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Question 681

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 682

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 683

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 684

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.

Question 685

Topic: Surgical Anatomy & Approaches

In the deltopectoral approach to the shoulder, the cephalic vein is typically identified and retracted laterally. This interval marks the internervous plane between which two nerves?

. Axillary nerve and musculocutaneous nerve
. Axillary nerve and medial pectoral nerve
. Axillary nerve and lateral pectoral nerve
. Suprascapular nerve and axillary nerve
. Radial nerve and axillary nerve

Correct Answer & Explanation

. Axillary nerve and lateral pectoral nerve


Explanation

The deltopectoral interval lies between the deltoid (innervated by the axillary nerve) and the pectoralis major (innervated by the medial and lateral pectoral nerves). Therefore, the plane is between the axillary and lateral pectoral nerves.

Question 686

Topic: Surgical Anatomy & Approaches

The posterolateral approach to the femur utilizes the internervous plane between the vastus lateralis and the biceps femoris. What is the innervation of these two muscles, respectively?

. Femoral nerve and sciatic nerve
. Obturator nerve and femoral nerve
. Sciatic nerve and tibial nerve
. Femoral nerve and superior gluteal nerve
. Superior gluteal nerve and sciatic nerve

Correct Answer & Explanation

. Femoral nerve and sciatic nerve


Explanation

The vastus lateralis is innervated by the femoral nerve, while the biceps femoris is innervated by the sciatic nerve (the long head by the tibial division, and the short head by the common peroneal division).

Question 687

Topic: Surgical Anatomy & Approaches

A patient presents with weakness in shoulder abduction and external rotation following a posterior shoulder dislocation. The nerve injured passes through a space bordered by which of the following sets of structures?

. Teres minor, teres major, long head of triceps, surgical neck of humerus
. Teres major, long head of triceps, lateral head of triceps
. Teres minor, teres major, long head of triceps
. Subscapularis, coracobrachialis, short head of biceps
. Latissimus dorsi, teres major, chest wall

Correct Answer & Explanation

. Teres minor, teres major, long head of triceps, surgical neck of humerus


Explanation

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

Question 688

Topic: Surgical Anatomy & Approaches

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

. Brachioradialis and pronator teres
. Flexor carpi radialis and palmaris longus
. Extensor carpi radialis brevis and extensor digitorum communis
. Flexor carpi ulnaris and flexor digitorum superficialis
. Pronator teres and flexor carpi radialis

Correct Answer & Explanation

. Brachioradialis and pronator teres


Explanation

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

Question 689

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the acetabulum, the surgeon must identify and ligate the "corona mortis" to prevent massive hemorrhage. This structure is an anastomosis between the:

. External iliac artery and internal iliac artery
. Obturator vessels and external iliac or inferior epigastric vessels
. Internal pudendal artery and inferior gluteal artery
. Superior gluteal artery and inferior gluteal artery
. Femoral artery and obturator artery

Correct Answer & Explanation

. Obturator vessels and external iliac or inferior epigastric vessels


Explanation

The corona mortis is a critical vascular anastomosis between the obturator vessels and the inferior epigastric or external iliac vessels. It is typically located on the posterior aspect of the superior pubic ramus.

Question 690

Topic: Surgical Anatomy & Approaches

During a posterolateral approach to the hip (Kocher-Langenbeck), the piriformis tendon is identified. What nerve exits the sciatic notch immediately superior to the piriformis?

. Sciatic nerve
. Pudendal nerve
. Superior gluteal nerve
. Inferior gluteal nerve
. Nerve to the obturator internus

Correct Answer & Explanation

. Superior gluteal nerve


Explanation

The superior gluteal nerve exits the greater sciatic foramen superior to the piriformis muscle. The sciatic, inferior gluteal, and pudendal nerves exit inferior to the piriformis.

Question 691

Topic: Surgical Anatomy & Approaches

In the standard volar (Henry) approach to the distal radius, the flexor carpi radialis (FCR) is retracted. Between which two tendons is the deep dissection carried out?

. FCR and brachioradialis
. FCR and palmaris longus
. Brachioradialis and extensor carpi radialis longus
. Flexor digitorum superficialis and flexor carpi ulnaris
. Palmaris longus and flexor digitorum superficialis

Correct Answer & Explanation

. FCR and brachioradialis


Explanation

The distal Henry approach exploits the interval between the brachioradialis (radially) and the FCR (ulnarly). The radial artery is mobilized carefully to access the pronator quadratus.

Question 692

Topic: Surgical Anatomy & Approaches

A patient sustains a mid-shaft humerus fracture. The radial nerve is at risk as it passes through the intermuscular septum. At what approximate distance from the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum?

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

Correct Answer & Explanation

. 10 cm


Explanation

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

Question 693

Topic: Surgical Anatomy & Approaches

During an anterior (Smith-Petersen) approach to the hip, the superficial interval is created. Which two muscles define this interval?

. Tensor fasciae latae and gluteus medius
. Sartorius and tensor fasciae latae
. Rectus femoris and gluteus medius
. Sartorius and rectus femoris
. Pectineus and adductor longus

Correct Answer & Explanation

. Sartorius and tensor fasciae latae


Explanation

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

Question 694

Topic: Surgical Anatomy & Approaches

During an open posterior approach to the shoulder, the axillary nerve is at risk as it exits the quadrangular space. What forms the superior boundary of this space?

. Teres major
. Long head of the triceps
. Surgical neck of the humerus
. Teres minor
. 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. The axillary nerve and posterior circumflex humeral artery exit the axilla through this space.

Question 695

Topic: Surgical Anatomy & Approaches

During the ilioinguinal approach to the acetabulum, significant hemorrhage occurs while dissecting near the superior pubic ramus. This is most likely due to an injury to the corona mortis, which represents an anastomosis between the obturator vessels and which of the following?

. Internal pudendal vessels
. External iliac or inferior epigastric vessels
. Internal iliac vessels
. Superior gluteal vessels
. Femoral vessels

Correct Answer & Explanation

. External iliac or inferior epigastric vessels


Explanation

The corona mortis ('crown of death') is a critical vascular connection between the obturator vessels and the external iliac or inferior epigastric vessels. It is located posterior to the superior pubic ramus at a distance of roughly 4-9 cm from the pubic symphysis.

Question 696

Topic: Surgical Anatomy & Approaches

The volar (Henry) approach to the proximal radius exposes the bone while navigating between muscle intervals. To safely protect the posterior interosseous nerve (PIN) during proximal exposure, the forearm should be placed in which position?

. Maximal pronation
. Neutral rotation
. Maximal supination
. Flexion and pronation
. Extension and pronation

Correct Answer & Explanation

. Maximal supination


Explanation

Maximal supination moves the insertion of the supinator muscle anteriorly and wraps the PIN laterally, away from the surgical field. This maneuver safely displaces the nerve during the proximal Henry approach.

Question 697

Topic: Surgical Anatomy & Approaches

During the deltopectoral approach to the shoulder, the conjoined tendon is often retracted to gain exposure. How far distal to the tip of the coracoid process does the musculocutaneous nerve typically enter the coracobrachialis muscle?

. 1 to 2 cm
. 5 to 8 cm
. 10 to 12 cm
. 15 to 17 cm
. It does not enter the coracobrachialis

Correct Answer & Explanation

. 5 to 8 cm


Explanation

The musculocutaneous nerve typically enters the coracobrachialis 5 to 8 cm distal to the coracoid process. Retractors placed below the conjoined tendon must be carefully positioned to avoid compression or traction injury to this nerve.

Question 698

Topic: Surgical Anatomy & Approaches

During a posterior (Kocher-Langenbeck) approach to the acetabulum, the quadratus femoris muscle is carefully preserved or only partially released. This is primarily to protect which of the following structures?

. Inferior gluteal artery
. Sciatic nerve
. Medial femoral circumflex artery
. Pudendal nerve
. First perforating artery

Correct Answer & Explanation

. Medial femoral circumflex artery


Explanation

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head and runs closely related to the superior border of the quadratus femoris. Protecting the quadratus femoris or leaving a stable cuff minimizes the risk of iatrogenic injury to the MFCA.

Question 699

Topic: Surgical Anatomy & Approaches

When performing a lateral transpsoas approach to the lumbar spine (LLIF), a surgeon must navigate the lumbar plexus safely. Which nerve lies directly on the anterior surface of the psoas major muscle?

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

Correct Answer & Explanation

. Genitofemoral nerve


Explanation

The genitofemoral nerve pierces the anterior surface of the psoas major muscle and runs longitudinally down its anterior aspect. It is at significant risk of iatrogenic injury during anterior and lateral approaches to the lumbar spine.

Question 700

Topic: Surgical Anatomy & Approaches

In an anterior pelvic approach (ilioinguinal), a vascular anastomosis known as the 'corona mortis' may be encountered. This structure typically connects the obturator vessels with which of the following?

. Internal pudendal vessels
. Superior gluteal vessels
. External iliac or deep inferior epigastric vessels
. Internal iliac vessels directly
. Femoral vessels

Correct Answer & Explanation

. External iliac or deep inferior epigastric vessels


Explanation

The corona mortis is an arterial or venous anastomosis between the obturator vessels and the external iliac or deep inferior epigastric vessels. It lies on the posterior aspect of the superior pubic ramus and can cause catastrophic bleeding if inadvertently disrupted.