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Question 1261

Topic: Surgical Anatomy & Approaches

During an anterior approach to the hip (Smith-Petersen), careful hemostasis is required as major vessels are encountered traversing the surgical interval. The ascending branch of the lateral femoral circumflex artery crosses between which two muscles?

. Tensor fasciae latae and sartorius
. Rectus femoris and vastus lateralis
. Tensor fasciae latae and gluteus medius
. Gluteus minimus and rectus femoris
. Iliopsoas and pectineus

Correct Answer & Explanation

. Tensor fasciae latae and sartorius


Explanation

The internervous plane of the Smith-Petersen approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The ascending branches of the lateral femoral circumflex artery traverse this interval and must be ligated for safe exposure.

Question 1262

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach to the shoulder for a fracture dislocation, you must identify the boundaries of the quadrangular space to protect the axillary nerve. Which of the following constitutes the superior boundary of this space?

. Teres major
. Long head of the triceps
. Teres minor
. 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 humeral shaft. It transmits the axillary nerve and the posterior circumflex humeral artery.

Question 1263

Topic: Surgical Anatomy & Approaches

During an anterior intrapelvic (modified Stoppa) approach for an acetabular fracture, significant hemorrhage occurs near the superior pubic ramus. This is most likely due to injury to an anastomotic vessel (corona mortis) communicating between the obturator vessels and the:

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

Correct Answer & Explanation

. External iliac or deep inferior epigastric vessels


Explanation

The corona mortis is a vascular anastomosis between the obturator system and the external iliac or deep inferior epigastric systems. It rests on the posterior aspect of the superior pubic ramus and is highly susceptible to iatrogenic injury during anterior pelvic approaches.

Question 1264

Topic: Surgical Anatomy & Approaches

A 28-year-old overhead athlete presents with insidious posterior shoulder pain and isolated weakness in external rotation. An MRI reveals a paralabral cyst located within the quadrangular space compressing the traversing nerve. Which of the following anatomic structures forms the inferior boundary of this space?

. Teres minor
. Teres major
. Long head of the triceps brachii
. Lateral head of the triceps brachii
. Subscapularis

Correct Answer & Explanation

. Teres minor


Explanation

The quadrangular space is bound 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 contains the axillary nerve and the posterior circumflex humeral artery. A cyst in this space typically causes quadrilateral space syndrome, leading to axillary nerve compression (deltoid and teres minor weakness).

Question 1265

Topic: Surgical Anatomy & Approaches

A 45-year-old carpenter presents with a 4-month history of deep, aching pain in his proximal dorsal forearm and progressive weakness in extending his index and middle fingers. On examination, wrist extension is maintained but demonstrates radial deviation. Which of the following anatomic structures is the most common site of compression for the affected nerve?

. Ligament of Struthers
. Lacertus fibrosus
. Arcade of Frohse
. Osborne's ligament
. Arcade of Struthers

Correct Answer & Explanation

. Arcade of Frohse


Explanation

The patient's presentation is classic for Posterior Interosseous Nerve (PIN) syndrome. Wrist extension is preserved but deviates radially because the Extensor Carpi Radialis Longus (ECRL) is innervated by the radial nerve proper, proximal to its bifurcation into the PIN and superficial branch. The most common site of PIN compression is the Arcade of Frohse, which is the proximal fibrous edge of the superficial head of the supinator muscle.

Question 1266

Topic: Surgical Anatomy & Approaches

A 55-year-old male sustains an unstable pelvic ring injury. An anterior ilioinguinal approach is utilized for open reduction and internal fixation. During dissection along the superior pubic ramus, brisk arterial hemorrhage is encountered. This bleeding most likely originates from the 'Corona Mortis,' which represents an anastomosis between the obturator artery and which of the following vessels?

. Internal pudendal artery
. Inferior gluteal artery
. Inferior epigastric artery
. Superior gluteal artery
. Deep circumflex iliac artery

Correct Answer & Explanation

. Inferior epigastric artery


Explanation

The Corona Mortis (Crown of Death) is a critical vascular anastomosis located on the posterior aspect of the superior pubic ramus. It connects the obturator vessels (branch of the internal iliac system) with the inferior epigastric or external iliac vessels (external iliac system). It must be carefully identified and ligated during ilioinguinal or Stoppa approaches to the pelvis to prevent catastrophic hemorrhage.

Question 1267

Topic: Surgical Anatomy & Approaches

A surgeon is performing a posterolateral approach to the distal tibia for fixation of a complex posterior malleolus fracture. To utilize a true internervous plane, the deep surgical dissection should occur between which of the following two muscle bellies?

. Gastrocnemius and Soleus
. Tibialis posterior and Flexor digitorum longus
. Flexor hallucis longus and Peroneus brevis
. Peroneus longus and Extensor digitorum longus
. Soleus and Flexor hallucis longus

Correct Answer & Explanation

. Flexor hallucis longus and Peroneus brevis


Explanation

The posterolateral approach to the distal tibia and posterior malleolus utilizes an internervous plane between the flexor hallucis longus (innervated by the tibial nerve) medially, and the peroneus brevis (innervated by the superficial peroneal nerve) laterally. This approach safely exposes the posterior aspect of the tibia without devascularizing the bone or placing major neurovascular bundles at excessive risk.

Question 1268

Topic: Surgical Anatomy & Approaches

During a surgical approach to the hip for internal fixation of a basicervical femoral neck fracture, the surgeon must exercise extreme caution to preserve the primary blood supply to the adult femoral head. Which of the following is the predominant source of this vascularity?

. Artery of the ligamentum teres
. Lateral femoral circumflex artery
. Inferior gluteal artery
. Superior gluteal artery
. Medial femoral circumflex artery

Correct Answer & Explanation

. Medial femoral circumflex artery


Explanation

The predominant blood supply to the adult femoral head is derived from the medial femoral circumflex artery (MFCA), specifically its deep branch, which gives rise to the posterior superior and posterior inferior retinacular vessels. While the lateral femoral circumflex artery and the foveal artery (via the ligamentum teres) contribute minimally in adults, the MFCA is the critical vessel at risk during femoral neck fractures and posterior surgical approaches.

Question 1269

Topic: Surgical Anatomy & Approaches

A 28-year-old professional volleyball player presents with insidious onset of vague posterior shoulder pain and paresthesias over the lateral deltoid. MRI of the shoulder demonstrates isolated atrophy of the teres minor muscle. Pathology within the quadrilateral space is suspected. Which structures traverse this anatomical space?

. Radial nerve and profunda brachii artery
. Suprascapular nerve and suprascapular artery
. Axillary nerve and posterior circumflex humeral artery
. Lower subscapular nerve and circumflex scapular artery
. Musculocutaneous nerve and anterior circumflex humeral artery

Correct Answer & Explanation

. Axillary nerve and posterior circumflex humeral artery


Explanation

Quadrilateral space syndrome occurs secondary to compression of the axillary nerve and posterior circumflex humeral artery. The boundaries of the quadrilateral space are the teres minor (superior), teres major (inferior), long head of the triceps (medial), and the surgical neck of the humerus (lateral). Compression here leads to axillary nerve palsy, often manifesting as teres minor atrophy on MRI, as well as deltoid weakness and lateral shoulder paresthesias.

Question 1270

Topic: Surgical Anatomy & Approaches

A surgeon is performing the volar (Henry) approach to the radius to fix a midshaft radius fracture. During the proximal superficial dissection, an internervous plane is developed. Which nerves supply the two muscles forming the boundaries of this proximal internervous plane?

. Musculocutaneous nerve and Median nerve
. Radial nerve and Median nerve
. Median nerve and Ulnar nerve
. Radial nerve and Anterior interosseous nerve
. Musculocutaneous nerve and Radial nerve

Correct Answer & Explanation

. Musculocutaneous nerve and Median nerve


Explanation

The volar (Henry) approach to the radius utilizes an internervous plane. Proximally, this plane is found between the brachioradialis (innervated by the radial nerve) and the pronator teres (innervated by the median nerve). Distally, the plane continues between the brachioradialis (radial nerve) and the flexor carpi radialis (median nerve). Utilizing this internervous interval allows for safe anterior exposure of the radius.

Question 1271

Topic: Surgical Anatomy & Approaches

In the distal extension of the anterolateral approach to the humerus, the brachialis muscle is split to expose the humeral shaft. What is the neurological basis that permits a safe, longitudinal split in the middle or lateral third of the brachialis muscle?

. It receives dual innervation from the median and musculocutaneous nerves.
. It receives dual innervation from the median and radial nerves.
. It receives dual innervation from the radial and ulnar nerves.
. It receives dual innervation from the radial and musculocutaneous nerves.
. It is solely innervated by the radial nerve, but the nerve enters proximal to the split.

Correct Answer & Explanation

. It receives dual innervation from the median and musculocutaneous nerves.


Explanation

The brachialis muscle has a unique dual innervation. The medial portion is innervated by the musculocutaneous nerve, while the lateral portion is innervated by the radial nerve. A longitudinal split in the brachialis utilizes this internervous plane, minimizing denervation to either half.

Question 1272

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach for the internal fixation of an anterior column acetabular fracture, the surgeon dissects near the superior pubic ramus and must be careful to ligate the 'corona mortis.' This structure represents an anastomosis between which two vascular systems?

. Internal pudendal artery and inferior epigastric artery
. Superior gluteal artery and internal iliac artery
. Inferior gluteal artery and medial femoral circumflex artery
. Obturator artery and external iliac (or inferior epigastric) system
. Deep circumflex iliac artery and superior epigastric artery

Correct Answer & Explanation

. Obturator artery and external iliac (or inferior epigastric) system


Explanation

The corona mortis (crown of death) is a vascular anastomosis between the obturator vessels (from the internal iliac system) and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus at an average distance of 5 cm from the symphysis pubis and can cause massive hemorrhage if inadvertently torn during anterior pelvic surgery.

Question 1273

Topic: Surgical Anatomy & Approaches

A 35-year-old male presents with right shoulder pain and weakness after a direct blow to the posterior shoulder. On examination, he has weakness in external rotation and abduction. An MRI shows isolated atrophy of the teres minor. Which of the following anatomic borders defines the space through which the affected nerve passes?

. Teres minor superiorly, teres major inferiorly, long head of triceps medially, surgical neck of humerus laterally
. Teres minor superiorly, teres major inferiorly, long head of triceps laterally, surgical neck of humerus medially
. Teres major superiorly, teres minor inferiorly, long head of triceps medially, surgical neck of humerus laterally
. Teres minor superiorly, teres major inferiorly, long head of triceps medially, anatomical neck of humerus laterally
. Subscapularis superiorly, teres major inferiorly, short head of biceps medially, coracobrachialis laterally

Correct Answer & Explanation

. Teres minor superiorly, teres major inferiorly, long head of triceps medially, surgical neck of humerus laterally


Explanation

The axillary nerve passes through the quadrangular space, innervating the deltoid and teres minor. The borders of the quadrangular space are the teres minor superiorly, teres major inferiorly, long head of triceps medially, and the surgical neck of the humerus laterally. The axillary nerve is accompanied by the posterior circumflex humeral artery in this space.

Question 1274

Topic: Surgical Anatomy & Approaches

An orthopedic surgeon is performing an anterior (ilioinguinal) approach for the fixation of an anterior column acetabular fracture. While dissecting along the posterior aspect of the superior pubic ramus, brisk, difficult-to-control arterial bleeding is encountered. This bleeding is most likely originating from an anastomotic vessel connecting which two vascular systems?

. Internal pudendal and external pudendal arteries
. External iliac and obturator systems
. Superior gluteal and internal pudendal systems
. Internal iliac and internal pudendal systems
. Inferior epigastric and internal pudendal systems

Correct Answer & Explanation

. External iliac and obturator systems


Explanation

The 'corona mortis' (crown of death) is a highly variable anatomical anastomosis between the external iliac system (usually the inferior epigastric artery or vein) and the internal iliac system (obturator artery or vein). It crosses over the superior pubic ramus at an average of 5-7 cm from the symphysis pubis and is highly susceptible to injury during anterior pelvic exposures (like the ilioinguinal or Stoppa approach).

Question 1275

Topic: Surgical Anatomy & Approaches

A patient sustains a penetrating trauma to the anterior arm, resulting in inability to flex the elbow and loss of sensation over the lateral aspect of the forearm. The injured nerve is a terminal branch of which cord of the brachial plexus, and it typically pierces which muscle?

. Lateral cord; Coracobrachialis
. Medial cord; Biceps brachii
. Posterior cord; Brachialis
. Lateral cord; Biceps brachii
. Medial cord; Coracobrachialis

Correct Answer & Explanation

. Lateral cord; Coracobrachialis


Explanation

The musculocutaneous nerve is the terminal branch of the lateral cord of the brachial plexus (C5, C6, C7). It typically pierces the coracobrachialis muscle in the upper arm, then descends between the biceps brachii and brachialis muscles, supplying all three. It then emerges lateral to the biceps tendon as the lateral antebrachial cutaneous nerve, providing sensation to the lateral forearm.

Question 1276

Topic: Surgical Anatomy & Approaches

A 45-year-old male is undergoing open reduction and internal fixation of a proximal humerus fracture via an anterolateral (deltoid-splitting) approach. The surgeon must be careful to avoid iatrogenic injury to the axillary nerve. Which of the following best describes the typical anatomic distance of the axillary nerve distal to the lateral edge of the acromion?

. 1 to 2 cm
. 3 to 4 cm
. 5 to 7 cm
. 8 to 10 cm
. 11 to 13 cm

Correct Answer & Explanation

. 5 to 7 cm


Explanation

The axillary nerve runs transversely across the deep surface of the deltoid muscle, typically traversing approximately 5 to 7 cm distal to the lateral edge of the acromion. When utilizing an anterolateral (deltoid-splitting) approach, the split should not extend beyond 5 cm from the acromion to prevent denervation of the anterior aspect of the deltoid muscle.

Question 1277

Topic: Surgical Anatomy & Approaches

A 35-year-old male is undergoing open reduction and internal fixation of an anterior column acetabulum fracture via an ilioinguinal approach. The surgeon is working primarily through the 'middle window' to visualize the pelvic brim. Which structures define the medial and lateral borders of this surgical window?

. Lateral: Iliopectineal fascia; Medial: External iliac vessels
. Lateral: Iliopectineal fascia; Medial: Iliopsoas muscle
. Lateral: Iliopsoas muscle; Medial: Iliopectineal fascia
. Lateral: External iliac vessels; Medial: Spermatic cord/round ligament
. Lateral: Iliopectineal fascia; Medial: Conjoint tendon

Correct Answer & Explanation

. Lateral: Iliopectineal fascia; Medial: External iliac vessels


Explanation

The ilioinguinal approach utilizes three primary anatomic windows. The lateral window is lateral to the iliopectineal fascia (containing the iliopsoas and femoral nerve). The middle window lies between the iliopectineal fascia laterally and the external iliac vessels medially. The medial window lies between the external iliac vessels laterally and the rectus abdominis/spermatic cord medially.

Question 1278

Topic: Surgical Anatomy & Approaches

During an anterolateral approach to the distal humerus, the radial nerve is at risk. Which of the following describes the correct anatomical plane and location to identify the radial nerve in this region?

. Between the biceps brachii and brachialis, piercing the medial intermuscular septum.
. Between the brachioradialis and extensor carpi radialis longus.
. Deep to the pronator teres, emerging between its two heads.
. Between the brachialis and brachioradialis, piercing the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle.
. Between the triceps lateral and long heads.

Correct Answer & Explanation

. Between the brachialis and brachioradialis, piercing the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle.


Explanation

The radial nerve pierces the lateral intermuscular septum from the posterior to the anterior compartment approximately 10 cm proximal to the lateral epicondyle. It then travels distally in the anterior compartment within the interval between the brachialis (medial) and the brachioradialis (lateral) before dividing into the posterior interosseous nerve (PIN) and the superficial radial nerve.

Question 1279

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the acetabulum, the surgeon develops three distinct surgical windows. When working in the middle window to access the pelvic brim and quadrilateral surface, which of the following neurovascular structures is primarily mobilized and at highest risk?

. Sciatic nerve
. External iliac artery and vein
. Obturator nerve
. Femoral nerve
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. External iliac artery and vein


Explanation

The ilioinguinal approach utilizes three windows: lateral, middle, and medial. The middle window is developed between the iliopectineal fascia (which overlies the iliopsoas and femoral nerve laterally) and the external iliac vessels medially. Therefore, the external iliac artery and vein are primarily manipulated and at risk in this specific window. The femoral nerve is in the lateral window.

Question 1280

Topic: Surgical Anatomy & Approaches

A 35-year-old male requires autologous bone grafting for a recalcitrant tibial nonunion. A posterolateral approach to the tibia is chosen to avoid the compromised anteromedial soft tissue envelope. During this approach, the correct internervous plane is developed between the lateral gastrocnemius, soleus, and flexor hallucis longus posteriorly, and which of the following muscles anteriorly?

. Tibialis anterior
. Extensor hallucis longus
. Peroneus brevis
. Tibialis posterior
. Extensor digitorum longus

Correct Answer & Explanation

. Tibialis posterior


Explanation

The posterolateral approach to the tibia accesses the bone through a plane between the lateral compartment (peroneus longus and brevis, innervated by the superficial peroneal nerve) anteriorly and the superficial/deep posterior compartments (lateral gastrocnemius, soleus, and flexor hallucis longus, innervated by the tibial nerve) posteriorly. The tibialis posterior lies deep and is elevated directly off the interosseous membrane.