Chapter 11 - Anatomy of the Spine

Question 1

Three primary ossification centers of the vertebra

Answer 1

1. centrum: anterior vertebral body
2. neural arch: posterior elements, pedicles, small portion of the anterior body
3. costal element: anterior portion of lateral mass, transverse process, rib

Question 2

Developmental origin of the nucleus pulposis

Answer 2

notochord cells

Question 3

Developmental origin of the annulus fibrosis

Answer 3

sclerotomal cells

Question 4

Most aggressive congenital scoliosis

Answer 4

hemivertebra with unsegmented bar on other side

Question 5

Klippel-Feil syndrome

Answer 5

defect of cervical segmentation. (Cervical brevicollis)

Question 6

Dorsal Column transmits what?

Answer 6

vibration, deep touch, proprioception

Question 7

Lateral spinothalamic tract

Answer 7

pain and temperature

Question 8

ventral spinothalamic tract

Answer 8

light touch sensation

Question 9

Lateral corticospinal tracts

Answer 9

voluntary motor function

Question 10

Most at risk cervical sympathetic ganglion

Answer 10

Middle ganglion, located at the medial border of the longus coli, at risk with C6 exposure

Question 11

Damage to the sympathetic nervous system can cause what syndrome?

Answer 11

Horner’s syndrome - ptosis, miosis, anhydrosis

Question 12

Innervation to the ALL, PLL, and intervertebral disc

Answer 12

Sinuvertebral nerve

Question 13

Innervation to facet joint capsule

Answer 13

nerve to the facet capsule

Question 14

What is the primary stabilizer of the C1-2 segment

Answer 14

Transverse atlantar ligament

Question 15

How much lumbar lordosis occurs through L5-S1 and l4-S1

Answer 15

47% thru L5-S1, 75% from L4-S1
(average lumbar lordosis is 60degrees, range 20-80)

Question 16

Pelvic parameters - pelvic incidence

Answer 16

Angle between
A line drawn from the center of the femoral hear to the midpoint of the sacral endplate
AND
A line perpendicular to the center of the sacral endplate
PI = PT + SS

Question 17

Increased pelvic incidence increases the risk of what condition

Answer 17

isthmic spondylolisthesis

Normal PI is 53+/-10degrees

Question 18

Pelvic parameters - pelvic tilt

Answer 18

Angle between
A vertical reference line
AND
A line drawn from the center of the femoral head to the center of sacral end plate

*** Pelvic tilt is influenced by Pelvic incidence

Question 19

Pelvic parameters - Sacral slope

Answer 19

angle between
A horizontal reference point
AND
The sacral end point line

Normal is 26.9 +/-8degrees

Question 20

Which pelvic parameter is NOT influenced by the position of the pwlvis in space?

Answer 20

Pelvic incidence

pelvic tilt and sacral slope depend on the position of the pelvis in space

Question 21

Vertebral artery enters the foramen transversarium at what level most commonly?

Answer 21

C6, less common is C5 > C7

Question 22

Pedicle size between T11-L2

Answer 22

T11,12 will have larger pedicles than L1-2

Question 23

Composition of annulus fibrosis

Answer 23

Type 1 collagen fibrills that are obliquely oriented

Question 24

Composition of nucleus pulposis

Answer 24

type 2 collagen

Question 25

Landmarks for the anterior cervical approach

Answer 25

C5-6 - cricoid cartilage
C4-5 - thyroid cartilage
C3 - hyoid bone
C2 - angle of mandible

Question 26

Nerves most at risk during ACDF approach?

Answer 26

recurrent and superior laryngeal nerves

Question 27

What sided approach is preferred in the anterolateral thoracolumbar approach

Answer 27

right side - allows more complete retraction (avoids heart, aorta, thoracic duct, and the artery of adamkiewicz all on left)

Question 28

what nerves are at risk during the anterolateral thoacolumbar approach?

Answer 28

Lumbar plexus (runs through posterior 2/3 of the iliopsoas), and the genitofemoral nerve directly anterior to the iliopsoas

Question 29

What lumbar level does the iliac crest correspond to?

Answer 29

L4-5

Question 30

Name the paraspinal muscles from medial to lateral

Answer 30

interspinalis, multifidus, longissimus, iliocostalis

Question 31

Safe zone for anterior halo pin placement

Answer 31

1cm above supraorbital ridge, below the equator, over the lateral 2/3 of the orbit

avoids supraorbital and supratrochlear nerves

Question 32

What structure is most at risk with bicortical C1 lateral mass screw placement and from C1-C2 transarticular screws?

Answer 32

Internal carotid a.

Lies 1mm anterior to ideal exit point of bicortical C1 lateral mass screw

Question 33

Ideal start point for C3-6 lateral mass screws

Answer 33

Just inside the inferior medial quadrant, aimed 30 degrees lateral, 15 degrees cephalad

Question 34

Where is the thickest cortex for thoracic pedicles?

Answer 34

medial

2-3x the lateral cortex

Question 35

Which thoracic vertebra has the smallest pedicle?

Answer 35

T5, and apical pedicles for scoli

Question 36

How to identify the midpoint of the lumbar pedicle?

Answer 36

midpoint of transverse process is typically in line with superior/inferior midpoint of the pedicle

Question 37

How to identify the medial border of the pedicle from l2-l4

Answer 37

In line with the lateral border of the pars