spine/peripheral nerve

Question 1

Which of the following nerves passes through the quadrangular space below the teres minor

Answer 1

The quadrangular space is lateral to the scapula and is defined by laterally by the humerus, medial by the triceps, rostrally by the teres minor and caudally by the teres major. The axillary nerve along with the circumflex artery exit caudal to the teres minor and rostral to the teres major, providing innervation to the deltoid. The suprascapular nerve originates from the upper trunk and passes across the posterior triangle of the neck providing innervation to the supraspinatus and infraspinatus. The thoracodorsal nerve originates from the posterior cord and provides innervation to the latissimus dorsi. The radial nerve innervates most of the upper extremity extensors and exits below the quadrangular space between the long and lateral heads of the triceps. The long thoracic nerve originates from roots C5, C6, and C7 traversing the chest to provide innervation of the serratus anterior muscle. Injury to the long thoracic nerve results in scapular winging.

Question 2

For patients with post ACDF horners syndrome, what was injured and how?

Answer 2

The sympathetic plexus or trunk is located running on the longus colli muscle. In anterior cervical surgery, the sympathetic plexus is at risk of injury due to unintentional thermal injury from using monopolar electrocautery directly on the longus colli muscle, or from prolonged retraction inducing stretching of the fibers.

Question 3

Thoracic pedicle morphology studies consistently show that the narrowest pedicle is most likely to be found at which of the following locations?

Answer 3

T5 as the transverse diameter of the thoracic pedicle decreases from T1 to its narrowest diameter between T4-6. From T7 -T12 the diameter of the thoracic pedicles progressively enlarge.

Question 4

Each somatic muscle fiber is innervated by?

Answer 4

Each somatic muscle fiber is innervated by an alpha motor neuron which has a cell body in either the spinal cord or brain stem. A motor neuron and muscle fibers it innervates is called a motor unit. The number of fibers innervated by one motor neuron can vary. A smaller innervation number leads to finer motor control. Gamma motor neurons adjust the sensitivity of muscle spindle fibers

Question 5

A 52-year-old man is brought to the emergency department after being involved in a motor vehicle collision. He has an L2 sensory level; muscle strength is 4/5 in the proximal lower extremities and 4-/5 in the distal lower extremities. X-ray films show a severe L2 fracture. Which of the following is the most likely ASIA Impairment Scale score (modified Frankel score) in this patient?

Answer 5

The patient here has sustained an ASIA D injury, where motor function is preserved below the neurological level, and more than half of the key muscles below the neurological level have a muscle strength of at least grade 3. An ASIA A injury is complete, an ASIA B injury is incomplete where sensory function is spared without motor function except for preservation of the sacral segments. An ASIA C injury has motor function preserved below the neurological level, and more than half of the key muscles below the neurological level have a muscle strength less than grade 3. ASIA E is normal strength.

Question 6

A 50-year-old man is evaluated because of a two-week history of low back pain and sciatica on the right side. Straight-leg raising test is positive at 30 degrees and extensor hallucis longus strength on the right side is 4/5. Which of the following disc herniations is most likely?

Answer 6

L5 radiculopathy.

Far lateral and foraminal disc herniations are most likely to affect the exiting nerve root at that level while central and paracentral herniations most likely affect the traversing nerve root.

Question 7

Vertebra plana (pancake VB) is classically associated with which spinal lesions?

Answer 7

eosinophilic granuloma otherwise known as Langerhan cell histiocytosis (LCH) or histiocytosis X, a proliferation of Langerhan cells and abundance of eosinophils, lymphocytes, and neutrophils. These cells produce prostaglandins which result in medullary bone resorption.

Hand-Schuller-Christian disease describes when the disease is chronic and disseminated in bone and viscera.

Letterer-Siwe describes a fatal form that occurs in young children.

Other causes of vertebrae plana can be identified from the mnemonic I MELT (infection, metastasis/myeloma, eosinophilic granuloma, lymphoma/leukemia, trauma/tuberculosis)

Question 8

Most common level at which the vertebral artery enters the vertebral foramen on the cervical spine?

Answer 8

C6

Question 9

Innervation of the median nerve:

Answer 9

The median nerve:
orginates from both the lateral and medial cords of the brachial plexus (C5-T1)

provides sensory innervation to the anterolateral surface of the hand and provides motor innervation to the following muscles – pronator teres, flexor carpi radialis, palmaris longus, and flexor digitorum superficialis, flexor pollicis longus and flexor digitorum profundus, pronator quadratus, opponens pollicis brevis, and flexor pollicis brevis, 1st and 2nd lumbricals.

Question 10

Innervation of obturator nerve:

Answer 10

originates from L2, L3, and L4, providing sensory innervation to the medial thigh and motor innervation to the adductor longus, adductor brevis, adductor magnus, external obturator, and variably to the pectineus

Question 11

How is pelvic incidence calculated?

Answer 11

Pelvic incidence is a fixed spinopelvic parameter.

It is calculated as the angle between the perpendicular line drawn from the center of the S1 endplate and the line that joins the center of the femoral heads to the center of the S1 endplate.

It is also defined by the formula: PI = PT + SS, (PI=pelvic incidence, PT=pelvic tilt, SS=sacral slope). Sacral slope and pelvic tilt can vary with retroversion of the pelvis, and lumbar lordosis changes with flexion and extension maneuvers.
Fractional scoliosis is a coronal plane parameter that is variable in the absence of spinal fusion.

Question 12

A patient is diagnosed with left vestibular schwannoma and bilateral hypoglossal canal meningiomas. This patient most likely has which of the following genetic conditions?

Answer 12

neurofibromatosis type 2 (NF2) is diagnosed when one of the following criteria are met.

1.  Bilateral vestibular schwannoma (VS), diagnosed before age 70
2.  First-degree relative family history of NF2 and unilateral VS, diagnosed before age 70
3.  First-degree relative family history of NF2 or unilateral VS or 2 of: meningioma, cataract, schwannoma, cerebral calcification (if unilateral VS and > 2 nonintradermal schwannomas, needs negative LZTR1 genetic testing)
4.  Multiple meningiomas (2 or more) and 2 of: unilateral VS, cataract, ependymoma, schwannoma, cerebral calcification
5.  Constitutional or mosaic pathogenic NF2 gene mutation in blood or identical mutations in 2 distinct tumors.

Question 13

Which muscles is innervated by the anterior interosseous nerve?

Answer 13

anterior interosseous nerve is a distal branch of the median nerve that originates at the level of the anterior forearm

It originates from the nerve roots C8 and T1

It intervates the flexor pollicis longus, flexor digitorum profundus, and the pronator quadratus.

Compression at the level of the forearm or parsonage turner syndrome are the most common pathologies producing varying degrees of weakness but without sensory deficit.

Question 14

Duchennes muscular dystophy: inheritance, lab abnormalities, and symptoms?

Answer 14

x linked recessive

caused by decreased dystophin

Increased creatinine kinase, muscle fiber necrosis

atrophy of shoulder and pelvic gridle muscles, calf pseudohypertrophy, CHF, + gowers test Tx: prednisone

Question 15

myotonic muscular dystophy: inheritance, lab abnormalities, and symptoms?

Answer 15

AD 19

CTG trinucleotide repeat

ring fibers, EMG: dive bomber frequency

face then extremity, MR, dysrythmias, cataracts, endocrinopathies

Tx: quinine, procainamide, and dilantin

Question 16

Beckers muscular dystophy: inheritance, lab abnormalities, and symptoms?

Answer 16

x linked

decreased dystrophin

less severe than duchennes

Question 17

Muscles of the tympanic cavity and their innervation:

Answer 17

Tensor tympani: CN5

stapedius: CN7

Question 18

Muscles of mastication:

Answer 18

temporalis, masseter, medial pterygoid, lateral pterygoid (only one that opens the mouth)

innervation: CN5

Question 19

Muscles of the tongue and innervation:

Answer 19

CN 12: genioglossus, hyoglossus, styloglossus

CN 10: palatoglossus

Question 20

Muscles of the palate and innervation:

Answer 20

CN 5: tensor veli palatini

CN 10: levator veli palatini, palatoglossus, and palatopharyngeus

Question 21

Muscles of the pharynx and innervation:

Answer 21

CN 9: stylopharyngeus

CN 10: salpingopharyngeus, superior, middle, and inferior pharyngeal constrictors

Question 22

Muscles of the larynx and innervation:

Answer 22

all CN 10

cricothyroid from external branch of the superior laryngeal nerve but all others by recurrent laryngeal nerve

Question 23

Brachial plexus subdivisions and level, innervation (branches) at each level:

Answer 23

Roots C5-T1:

• C5-8: longus colli and scalene muscles
• C5: dorsal scapular nerve -> rhomboids and levator scapula
• C5-7: long thoracic nerve –> serratus anterior

Trunks:

• upper: suprascapular nerve -> supra and infraspinatus
• middle: no branches (runs under the anterior scalene)
• lower: no branches (behind the subclavian artery)

cords:

• lateral: lateral pectoral nerve -> pectoral muscles
• posterior: upper/lower subscapular nerves -> teres major, subscapularis ; thoracodorsal nerve -> latissimus dorsi ; terminates as the axillary and radial nerves
• medial: medial pectoral nerve -> pectoral muscles; medial brachial cutaneous nerve -> arm; medial antebrachial cutaneous nerve -> forearm; terminates as median cutaneous and ulnar nerves

Nerves:

• musculocutaneous: coracobrachialis, biceps, and brachialis
• axillary: deltoid and teres minor
• radial: triceps, brachioradialis, extensor carpi radialis longus and brevis; continues as the posterior interosseous nerve (C7-8) -> supinator, externsor carpi ulnaris, extensor digitorum, extensor digiti minimi, abductor pollicus longus, extensor pollicus longus and brevis, and extensor indicis
• median:
• ulnar:

Question 24

Which type of muscle has a longer depolarization and plateau phase?

Answer 24

cardiac muscle due to fast voltage-gated sodium channels, slow voltage-gated calcium channels, and potassium channels that do not open until the end of the plateau

Question 25

what is the conduction velocity in small, unmyelinated fibers?

Answer 25

0.5m/s

Question 26

What are the 5 types of sensory fibers and how are they organized/what do they transmit?

Answer 26

Ia (type A-alpha [Aα])—annulospiral endings of muscle spindles; largest (i.e., 17-μm diameter) and fastest (120 m/s). Ib (Aα)—Golgi’s tendon organs; 16 μm in diameter. II (type A-beta [Aβ] and A-gamma [Aγ])—flower-spray endings of muscle spindles and cutaneous tactile receptors; 8 μm in diameter. III (type A-delta [Aδ])—temperature, crude touch, and pricking pain; 3 μm in diameter. IV (type C)—unmyelinated fibers relaying pain, itch, temperature, and crude touch sensations; 0.5 to 2 μm in diameter.

Question 27

What are the 3 types of motor nerve fibers?

Answer 27

Skeletal muscle—α-type A (myelinated; fastest fibers). Muscle spindle—γ-type A (myelinated). Sympathetic—type C (unmyelinated; slowest fibers).

Question 28

What are the two types of anterior motor neurons?

Answer 28

α motor neurons—larger. They innervate skeletal muscle by sending α-type A fibers to large skeletal muscle fibers within the motor unit. Gamma motor neurons—smaller. They are 50% less numerous and relay γ-type A fibers to the intrafusal fibers of the muscle spindle.

Question 29

Describe muscle spindle organization, type of endings with attached fibers, and types of intrafusal fibers:

Answer 29

spindles lie parallel to fibers, composed of 3-12 intrafusal fibers attached to larger extrafusal fibers detects length and velocity of change in length of the muscle two sensory endings of the spindle: primary (type Ia fiber with 70-120m/s impulse relay) and secondary (type II flower spray, slower conduction) Two types of intrafusal fibers: -nuclear bag fibers: 1-3/spindle and innervated by primary endings -nuclear chain: 3-9/spindle; smaller and innervated by primary and secondary endings

Question 30

Primary motor cortex: cells?

Answer 30

brodmanns area 4. Bets cells are large pyramidal neurons found only in the primary motor cortex; they relay impulses at 70 m/s

Question 31

Efferent fibers from the motor cortex to:

Answer 31

collateral fibers to the cortex (for lateral inhibition), caudate and putamen, red nucleus (rubrospinal fibers), reticular formation (reticulospinal, cerebellar fibers), vestibular system (vestibulospinal, cerebellar fibers), and inferior olive (olivocerebellar fibers)

Question 32

Afferent fibers to the motor cortex from:

Answer 32

input from somatosensory systems (e.g., muscle spindles), visual cortex, auditory cortex, frontal cortex, contralateral motor cortex (via the corpus callosum), ventrobasal thalamus, ventrolateral (VL) and ventroanterior (VA) thalamus (with input from the cerebellum and basal ganglia), and intralaminar nuclei of the thalamus (which regulate the level of excitability)

Question 33

descending motor pathway:

Answer 33

contains 1 million fibers (30% from area 4, 30% from premotor and supplementary motor cortices [area 6], and 40% from sensory fibers). 40% of the fibers are from the parietal lobe. Cells (Betz cells) arise from layer 5. travels in the posterior limb of the internal capsule and down through the brainstem, forming the medullary pyramid most fibers then cross and descend in the lateral corticospinal tract, terminate on interneurons (in cord gray matter, mostly Lamina VII), sensory relay neurons (in the dorsal horn), and anterior motor neurons Some fibers, however, remain ipsilateral; these descend in the ventral corticospinal tract, ultimately crossing at lower levels within the spinal cord. These fibers are used for bilateral postural control, relaying impulses from the supplementary motor area

Question 34

What is the appearance of SNAPs in nerve root avulsion? what does it look like if the lesion is distal to the DRG?

Answer 34

If lesion is proximal, there is still a normal SNAP but no sensation since the axon is attached to the cell body if lesion is distal to cell body, the SNAP is abnormal

Question 35

What does the nervi erigentes innervate?

Answer 35

parasympathetic supply to the pelvis and perineum also called the pelvic splanchnic nerve; S2, 3, 4

Question 36

cause and symptoms of meralgia paresthetica?

Answer 36

entrapment or injury of the lateral femoral cutaneous nerve causing pain and numbness in the anterolateral thigh

Question 37

Wartenbergs sign is associated with which nerve injury?

Answer 37

Ulnar nerve inability to adduct the little finger due to weakness of interossei secondary to ulnar n palsy. The little finger is abducted due to the unopposed action of extensor digiti minimi.

Question 38

what is the membrana tectoria?

Answer 38

cranial extension of the PLL and connects C2 to clivus The transverse ligament of atlas is anterior to it. (There is another tectorial membrane in the inner ear and is involved with hearing)

Question 39

which tract carries pain and temp from contralateral body?

Answer 39

lateral (neo) spinothalamic tract transmits pain and temperature from the contralateral body and is somatotopically organized with the legs laterally. The ventral (paleo) spinothalamic is involved in light touch.

Question 40

Substance P is the main neurotransmitter in the:

Answer 40

substantia gelatinosa of Rolando (II) and is involved in pain sensation

Question 41

All of the following tracts enter the cerebellum through the inferior cerebellar peduncle, except:

Answer 41

Ventral spinocerebellar (enters through the superior cerebral peduncle) Dorsal spinocerebellar Ventral external arcuate fibers Dorsal external arcuate fibers Olivocerebellar

Question 42

which nerve injury causes wrist drop?

Answer 42

radial nerve

Question 43

Which nerve injury causes benediction hand?

Answer 43

median n.

Question 44

which nerve injury causes ulnar claw and froments sign?

Answer 44

ulnar n.

Question 45

Which nerve injury causes an inability to make the OK sign?

Answer 45

AIN

Question 46

Posterior interosseous nerve (PIN) palsy causes:

Answer 46

finger drop and radial deviation with wrist extension due to the intact extensor carpi radialis longus and brevis while the extensor carpi ulnaris is paralyzed

Question 47

What is the best way to assess nerve functionality through a neuroma in continuity?

Answer 47

nerve action potential. If there is a signal, then there is a chance of 70% return of function with resection of neuroma if there is no signal, then should resect and graft nerve

Question 48

What is an oberlin transfer?

Answer 48

a technique in which the ulnar nerve is transferred to the biceps brachii muscle to restore elbow flexion. used when there is isolated injury to the musculocutaneous nerve or with an upper plexus injury in which C5 to C7 nerve damage exists, such as a traumatic brachial plexus avulsion injury

Question 49

What is trigeminal deafferentation pain? How is that different from trigeminal neuropathic pain?

Answer 49

pain that develops following ablative treatment for trigeminal neuralgia usually distinctly different from original trigeminal neuralgia pain usually constant and burning, and occurs in the territory of reduced, but not anesthetic, sensation Trigeminal neuropathic pain is a similar, except that it occurs in patients who do not have a history of trigeminal neuralgia

Question 50

Where should a spinal cord stimulator be placed to get relief of low back and lower extremity pain?

Answer 50

T9

Question 51

Where should a spinal cord stimulator be placed to get relief of lower extremity and foot pain?

Answer 51

T11

Question 52

The supinator muscle is innervated by:

Answer 52

the radial nerve

Question 53

flexor carpi radialis is innervated by:

Answer 53

median nerve

Question 54

Pain circuits within the substantia gelatinosa receive descending, inhibitory, serotonergic and adrenergic inputs from which brain structure?

Answer 54

locus ceruleus cells enter DRG, ascend lissaurs tract, and synapse in lamina II. Second order neurons then ascend to the spinal thalamic tract but will receive inhibitory signals directly on lamina II from locus ceruleus

Question 55

Radiofrequency facet denervation is an interventional pain procedure used to treat:

Answer 55

low back pain

Question 56

AIN is a branch of which muscle? what does it innervate?

Answer 56

branch of the median nerve that originates in the proximal forearm and continues distally to innervate the flexor pollicis longus, flexor digitorum profundus 1, and pronator quadratus muscles There is no sensory component

Question 57

What muscles does the median nerve innervate?

Answer 57

opponens pollicis, abductor pollicis brevis, pronator teres, and flexor digitorum superficialis, and first and second lumbrical muscles

Question 58

What is hyperpathia?

Answer 58

escalating pain response with a repetitive painful stimulus

Question 59

What is mechanical hyperalgesia?

Answer 59

increased sensitivity to pain that occurs on passive joint movements

Question 60

Which analgesics works by binding to spinal cord vanilloid (TRVP1) receptors, thus causing prolonged depolarization and defunctionalization of the pain pathways?

Answer 60

Capsaicin

Question 61

What is geniculate (nervus intermedius) neuralgia?

Answer 61

lancinating pain involving the deep aspect of the ear canal

Question 62

What is opioid-induced hyperalgesia?

Answer 62

occurs when patients on chronic opioid medication develop worsening of their pain that paradoxically becomes less responsive to continued or even increased opioid dosing

Question 63

Location of the nerve entrapment that presents as pain along the left medial knee and electrical shocks that shoot down the anteromedial left leg to the ankle?

Answer 63

saphenous nerve (sensory only) distribution terminal branch of femoral nerve site of entrapment is the adductor canal in the distal thigh

Question 64

How does thoracic outlet syndrome manifest?

Answer 64

arm pain and affects muscles in the hand in the ulnar and median distributions

Question 65

most common nerve injured during posterior cervical lymph node biopsy? symptoms?

Answer 65

spinal accessory nerve present with shoulder pain and inability to adduct the shoulder more than 90*

Question 66

What is neuroplasty (external neurolysis)? when is it used?

Answer 66

circumferential dissection of a nerve from the surrounding tissues used to decompress the entrapped nerve

Question 67

which nerve courses through the achilles tendon and medial malleolus?

Answer 67

Tibial nerve branch of sciatic nerve at a distal thigh level

Question 68

How do the trigeminal nerve branches course through meckels cave?

Answer 68

Question 69

Internal neurolysis is best for:

Answer 69

good technique for decompressing hourglass constrictions in the nerve or separating scarred fascicles from non-scarred fascicles

Question 70

How does parsonage-turner syndrome present?

Answer 70

acute polyradicular pain without weakness, which resolves over days to weeks, only to develop into weakness affecting multiple nerve root distributions, most prominently the proximal arm and shoulder girdle

Question 71

What is the best way to ABORT a cluster headache?

Answer 71

subcutaneous sumatriptan

Question 72

What is the difference between type I and type II complex regional pain syndrome? What are the symtoms?

Answer 72

Allodynia, mechanical hyperalgesia, color changes, temperature and sudomotor abnormalities, and motor disorders can all occur. Complex regional pain syndrome type 1 occurs in the absence of a discernible nerve injury, whereas complex regional pain syndrome type 2 occurs in the presence of a discernible nerve injury

Question 73

What are the median nerve innervated hand muscles?

Answer 73

Question 74

What are the ulnar nerve innervations of the hand muscles?

Answer 74

Question 75

Where does the lateral femoral cutaneous nerve course?

Answer 75

in front of the ASIS, through the inguinal ligament, and just medial to the sartorius muscle

Question 76

where is the usual site of compression for PIN?

Answer 76

leading edge of the supinator as the PIN dives deep to the arcade of frohse

Question 77

Isolated weakness of dorsiflexion and ankle inversion is attributable to which nerve radiculopathy?

Answer 77

L5

Question 78

Isolated weakness of plantarflexion and ankle eversion is attributable to which nerve radiculopathy?

Answer 78

S1

Question 79

weakness of dorsiflexion and ankle eversion is attributable to which nerve radiculopathy?

Answer 79

peroneal nerve

Question 80

weakness of plantarflexion and ankle inversion is attributed to which nerve?

Answer 80

tibial mononeuropathy

Question 81

What is one of the best ways to ascertain that ulnar nerve compression is distal (at the wrist) and not proximal (at the elbow)?

Answer 81

Test ulnar sensation on the dorsal surface of the hand

Question 82

What is the course of the sciatic nerve and the divisions (tibial and peroneal)?

Answer 82

The sciatic nerve traverses the posterior thigh between the hamstring muscles. At a somewhat variable location in the distal thigh, the sciatic nerve splits into the tibial and peroneal nerves. The tibial nerve continues down the midline of the leg, whereas the peroneal nerve courses laterally across the back of the knee towards the fibular head

Question 83

For medically refractory postherpetic neuralgia of the trigeminal nerve, which therapeutic intervention is most likely to alleviate pain?

Answer 83

Caudalis dorsal root entry zone procedure

Question 84

Which of the major nerves arising from the brachial plexus has the worst prognosis for return of motor function following injury?

Answer 84

Ulnar. hand intrinsic muscles make the worst recovery

Question 85

what type of pain does The dorsal root entry zone (DREZ) procedure is used to treat?

Answer 85

upper extremity pain that results from nerve root avulsion injury

Question 86

What is Raeder's paratrigeminal neuralgia?

Answer 86

paratrigeminal neuralgia is associated with ptosis and miosis and facial pain

Question 87

What is the nerve in tarsal tunnel syndrome? symptoms? ligament?

Answer 87

Tibial n plantar foot pain, usually sparing the heel (which is innervated by the calcaneal branch) lancinate ligament on medial surface of ankle, posterior to medial malleolus

Question 88

What does the suprascapular nerve innervate? symptoms?

Answer 88

supraspinatus muscle enables the first 60˚ or so of shoulder abduction, whereas the infraspinatus muscle enables external shoulder rotation weakness in shoulder abduction and external rotation

Question 89

What is Ramsay-Hunt syndrome?

Answer 89

sudden onset of ear pain, facial paralysis, hearing loss and vertigo from zoster oticus neuritis?

Question 90

The upper trunk (C5, C6) of the brachial plexus divides into which nerves (SPA)?

Answer 90

suprascapular n (S) (supraspinatus and infraspinatus), posterior division (P) (axillary n, deltoid), and anterior division (A) (musculocutaneous n, biceps), hence the mnemonic SPA

Question 91

How many ossification centers does the odontoid have?

Answer 91

Two primary and one secondary

Question 92

After a type II odontoid fracture, the integrity of which of the following ligaments/membranes most strongly influences treatment options?

Answer 92

Tranverse ligament Rupture of the transverse ligament (the most biomechanically important portion of the cruciate ligament) allows translation of C1 on C2, evidenced by an increase in the atlantodental interval (ADI). Incompetence of this ligament is a contraindication to odontoid screw fixation and is associated with delayed instability. Incompetence may be diagnosed based on either increase in the ADI (greater than 3 mm in adults, 5 mm in children < 15 years old, and 7 mm in Down's syndrome considered abnormal) or magnetic resonance imaging findings

Question 93

What is the mechanism of action of entacapone?

Answer 93

Entacapone is a COMT inhibitor, which decrease the breakdown of dopamine from the synaptic cleft and is used in the treatment of Parkinson’s disease

Question 94

Which drug blocks the uptake of dopamine into synaptic vesicles?

Answer 94

Tetrabenazine dopamine is unique in that it is completely synthesized in the cytosol of the neuron and requires uptake into synaptic vesicles.

Question 95

Isolation of Streptococcus milleri from a brain abscess should prompt inspection of which body part?

Answer 95

Oral cavity

Question 96

The sural nerve is formed by contributions from which nerves?

Answer 96

tibial and common peroneal nerves

Question 97

Innervation of the facet joints in the lumbar spine is provided by what nerve?

Answer 97

medial branch of the dorsal ramus

Question 98

A 42 year old male is undergoing L5-S1 anterior lumbar interbody fusion for spondylolisthesis. What anatomic structure overlying the disc space is potentially at risk during exposure for discectomy?:

Answer 98

The autonomic nerves (i.e. hypogastric plexus) traverse the prevertebral space at L5-S1 and may be susceptible to thermal injury (e.g. monopolar cautery) resulting in retrograde ejaculation in men.

Question 99

Vertebral artery injury during C1-2 transarticular screw placement is most likely to result when the screw is misplaced in which direction?

Answer 99

caudally The vertebral foramen lies caudal to the pars of C2, and anatomic variations of the foramen can place the vertebral artery at risk during placement of a transarticular screw. Cranial misdirection of the screw could possibly affect the occiput-C1 joint, although this occurrence is extremely uncommon. Medial placement of a transarticular screw could result in dural laceration, with or without spinal cord injury. Placement of a transarticular screw too far anteriorly has been reported to cause hypoglossal nerve dysfunction in few case reports.

Question 100

How much rotation occurs at the C1-C2 level?

Answer 100

about 50%

Question 101

The sagittal vertical axis is the horizontal distance measured from a C7 vertical plumb line and which other structure?

Answer 101

Posterior Superior Corner of S1

Question 102

What is the modulus of elasticity? In which material is it highest?

Answer 102

measures the stiffness of a material by calculating the slope of the material's stress-strain curve highest in carbon fiber

Question 103

A 35-year-old man has had increased difficulty walking, leg numbness, and urinary hesitancy for two weeks. He had a similar episode three years ago that resolved spontaneously. Which of the following electrodiagnostic studies is the most appropriate next step?

Answer 103

Visual evoked cortical potential (VEP) latency combined with MRI could improve the accuracy of MS prediction.

Question 104

Pedicle subtraction osteotomy (PSO) produces what degree of correction in sagittal balance?

Answer 104

PSO creates a wedge in the vertebral body and achieves 30°–35° of sagittal balance correction. It is usually performed in the mid-lumbar spine (L3 or L2). Ponte osteotomy creates a wedge in the lamina and facets and achieves 10°–15° correction per level. Smith–Peterson osteotomy (SPO) in addition creates a distraction opening of the anterior longitudinal ligament, thus increasing the risk of vascular injuries.