dorsal (deep) to the tibialis posterior
. The flexor hallucis longus crosses dorsal (deep) to the tibialis posterior

Correct Answer & Explanation

. The flexor hallucis longus crosses volar (superficial) to the flexor digitorum longus

Explanation

The Master Knot of Henry is an anatomical landmark in the plantar midfoot where the flexor hallucis longus (FHL) tendon crosses dorsal (deep) to the flexor digitorum longus (FDL) tendon. It is a key landmark for tendon transfers and identifying the plantar vessels/nerves.

Question 12263

Topic: 1. General Principles & Basic Science

A patient with posterior interosseous nerve (PIN) syndrome fails conservative management and undergoes surgical release. What is the most common anatomical site of PIN compression?

. The distal edge of the pronator teres
. The proximal edge of the superficial head of the supinator
. The distal edge of the superficial head of the supinator
. The fibrous arch of the flexor digitorum superficialis
. The lacertus fibrosus

Correct Answer & Explanation

. The distal edge of the pronator teres

Explanation

The Arcade of Frohse, which is the thickened proximal edge of the superficial head of the supinator muscle, is the most common site of entrapment for the posterior interosseous nerve (PIN).

Question 12264

Topic: 1. General Principles & Basic Science

During a distal femoral osteotomy, retractors are placed cautiously on the medial side to protect the contents of the adductor canal (Hunter's canal). Which of the following structures exits the anterior aspect of the adductor canal by piercing the vastoadductor membrane?

. Superficial femoral artery
. Superficial femoral vein
. Saphenous nerve
. Nerve to vastus medialis
. Obturator nerve

Correct Answer & Explanation

. Superficial femoral artery

Explanation

The adductor canal contains the superficial femoral artery, superficial femoral vein, saphenous nerve, and the nerve to the vastus medialis. Only the saphenous nerve and the descending genicular artery exit the canal anteriorly by piercing the vastoadductor membrane.

Question 12265

Topic: Surgical Anatomy & Approaches

In approximately 10% of the population, a variation in the relationship between the sciatic nerve and the piriformis muscle exists (Beaton and Anson classification). Which of the following describes the most common anomalous relationship?

. The entire sciatic nerve pierces the piriformis.
. The tibial division pierces the piriformis, and the common peroneal passes superiorly.
. The common peroneal division pierces the piriformis, and the tibial division passes inferiorly.
. The entire sciatic nerve passes superior to the piriformis.
. The common peroneal division passes superior to the piriformis, and the tibial passes inferiorly.

Correct Answer & Explanation

. The entire sciatic nerve pierces the piriformis.

Explanation

Normally (approx 85-90%), the entire sciatic nerve exits the greater sciatic foramen inferior to the piriformis. The most common variation (approx 10%, Type B) is the common peroneal division piercing the piriformis muscle while the tibial division passes inferior to it.

Question 12266

Topic: Surgical Anatomy & Approaches

During a Kocher-Langenbeck approach for an acetabular fracture, the surgeon carefully dissects near the inferior border of the piriformis. The intrinsic blood supply to the sciatic nerve in this region (arteria comitans nervi ischiadici) is derived from which of the following vessels?

. Superior gluteal artery
. Internal pudendal artery
. Inferior gluteal artery
. Medial circumflex femoral artery
. First perforating artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

The arteria comitans nervi ischiadici is a distinct branch of the inferior gluteal artery that runs alongside and supplies the sciatic nerve. Iatrogenic injury to this vessel during posterior approaches to the hip can devascularize the proximal segment of the sciatic nerve.

Question 12267

Topic: 1. General Principles & Basic Science

Several tendinous and ligamentous structures insert or originate on the proximal fibula. Which of the following structures does NOT attach to the fibular head or styloid process?

. Biceps femoris tendon
. Lateral collateral ligament (LCL)
. Arcuate ligament
. Popliteofibular ligament
. Popliteus muscle

Correct Answer & Explanation

. Biceps femoris tendon

Explanation

The popliteus muscle originates from the popliteal sulcus on the lateral femoral condyle and inserts onto the posterior surface of the proximal tibia above the soleal line; it does not attach to the fibula. The biceps femoris, LCL, arcuate ligament, and popliteofibular ligament all attach to the proximal fibula.

Question 12268

Topic: 1. General Principles & Basic Science

In cases of severe proximal axillary artery injury requiring ligation between the thyrocervical trunk and the subscapular artery, the upper extremity is kept viable by collateral circulation around the scapula. The suprascapular artery anastomoses directly with which branch of the subscapular artery?

. Posterior circumflex humeral artery
. Circumflex scapular artery
. Thoracodorsal artery
. Lateral thoracic artery
. Dorsal scapular artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

The primary scapular anastomosis provides a crucial bypass connecting the first part of the subclavian artery to the third part of the axillary artery. The suprascapular artery (from the thyrocervical trunk) and dorsal scapular artery anastomose with the circumflex scapular artery, which is a major branch of the subscapular artery.

Question 12269

Topic: Surgical Anatomy & Approaches

During the anterior (Henry) approach to the proximal radius, the surgeon develops the internervous plane between the brachioradialis and the pronator teres. To fully mobilize the mobile wad laterally, what vascular structure must be identified and ligated?

. Recurrent interosseous artery
. Radial recurrent artery
. Anterior interosseous artery
. Deep branch of the radial artery
. Posterior interosseous recurrent artery

Correct Answer & Explanation

. Recurrent interosseous artery

Explanation

The radial recurrent artery and its accompanying venous plexus (often termed the 'leash of Henry') originate from the radial artery and pass laterally across the surgical field. They tether the brachioradialis and must be ligated and divided to permit adequate lateral retraction of the mobile wad and full exposure of the supinator and proximal radius.

Question 12270

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach for an acetabular fracture, severe bleeding may be encountered from the 'corona mortis'. This anomalous vessel typically lies on the posterior aspect of the superior pubic ramus and represents an anastomosis between the:

. Internal iliac and external iliac arteries
. Obturator and external iliac (or inferior epigastric) vessels
. Superior gluteal and internal pudendal vessels
. Femoral and deep circumflex iliac vessels
. External iliac and internal pudendal vessels

Correct Answer & Explanation

. Internal iliac and external iliac arteries

Explanation

The corona mortis is a potentially lethal vascular connection (either arterial, venous, or both) between the obturator vessels (internal iliac system) and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus ~4-9 cm from the pubic symphysis.

Question 12271

Topic: Surgical Anatomy & Approaches
A 25-year-old overhead athlete presents with vague posterior shoulder pain and selective atrophy of the teres minor. MRI reveals a paralabral cyst compressing the axillary nerve within the quadrangular space. The boundaries of the quadrangular space include all of the following EXCEPT:
. Teres minor
. Teres major
. Long head of the triceps
. Lateral head of the triceps
. Surgical neck of the humerus

Correct Answer & Explanation

. Lateral head of the triceps

Explanation

The boundaries 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). The lateral head of the triceps forms the lateral border of the lower triangular space and triangular interval, but is not a boundary of the quadrangular space.

Question 12272

Topic: Surgical Anatomy & Approaches

An anterolateral surgical approach to the distal tibia and ankle joint is performed for a pilon fracture. During superficial dissection, which sensory nerve is at greatest risk of iatrogenic injury as it crosses the operative field?

. Sural nerve
. Deep peroneal nerve
. Saphenous nerve
. Superficial peroneal nerve
. Medial plantar nerve

Correct Answer & Explanation

. Sural nerve

Explanation

The superficial peroneal nerve pierces the deep fascia of the lateral compartment in the distal third of the leg. Its medial and intermediate dorsal cutaneous branches course directly over the anterolateral aspect of the ankle joint, making it highly vulnerable during an anterolateral approach.

Question 12273

Topic: 1. General Principles & Basic Science

In the plantar aspect of the midfoot, the 'Master Knot of Henry' is a key anatomical landmark where two major tendons intersect. At this junction, what is the correct orientation of these tendons?

. Flexor hallucis longus lies plantar (superficial) to flexor digitorum longus
. Flexor digitorum longus lies plantar (superficial) to flexor hallucis longus
. Tibialis posterior lies plantar (superficial) to flexor hallucis longus
. Flexor digitorum longus lies plantar (superficial) to tibialis posterior
. Peroneus longus lies plantar (superficial) to flexor hallucis longus

Correct Answer & Explanation

. Flexor hallucis longus lies plantar (superficial) to flexor digitorum longus

Explanation

At the Master Knot of Henry, located beneath the navicular and medial cuneiform, the flexor digitorum longus (FDL) tendon crosses plantar (superficial) to the flexor hallucis longus (FHL) tendon. The FHL is located dorsal (deep) to the FDL at this crossing point.

Question 12274

Topic: 1. General Principles & Basic Science

The medial circumflex femoral artery (MCFA) is the predominant blood supply to the adult femoral head. After originating from the profunda femoris and giving off superficial branches, the deep branch of the MCFA typically courses posteriorly between which two structures before giving off its terminal retinacular branches?

. Pectineus and iliopsoas
. Gluteus medius and piriformis
. Quadratus femoris and inferior gemellus
. Obturator externus and quadratus femoris
. Obturator internus and superior gemellus

Correct Answer & Explanation

. Pectineus and iliopsoas

Explanation

According to classic anatomical studies (e.g., Gautier), the deep branch of the MCFA passes posteriorly between the obturator externus (which is deep/anterior to the artery) and the quadratus femoris (which is superficial/posterior to the artery) before traveling along the superior gemellus and ascending the femoral neck.

Question 12275

Topic: Surgical Anatomy & Approaches

During the ilioinguinal approach to the acetabulum, the surgeon must be cautious of the 'corona mortis'. This vascular structure represents an anastomosis between which two vascular systems?

. Obturator and inferior epigastric or external iliac vessels
. Superior gluteal and internal pudendal vessels
. Deep circumflex iliac and inferior epigastric vessels
. Internal pudendal and external iliac vessels
. Femoral and superficial epigastric vessels

Correct Answer & Explanation

. Obturator and inferior epigastric or external iliac vessels

Explanation

The corona mortis ('crown of death') is an important anatomical variant consisting of an anastomosis between the obturator vessels (internal iliac system) and the inferior epigastric or external iliac vessels. It is located on the posterior aspect of the superior pubic ramus and is at significant risk of avulsion during the anterior approaches to the pelvis (such as the ilioinguinal or Stoppa approach), potentially leading to massive hemorrhage.

Question 12276

Topic: Surgical Anatomy & Approaches

The anterior (Smith-Petersen) approach to the hip relies on a true internervous plane. Which of the following accurately describes the muscular interval and the respective innervation of this plane?

. Sartorius (Femoral nerve) and Tensor fasciae latae (Superior gluteal nerve)
. Tensor fasciae latae (Superior gluteal nerve) and Gluteus medius (Superior gluteal nerve)
. Rectus femoris (Femoral nerve) and Vastus lateralis (Femoral nerve)
. Gluteus medius (Superior gluteal nerve) and Gluteus minimus (Superior gluteal nerve)
. Pectineus (Femoral nerve) and Adductor longus (Obturator nerve)

Correct Answer & Explanation

. Sartorius (Femoral nerve) and Tensor fasciae latae (Superior gluteal nerve)

Explanation

The Smith-Petersen approach utilizes the true internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve) superficially. Deeply, the plane passes between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 12277

Topic: Surgical Anatomy & Approaches
The brachial plexus is arranged into roots, trunks, divisions, cords, and branches. The posterior cord gives rise to all of the following terminal branches EXCEPT:
. Upper subscapular nerve
. Thoracodorsal nerve
. Musculocutaneous nerve
. Lower subscapular nerve
. Axillary nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

The posterior cord of the brachial plexus gives rise to the upper subscapular, thoracodorsal (middle subscapular), lower subscapular, axillary, and radial nerves (mnemonic: ULTRA). The musculocutaneous nerve arises from the lateral cord.

Question 12278

Topic: Surgical Anatomy & Approaches

The gluteus maximus is the primary extensor of the hip joint. What is its motor innervation and the corresponding primary spinal nerve roots?

. Superior gluteal nerve (L4, L5, S1)
. Nerve to quadratus femoris (L4, L5, S1)
. Sciatic nerve (L4-S3)
. Inferior gluteal nerve (L5, S1, S2)
. Pudendal nerve (S2, S3, S4)

Correct Answer & Explanation

. Superior gluteal nerve (L4, L5, S1)

Explanation

The gluteus maximus is uniquely innervated by the inferior gluteal nerve, which arises from the L5, S1, and S2 nerve roots. The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and tensor fasciae latae.

Question 12279

Topic: Surgical Anatomy & Approaches

The radial nerve descends in the posterior compartment of the arm within the spiral groove. At what approximate distance proximal to the lateral epicondyle does the radial nerve typically pierce the lateral intermuscular septum to enter the anterior compartment?

. 2 cm
. 5 cm
. 10 cm
. 15 cm
. 20 cm

Correct Answer & Explanation

. 2 cm

Explanation

The radial nerve pierces the lateral intermuscular septum to move from the posterior compartment to the anterior compartment of the arm approximately 10 cm (range 10-12 cm) proximal to the lateral epicondyle. This is a critical anatomical landmark when utilizing the anterolateral or posterior approaches to the distal humerus to avoid iatrogenic nerve injury.

Question 12280

Topic: Surgical Anatomy & Approaches

In the deltopectoral approach to the shoulder, the cephalic vein is typically identified and retracted laterally to preserve its primary venous drainage. Between which two muscles does this vein travel, and what is their respective innervation?

. Deltoid (axillary n.) and Pectoralis major (medial and lateral pectoral n.)
. Deltoid (axillary n.) and Pectoralis minor (medial pectoral n.)
. Pectoralis major (medial/lateral pectoral n.) and Coracobrachialis (musculocutaneous n.)
. Biceps brachii (musculocutaneous n.) and Deltoid (axillary n.)
. Subscapularis (upper/lower subscapular n.) and Pectoralis major (medial/lateral pectoral n.)

Correct Answer & Explanation

. Deltoid (axillary n.) and Pectoralis major (medial and lateral pectoral n.)

Explanation

The internervous plane of the deltopectoral approach lies between the deltoid (axillary nerve) and pectoralis major (medial and lateral pectoral nerves). The cephalic vein resides in this groove and is classically retracted laterally to protect its dominant deltoid tributaries.

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