Spine Anatomy Flashcards

1
Q

when is the body of C1 visible radiographically?

A

1 year old

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2
Q

when do the posterior spinous process synchondroses fuse?

A

3 years

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3
Q

when do the synchondrosis of the ondontoid and C2 fuse?

A

3-6 years

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4
Q

when does anterior wedging of the vertebral bodies resolve?

A

age 3-6 years

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5
Q

when doe the cervical spine assume lordosis

A

8 years

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6
Q

when does pseudosubluxation and widening of predental space resolve?

A

8 years old

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7
Q

when do secondary ossification centres appear at the tips of the spinous processes?

A

puberty

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8
Q

when to the secondary ossification centres at the tips of the SPs fuse?

A

25 years

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9
Q

when do the superior and inferior epiphyseal rings fuse to the main vertebral body?

A

25 years old

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10
Q

where does the spinal column end?

A

L1

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11
Q

where do you do a lumbar puncture?

A

L4/5 space

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12
Q
A

central grey matter

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13
Q
A

dorsal columns:

gracile and cuneate respectively

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14
Q
A

lateral corticospinal tract

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15
Q
A

spinothalamic tract

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16
Q
A

ventral white commissure

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17
Q

describe central cord syndrome

A

a disruption in trauma of the central cord resulting in disproportionally greater motor impairment in upper compared to lower extremities with variable degree of sensory loss below the level of injury.

usually combined with bladder/bowel dysfunction and urinary retention

caused by acute hyperextension, mostly in elderly with cervical spondylosis

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18
Q

describe anterior cord syndrome

A

due to ischemia from the anterior spinal artery supply disruption

loss of motor function below injury

loss of pain and temperature

*preservation of touch, vibration and proprioception

*the most common type of spinal cord infarction

urinary retention and flaccid anus

autonomic dysreflexia above T6

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19
Q

describe brown-sequard syndrome

A

damage to 1/2 of the spinal cord

paralysis and loss of touch/proprioception ipsilaterally

loss of pain/temperature opposite

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20
Q

what does the corticospinal tract do?

A

descending motor function

crosses in lower medulla

therefore ipsilateral with respect to spinal injury and deficit

*the exception is the 10% of fibres in the anterior bundle that do not cross until they reach their destination to innervate truncal muscles

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21
Q

what does the posterior column of the spinal cord do?

A

there are 2 bundles: gracile (legs) medial and cuneate (arms) lateral

they provide ascending fine touch and proprioception

cross at the upper medulla - therefore causes ipsilateral deficits with respect to spinal injuries

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22
Q

what does the spinal thalamic tract do?

A

lateral and anterior bundles that transmit ascending pain and temperature (lateral) and crude touch (anterior) to the brain

cross at the level of their innervation - therefore the cause contralateral deficits with respect to spinal injuries

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23
Q

what is the bulbocavernous reflex?

A

compression of the glans should elicit anal sphincter contraction

dervied from S2-4

the abscence of reflex in acute traumatic paralysis is actually good - it means that there is spinal shock. A spinal cord transection with have maintained reflex.

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24
Q

what is autonomic dysreflexia?

A

presents as uncontrolled hypertension and bradycardia

lesion above T6

triggered by sympathetic stimulation below the lesion that cannot be counteracted by descending parasympathetic flow when barorecptors notice a problem. Essentially, your circulation CAN go across the lesion, but your neuro CANNOT.

often triggered by urinary bladder distention

25
Q

explain ASIA grading

A

A = no response below lesion

B = sensation preserved below lesion

C = >50% of muscles are < 3/5

D = > 50% of muscles are >/= 3/5

E = full function

26
Q

what do we mean when we say ‘motor level’ in a spinal cord injury?

A

the most caudal level where power is not 5/5

27
Q

what do we mean by ‘sensory level’ in spinal cord injury?

A

most caudal level with normal pinprick and light touch

28
Q

what is the highest level of spinal cord injury that can be ventilator independent initially? how about after time?

A

C5

eventually C3 and C4 can become independent

29
Q

where do the majority of stenoses occur?

A

at the level of the disc anteriorly with facet joint posteriorly

30
Q

where is the foramen in relation to the pedicle?

A

the pedicles arise from the superior portion of the vertebrae, the nerves exit below them and superior to the disc

31
Q

what are the boundaries of the foramen?

A

the pedicle superiorly

the superior facet inferiorly

the pars posteriorly

the vertebral body anteriorly

32
Q

where is the lateral recess?

A

the space between the medial pedicle and medial superior facet

notice that this means the vertebral body/disc is anterior and the superior facet of the vertebra below is posterior

33
Q

which nerve will an L4/5 foraminal (far lateral) bulge impinge?

A

L4

34
Q

which nerve will a posterolateral (lateral recess) disc herniation of L4/5 impinge?

A

L5

35
Q

which layer increases in width in lumbar spinal stenosis caused by hypertrophied ligamentum flavum?

A

the cartilage layer under the ligament

36
Q

what are the signs of unstable spine?

A

pain with dynamic movement

dynamic shift on imaging

lack of osteoarthritic signs

facet joint effusions

evolving neurologic symptoms

37
Q

where should occipital screws be placed?

A

+/- 2 cm at the nuchal line

+/- 1 cm 1 cm below nuchal line

+/- 0.5 cm 2 cm below nuchal line

*we are talking about the superior nuchal line, found in line with the EOP

38
Q

why don’t you place transarticular C1-2 screws?

A

1) if there is a high-riding vertebral artery (present in 20%)
2) subluxation of C1-2
3) if there is cervicothoracic kyphosis

39
Q

what is the relationship of the vertebral artery to C1?

A

emerge superiorly through the lateral foraminae then track medial on the superior aspect of the pedicles of C1 before continuing superiorly with the spinal cord to enter the cranium

40
Q

where is the ICA in relation to C1?

A

abutting the anterolateral aspect of C1

41
Q

where do you place a thoracic pedicle screw?

A

start at the junction of a lines:

1) vertically along midpoint of facet joint
2) along superior ridge of transverse process

42
Q

where do you start a lumbar pedicle screw

A

intersection of lines:

1) vertically along the superior facet
2) horizontally along midpoint of transverse process

43
Q

largest thoracic vertebra

A

T1

44
Q

smallest thoracic vertebra

A

T4

45
Q

smallest lumbar vertebra

A

L1

46
Q

what screw size for lumbar spine?

A

L1 = 7.5

L2 = 8.0

L3 = 9.5

L4 = 12.5

L5 = 11.5

47
Q

what is the toeing in trend for pedicle screws?

A

less as you go down T spine

to 5-10° at L1

then increase 5° per level from L1 down

48
Q

where can you place S1 pedicle screws?

A

zone 1 = superior facet directed 10° from sagittal

zone 2 = notch lateral to facet directed 40° from sagittal

49
Q

where are the safe zones for halo placement?

A

superolateral half of frontal bone above orbit

this avoids the temporalis muscle laterally, the supraorbital nerve over medial half of frontal bone above orbit, and the supratrochlear nerve arising from the superomedial aspect of the orbit

50
Q

normal thoracic kyphosis

A

10-40°

51
Q

what is the normal lumbar lordosis?

A

TK + 30°

52
Q

what is normal sagittal alignment of the spine?

A

C7 should drop a vertical line through the posterior superior margin of the sacrum +/- 2.5 cm

53
Q

normal sacral slope

A

41° +/- 16°

54
Q

normal pelvic tilt

A

first, vertical line from center of acetabulum, second line from center of acetabulum and middle of sacrum

normal is 13° +/- 12°

55
Q

what is pelvic incidence?

A

PT + SS

56
Q

why is pelvic incidence important?

A

it dictates the lumbar lordosis, where

PI = LL + 10°

57
Q

how can you increase lordosis?

A

spinous process + facet joint osteotomy

58
Q

explain the arterial supply to the spinal cord

A

cervical and upper thoracic supplied by radicular branches or vertebral, ascending cervical and superior intercostal arteries

*watershed exists in mid-upper thoracic spine

mid/lower thoracic is supplied solely by the artery of adamkiewicz, which usually arises between 9th and 12th intercostal arteries, 70% of the time from the Left

lower thoracic-lumbar spine supplied by large vessel near diaphram

cauda supplied from lower lumbar, iliolumbar and lateral sacral arteries

59
Q

what is ossification of PLL and how is it treated?

A

AS PER REVIEW BY CHOI 2011 - Asian Spine Journal

elderly, male, asians (2.4% of all asians)

type 2 diabetes also a risk

myelopathy is the indication for surgery, however this is less common as the disease is not usually rapidly progressive (Matsunaga - 450 patients)

(Chiba - 50% progression even with surgery - 131 patients - worse for posterior approach 70%, than anterior 50%)