Sievert: Back, Vertebral Column, and Spinal Cord Flashcards
T/F: Fractures may cause compression of nerve roots or spinal cord.
True
Spondylolisthesis can cause these things.
damage to the cord, roots, or exiting spinal nerves.
This can put pressure on exiting nerve roots.
Herniating discs
T/F: osteophytes may impinge on the exiting spinal nerve.
True
Components of the axial skeleton - is the pelvis included?
Skull Vertebral column Ribs Sternum No pelvis!
How many cervical vertebrae are there? Thoracic? Lumbar? Sacral? Coccygeal?
7; 12; 5; 5; 4
How many vertebrae are there?
33, but it can vary from 32-34
Which sections of the vertebral column contains primary curvatures? Secondary curvatures?
thoracic and sacral; cervical and lumbar
What is C1 called? What is C2 called?
atlas; axis
T/F: abnormal curves may be exaggerated normal curves or simply curves that don’t belong.
True
Three components of the vertebral foramen of the spinal cord.
body, pedicle, and lamina
What are the three processes that protrude from the vertebra?
transverse processes
spinous process
articular processes (superior and inferior)
What two components make up the intervertebral foramen?
inferior and superior vertebral notches.
*note: the inferior vertebral notch forms most of the foramen and is actually up top!
These structures are found on the lateral surface of each superior articular facet for muscle attachment
mammillary processes
What are two specific features of the sacrum?
anterior and posterior foramina
sacral hiatus
What two spinal nerves exit out of the sacral hiatus?
S5 and the spinal nerve of the coccyx
How can you distinguish a cervical vertebra?
spinous process is bifid
transverse foramen for the passage of the vertebral artery as it courses toward the brain
What way are the articular facets pointing in a cervical vertebra?
inferior and superior
How can you distinguish a thoracic vertebra?
larger vertebral body
has articular facets for the ribs
has spinous process that points inferiorly
How can you distinguish a lumbar vertebra?
largest body
massive neural arch
large squarish spinous process
articular facets are facing medially and laterally
Which vertebral region has the most “degrees of freedom?” Which has the least?
cervical has the most; lumbar has the least
This vertebral body has an anterior and a posterior arch to hold the dens in place, a transverse foramen, and a superior and inferior articular fovea
atlas C1
This vertebral body has a dens
axis C2
Which vertebral body does the head “spin” on? Which does it “rock” on?
spins on the atlas; rocks on the axis
Along which axis does flexion/extension occur?
transverse axis
Along which axis does lateral bending occur?
anteroposterior
Along which axis does rotation occur?
vertical
What four factors can allow or restrict movement of the trunk?
- the thickness of the intervertebral discs
- the orientation of the articular facets
- the attachment of ribs
- the size, elasticity and orientation of the muscles of the back, and abdominal wall
Which region of the vertebral column is the most mobile?
cervical region
Which region of the vertebral column is least mobile? Why?
thoracic region; ribs and thin discs
Which region of the vertebral column allows for considerable flexion and extension?
lumbar
Stress fracture of pars interarticularis
spondylolysis
Where is the pars interarticularis located?
in between the superior and inferior articular facets
What is a characteristic sign of spondylolysis (fracture of pars interarticularis) on an xray?
Scotty dog sign in posterolateral oblique view – a “collar” on the neck
Fracture of pars interarticularis, portion forming dog’s neck where collar belongs
Scotty dog
Repeated stress to the spine can cause this
spondylolysis
What can bilateral spondylolysis cause?
spondylolithesis
What is spondylolithesis?
“slipping” of one vertebra relative to the others
List the three vertebral ligaments
anterior longitudinal ligament
posterior longitudinal ligament
ligamentum flavum
What does the anterior longitudinal ligament do? Where is it located?
limits extension; anterior half of the vertebral body
What does the posterior longitudinal ligament do? Where is it located?
limits flexion; posterior side of vertebra, beneath the lamina
What does the ligamentum flavum do? Is it continuous between each vertebra?
limits flexion; no, does not run the whole length of the vertebral column
If a herniated disc came out of place, which direction would it move in?
postero-lateral
Two other important ligaments of the spinal column
interspinous ligament
supraspinous ligament
What ligament attaches the dens of the atlas to the occipital bone? What do these ligaments do?
alar ligaments on either side; limit rotation
This feature of the atlanto-occipital joint adds strength
capsule
How many components does the cruciate ligament have? What are they?
3 components; strong transverse component and two weaker superior and inferior parts
What covers all three portions of the cruciate ligament posteriorly?
tectorial membrane (a continuation of the posterior longitudinal ligament)
Two important components of the intervertebral discs
annulus fibrosis
nucleus pulposis
peripheral ring of fibrocartilage around each intervertebral disc
annulus fibrosis
Is the annulus fibrosis thinner anteriorly or posteriorly?
posteriorly
gelatinous core of the intervertebral disc
nucleus pulposis
*think pulp = juicy
In what direction do herniated discs usually occur?
posterolateral
In what region are herniated discs most common?
L5-S1 and second L4-5 levels
When a disc herniates, which nerve roots are affected?
the herniated disc will push on the nerve root of the level below
ex: L4 herniated disc will compress L5 nerve root
What is different between the way spinal nerves exit in the cervical region vs the lumbar, thoracic and sacral levels?
Spinal nerves in the cervical region exit ABOVE the vertebra with the same number, while spinal nerves in the lumbar, thoracic and sacral levels exit BELOW the vertebra with the same number
Herniating discs most frequently impinge the root (blank) the herniating level
BELOW
Spinal nerves in the cervical region exit (blank) the vertebra with the same number. Spinal nerves in the thoracic, lumbar and sacral levels exit (blank) the vertebra with the same number.
ABOVE; BELOW
How can exiting nerve fibers avoid the herniation?
rather large opening created by the inferior intervertebral notch
Spinal meninges: list the layers from the spinal cord out
spinal cord pia mater subarachnoid space arachnoid subdural space (potential space) dura mater epidural space (fatty) vertebra
What’s contained in the subarachnoid space?
CSF
What does the pia mater form in order to stabilize the spinal cord within the column?
denticulate ligaments
Portions of the pia mater that poke out and project through the arachnoid to attach to the dura.
denticulate ligaments
Is the “H shaped” center of the spinal cord gray or white matter? What’s unique about the white matter?
gray matter; there are ascending and descending fibers in the white matter. Some go up, some go down. If you cut these fibers, you will lose signal from the brain to everything below the cut. If you cut a tract that is going up to the brain (ex: L4), you will deprive that person of all sensory information below the site of the cut
What kind of neurons leave via the lateral horn?
autonomic preganglionic neurons (T1-L2: sympathetic, sacral S2-4: parasympathetic)
If someone sustains a spinal cord injury, they can experience a level loss or a segmental loss. What’s the difference?
Ex of level loss: if you cut L1, everything motor and sensory will be lost below the cut. Generally have to cut white matter.
If you damage the gray matter (like a tumor growing in there), this would cause a segmental loss. Segmental loss is like loss in sensation in a particular dermitome.
Level loss: generally have to “cut” white matter.
Segmental loss: have to “cut” the gray matter.
Put these in order: dura mater, pia mater, arachnoid
pia mater closest to spinal cord, then arachnoid, then dura mater
In which regions of the spinal column are there enlargements? Why?
cervical and lumbosacral regions, because C5-8 and T1 must give rise to ALL neurons of the upper limbs and carry lots of fine motor information. This is different from regions of the spinal cord that innervate large motor units, like the glutes.
At what vertebral level does the spinal cord end?
L2
The inferior, tapered end of the spinal cord
conus medullaris
How many cervical nerves are there? Thoracic? Lumbar? Sacral? Coccygeal?
8 pairs, 12 pairs, 5 pairs, 5 pairs, 1 pair
As you move down the spinal cord towards the cauda equina each successive nerve root must get (blank) to reach its appropriate intervertebral foramen
longer and longer
Where does the dural sac end? What significance does this have for injecting anesthesia?
ends at S2 vertebral level; can inject anesthesia outside of the dural sac to bathe the most caudal spinal nerves –> epidural block
Because the spinal cord ends at vertebral level L2, the dorsal and ventral roots for more caudal spinal nerves must descend within the vertebral canal before exiting through the correct intervertebral foramina. What are these nerve roots collectively called?
the cauda equina
What is the middle nerve at the caudal end referred to as?
filum terminale
T/F: cauda equina is important for lumbar puncture and epidural anesthesia
True
What is the first “thing” that gets pushed on if a disc is herniated? What can this cause?
ventral/motor nerve roots; this can lead to motor weakness or paralysis in the body part innervated by that nerve
What dermatome is along the side of the foot? The butt hole? The umbilicus? The nipple? Back of head?
S1; S3-S5; T10; T4; C2
The posterior intercostal arteries give rise to these branches
anterior medullary artery and posterior radicular artery
The posterior radicular artery communicates with what artery? The anterior medullary artery communicates with what artery?
posterior spinal artery; anterior spinal artery
This artery arises low in the brainstem and does not have enough blood flow to support the nervous system all the way down, so it gets tributaries from radicular branches
anterior spinal artery
Anterior spinal artery doesn’t get enough flow to supply the entire length of the cord. Where does it get segmental contributions from to boost flow?
anterior segmental medullary arteries
Blockage of the anterior spinal artery can cause anterior spinal artery syndrome. What region is the origin of the most important medullary artery (Adamkiewicz) due to prevalence of aortic aneurysm in the area?
T8-L2
Does anterior spinal artery syndrome cause complete level loss for all different types of sensations?
No; it spares some types of sensations – level losses are not complete
The internal vertebral venous plexus communicates with both the venous sinuses of the brain and a venous plexus associated with the pelvis (prostatic venous plexus). Why is this important?
It is possible for cancer of the prostate to metastasize to the CNS
Loss of sensation or muscle strength in a specific location that correlates with either a dermatome or a myotome
segmental loss
Loss of sensation or muscle strength that starts at the toes and ascends to a particular level
level loss
First notable spinous process on the posterior surface of the back? What other processes are notable?
C7 spinous process; T1, T2, supraspinous ligament, and T4
At what vertebral level are the iliac crests found?
L4/5
At what vertebral level are the dimples of the back?
spine of S2
List some extrinsic back muscles
Levator scapulae Trapezius Rhomboids Latissimus dorsi Serratus posterior superior and inferior
These two muscles are accessory respiratory muscles
serratus posterior superior and inferior
3 layers of intrinsic back muscles
spinotransverse (superficial)
erector spinae (intermediate)
transversospinae (deep)
Erector spinae muscles are (blank) oriented. There are 3 groups. (blank) – most medial, go from spine to spine. (blank) – more lateral, goes from spine to limbs. (blank) –most lateral, out to ribs from iliac crest. What do these do in terms of movement?
vertically; spinalis; longissimus; ileocostalis; Involved in bilateral movement and in flexion
This muscle attaches the spinous processes to the skull or to the transverse processes of cervical vertebrae
splenius muscle
Two components of the splenius muscle
splenius capitis (head) splenius cervicis (neck)
Three erector spinae muscles. Which is most medial? Which is most lateral?
spinalis (medial)
longissimus
iliocostalis (lateral)
What innervates the erector spinae muscles?
dorsal rami
These muscles are oriented vertically along either side of the vertebral column and are powerful extenders
erector spinae
These muscles are oriented from inferior transverse to superior spine; divided into four muscles
transversospinae muscles
How many vertebrae do the long rotators span? How many do the short rotators span? How many do the semispinalis span? How about the multifidus?
2; 1; 6-8; 3-5
What do the transversospinae muscles do? What’s an exception to this?
involved in rotation; the semispinalis capitis extends the head because of its attachment to skull instead of spinous process
What three muscles of the back of the head make up the suboccipital triangle?
rectus capitis minor/major (medial), superior oblique (lateral), and inferior oblique
C1 spine to occipital bone
C2 spine to occipital bone
rectus capitis minor
rectus capitis major
C1 transverse to occipital bone
C2 spine to C1 transverse
superior oblique
inferior oblique
This nerve is sensory to the back of the head, from the dorsal ramus of C2, nice landmark for inferior oblique muscle
greater occipital nerve
T/F: Anterior spinal artery syndrome is characterized by loss of motor function below the level of injury, loss of sensations carried by the anterior columns of the spinal cord (pain and temperature), and preservation of sensations carried by the posterior columns (fine touch and proprioception).
True
