Spine Flashcards
the occiput-c1 (Atlas) joint provides most of what ROM? How much?
flexion/extension. 50%
c1-c2 joint (Axis) 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
L2
L4
L4-5
T4: nipples (variable)
T7: distal tip of scapula
L2: Renal Arteries
L4: Aortic Bifurcation
L4-5: iliac crest (L4 spinous process is at the level of the iliac crest)
what spinal vertebrae have bifid spinous processes?
C2-6
At what level is the spinal cord largest in the c-spine?
C2
L-spine vert bodies are what shape?
T Spine?
L spine - kidney
T spine - heart
mamillary processes occur in what spinal region?
from what structure do they project from?
L-spine
from superior articular process
allow for attachment of the multifidis muscles.
How many sacral foramina are there?
4 pairs dorsal and ventral
The dorsal and ventral primary rami exit respectively
how many vertebrae fused embryologically to form the coccyx?
usually 4 sometimes 5
most common site of disc herniation?
second most common?
L5/S1 first, L4/5 second
What is the Tectorial membrane?
the extension of the PLL from C1 to the skull
Where does the transverse ligament of the c-spine live?
Posterior to Dens, stabilizes a-a joint and keeps dens up against anterior arch of c1
Part of the cruciate ligament which lies anterior to the tectorial membrane, behind the odontoid process
- The transverse atlantal ligament is the strongest component, connecting the posterior odontoid to the anterior atlas arch, inserting laterally on bony tubercles
- Vertical bands extend from the transverse ligament to the foramen magnum and body of the axis.
What is the Anterior Atlanto-Occipital membrane?
an extension of the ALL from C1 to the skull.
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
What are the two layers of the intervertebral discs and which layer contains nerve endings?
annulus fibrosis and nucleus pulposus
The AF contains nerve fibers.
What type of fibers compose the annulus fibrosis and how are they oriented?
type I collagen fibers oriented obliquely.
nucleus pulposis is mostly what collagen type?
type II
What is the orientation of the facet joints as your progress down the spine?
Sagittal Coronal
C 45° 0°
T 60° 20°
L 90° 45°
Describe the amount of pedicle screw “intoeing” you need as you go from T1-L5
Thoracic spine:
DECREASES at you go down from T1-T12
In males, goes from ~40 deg to ~15 deg
Therefore greatest at T1
Lumbar spine:
INCREASES as you go down from L1-L5
L1 approximately 5-10 deg
increases ~5 deg per level from L1 down to sacrum
What are the landmarks for the T-spine pedicle screw start point?
Superior ridge of TP
Midpoint of inferior articular facet
What is the landmarks for a 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
What is the smallest pedicle in T spine?
What is the smallest within L-spine?
T4
L1
What are some what nerve injuries can occur with appication of Halo traction?
Supraorbital nerve most common - avoid by
Cranial nerve injuries have also been described. 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)
place anterior pins lateral enough to avoid injury to the frontal sinus, supratrochlear and supraorbital nerves
place pins anterior enough to avoid the temporalis muscle
pinsposterior pins. 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 are 3 contraindications to C1-C2 transarticular screws?
What about contraindications to C1-2 wiring?
Screws:
- abberant vertebral artery (medial or high riding)
- subluxation of C1-2
- cervicothoracic kyphosis precludes screw placement
Wiring:
•Need Intact Posterior Elements
- Decompression
- Trauma
- Tumour
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 (center of femoral head)
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 aa
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 - anastomosis with the anterior spinal artery, supplying arterial blood to the spinal cord from T8 to the conus medullaris
usually occurs on left side at T9-12
can be between T7 and L4
AKA arteria radicularis magna
It arises from the radiculomedullary branch of the posterior branch of the intercostal or lumbar artery, which arise from the thoracic or abdominal aorta respectively 1. It has a diameter of ~1 mm (range 0.8-1.3 mm)
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
The supraspinous ligament only runs from C7 to sacrum
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 the Basion and Opisthion?
basion: anterior point on the foramen magnum
opisthion: posterior point on the foramen magnum
What is the presentation and prognosis of anterior cord syndrome?
Injury to anterior spinal cord caused by
direct compression (osseous) of the anterior spinal cord
anterior spinal artery injury
anterior 2/3 spinal cord supplied by anterior spinal artery
Mechanism
usually result of flexion/ compression injury
Exam
lower extremity affected more than upper extremity
loss
Corticospinal tract (motor)
Spinothalamic tract (pain, temperature)
preserved
DC (proprioception, vibratory sense)
Prognosis
worst prognosis of incomplete SCI
most likely to mimic complete cord syndrome
10-20% chance of motor recovery
What is the presentation of posterior spinal cord syndrome?
very rare
Exam:
loss:
proprioception (dorsal columns)
preserved:
motor (corticospinal) pain
light touch (Lateral and ventral spinothalamic)
What is the common presentation and prognosis of central cord syndrome?
spinal cord compression and central cord edema with selective destruction of lateral corticospinal tract white matter
UE weaker than LE
preserved perianal sensation (sacral sparing)
75% recover (not fully but fairly fuctional)
Epidemiology/incidence
most common incomplete cord injury
demographics often in elderly with minor extension injury mechanisms
due to anterior osteophytes and posterior infolded ligamentum flavum
Pathophysiology
believed to be caused by spinal cord compression and central cord edema with selective destruction of lateral corticospinal tract white matter
anatomy of spinal cord explains why upper extremities and hand preferentially affected
hands and upper extremities are located “centrally” in corticospinal tract
Presentation/symptoms
weakness with hand dexterity most affected
hyperpathia (burning in distal upper extremity)
physical exam
loss:
motor deficit worse in UE than LE (some preserved motor function)
hands have more pronounced motor deficit than arms
preserved –> sacral sparing
late clinical presentation
UE have LMN signs (clumsy)
LE has UMN signs (spastic)
Prognosis/final outcome
good prognosis although full functional recovery rare
usually ambulatory at final follow up
usually regain bladder control
upper extremity and hand recovery is unpredictable and patients often have permanent clumsy hands
recovery occurs in typical pattern
- lower extremity recovers first
- bowel and bladder function next
- proximal upper extremity next
- hand function last to recover
What is the presentation and prognosis of brown-sequard syndrome?
a unilateral cord injury
- Ipsilateral hypotonic paralysis at the level of injury (loss of LMN at that level) (ANTERIOR HORN CELLS, GREY MATTER)
- Ipsilateral spastic paralysis below the level of injury (CORTICOSPINAL TRACT)
- Ipsilateral loss of vibration and proprioception (DORSAL COLUMNS)
- Loss of pain and temperature contralaterally from the level of 2 below the lesion (SPINOTHALAMIC TRACT)
99% ambulatory at final follow up
best prognosis for function motor activity
Explain the ASIA scale ABCDE
A = Complete: No motor or sensory function is preserved in the sacral segments S4-S5.
B = Incomplete: Sensory but not motor function is preserved below the neurological level and includes the sacral segments S4-S5.
C = Incomplete: Motor function is preserved below the neurological level, and more than half of key muscles below the neurological level have a muscle grade less than 3.
D = Incomplete: Motor function is preserved below the neurological level, and at least half of key muscles below the neurological level have a muscle grade of 3 or more.
E = Normal: Motor and sensory function are normal.
what is the definition of neurological level?
The most caudal (lowest) level at which both motor and sensory modalities are intact on both sides of the body.
- Motor >3 or more w/ levels above being 5/5
- Sensory intact bilaterally for LT and PP with all sensation above intact
Smith-robinson approach: from left or right side? Which is better and why?
left is better
reasons:
predictable course 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
Incision
Mandible C2-3
Hyoid C3
Thyroid C4-5
Cricoid C6
- make transverse skin crease incision at appropriate level
- extend obliquely from the midline to the posterior border of the SCN
- Superficial Dissection
- incise fascia over platysma
- spit platysma with finger
- identify anterior border of SCM
- incise fascia and retract SCM lateral
- identify and retract strap muscles medially (sternohyoid and sternothyroid)
- identify the carotid pulse and retract carotid sheath lateral
- cut through pretrachial fascia
- localize superior and inferior thyroid arteries and tie off if necessary
- Structures at risk -
- contents of carotid sheath
- Recurrent Laryngeal nerve
- Deep dissection
- Once thru pretracheal fascia this should bring you down onto the longus colli mm. Place retractors. ?deflate and inflate cuff to decrease risk of RLN palsy, conflicting evidence
- split longus colli muscles and anterior longitudinal ligament
- be aware of sympathetic chain that lies on longus colli lateral to vertebral body
- The prevertebral fascia is divided in the midline using rolled gauze (“peanuts”) in Kelly clamps. The longus colli is elevated subperiosteally on either side of the spine, taking care not to err anterior and lateral to the muscle mass so as to avoid damage to the sympathetic chains flanking the spine
- subperiostally disect to expose anterior surface of vertebral body
- retract longus colli muscles and ALL laterally
- identify level with needle in disc space and lateral xray
- Structures at risk
- Sympathetic chain (10.6 mm from medial border of longus coli)s
- Esophagus
- recurrent laryngeal nerve tracheoesophageal groove
ACDF
Once we have exposure
check level radiographically
rectangle in annulus
discetomy
bone graft
instrumentation
Name the 3 fascial layers you pass through in the smith robinson approach, from superficial to deep
deep cervical fascia
pretracheal fascia
prevertebral fascia
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 (Sheath contains IJV, vagus n, common carotid a)
go between left and right longus colli (segmental n)
go thorugh prevertebral fascia
Reminder of levels
- Mandible C2-3
- Hyoid C3
- Thyroid C4-5
- Cricoid C6
Full description of approach:
Incision
make transverse skin crease incision at appropriate level
extend obliquely from the midline to the posterior border of the SCN
Superficial Dissection
incise fascia over platysma
spit platysma with finger
identify anterior border of SCM
incise fascia and retract SCM lateral
identify and retract strap muscles medially (sternohyoid and sternothyroid innervation:Ansa cervicalis)
identify the carotid pulse and retract carotid sheath lateral
cut through pretrachial fascia
localize superior and inferior thyroid arteries and tie off if necessary
Structures at risk -
contents of carotid sheath
Recurrent Laryngeal nerve
Deep dissection
Once thru pretracheal fascia this should bring you down onto the longus colli mm. Place retractors. ?deflate and inflate cuff to decrease risk of RLN palsy, conflicting evidence
split longus colli muscles and anterior longitudinal ligament
be aware of sympathetic chain that lies on longus colli lateral to vertebral body
The prevertebral fascia is divided in the midline using rolled gauze (“peanuts”) in Kelly clamps. The longus colli is elevated subperiosteally on either side of the spine, taking care not to err anterior and lateral to the muscle mass so as to avoid damage to the sympathetic chains flanking the spine
subperiostally disect to expose anterior surface of vertebral body
retract longus colli muscles and ALL laterally
identify level with needle in disc space and lateral xray
Structures at risk
Sympathetic chain (10.6 mm from medial border of longus coli)s
Esophagus
recurrent laryngeal nerve tracheoesophageal groove
ACDF
Once we have exposure
check level radiographically
rectangle in annulus
discetomy
bone graft
instrumentation
Explain posterolateral approach to the thoracic spine
AKA costotransversectomy
incision adjacent to spinous processes over rib
split trapezius 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
What is the orientation of the zygopophyseal joints of the cervical, thoracic and lumbar spine?
Sagittal Coronal
C 45° 0° - Oriented A to P
T 60° 20° - almost vertical
L 90° 45° - wrapped
Describe the safe zone for 8mm occipital screws. What are the dangers?
The safe zone for screw placement in the occiput for occipitocervical fusion is in a triangular region created by connecting 2 dots 2cm lateral to the EOP and a point 2 cm inferior to the EOP.
6 screws can be placed in a V formation
1st is on Nuchal line 2cm away from center of EOP
2nd is 1cm down and 1cm over
3rd is 2cm down and 5mm over
The dangers are the superior saggital sinus and the transverse sinus
Which of the following pedicles has the smallest transverse diameter in most people?
A: T1
B: T12
C: L1
D: L3
E: S1
3: L1
T4 is the smallest overall.
T1 is biggest in thoracic spine
S1 > L3 > L1
T1 > T12
So this questions asks which is bigger T12 or L1. T12 is bigger so L1 is the answer
Describe the main blood supply to the spine? What is the name of the collateral blood supply?
Main:
1x median longitudinal anterior spinal artery
2x (right & left) longitudinal posterior spinal arteries
These are supplied by various radicular arteries
Collateral: Vaso Corona: anastomosis between the longitudinal vessels forming a fine pial plexus Gives limited blood supply
What are Harris’ measurements of the spine? What do they measure?
They measure atlanto-occipital dissociation There are 2 measurements:
- Basion to the tip of the dens (BDI)
- Basion to the posterior axial line (BAI - basion posterior-axial interval)
***Neither one should be >12mm (Rule of 12’s) or this is a sign of AO dissociation
What is a Hangman’s fracture? mechanism?
bilateral C2 pars fracture.
hyperextension and distraction.
traumatic spondylolisthesis of C2 on C3
How is it treated?
Undisplaced - collar
Displaced - Halo or surgery
What are the contents of the carotid sheath?
- Common carotid artery +/- internal carotid artery Internal jugular vein
- Vagus nerve
- Deep cervical lymph nodes
Artery is medial to vein, with nerve in between
What are the ligamentous attachments to the dens?
- Apical odontoid ligament
- Alar ligaments x2
Transverse ligament of the atlas (part of cruciform ligament) - doesnt actually attach to the dens
(Anterior atlantoaxial ligament (membrane) is anterior and not actually attached to the dens)
What is autonomic dysreflexia?
Develops in individuals with spinal cord injury at or above the level of T6, resulting in acute, uncontrolled hypertension.
Painful stimulus below the lesion is sensed by the spinal cord and transmitted proximally. Interrupted by lesion so pt does not feel sensation.
This causes sympathetic response/discharge
–> vasoconstriction, most notably in the splanchnic circulation.
This is sensed proximally and there is a vagal, parasympathetic discharge to try to counteract this.
This discharge is unable to pass the lesion therefore. You have unopposed hypertension.
Symptoms:
The sympathetic response causes vasoconstriction, resulting in hypertension, pounding headache, visual changes, anxiety, pallor and goosebumps (below the level of injury)
Above the level of injury you get BRADYCARDIA and FLUSHING and NASAL CONGESTION (rhinorhea (cholinergic discharge)
What are Harris’s measurements of the spine? What do they measure?
Measure occitio-atlanto dissociation 2 measurements: - Basion to the tip of the dens (BDI) and basion to the posterior axial line (BAI) - Neither one of these should be >12mm - This is the rule of 12’s
What is Swischuk’s Line?
Used to differentiate between subluxation and pseudosubluxation in pediatric patients
Connects the anterior aspect of the spinous processes of C1 and C3.
If the anterior aspect of the spinous process of C2 misses this line by ⩾2 mm true subluxation of hangman’s fracture must be considered.
***For true subluxation to be diagnosed then there has to be SUBLUXATION and DEVIATION <2MM from SWISHCUKS LINE
The distance is frequently 2 mm or more if no subluxation is apparent.
Figure:
(A) No subluxation. Therefore, PCL (posterior cervical line) cannot be applied. Anterior aspect of spinous process of C2 commonly misses PCL by 2 mm.
(B) Subluxation is present. The anterior aspect of spinous process of C2 misses the PCL >2 mm. Finding is suggestive of a hangman’s fracture of the neural arches of C2.
(C) Pseudosubluxation is present. The anterior aspect of spinous process of C2 touches or lies within 2 mm of PCL. (Adapted from figure from Fesmire FM and Luten RC.16)
Describe the cervicomedullary angle and its significance:
The cervicomedullary angle can be measured on MRI by drawing a line along the anterior aspect of the cervical spinal cord and the medulla.
This angle is normally between 135° and 175°
• Cervicomedullary angle <135° linked to myelopathy
Figures 8a and 8b show the radiograph and MRI scan of a 31-year-old man with severe back pain and intermittent leg pain. Which of the following anatomic measurements has been best correlated with this patient’s condition?
- Pelvic tilt
- Pelvic Incidence
- Lumbar Lordosis
- Thoracic Kyphosis
- C7 Sagittal plumb line
2.Pelvic Incidence
Name the intrinsic craniocervical ligaments (3).
The intrinsic ligaments, located within the spinal canal, provide most of the ligamentous stability. These ligaments form three layers anterior to the dura. From dorsal to ventral, they include:
- Tectorial membrane: connects posterior body of axis to anterior foramen magnum. Is the cephalad continuation of the PLL
- Cruciate ligament: lies anterior to tectorial membrane, behind the odontoid process
- Odontoid ligaments (alar and apical)
(The Atlanto-occipital membrane (continuation of ALL is extrinsic)
Name the extrinsic ligaments of the craniocervical spine
- Ligamentum nuchae: extends from external occipital protuberance to the posterior aspect of the atlas and cervical spinous processes
- Anterior Atlantoocciptal Membrane: Continuation of ALL, intervertebral disks, and ligamentum flavum between the occiput and atlas and between the atlas and axis
- Atlanto-occipital joint capsule
- Atlanto-axial joint capsule
Figure 255 shows the axial CT scan of a 33-year-old man with severe neck pain after a motor vehicle collision. Which structure is most important in guiding treatment?
- VA
- Alar Lig
- Apical Lig
- Transverse Lig
- Post Lig Complex
- Transverse ligament
What osseous structure is seen by the * in Figure 237?
1- Inferior articular facet of C4
2- Inferior articular facet of C5
3- Superior articular facet of C5
4- Pedicle of C5
5- Pars interarticularis of C5
- Inferior articular process of C4
Figures 89a and 89b are the parasagittal and axial CT scans of a 42-year-old patient seen after a motor vehicle collison. What anatomic structure is identified by the asterisk in Figure 89b?
- C6 facet
- C7 facet
- C6 pars
- C6 pedicle
- C7 pedicle
- C6 Facet
What is the nerve injury shown?
Abducens nerve palsy, reported as a complication of Halo. CN VI
No lateral gaze, eye down and in.
What is Chassaignac’s Tubercle ?
- the Carotid tubercle - the anterior tubercle of transverse process of C6
- This separates the carotid artery from the vertebral artery and the carotid artery can be massaged against this tubercle to relieve the symptoms of supraventricular tachycardia.
- Important landmark for a plexus block
- The stellate ganglion lies just inferior, anterior to the transverse process of C7, superior to the neck of the first rib, and just below the subclavian artery.
