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Surgical Anatomy & Approaches MCQs

Practice Set 3 of 102

This practice set contains high-yield board review questions covering key concepts in Surgical Anatomy & Approaches. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 41

Topic: Surgical Anatomy & Approaches

Which adverse outcome is most common in adults undergoing periacetabular osteotomy for hip dysplasia:

. Sciatic nerve palsy
. Femoral nerve palsy
. Nonunion of the osteotomy
. Persistent or worsening joint pain
. Heterotopic ossification

Correct Answer & Explanation

. Persistent or worsening joint pain

Explanation

Heterotopic ossification occurs in fewer than 5% of patients undergoing various types of periacetabular osteotomy. Femoral nerve palsy and sciatic nerve palsy occur in only 1% to 2% of patients. Nonunion is rare in this region because of abundant cancellous bone contact. Persistent or worsening joint pain is the most frequent adverse outcome and is least common in those patients with preoperative degenerative changes.

Question 42

Topic: Surgical Anatomy & Approaches

A 5-year-old boy falls on an outstretched hand. Radiographs confirm a completely displaced, extension-type supracondylar humerus fracture. Which nerve is most commonly injured in this specific fracture pattern?

. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve (AIN)
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most frequently injured nerve in extension-type supracondylar humerus fractures. Injury manifests clinically as the inability to form an 'OK' sign.

Question 43

Topic: Surgical Anatomy & Approaches

A 56-year-old man with confirmed squamous-cell carcinoma of the right upper lobe of the lung has a normal FEV1 and normal serum biochemistry. Which one of the following investigations is most appropriate to assess operability?

. Bone scan
. Chest computed tomography
. Differential perfusion lung scan
. Measurement of total lung capacity
. Sputum cytology

Correct Answer & Explanation

. Chest computed tomography

Explanation

Correct Answer: B- Chest computed tomography Explanation Chest computed tomography Chest computed tomography is the best method for staging squamous-cell carcinoma of the lung. This would indicate the extent of involvement and would inform the surgical approach. Five-year survival rates are > 75% in stage I disease (no nodes, tumour confined within the visceral pleura) and 55% in stage II disease, which includes resection in patients with ipsilateral peribronchial or hilar node involvement. Bone scan Bone scan is incorrect. A bone scan is not required as there is no clinical, haematological or biochemical evidence of tumour spread to bony sites. Differential perfusion lung scan Differential perfusion lung scan is incorrect. Differential perfusion lung scans are not helpful in staging. Measurement of total lung capacity Measurement of total lung capacity is incorrect. Measurement of total lung capacity is not helpful in staging. Sputum cytology Sputum cytology is incorrect. Sputum cytology is irrelevant, as the diagnosis has already been established.

Question 44

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach to the shoulder, the cephalic vein is identified. Which interval is being utilized, and which nerve is at greatest risk if dissection proceeds excessively inferior to the subscapularis?

. Pectoralis major and anterior deltoid; Axillary nerve
. Pectoralis minor and anterior deltoid; Musculocutaneous nerve
. Pectoralis major and short head of biceps; Radial nerve
. Pectoralis major and anterior deltoid; Suprascapular nerve
. Pectoralis minor and coracobrachialis; Axillary nerve

Correct Answer & Explanation

. Pectoralis major and anterior deltoid; Axillary nerve

Explanation

The deltopectoral interval lies between the pectoralis major and anterior deltoid. The axillary nerve is at risk inferior to the lower border of the subscapularis muscle.

Question 45

Topic: Surgical Anatomy & Approaches
A 6-year-old boy presents with a Gartland type III extension-type supracondylar humerus fracture with posteromedial displacement of the distal fragment. Which nerve is at the highest risk of injury?
. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

Posteromedial displacement of the distal fragment forces the proximal spike anterolaterally, directly risking stretch or entrapment of the radial nerve.

Question 46

Topic: Surgical Anatomy & Approaches

A 25-year-old male sustains an anterior shoulder dislocation during a rugby tackle. Following successful closed reduction, he notes persistent numbness over the lateral aspect of his deltoid muscle. Which nerve is most likely injured?

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

Correct Answer & Explanation

. Axillary nerve

Explanation

The axillary nerve is the most frequently injured nerve during anterior shoulder dislocations. It supplies motor innervation to the deltoid and teres minor, and sensory innervation to the skin over the lateral shoulder.

Question 47

Topic: Surgical Anatomy & Approaches

During an ilioinguinal approach to the acetabulum, brisk arterial bleeding is encountered near the posterior aspect of the superior pubic ramus. This vessel is most likely an anastomosis between which two arteries?

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

Correct Answer & Explanation

. Inferior epigastric and obturator

Explanation

The corona mortis is a vascular anastomosis between the external iliac system (inferior epigastric artery/vein) and the internal iliac system (obturator artery/vein). It is located on the posterior aspect of the superior pubic ramus.

Question 48

Topic: Surgical Anatomy & Approaches

A 35-year-old female sustains a closed midshaft humeral fracture and presents with a radial nerve palsy (wrist drop). The fracture is managed non-operatively in a functional brace. At 12 weeks, there is no clinical or EMG evidence of nerve recovery. What is the most appropriate next step in management?

. Continue observation for another 12 weeks
. Tendon transfers for wrist and finger extension
. Surgical exploration of the radial nerve
. Amputation of the affected limb
. Botulinum toxin injection to the flexors

Correct Answer & Explanation

. Surgical exploration of the radial nerve

Explanation

Failure of radial nerve recovery by 3 months (12 weeks) post-injury, confirmed by lack of clinical and EMG evidence of reinnervation, is an indication for surgical exploration of the nerve. Tendon transfers are typically reserved for permanent, unrecoverable injuries.

Question 49

Topic: Surgical Anatomy & Approaches

A 28-year-old athlete sustains a traction injury to the brachial plexus. Examination reveals profound weakness in shoulder abduction and external rotation, but normal internal rotation and adduction. Sensation is diminished over the lateral deltoid. Which neural structure is most likely injured?

. Upper trunk (C5-C6)
. Middle trunk (C7)
. Lower trunk (C8-T1)
. Posterior cord
. Medial cord

Correct Answer & Explanation

. Upper trunk (C5-C6)

Explanation

The clinical picture describes Erb's palsy, caused by an injury to the upper trunk of the brachial plexus (C5-C6). This affects the suprascapular, axillary, and musculocutaneous nerves, leading to loss of abduction and external rotation.

Question 50

Topic: Surgical Anatomy & Approaches

A 40-year-old woman undergoes prolonged pelvic surgery in the lithotomy position. Post-operatively, she complains of numbness over the anterolateral aspect of her leg and the dorsum of her foot, accompanied by a foot drop. Which nerve was most likely injured due to poor positioning?

. Femoral nerve
. Sciatic nerve
. Tibial nerve
. Common peroneal nerve
. Obturator nerve

Correct Answer & Explanation

. Common peroneal nerve

Explanation

The common peroneal nerve is highly vulnerable to compression against the fibular head when the patient is in the lithotomy position. Injury results in foot drop (loss of dorsiflexion) and sensory loss over the anterolateral leg and dorsum of the foot.

Question 51

Topic: Surgical Anatomy & Approaches

When planning a tendon transfer procedure for a patient with radial nerve palsy, the surgeon must consider muscle mechanics. Muscle excursion is primarily determined by which of the following characteristics?

. Physiological cross-sectional area
. Muscle fiber length
. Tendon length
. Pennation angle
. Motor unit ratio

Correct Answer & Explanation

. Muscle fiber length

Explanation

Muscle excursion, which is the distance a muscle can contract, is proportional to the length of its resting muscle fibers. In contrast, a muscle's force-generating capacity is determined by its physiological cross-sectional area.

Question 52

Topic: Surgical Anatomy & Approaches

During an anterolateral (Watson-Jones) approach to the hip, the superficial surgical interval is developed between which two muscles?

. Tensor fasciae latae and Sartorius
. Tensor fasciae latae and Gluteus medius
. Gluteus medius and Gluteus minimus
. Sartorius and Rectus femoris
. Rectus femoris and Pectineus

Correct Answer & Explanation

. Tensor fasciae latae and Gluteus medius

Explanation

The Watson-Jones (anterolateral) approach utilizes the muscular interval between the tensor fasciae latae and the gluteus medius. Although both are innervated by the superior gluteal nerve, it is a safe and widely used plane for hip exposure.

Question 53

Topic: Surgical Anatomy & Approaches

A patient with hemophilia A has a hematoma of the iliopsoas. He has a partial femoral nerve palsy. Treatment involves continuous factor replacement and:

. Open drainage
. Decompression of the fascia over the femoral nerve
. Percutaneous insertion of a drainage tube
. Embolization of feeder vessels by interventional radiologist
. Observation

Correct Answer & Explanation

. Observation

Explanation

The standard treatment of a psoas abscess is continuous factor replacement. Surgery is usually unnecessary, but it may be considered in cases of acute palsy with severe pain unresponsive to medical therapy. A percutaneous drainage tube is not recommended because the hematoma may be difficult to locate or drain.

Question 54

Topic: Surgical Anatomy & Approaches
During the anterior approach to the pelvic ring for symphyseal plating of an APC-III injury, significant hemorrhage is suddenly encountered over the superior pubic ramus. Which vascular anastomosis (the corona mortis) is most likely injured in this location?
. Internal pudendal artery and inferior gluteal artery
. Superior gluteal artery and iliolumbar artery
. Inferior epigastric artery and obturator artery
. External pudendal artery and obturator artery
. Deep circumflex iliac artery and femoral artery

Correct Answer & Explanation

. Inferior epigastric artery and obturator artery

Explanation

The corona mortis is a vascular anastomosis between the external iliac or inferior epigastric vessels and the obturator vessels. It is located on the posterior aspect of the superior pubic ramus and is at high risk of injury during anterior pelvic approaches.

Question 55

Topic: Surgical Anatomy & Approaches

The radial nerve is at risk during a lateral approach to the distal humerus. At approximately what distance proximal to the lateral epicondyle does the radial nerve pierce the lateral intermuscular septum to transition from the posterior to the anterior compartment?

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

Correct Answer & Explanation

. 10 cm

Explanation

The radial nerve courses from posterior to anterior by piercing the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle. This anatomical landmark is critical when extending surgical exposures of the distal humerus.

Question 56

Topic: Surgical Anatomy & Approaches

A 42-year-old male undergoes a single-incision anterior approach for the repair of an acute distal biceps tendon rupture. Postoperatively, he complains of numbness along the lateral aspect of his forearm. Which nerve was most likely injured?

. Posterior interosseous nerve
. Lateral antebrachial cutaneous nerve
. Superficial radial nerve
. Anterior interosseous nerve
. Musculocutaneous nerve proper

Correct Answer & Explanation

. Lateral antebrachial cutaneous nerve

Explanation

The lateral antebrachial cutaneous nerve (LABCN) is the terminal sensory branch of the musculocutaneous nerve. It exits the deep fascia lateral to the biceps tendon and is the most commonly injured nerve in an anterior single-incision distal biceps repair.

Question 57

Topic: Surgical Anatomy & Approaches

During a posterior approach to the shoulder, the axillary nerve is visualized emerging through the quadrangular space. Which muscle forms the inferior border of this anatomical space?

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

Correct Answer & Explanation

. Teres minor

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. It transmits the axillary nerve and the posterior circumflex humeral artery.

Question 58

Topic: Surgical Anatomy & Approaches

During hip arthroscopy, establishing the anteroinferior portal carries the highest risk of injury to which of the following neurological structures?

. Lateral femoral cutaneous nerve
. Femoral nerve
. Sciatic nerve
. Superior gluteal nerve
. Obturator nerve

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

The anteroinferior portal in hip arthroscopy places the lateral femoral cutaneous nerve (LFCN) at greatest risk. The nerve courses near the anterior superior iliac spine (ASIS) and can be easily injured if portal placement is poorly controlled.

Question 59

Topic: Surgical Anatomy & Approaches

What is the most common site of posterior interosseous nerve entrapment:

. The arcade of Frohse
. The flexor retinaculum
. The first cervical rib
. In the spiral groove of the humerus
. Ligament of Struthers

Correct Answer & Explanation

. The arcade of Frohse

Explanation

The most common site of posterior interosseous nerve entrapment is at the arcade of Frohse, which is a fibrotendinous ring found within the fibers of the supinator muscle as the posterior interosseous nerve originates from the radial nerve.

Question 60

Topic: Surgical Anatomy & Approaches

All of the following transfers may be used to improve function in a patient who has had radial nerve paralysis longer than 6 months, except:

. Pronator to extensor carpi radialis brevis
. Flexor carpi radialis extensors
. Flexor digitorum superficialis of the ring finger to digital extensors
. Flexor digitorum superficialis of the ring finger to brachioradialis
. Flexor palmaris longus to extensor pollicis longus

Correct Answer & Explanation

. Pronator to extensor carpi radialis brevis

Explanation

Radial nerve paralysis is a common injury, and many patients recover after repair. Tendon transfers should be delayed until sufficient time for reinnervation has passed. Pronator to extensor carpi radialis brevis can be performed at time of nerve repair to provide wrist extension and grasp during period of nerve recovery. Transfers for radial nerve palsy need to address wrist extension, thumb extension, and finger extenstion. All of the above transfer would provide these functions except a transfer to the brachioradialis.

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