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6. Spine MCQs

Practice Set 237 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 4721

Topic: 6. Spine

A 55-year-old male with a longstanding history of ankylosing spondylitis presents to the emergency department after a ground-level fall. He complains of severe lower neck pain but has a normal neurological examination. Plain AP and lateral radiographs of the cervical spine show a "bamboo spine" but no obvious fracture. What is the most appropriate next step in management?

. Discharge home with a soft collar and NSAIDs
. Obtain dynamic flexion-extension cervical radiographs
. Perform a CT scan of the entire cervical spine
. Administer high-dose intravenous methylprednisolone

Correct Answer & Explanation

. Discharge home with a soft collar and NSAIDs

Explanation

Patients with ankylosing spondylitis have highly altered, osteopenic spinal biomechanics, making fractures notoriously difficult to see on plain films. A CT scan of the entire cervical spine is mandatory to rule out a highly unstable occult fracture.

Question 4722

Topic: 6. Spine

A 70-year-old male complains of bilateral leg pain and cramping that worsens with walking. Which of the following clinical findings is most specific for differentiating neurogenic claudication from vascular claudication?

. Diminished dorsalis pedis and posterior tibial pulses
. Symptom relief achieved solely by standing stationary
. Symptom exacerbation when walking uphill
. Symptom relief when leaning forward on a shopping cart

Correct Answer & Explanation

. Diminished dorsalis pedis and posterior tibial pulses

Explanation

Neurogenic claudication is exacerbated by lumbar extension and relieved by lumbar flexion, which increases the cross-sectional area of the spinal canal. Leaning forward on a shopping cart (the "shopping cart sign") provides distinct relief specific to neurogenic claudication.

Question 4723

Topic: 6. Spine

A 62-year-old female presents with new-onset radiculopathy three years after undergoing an L3-S1 posterolateral fusion. MRI confirms severe stenosis at the L2-L3 level. Which of the following is the most significant biomechanical risk factor for the development of this adjacent segment disease (ASD)?

. Use of rigid titanium pedicle screws instead of PEEK rods
. Postoperative sagittal malalignment with lumbar hypolordosis
. Patient age exceeding 60 years at the time of index surgery
. Use of interbody cages during the index procedure

Correct Answer & Explanation

. Use of rigid titanium pedicle screws instead of PEEK rods

Explanation

Postoperative sagittal malalignment, particularly fusing the lumbar spine in hypolordosis (flatback), dramatically increases biomechanical stress on adjacent motion segments. This is widely recognized as a primary driver of adjacent segment disease.

Question 4724

Topic: Cervical Spine

A 21-year-old collegiate baseball pitcher presents with chronic medial elbow pain that is worse during the late cocking and early acceleration phases of throwing. MRI demonstrates a high-grade partial tear of the ulnar collateral ligament (UCL). He has failed 4 months of conservative management and is opting for reconstruction. Which specific structure provides the primary restraint to valgus stress at the elbow between 30 and 120 degrees of flexion?

. Posterior bundle of the UCL
. Radial collateral ligament
. Anterior bundle of the UCL
. Flexor-pronator mass
. Transverse ligament (Cooper's ligament)

Correct Answer & Explanation

. Posterior bundle of the UCL

Explanation

The anterior bundle of the ulnar collateral ligament (UCL) is the primary static stabilizer to valgus stress at the elbow, particularly functioning between 30 and 120 degrees of flexion. It originates on the anteroinferior surface of the medial epicondyle and inserts on the sublime tubercle of the ulna. The posterior bundle is a secondary restraint that is tightest in full flexion. The flexor-pronator mass provides secondary dynamic stability to valgus stress.

Question 4725

Topic: 6. Spine

Which of the following is an absolute contraindication to regional anesthesia in orthopedic surgery?

. Anticoagulation with an INR of 1.5
. Patient refusal
. Pre-existing peripheral neuropathy
. Surgical site infection near the planned injection site
. History of epidural abscess

Correct Answer & Explanation

. Anticoagulation with an INR of 1.5

Explanation

Patient refusal is an absolute contraindication to any medical procedure, including regional anesthesia. While anticoagulation, pre-existing neuropathy, and history of epidural abscess are significant concerns and often contraindications, they are typically considered relative depending on the specific block, patient factors, and risk/benefit analysis. An INR of 1.5 is often acceptable for certain peripheral nerve blocks, but not an absolute contraindication across the board for all regional blocks (e.g., neuraxial blocks). Surgical site infection at the injection site is an absolute contraindication due to risk of spreading infection.

Question 4726

Topic: 6. Spine

Which bone is considered an irregular bone?

. Femur
. Patella
. Scapula
. Vertebra
. Rib

Correct Answer & Explanation

. Femur

Explanation

Vertebrae are classified as irregular bones due to their complex and unique shapes that do not fit into other categories (long, short, flat, sesamoid). The femur is a long bone, patella is a sesamoid bone, scapula and rib are flat bones.

Question 4727

Topic: Cervical Spine

The 'SAFE' interval in anterior cervical discectomy and fusion (ACDF) refers to the safe surgical corridor between which two anatomical structures?

. Carotid artery and jugular vein
. Trachea and esophagus
. Recurrent laryngeal nerve and longus colli muscle
. Prevertebral fascia and carotid sheath
. Common carotid artery and thyroid gland

Correct Answer & Explanation

. Carotid artery and jugular vein

Explanation

The 'SAFE' (Superior, Anterior, Fascial, Esophageal) interval or 'danger zone' in ACDF refers to the space between the carotid sheath (containing the carotid artery, jugular vein, vagus nerve) laterally and the esophagus/trachea medially, anterior to the prevertebral fascia. This corridor allows access to the cervical spine while minimizing injury to vital structures. The recurrent laryngeal nerve is within the tracheoesophageal groove, and careful retraction is needed to protect it.

Question 4728

Topic: 6. Spine

A 7-year-old boy with autism spectrum disorder and a highly restrictive diet consisting only of carbohydrate-rich snacks presents with bone pain, refusing to bear weight, and swollen, bleeding gums. Radiographs of his bilateral lower extremities demonstrate diffuse osteopenia, a dense metaphyseal zone of provisional calcification (white line of Frankel), and a radiolucent band just diaphyseal to it. The patient's condition is directly caused by an acquired deficiency impairing which of the following specific biochemical steps?

. Carboxylation of glutamic acid residues
. Cleavage of procollagen C- and N-terminals
. Cross-linking of collagen via lysyl oxidase
. Mineralization of osteoid
. Hydroxylation of proline and lysine residues

Correct Answer & Explanation

. Carboxylation of glutamic acid residues

Explanation

The patient has clinical and radiographic signs of scurvy, caused by Vitamin C (ascorbic acid) deficiency. Vitamin C acts as an essential electron donor for prolyl hydroxylase and lysyl hydroxylase, enzymes that are responsible for the hydroxylation of proline and lysine residues within the rough endoplasmic reticulum. This modification is critical for hydrogen bonding and the stabilization of the collagen triple helix. Lysyl oxidase cross-links collagen extracellularly and requires copper as a cofactor, not Vitamin C.

Question 4729

Topic: 6. Spine

Regarding the vertebral column, which ligament limits flexion and provides significant stability, becoming taut during this movement and acting as a strong restraint in the lumbar spine?

. Ligamentum flavum
. Anterior longitudinal ligament
. Posterior longitudinal ligament
. Supraspinous ligament
. Interspinous ligament

Correct Answer & Explanation

. Ligamentum flavum

Explanation

The supraspinous ligament connects the tips of the spinous processes from C7 to the sacrum, blending with the nuchal ligament in the cervical region. It is a strong fibrous band that limits hyperflexion of the spine. The interspinous ligaments connect adjacent spinous processes but are relatively weak. The ligamentum flavum connects laminae and resists flexion, but its primary role is to maintain intradiscal pressure and act as an elastic recoil. The anterior longitudinal ligament limits extension, while the posterior longitudinal ligament limits flexion but is weaker than the supraspinous ligament in the lumbar region and located anterior to the spinal canal. Thus, the supraspinous ligament is the most significant restraint against flexion posteriorly in the lumbar spine.

Question 4730

Topic: 6. Spine

During a posterior approach to the lumbar spine, the surgeon encounters a tough, elastic, yellowish ligament spanning between the laminae. This ligament is known for its high elastin content and its role in maintaining erect posture and preventing hyperflexion. Which ligament is being described?

. Anterior longitudinal ligament
. Posterior longitudinal ligament
. Ligamentum flavum
. Supraspinous ligament
. Interspinous ligament

Correct Answer & Explanation

. Anterior longitudinal ligament

Explanation

The ligamentum flavum (yellow ligament) connects the laminae of adjacent vertebrae. It is distinctive for its high elastin content (about 80% elastin, 20% collagen), giving it a yellowish appearance and elasticity. This elasticity helps maintain the upright posture, provides smooth recoil from flexion, and prevents sudden internal buckling into the spinal canal during extension. It also helps preserve intradiscal pressure. The anterior and posterior longitudinal ligaments primarily resist extension and flexion respectively. The supraspinous and interspinous ligaments are also posterior but have a different composition and location relative to the laminae.

Question 4731

Topic: 6. Spine

A 60-year-old patient with severe lumbar stenosis undergoes a laminectomy. During the procedure, the surgeon meticulously removes hypertrophied ligamentous structures. Which ligament directly connects adjacent vertebral laminae and contributes significantly to spinal canal stenosis when hypertrophied?

. Anterior longitudinal ligament
. Posterior longitudinal ligament
. Ligamentum flavum
. Intertransverse ligament
. Supraspinous ligament

Correct Answer & Explanation

. Anterior longitudinal ligament

Explanation

The ligamentum flavum (yellow ligament) connects the laminae of adjacent vertebrae. It is highly elastic due to its high elastin content and plays a role in maintaining posture. However, with age, it can undergo hypertrophy, calcification, and infolding, directly contributing to narrowing of the spinal canal (stenosis) by bulging posteriorly into the canal. The anterior and posterior longitudinal ligaments are located anterior and posterior to the vertebral bodies, respectively, and don't directly contribute to canal stenosis via hypertrophy as much as the ligamentum flavum. The intertransverse ligaments are between transverse processes. The supraspinous ligament is superficial to the laminae.

Question 4732

Topic: 6. Spine

A 70-year-old patient presents with symptoms of cervical myelopathy due to spinal cord compression. The spinal cord ends inferiorly as the conus medullaris at which typical vertebral level in adults?

. T10
. T12
. L1/L2
. L3/L4
. S1

Correct Answer & Explanation

. T10

Explanation

In adults, the spinal cord typically terminates as the conus medullaris at the level of the L1-L2 vertebral body. In children, it can extend lower, usually to L3. This anatomical distinction is crucial for procedures like lumbar puncture, which are safely performed below L2 (e.g., L3/L4 or L4/L5 interspaces) to avoid spinal cord injury. Therefore, L1/L2 is the most accurate typical adult termination level.

Question 4733

Topic: 6. Spine

During surgical repair of a perineal laceration, the surgeon must be mindful of the pudendal nerve's course. Which anatomical structure forms the medial wall of Alcock's canal, where the pudendal nerve travels?

. Ischial spine
. Sacrotuberous ligament
. Obturator internus muscle
. Ischiopubic ramus
. Piriformis muscle

Correct Answer & Explanation

. Ischial spine

Explanation

The pudendal nerve, along with the internal pudendal artery and vein, passes through Alcock's canal (also known as the pudendal canal). This canal is formed by a splitting of the obturator internus fascia. Therefore, the obturator internus muscle itself forms the lateral wall, and its fascia forms the medial wall of the canal. The ischial spine is a landmark for the nerve's entry into the perineum but not part of the canal itself. The sacrotuberous ligament contributes to the greater sciatic foramen. Ischiopubic ramus is bone forming part of the pelvis. Piriformis muscle is more superior in the pelvis.

Question 4734

Topic: 6. Spine

Regarding the innervation of intervertebral discs, which type of nerve fibers primarily innervates the outer annulus fibrosus, contributing to discogenic pain?

. Ventral rami
. Dorsal rami
. Sinuvertebral nerves (recurrent meningeal nerves)
. Sympathetic chain ganglia
. Phrenic nerve

Correct Answer & Explanation

. Ventral rami

Explanation

The outer one-third of the annulus fibrosus of the intervertebral disc is richly innervated, primarily by the sinuvertebral nerves (also known as recurrent meningeal nerves). These nerves are branches of the spinal nerves that re-enter the vertebral canal to innervate the posterior longitudinal ligament, the annulus fibrosus, and the dura mater. They carry nociceptive fibers, which explain why damage or inflammation to the outer annulus can cause significant discogenic pain. The nucleus pulposus and inner annulus are largely aneural. Dorsal and ventral rami innervate paraspinal muscles and skin, respectively.

Question 4735

Topic: 6. Spine

A 55-year-old male is undergoing a transforaminal endoscopic lumbar discectomy at L4-L5. The surgeon utilizes Kambin's triangle to safely access the intervertebral disc space. Which of the following structures constitutes the anterior (hypotenuse) boundary of Kambin's triangle?

. The exiting nerve root
. The traversing nerve root
. The superior endplate of the L5 vertebral body
. The superior articular process of the L5 vertebra
. The inferior articular process of the L4 vertebra

Correct Answer & Explanation

. The exiting nerve root

Explanation

Kambin's triangle is an anatomical safe zone for accessing the lumbar disc space posterolaterally. Its boundaries are: the exiting nerve root (anterior/superior forming the hypotenuse), the superior articular process of the inferior vertebra (posterior/vertical height), and the superior endplate of the inferior vertebral body (inferior base).

Question 4736

Topic: 6. Spine

A 60-year-old male is undergoing an anterior cervical decompression for myelopathy. During the lateral resection of the uncinate process at the C5-C6 level, brisk arterial bleeding is encountered from the adjacent foramen transversarium. In normal anatomy, the vertebral artery typically enters the foramen transversarium at which cervical level?

. C7
. C6
. C5
. C4
. C3

Correct Answer & Explanation

. C7

Explanation

The vertebral artery typically branches from the subclavian artery and enters the foramen transversarium at the C6 level in approximately 90-95% of individuals. It does not typically pass through the foramen transversarium of C7, which usually contains only the accessory vertebral vein.

Question 4737

Topic: 6. Spine

When placing a lateral mass screw in the subaxial cervical spine (C3-C6) using the Magerl technique, the optimal starting point is 1 mm medial and 1 mm superior to the center of the lateral mass. The trajectory is angled 25 degrees laterally and 25 degrees sagittally (upward). Which anatomical structure is placed at greatest risk if the screw trajectory is inadvertently directed too far medially?

. Exiting nerve root
. Vertebral artery
. Spinal cord
. Superior articular facet
. Inferior articular facet

Correct Answer & Explanation

. Exiting nerve root

Explanation

In lateral mass screw fixation of the cervical spine, lateral angulation is required to avoid the foramen transversarium. A trajectory that is too medial places the vertebral artery at significant risk, as it runs anterior and medial to the lateral mass. A trajectory that is too caudal risks the exiting nerve root.

Question 4738

Topic: 6. Spine

A 62-year-old female presents with severe right leg pain following a radicular L4 distribution. MRI reveals an L4-L5 far lateral extraforaminal disc herniation compressing the exiting L4 nerve root. A Wiltse paraspinal approach is utilized for extraforaminal decompression. To safely identify the exiting L4 nerve root, the surgeon must understand the borders of the lumbar intervertebral foramen. Which structure forms the superior boundary of the L4-L5 neural foramen?

. Superior articular process of L5
. Inferior pedicle (L5)
. Superior pedicle (L4)
. Ligamentum flavum
. Intervertebral disc

Correct Answer & Explanation

. Superior articular process of L5

Explanation

The lumbar intervertebral foramen is bordered superiorly by the inferior margin of the superior pedicle (in the case of the L4-L5 foramen, this is the L4 pedicle). It is bordered inferiorly by the superior margin of the inferior pedicle (L5 pedicle), anteriorly by the vertebral bodies and intervertebral disc, and posteriorly by the pars interarticularis and the ligamentum flavum covering the facet joint. The exiting nerve root travels below the corresponding pedicle (e.g., L4 root exits beneath the L4 pedicle).

Question 4739

Topic: 6. Spine

A 65-year-old male is undergoing posterior C1-C2 fusion for atlantoaxial instability. During the exposure of the posterior arch of C1, the surgeon meticulously dissects laterally. The vertebral artery is at risk of iatrogenic injury in this region. Which of the following describes the precise anatomical course of the V3 segment of the vertebral artery as it relates to C1?

. It courses anterior to the anterior arch of C1 before ascending to the foramen magnum.
. It exits the C1 transverse foramen and courses posteromedially in the vertebral groove on the superior surface of the posterior arch of C1.
. It passes inferior to the posterior arch of C1, entering the spinal canal directly between C1 and C2.
. It runs strictly lateral to the C1 lateral mass without intimately contacting the posterior arch.
. It courses medially beneath the atlantooccipital membrane directly into the spinal canal at the C2-C3 level.

Correct Answer & Explanation

. It courses anterior to the anterior arch of C1 before ascending to the foramen magnum.

Explanation

The V3 segment of the vertebral artery exits the C1 transverse foramen, courses posteromedially around the superior articular process of C1, and lies in the vertebral groove (sulcus arteriosus) on the superior surface of the posterior arch of C1. During posterior exposure of C1, dissection on the superior aspect of the C1 arch must stay strictly within 1.5 cm of the midline (often stated as a 15 mm safe zone) to avoid injuring the vertebral artery.

Question 4740

Topic: Cervical Spine

A 45-year-old woman undergoes an anterior cervical discectomy and fusion (ACDF) at C5-C6. During the exposure, the surgeon dissects laterally along the uncinate process. Which of the following structures is at greatest risk of iatrogenic injury if lateral dissection extends excessively beyond the uncinate process at this level?

. Superior laryngeal nerve
. Recurrent laryngeal nerve
. Vertebral artery
. Internal jugular vein
. Sympathetic trunk

Correct Answer & Explanation

. Superior laryngeal nerve

Explanation

In the lower cervical spine, the uncinate process serves as a crucial anatomic landmark, forming the medial border of the transverse foramen. The vertebral artery courses through the transverse foramina typically from C6 to C1. Dissection extending lateral to the uncinate process places the vertebral artery at significant risk of iatrogenic injury.

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