the occiput-c1 joint provides most of what ROM? how much?
c1-c2 joint provides most of what ROM? how much?
surface land marks:
C4-5: thyroid cartilage
C6: cricoid cartilage
C7: vertebral prominens
T3: scapular spine
T4: nipples (variable)
T7: distal tip of scapula
L4-5: iliac crest
what is a motion segment? what is it also called?
smallest segment of spine that shows biomech characteristics of the entire spine
i.e. 2 adjacent vertebrae and intervening ligamentous tissues
AKA functional spinal unit
what spinal vertebrae have bifid spinous processes?
at what level is the spinal cord largest in the c-spine?
what shape is the vertebral body in the t-spine?
L-spine vert bodies are what shape?
mamillary processes occur in what spinal region?
from what structure do they project from?
from superior articular process
how many sacral foramina are there?
4 pairs dorsal and ventral
how many vertebrae fused embryologically to form the coccyx?
most common site of disc herniation?
second most common?
L5/S1 first, L4/5 second
transverse ligament of the c-spine occurs where?
posterior to Dens, stabilizes a-a joint and keeps dens up against anterior arch of c1
alar ligaments joint what to what?
embryologically they are remnants of what?
from occiput to tip of dens
remnant of notochord
cruciform ligament of atlas is made of what?
includes the transverse ligament
plus inferior and superior longitudinal bands
annulus fibrosus is mostly what type of collagen?
nucleus pulposis is mostly what collagen type?
in the saggital and coronal planes, c-spine facet joints are oriented how?
saggital: 45 deg
coronal 0 deg
i.e. roof shingles angled posteriorly at 45 deg
T-spine facet joints are oriented how in the sagg and coronal planes?
saggital 60 deg
coronal 20 deg
i.e. similar to roof shingles but tilted 20 deg towards being saggital
L-spine facet joints are oriented how in the saggital and coronal planes?
saggital: 90 deg
coronal: 45 deg
i.e. straight up and down plane of joint, but tilted out 45 deg
amount of "intoeing" for pedicle screws is greatest where? least where?
greatest at T1 and L5
least at T12
decreases from T1 and L5 towards T12
L1 approximately 5-10 deg
increases ~5 deg per level from L1 down to sacrum
T-spine pedicle screw start point
intersection of middle of TP and middle of inferior articular facet
lumbar pedicle screw start point?
midpoint of TP
midpoint of superior articular process
nb: pars lines up with medial aspect of pedicle
upper spine largest pedicle?
L-spine largest pedicle?
smallest within L-spine?
post-halo: what nerve injuries can occur?
basically supraorbital nerve, CN 4,6,10,11,12
CN VI - abducens n
can hit it at petrosphenoidal junction. get eyes that look down and in
Glossopharyngeal (4) + vagus (10) + hypoglossal (12)
dysphagia, loss of palatal/pharyngeal reflexes, weakness of tongue
from penetration of jugular foramen
CN eleven accessory n
supraorbital nerve - from anterior pins too medial
describe pin placement for halo
anterolateral pins: just below head equator, 1cm above orbit, in lateral 2/3 of orbit (avoid supraorbital nerve)
posterior pins - avoid temporalis muscle. Usually place just directly above ear pinna
list the fixation options for c1-2 fusion
lateral mass screw (c1) and pars screw (c2)