Osteology of Spine and Articulations Flashcards
How many vertebrae are there? Divisions?
33
7 cervical, 12 thoracic, 5 lumbar, 5 sacral(fused) and 4 coccygeal(usually fused)
How consistent are sacral fusion patterns
vary in 5 % population
Differentiate between sacralization and lumbarization
sacralization- fusion of L5 with sacrum
lumbarization- lack of fusion of S1 with sacrum
what is the general size patterns of vertebrae
get larger as descent spine because of weight bearing
Describe composition of the body of the vertebrae
cancellous (spongy) bone. thing layer around of compact (cortical) bone
Compression fractures are usually due to
demineralization of the cancellous bone in vertebral body
What type of cartilage covers body of vertebrae
hyaline cartilage
What are the posterolateral processes that project from the vertebral body
pedicles
Structures found on pedicles
superior and inferior vertebral notches
What structures form vertebral foramina
when the superior and inferior notches of adjacent vertebrae come together
What passes through spinal foramina
spinal nerves and vessels
What is the continuation of the pedicles posteromedially to complete vertebral arch
Laminae
Name all of the articular processes
2 superior and 2 inferior located between the pedicel and lamina– articular facets
What makes up a spinal process
fusion of two laminae
What are the characteristics of the vertebral bodies of Cervical vertebrae
the body is small and shaped laterally
Describe the transverse process on cervical vertebrae
Arise from pedicle and articulating processes. Directed anterolateral
Form costotransverse foramen (transverse cervical foramen)
What travels through the costotransverse foramen
vertebral artery, vein and sympathetic nervous plexus
What parts of cervical vertebrae provide sites for attachment of neck and superficial back muscles
the anterior and posterior tubercles formed by termination of the costal and transverse processes
Why is the connection between the costal and transverse processes (Cervical) grooved
superior surface for passage of spinal nerve
Describe articular facets of Cervical vertebrae
posterior to transverse process
flat and oval shaped and oriented OBLIQUELY in coronal plane
Superior facets directed up and back
Inferior facets directed down and forward
What do the spinal processes look like on cervical vertebrae
short, bifid* and downward projecting
Describe vertebral arch of cervical vertebrae
triangularly shaped
Describe the C1 vertebra
Atlas. No body. Anterior arch and posterior arch with lateral masses
Anterior arch of C1 vs posterior
Anterior- tubercle and is the facet for dens of CV2
Posterior- tubercle and is the sulcus for vertebral artery
Describe the lateral masses on C1
Superior and Inferior articulating facets And transverse process
superior- articulate with occipital condyles
inferior- articulate with sup articulating on C2
Transverse process are attachments sites for head rotating muscles
Why does C1 have such a large vertebral foramen
space for caudal medulla
Describe C2 vertebra
Axis. has the dens (odontoid process)
dens has smooth articulating facet which receives anterior arch
Sup articular facets articulate with C1
Spinous process is thick and bifid
What is special about C7
Cervical prominens. Transition between C and T vertebrae
very long horizontal spinous pocess
What runs through the transverse foramina of C7
ONLY vertebral vein (if have the foramina- many times is not there)
Describe the vertebral body of thoracic vertebrae
Heart-shaped, intermediate size
2 costal facets per side
Which Thoracic Vertebra have a complete facet(not just half)
T1 T10 T11 T12
Describe T articulating processes
thing and flat- VERTICALLY in coronal plane
superior facets face posterior superior and lateral
inferior facets face anterior, inferior and medial
Describe T transverse processes
Thick, strong and long
directed posterolateral
facet on anterior surface for articulation with costal tubercle
Describe characteristic of T laminae
overlapping like roofing shingles
Describe spinous processes of T vertebrae
Overlap one another and directed inferiorly*
Which level of vertebra is the vertebral foramen the most narrow in diameter
Thoracic
Describe body of Lumbar vertebrae
largest because of weight bearing
Why are the pedicles closer in L vertebrae
stronger, less torque
Describe transverse processes of L vertebrae
anterior to articulating processes. direct laterally
Describe articulating processes of L vertebrae
VERTICALLY in SAGITTAL plane
superior- face medially and posteriorly
inferior- face laterally and anteriorly
Describe laminae of L vertebrae
short- non overlapping.
facilitate lumbar puncture because when flexed can get needle through
What is the pars interarticularis
area of lamina between superior and inferior articulating processes
What does the erector spinae mm attach to on L vertebrae
spinous processes
mammillary processes
accessory mammillary processes
Describe vertebral foramen in L vertebrae
triangular shaped with apex directed posteriorly
What is the superior surface of the sacrum
Promontory- anteriorly facing
What are the lateral surfaces of sacrum
Alae- fused costal and transverse processes of SV1
What is the auricular surface of the sacrum
anterolateral surface of the alas- articulate with ilium
Describe ventral surface of sacrum
concave and smooth
pierced by 4 paris of sacral foramina
What runs through ventral sacral foramina
ventral primary rami of sacral spinal nerves
Describe dorsal surface of sacrum
convex and rough. Four pairs of dorsal sacral foramina. Median sacral crest
Sacral hiatus
What runs through the dorsal sacral foramina
dorsal primary rami of sacral spinal nerves
What makes up the median sacral crest
fusion of sacral spinous processes
Where is the site for epidural anesthetic injection
sacral hiatus
What creates the sacral hiatus
failure of S5 fusion, sometimes S4 too
What makes up the intermediate sacral crest
fused articular processes
What are the sacral cornua
tubercles of inferior articulating processes of S5
What makes up the lateral sacral crest, site for what?
fused transverse processes,
site for attachment of sacroiliac, sacrotuberous and sacrospinous ligaments
What makes up the coccyx
4 fused segments- bodies only
coccygeal horns are posterior tubercles which articulate with sacral horns from S5 vertebral foramen
What are the normal curvatures
Primary- anterior concavity of the vertebral column
Secondary- anterior convexity of the vertebral column (Cervical and Lumbar when we can walk)
Abnormal curvatures and describe each
Lordosis- exaggerated secondary curve of lumbar
Kyphosis- exaggerated primary curve of thoracic
Scoliosis- lateral S shape in any region
What are the components of an intervertebral disc
Annulus fibrosis and Nucleus Pulposis
How much of the length of the spine is attributed to intervertebral discs and does this change?
1/4
decrease in thickness as age increases due to dehydration
What is the shape of intervertebral discs
wedge shaped. thicker anteriorly in cervical and lumbar to maintain secondary curves
What is a ruptured disc
tear of the annulus fibrosis leading to loss of integrity between contiguous vertebrae
What is a herniated disc
nueclue pulposus squeezes through the ruptured disc and may contact roots of spinal nerves.
Differences in herniated discs based on the level they occur
In Cervical regions- affect spinal nerves at same level
In Lumbar regions- affect spinal nerves one or more levels lower
What is the ligament that runs on the anterior surface of all vertebrae
anterior longitudinal ligament
Layers of anterior long lig
deep layer- short fibers that span contiguous vertebrae
superficial layer- long fibers that span many vertebrae
What ligament prevents excessive extension
anterior long spinal lig
Where is the post long lig and its function
located on post surface of all vertebral bodies- same fibers as anterior log.
Prevents excessive flexion
*directs intervertebral dis herniation posterolaterally
Zygapophysis
facet joints. synovial joint
Describe motion limits of zygapophysis regarding to the segment
Cervical- flexion, extension, rotation, lateral flexion
Thoracic- rotation, lateral flexion(little flexion no extension)
Lumbar- flexion, extension, side bending, very limited rotation
Why is the zygapophysis in the thoracic region more restricted?
presence of ribs, long thoracic spinal processes and thin intervertebral discs
What is the ligamentum flava
unites internal surfact of adjacent laminae from C2 downward.
Maintains upright posture by LIMITING flexion and ALIGNS facet joints
Why is the ligamentum flava yellow
high in elastic fibers
What is the strongest ligament posterior to vertebral bodies
ligamentum flava
Describe the Interspinal ligament
Unites adjacent processes from tip to laminae
most robust at lumbar levels.
Describe the Supraspinal ligament
Connects tips of spinous procceses from C7 to sacrum
continuous with interspinous lig
What are the two layers of supraspinal ligament
deep- span adjacent spinous process
superficial- span several vertebrae
What is the Ligamentum Nuchae
Nuchal lig.
median sheet like upward extension of the supra spinal ligament
extends from C7 to external occiptal protuberance
acts ans intermuscular septum
Provides muscular attachment without limiting extension of cervical column
What are the boundaries of the intervertebral foramina
Superior- inferior vertebral notch of vertebra
Inferior- Superior vertebral notch of vertebra
Anterior- Posterior portion of vertebra above intervertebral disc
Posterior- facet joint between 2 opposing vertebrae
How deep is the intervertebral foramen
width of pedicle
What runs within the intervertebral foramen
Dorsal and ventral roots
Dorsal root Ganglion
Spinal Nerve
Spinal a and intervertebral vein
What type of joint is the Atlantoocciptal joint
gliding, or plane synovial joint between occipital condyles of skull and superior articulating facets (C1) atlas
What movement does atlantoocciptal joint permit
Yes movement. flexion and extension
What are the accessory ligaments of the atlantoocciptal joint
Anterior membrane- between ant margin of foramen magnum and anterior arch of atlas
Posterior membrane- between post margin of foramen magnum and post arch of atlas
What runs through the openings in the posterior atlantooccipital membrane
lateral passage for vertebral arteries and suboccipital nerve (dorsal ramus C1)
Where do the Ant and Post membranes of atlanto-occipital joint fuse
laterally
What is the atlantoaxial joint: type and function
gliding synovial between atlas and axis
No movement- rotation because pivot at the dens on axis
What are the ligaments of Atlantoaxial joint
Transverse lig of atlas- attaches to internal surface of anterior arch of C1 forming socket
Sueprior crus- from transverse log superiorly to attach to ant edge of foramen magnum
Inferior crus- transverse lig inferiorly to attach to post surface of axis body
What is the collective name for the ligament of the atlantoaxial joint
Cruciform ligament of the atlas
What are the accessory ligaments for C1/C2
Apical dental lig(deep to superior crus)
Alar ligaments- arise from dens laterally to attach to occipital condyles(rotation restriction)
Tectorial membrane- covers dens and assoc ligaments
Anterior atlantoaxial membrane and Posterior
What does the tectorial ligament fuse with
anteriorly fuses with dura mater, inferiorly to C2 to the posterior longitudinal ligament
Describe anterior and posterial atlantoaxial membranes
anterior- from ant arch of atlas to ant body of axis
Posterior- posterior arch of atlas to lamina of axis- continuous with ligamentum flava
What is an injury seen with C1/C2 joint
fractures of dens. dislocation super rare because of extensive ligaments
Spondylosis
usually developmental defect in pars interarticularis
Spondylolisthesis
bilateral spondylosis. Entire column affected as it slide forward on vertebra below. Most commonly seen at L5 on S1
What is the arterial supply in column
Spinal arteries:
vertebral a, ascending cervical a, posterior intercostal aa, lumbar aa, iliolumbar a, lateral sacral a
What are the divisions of spinal arteries
Osseous and neural branches
Describe osseous branches of spinal aa
anastomose with like branches above, below and opposite to form plexi within vertebral canal(epidural) posterior to the post long ligament and ant to ligamentum flava
Describe the neural branches of spinal aa
Provide RADICULAR branches which enter dural sac along spinal nerve. (course along dorsal and ventral roots)
What is a precaution in heart surgery because of spinal aa
Special procedures to supply this blood when aorta is clamped
4 General considerations of Veins in vertebral column
1) Four venous plexi drain vertebral column
2) All four run the entire length
3) all four freely intercommunicate
4) They do NOT have valves
What are the four plexuses
Anterior external- ant surface vertebral bodies
Posterior external- external surface of spinous, articular and transverse processes
Anterior internal- In epidural space adjacent to posterior long spinal ligament
Posterior internal- in epidural space adjacent to laminae and ligament flava
Describe two components of venous flow in column
Basivertebral vv- drain bodies to anterior internal plexus
Intervertebral vv- drain all 4 venous plexuses
these drain into vertebral, posterior intercostal, lumbar and lateral sacral vv
What is particular about the vertebral vascular plexus due to its no valves
receives blood from pelvic, abdominal, thoracic and cranial cavities. Changes in intra-thoracic and intra-abdominal Pressures also have changes in venous flow
Why is this no valve system important clinically
metastatic spread of cancer cells(prostate and breast)
also spread of infectious disease to vertebral column
