Chapter 11 - Anatomy of the Spine Flashcards
Three primary ossification centers of the vertebra
- centrum: anterior vertebral body
- neural arch: posterior elements, pedicles, small portion of the anterior body
- costal element: anterior portion of lateral mass, transverse process, rib
Developmental origin of the nucleus pulposis
notochord cells
Developmental origin of the annulus fibrosis
sclerotomal cells
Most aggressive congenital scoliosis
hemivertebra with unsegmented bar on other side
Klippel-Feil syndrome
defect of cervical segmentation. (Cervical brevicollis)
Dorsal Column transmits what?
vibration, deep touch, proprioception
Lateral spinothalamic tract
pain and temperature
ventral spinothalamic tract
light touch sensation
Lateral corticospinal tracts
voluntary motor function
Most at risk cervical sympathetic ganglion
Middle ganglion, located at the medial border of the longus coli, at risk with C6 exposure
Damage to the sympathetic nervous system can cause what syndrome?
Horner’s syndrome - ptosis, miosis, anhydrosis
Innervation to the ALL, PLL, and intervertebral disc
Sinuvertebral nerve
Innervation to facet joint capsule
nerve to the facet capsule
What is the primary stabilizer of the C1-2 segment
Transverse atlantar ligament
How much lumbar lordosis occurs through L5-S1 and l4-S1
47% thru L5-S1, 75% from L4-S1
(average lumbar lordosis is 60degrees, range 20-80)
Pelvic parameters - pelvic incidence
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
Increased pelvic incidence increases the risk of what condition
isthmic spondylolisthesis
Normal PI is 53+/-10degrees
Pelvic parameters - pelvic tilt
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
Pelvic parameters - Sacral slope
angle between
A horizontal reference point
AND
The sacral end point line
Normal is 26.9 +/-8degrees
Which pelvic parameter is NOT influenced by the position of the pwlvis in space?
Pelvic incidence
pelvic tilt and sacral slope depend on the position of the pelvis in space
Vertebral artery enters the foramen transversarium at what level most commonly?
C6, less common is C5 > C7
Pedicle size between T11-L2
T11,12 will have larger pedicles than L1-2
Composition of annulus fibrosis
Type 1 collagen fibrills that are obliquely oriented
Composition of nucleus pulposis
type 2 collagen
Landmarks for the anterior cervical approach
C5-6 - cricoid cartilage
C4-5 - thyroid cartilage
C3 - hyoid bone
C2 - angle of mandible
Nerves most at risk during ACDF approach?
recurrent and superior laryngeal nerves
What sided approach is preferred in the anterolateral thoracolumbar approach
right side - allows more complete retraction (avoids heart, aorta, thoracic duct, and the artery of adamkiewicz all on left)
what nerves are at risk during the anterolateral thoacolumbar approach?
Lumbar plexus (runs through posterior 2/3 of the iliopsoas), and the genitofemoral nerve directly anterior to the iliopsoas
What lumbar level does the iliac crest correspond to?
L4-5
Name the paraspinal muscles from medial to lateral
interspinalis, multifidus, longissimus, iliocostalis
Safe zone for anterior halo pin placement
1cm above supraorbital ridge, below the equator, over the lateral 2/3 of the orbit
avoids supraorbital and supratrochlear nerves
What structure is most at risk with bicortical C1 lateral mass screw placement and from C1-C2 transarticular screws?
Internal carotid a.
Lies 1mm anterior to ideal exit point of bicortical C1 lateral mass screw
Ideal start point for C3-6 lateral mass screws
Just inside the inferior medial quadrant, aimed 30 degrees lateral, 15 degrees cephalad
Where is the thickest cortex for thoracic pedicles?
medial
2-3x the lateral cortex
Which thoracic vertebra has the smallest pedicle?
T5, and apical pedicles for scoli
How to identify the midpoint of the lumbar pedicle?
midpoint of transverse process is typically in line with superior/inferior midpoint of the pedicle
How to identify the medial border of the pedicle from l2-l4
In line with the lateral border of the pars
