the occiput-c1 joint provides most of what ROM? how much?
flexion. 50%
c1-c2 joint provides most of what ROM? how much?
rotation. 50%
surface land marks:
C2-3
C3
C4-5
C2-3: mandible
C3: hyoid
C4-5: thyroid cartilage
surface landmarks:
C6
C7
T3
C6: cricoid cartilage
C7: vertebral prominens
T3: scapular spine
surface landmarks:
T4
T7
L4-5
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?
C2-6
at what level is the spinal cord largest in the c-spine?
c2
what shape is the vertebral body in the t-spine?
heart
L-spine vert bodies are what shape?
kidney
mamillary processes occur in what spinal region?
from what structure do they project from?
L-spine
from superior articular process
how many sacral foramina are there?
4 pairs dorsal and ventral
how many vertebrae fused embryologically to form the coccyx?
usually 4
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?
type I
nucleus pulposis is mostly what collagen type?
type II
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?
T1
L5
smallest pedicle?
smallest within L-spine?
T4
L1
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
transarticular screw
wiring
lateral mass screw (c1) and pars screw (c2)
clamp
list the c2 fixation options
transarticular screw (with c1)
pars screw
pedicle screw
translaminar screw
clamp
wiring
what is pelvic incidence?
fixed parameter describing the tilt of the S1 endplate relative to the centre of the acetabulum
on lateral view, make line from middle of S1 endplate to centre of acetabulum
make another line perpendicular to S1 endplate
angle between these lines is pelvic incidence
Geometrically ends up being equal to pelvic tilt + sacral slope
pelvic tilt=angle between vertical and line joining middle of S1 endplate to centre of acetabulum
sacral slope=angle between s1 endplate and horizontal
describe the spinal cord blood supply - only immediately around the cord
single anterior spinal artery
two posterior spinal arteries
they have branches that form an anastmosis/plexus around the cord - vaso corona
what arteries feed the spinal arteries in c-spine?
vertebral a
PICA
segmental branches
what arteries feed the spinal arteries in the T-L spine?
radicular arteries
what is the artery of adamkiewicz?
principle arterial suply of lower 2/3 of spinal cord - feeds the anterior and posterior spinal arteries
usually occurs on left side at T10 (between T9-11)
can be between T7 and L4
AKA arteria radicularis magna
it is a large segmental radicular artery
enters through intervertebral foramen
extension of ALL from C1 to skull is called what?
anterior atlanto-occipital membrane
extension of PLL from C1 to skull is called what?
tectorial membrane
what is ligamentum nuchae?
c-spine supraspinous ligament
vertebral foramina occur in what vertebrae?
through which does the vertebral artery pass?
C1-7
artery exists in c1-6
continuation of ligamentum flavum from C1 to skull is called what?
posterior atlanto-occipital membrane
what are:
basion
opisthion
basion: anterior point on the foramen magnum
opisthion: posterior point on the foramen magnum
anterior cord syndrome
presentation
prognosis?
loss of spinothalamic and corticospinal tracts
loss of pain/temp, motor
worse prognosis (10% recover)
posterior cord syndrome: presentation?
loss of dorsal white columns
loss of proprioception, fine touch
rare
central cord syndrome: presentation, prognosis?
UE weaker than LE
preserved perianal sensation
75% recover
brown-sequard syndrome: presentation, prognosis?
hemi-cord loss.
lose contralateral pain and temp 2 levels below and ipsilateral motor
90% recovery. best prognosis
explain the ASIA scale ABCDE
A - complete loss below level
B: incomplete - sensory intact, but no motor below level at all
c: incomplete - motor function exists below level but most are <3/5
d - incomplete - motor exists below level and most have 3/5 or more
e: normal neuro exam
what is the definition of neurological level?
lowest (most caudal) level with intact motor AND sensory
where is the watershed region of the spinal cord?
T4-9. narrowest spinal canal and poorest blood supply.
Smith-robinson approach: from left or right side? Which is better and why?
left is better
reasons:
predictable clourse of recurrent laryngeal n (around aortic arch, runs between trachea and esophagus. Problem: most ppl right handed
c.f. right side: loops around subclavian a and crosses field from lateral to medial to run next to trachea. can be abberant at thyroid level
name the 3 fascial layers you pass through in the smith robinson approach, from superficial to deep
deep cervical fascia
pretracheal fascia
prevertebral fascia
name 2 major anatomical structures superficial to deep cervical fascia (not skin and fat)
external jug v
platysma
Describe the smith robinson approach, and identifiy the important intervals.
transverse incision
split fibres of platysma (vertical) - CN VII facial n
go through deep cervical fascia
go between SCM (CN XI accessory) and strap muscles (omohyoid, sternothyroid, sternohyoid, thyrohyoid - all ansa cervicalis innervation)
go through pretrachial fascia anterior to carotid sheath (contains IJV, vagus n, common carotid a)
go between left and right longus colli (segmental n)
go thorugh prevertebral fascia
dangers of smith robinson approach
carotid sheath (vagus n, common coarotid a, IJV)
thyroid arteries
trachea
esopahgus
recurent laryngeal n
stellate ganglion/sympathetic chain
vertebral a
explain posterolateral approach to spine
AKA costotransversectomy
incision adjacent to spinous processes over rib
split trapezeus fibres
subperiosteal dissection around rib
watch for intercostal bundle
remove rib up to TP
operate via retroperitoneal space
interval of wiltse approach (modern variant)
between multifidus and longissimus
