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Surgical Anatomy & Approaches MCQs

Practice Set 2 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 21

Topic: Surgical Anatomy & Approaches

During a lateral transpsoas interbody fusion at L4-L5, the patient develops immediate postoperative ipsilateral hip flexion weakness and anterior thigh numbness. What is the most likely cause?

. Injury to the cauda equina
. Femoral nerve or lumbar plexus neuropraxia
. Sciatic nerve injury
. Spinal cord ischemia
. L5 nerve root avulsion

Correct Answer & Explanation

. Femoral nerve or lumbar plexus neuropraxia

Explanation

The lumbar plexus lies within the posterior aspect of the psoas major muscle. The transpsoas approach puts the lumbar plexus (specifically the femoral nerve components) at risk, causing temporary or permanent anterior thigh numbness and iliopsoas weakness.

Question 22

Topic: Surgical Anatomy & Approaches

Retrograde ejaculation is a known complication of anterior lumbar interbody fusion (ALIF). This is caused by injury to the:

. Parasympathetic pelvic splanchnic nerves
. Pudendal nerve
. Superior hypogastric plexus
. Genitofemoral nerve
. Ilioinguinal nerve

Correct Answer & Explanation

. Superior hypogastric plexus

Explanation

Retrograde ejaculation occurs due to injury to the superior hypogastric plexus (sympathetic nerves), which lies anterior to the lower lumbar vertebrae and L5-S1 disc space. Careful blunt dissection and avoiding electrocautery over the disc space minimizes this risk.

Question 23

Topic: Surgical Anatomy & Approaches

A 60-year-old male undergoes a minimally invasive extreme lateral interbody fusion (XLIF) at L4-L5. Postoperatively, he presents with profound weakness in hip flexion and knee extension, along with anterior thigh numbness. Which structure was most likely injured?

. Sciatic nerve
. Superior gluteal nerve
. Lumbar plexus
. Sympathetic chain
. Ilioinguinal nerve

Correct Answer & Explanation

. Lumbar plexus

Explanation

The lateral transpsoas approach (XLIF/DLIF) risks injury to the lumbar plexus, which lies within the posterior third of the psoas major muscle. This risk is highest at the L4-L5 level.

Question 24

Topic: Surgical Anatomy & Approaches

A 45-year-old female presents with a rigid, focal, angular kyphotic deformity of 65 degrees following an old burst fracture. To achieve optimal correction, which of the following osteotomies is most indicated?

. Multiple Smith-Petersen Osteotomies (SPO)
. Ponte Osteotomies
. Pedicle Subtraction Osteotomy (PSO)
. Vertebral Column Resection (VCR)
. Anterior Longitudinal Ligament release

Correct Answer & Explanation

. Vertebral Column Resection (VCR)

Explanation

Vertebral Column Resection (VCR) is a three-column osteotomy involving complete removal of the vertebral body and posterior elements. It is indicated for rigid, focal, and severe coronal or sagittal deformities exceeding 40 degrees where a PSO would be insufficient.

Question 25

Topic: Surgical Anatomy & Approaches

A surgeon plans to perform a Smith-Petersen osteotomy (SPO) to correct a sagittal deformity. Which of the following is a strict prerequisite for an SPO to effectively induce lordosis?

. An ossified anterior longitudinal ligament
. A mobile anterior disc space
. A fused posterior column
. Previous total disc replacement
. Severe anterior wedging of the vertebral body

Correct Answer & Explanation

. A mobile anterior disc space

Explanation

An SPO relies on hinging through the posterior column while the anterior column acts as an opening wedge. Therefore, a mobile anterior disc space is an absolute prerequisite for the osteotomy to close posteriorly and successfully achieve lordosis.

Question 26

Topic: Surgical Anatomy & Approaches

A 40-year-old male with iatrogenic flatback syndrome requires surgical correction. The surgeon plans a Pedicle Subtraction Osteotomy (PSO) at L3. Approximately how many degrees of sagittal correction can be expected from a single-level standard PSO?

. 5 to 10 degrees
. 10 to 15 degrees
. 30 to 40 degrees
. 50 to 60 degrees
. 70 to 80 degrees

Correct Answer & Explanation

. 30 to 40 degrees

Explanation

A pedicle subtraction osteotomy (PSO) is a three-column closing wedge osteotomy that typically provides 30 to 40 degrees of sagittal correction at a single level. In contrast, a Smith-Petersen Osteotomy (SPO) yields about 10 degrees per level.

Question 27

Topic: Surgical Anatomy & Approaches

A patient with rigid positive sagittal imbalance requires 30 degrees of lordotic correction at a single level. Which of the following techniques is most appropriate to achieve this exact degree of correction?

. Single Smith-Petersen Osteotomy (SPO)
. Multiple contiguous Ponte osteotomies
. Pedicle Subtraction Osteotomy (PSO)
. Anterior Lumbar Interbody Fusion (ALIF) alone
. Vertebral Column Resection (VCR)

Correct Answer & Explanation

. Pedicle Subtraction Osteotomy (PSO)

Explanation

A Pedicle Subtraction Osteotomy (PSO) is a three-column, closing wedge osteotomy that typically provides 30 to 35 degrees of sagittal correction at a single level. In contrast, an SPO provides approximately 10 degrees per level.

Question 28

Topic: Surgical Anatomy & Approaches

A patient presents with isolated weakness of the deltoid and biceps after a high-energy motor vehicle accident. Which cervical nerve root is most likely compromised?

. C4
. C5
. C6
. C7
. C8

Correct Answer & Explanation

. C5

Explanation

The C5 nerve root primarily innervates the deltoid (via the axillary nerve) and biceps (via the musculocutaneous nerve). Deficits result in profound weakness in shoulder abduction and elbow flexion.

Question 29

Topic: Surgical Anatomy & Approaches

A 55-year-old male presents with progressive spastic paraparesis and hyperreflexia. Magnetic resonance imaging demonstrates a large, calcified, central thoracic disk herniation at T8-T9 causing severe cord compression. Which of the following surgical approaches is contraindicated?

. Costotransversectomy
. Transthoracic anterior decompression
. Lateral extracavitary approach
. Standard posterior laminectomy
. Transpedicular decompression

Correct Answer & Explanation

. Standard posterior laminectomy

Explanation

A standard posterior laminectomy is strictly contraindicated for central, calcified thoracic disk herniations. Removing posterior elements allows the spinal cord to bowstring posteriorly over the anterior mass, creating an unacceptably high risk of catastrophic iatrogenic spinal cord injury.

Question 30

Topic: Surgical Anatomy & Approaches

Discogenic low back pain is a common entity. The outer annulus fibrosus of the lumbar intervertebral disc is capable of nociception. Which nerve provides the primary innervation to the outer posterior third of the annulus fibrosus?

. Pudendal nerve
. Sinuvertebral nerve
. Sciatic nerve
. Superior gluteal nerve
. Genitofemoral nerve

Correct Answer & Explanation

. Sinuvertebral nerve

Explanation

The sinuvertebral nerve (recurrent meningeal nerve) originates from the ventral ramus and sympathetic trunk, innervating the posterior aspect of the annulus fibrosus, posterior longitudinal ligament, and anterior dura.

Question 31

Topic: Surgical Anatomy & Approaches

A 40-year-old male undergoes an Anterior Lumbar Interbody Fusion (ALIF) at L5-S1. Postoperatively, he has no motor or sensory deficits in his legs. What is a specific, well-documented risk uniquely associated with this surgical approach?

. Retrograde ejaculation
. Erectile dysfunction
. Ureteral transection
. Bowel perforation
. Deep vein thrombosis

Correct Answer & Explanation

. Retrograde ejaculation

Explanation

ALIF at L5-S1 puts the superior hypogastric sympathetic plexus at risk during anterior exposure. Injury to this plexus can cause retrograde ejaculation, occurring in 1-2% of cases.

Question 32

Topic: Surgical Anatomy & Approaches

When performing a neurological examination, if a surgeon has a patient resist thigh adduction against resistance, the surgeon is testing which nerve(s):

. Segmental nerves from T1-L1
. Femoral nerve
. Obturator nerve
. Sciatic nerve
. Segmental nerves from L5-S1

Correct Answer & Explanation

. Obturator nerve

Explanation

The obturator nerve innervates most of the hip adductor group, which consists of neurologic levels L2, L3, and L4.

Question 33

Topic: Surgical Anatomy & Approaches

C ertain physical examination maneuvers attempt to elicit tension signs. When used in the supine position, these maneuvers are designed to apply stretch or tension on the sciatic nerve and any inflamed nerve root against a herniated lumbar disk. Which of the following physical examination tests is not a tension sign maneuver:

. Lasegue sign
. McMurray sign
. Bowstring sign
. The sitting room test
. C ontralateral straight-leg raising test

Correct Answer & Explanation

. McMurray sign

Explanation

McMurray sign is used to detect a torn meniscus in the knee and will have minimal effect on the sciatic nerve. Lasegue sign is the classic straight-leg raising test. The bowstring sign is a variation of the straight-leg raising test performed with the knee in a flexed position. Digital pressure is then applied over the popliteal space in an attempt to reproduce the tension sign. The sitting room test is performed with the patient in a sitting position. The hip remains flexed at 90° while the examiner extends the ipsilateral knee. The contralateral straight-leg raising test is performed in the same manner as the straight-leg raising test except the contralateral, or nonpainful, leg is raised.

Question 34

Topic: Surgical Anatomy & Approaches

A 7-year-old sustains a traumatic fall. Radiographs demonstrate an anterior dislocation of the radial head with an associated diaphyseal fracture of the ulna that is apex-anterior. Which nerve palsy is most commonly associated with this specific injury pattern?

. Ulnar nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Superficial radial nerve
. Axillary nerve

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

This describes a Bado Type I Monteggia lesion. The posterior interosseous nerve (PIN) is the most frequently injured nerve in this anterior dislocation pattern.

Question 35

Topic: Surgical Anatomy & Approaches



A 6-year-old falls on an outstretched hand, sustaining a completely displaced supracondylar humerus fracture. If the distal fragment is displaced posteromedially, which neurovascular structure is at highest risk of injury?

. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In a posteromedially displaced supracondylar fracture, the proximal fragment spikes anterolaterally, putting the radial nerve at the greatest risk of tethering or injury.

Question 36

Topic: Surgical Anatomy & Approaches

A 6-year-old girl falls from monkey bars and sustains a widely displaced posterolateral extension-type supracondylar humerus fracture. Which nerve is most at risk in this specific displacement pattern?

. Median nerve (Anterior interosseous branch)
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Median nerve (Anterior interosseous branch)

Explanation

In a posterolateral supracondylar fracture, the proximal fragment is driven anteromedially, putting the median nerve and its anterior interosseous branch (AIN) at highest risk. Posteromedial displacement places the radial nerve at risk.

Question 37

Topic: Surgical Anatomy & Approaches

During a lateral approach to the elbow (Kocher approach), the surgical interval is developed between which two muscles?

. Extensor carpi radialis brevis and extensor digitorum communis
. Anconeus and extensor carpi ulnaris
. Brachioradialis and extensor carpi radialis longus
. Pronator teres and flexor carpi radialis
. Triceps and brachialis

Correct Answer & Explanation

. Anconeus and extensor carpi ulnaris

Explanation

The Kocher approach utilizes the internervous plane between the anconeus (radial nerve) and the extensor carpi ulnaris (posterior interosseous nerve). This provides excellent access to the radial head and capitellum.

Question 38

Topic: Surgical Anatomy & Approaches

In a pediatric patient with an extension-type supracondylar humerus fracture that is displaced posteromedially, which nerve is at the highest risk of injury due to tethering over the proximal fragment?

. Radial nerve
. Median nerve (anterior interosseous branch)
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In an extension-type supracondylar humerus fracture with posteromedial displacement of the distal fragment, the proximal fragment is directed anterolaterally. This anteriorly displaced bony spike places the radial nerve at the highest risk of injury.

Question 39

Topic: Surgical Anatomy & Approaches

During a single-incision anterior approach for distal biceps tendon repair, excessive radial retraction is applied. Postoperatively, the patient is unable to extend their fingers or thumb at the MCP joints, but wrist extension is preserved with radial deviation. Which nerve was most likely injured?

. Median nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Superficial radial nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Posterior interosseous nerve

Explanation

The posterior interosseous nerve (PIN) is highly susceptible to traction injury from radial retractors during the anterior approach to the elbow. PIN palsy presents with loss of digit extension and radial-deviated wrist extension, as ECRL innervation is proximal to the PIN.

Question 40

Topic: Surgical Anatomy & Approaches

Which of the following factors most significantly increases the risk of developing heterotopic ossification (HO) following surgical management of severe traumatic elbow injuries?

. Use of a posterior surgical approach
. Concurrent ipsilateral distal radius fracture
. Use of indomethacin postoperatively
. Early active range of motion
. Concurrent severe traumatic brain injury

Correct Answer & Explanation

. Concurrent severe traumatic brain injury

Explanation

Patients with severe elbow trauma coupled with central nervous system injuries, particularly severe traumatic brain injury, have a markedly increased risk of developing clinically significant heterotopic ossification.

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