Spine Anatomy

Question 1

when is the body of C1 visible radiographically?

Answer 1

1 year old

Question 2

when do the posterior spinous process synchondroses fuse?

Answer 2

3 years

Question 3

when do the synchondrosis of the ondontoid and C2 fuse?

Answer 3

3-6 years

Question 4

when does anterior wedging of the vertebral bodies resolve?

Answer 4

age 3-6 years

Question 5

when doe the cervical spine assume lordosis

Answer 5

8 years

Question 6

when does pseudosubluxation and widening of predental space resolve?

Answer 6

8 years old

Question 7

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

Answer 7

puberty

Question 8

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

Answer 8

25 years

Question 9

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

Answer 9

25 years old

Question 10

where does the spinal column end?

Answer 10

L1

Question 11

where do you do a lumbar puncture?

Answer 11

L4/5 space

Question 12

Answer 12

central grey matter

Question 13

Answer 13

dorsal columns:

gracile and cuneate respectively

Question 14

Answer 14

lateral corticospinal tract

Question 15

Answer 15

spinothalamic tract

Question 16

Answer 16

ventral white commissure

Question 17

describe central cord syndrome

Answer 17

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

Question 18

describe anterior cord syndrome

Answer 18

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

Question 19

describe brown-sequard syndrome

Answer 19

damage to 1/2 of the spinal cord

paralysis and loss of touch/proprioception ipsilaterally

loss of pain/temperature opposite

Question 20

what does the corticospinal tract do?

Answer 20

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

Question 21

what does the posterior column of the spinal cord do?

Answer 21

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

Question 22

what does the spinal thalamic tract do?

Answer 22

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

Question 23

what is the bulbocavernous reflex?

Answer 23

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.

Question 24

what is autonomic dysreflexia?

Answer 24

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

Question 25

explain ASIA grading

Answer 25

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

Question 26

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

Answer 26

the most caudal level where power is not 5/5

Question 27

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

Answer 27

most caudal level with normal pinprick and light touch

Question 28

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

Answer 28

C5 eventually C3 and C4 can become independent

Question 29

where do the majority of stenoses occur?

Answer 29

at the level of the disc anteriorly with facet joint posteriorly

Question 30

where is the foramen in relation to the pedicle?

Answer 30

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

Question 31

what are the boundaries of the foramen?

Answer 31

the pedicle superiorly the superior facet inferiorly the pars posteriorly the vertebral body anteriorly

Question 32

where is the lateral recess?

Answer 32

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

Question 33

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

Answer 33

L4

Question 34

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

Answer 34

L5

Question 35

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

Answer 35

the cartilage layer under the ligament

Question 36

what are the signs of unstable spine?

Answer 36

pain with dynamic movement dynamic shift on imaging lack of osteoarthritic signs facet joint effusions evolving neurologic symptoms

Question 37

where should occipital screws be placed?

Answer 37

+/- 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

Question 38

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

Answer 38

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

Question 39

what is the relationship of the vertebral artery to C1?

Answer 39

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

Question 40

where is the ICA in relation to C1?

Answer 40

abutting the anterolateral aspect of C1

Question 41

where do you place a thoracic pedicle screw?

Answer 41

start at the junction of a lines: 1) vertically along midpoint of facet joint 2) along superior ridge of transverse process

Question 42

where do you start a lumbar pedicle screw

Answer 42

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

Question 43

largest thoracic vertebra

Answer 43

T1

Question 44

smallest thoracic vertebra

Answer 44

T4

Question 45

smallest lumbar vertebra

Answer 45

L1

Question 46

what screw size for lumbar spine?

Answer 46

L1 = 7.5 L2 = 8.0 L3 = 9.5 L4 = 12.5 L5 = 11.5

Question 47

what is the toeing in trend for pedicle screws?

Answer 47

less as you go down T spine to 5-10° at L1 then increase 5° per level from L1 down

Question 48

where can you place S1 pedicle screws?

Answer 48

zone 1 = superior facet directed 10° from sagittal zone 2 = notch lateral to facet directed 40° from sagittal

Question 49

where are the safe zones for halo placement?

Answer 49

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

Question 50

normal thoracic kyphosis

Answer 50

10-40°

Question 51

what is the normal lumbar lordosis?

Answer 51

TK + 30°

Question 52

what is normal sagittal alignment of the spine?

Answer 52

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

Question 53

normal sacral slope

Answer 53

41° +/- 16°

Question 54

normal pelvic tilt

Answer 54

first, vertical line from center of acetabulum, second line from center of acetabulum and middle of sacrum normal is 13° +/- 12°

Question 55

what is pelvic incidence?

Answer 55

PT + SS

Question 56

why is pelvic incidence important?

Answer 56

it dictates the lumbar lordosis, where PI = LL + 10°

Question 57

how can you increase lordosis?

Answer 57

spinous process + facet joint osteotomy

Question 58

explain the arterial supply to the spinal cord

Answer 58

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

Question 59

what is ossification of PLL and how is it treated?

Answer 59

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%)