primary curvature of the back
anterior concavity of the vertebral column
kyphodic curve
exists in fetal life throughout the column
persists in adult life in the thoracic and sacral areas
secondary curves of spine
anterior convexity of the vertebral column
develops in response to lifting head and the assumption of the erect position
exists in cervical and lumbar areas
lordosis
exaggerated secondary curve of the lumbar area
kyphosis
exaggerated primary curve of the thoracic area
scoliosis
lateral S shape any area of vertebral column
zygopophysis (facet joints)
articulations between vertebral arches
true synovial joints
3 major classifications of joints
membranous
cartilaginous
synovial
what is a synovial joint?
articulating bones of a synovial joint are united by a joint capsule
the joint capsule has two parts:
outer fibrous layer
lined by a serous synovial membrane spanning and enclosing an articular cavity
the joint cavity contains synovial fluid
articular cartilage covers the articulating surfaces of the bones
PROVIDES FREE MOVEMENT
articulations between vertebral bodies?
intervertebral discs
annulus fibrosis
part of the intervertebral discs
outer fibrocartilaginous ring
consists of concentric lamellae (layers) of fibrocartilage*** Superstrength
the fibers of adjacent lamellae cross each other obliquely in opposite directions -> allows limited rotation b/w adjacent vertebrae
thinner posteriorly*** in cervical and lumbar regions which assists in maintaining secondary curves of these areas
nucleus pulposus
the core of the IV disc
inner highly elastic , highly hydrated gelatinous mass
can be pushed around during movement
extension–> moved anteriorly
flexion–> moved posteriorly
sidebending–> moved to opposite side of the bending
intervertebral discs attachments
attached above and below to the hyaline cartilage of vertebral bodies
attached anteriorly and posteriorly to longitudinal spinal ligaments
function of IV
shock absorbers
during compression they bulge past the margins of the vertebral body
posterior longitudinal ligament
n
ruptured disc
tear of annulus fibrosis leading to loss of integrity between contiguous vertebrae
herniated disc
nucleus pluposus squeezes through the ruptured disc and may impinge/contact roots of spinal nerves
posterolateral herniation versus a posterior herniation ?
posterolateral herniation pushes on spinal nerve
posterior herniation directly on spinal nerve right next to it AND on cauda equina –SO this is more of a problem
L4-L5
L5-S1 are the most common areas of herniation in the body
if you have a posterolateral herniation of IV between LV4 and LV5 which nerve is impinged?
L5 b/c L4 has already left the vertebral column
herniations that occur in the cervical region affect spinal nerves at …
the same level as the herniation
herniations that occur in the lumbar region….
due to the angle at which the spinal nerves descend from the spinal cord relative to the herniated IV disk, affect the spinal nerve one or more segments lower
anterior longitiudinal spinal ligament
location
-anterior surface of ALL vertebrae extending from the basilar portion of he occipital bone to the pelvic surface of the sacrum
- only ligament that prevents excessive extension
- composed of two layers
two layers of anterior longitudinal spinal ligament
deep layer composed of short fibers which span contiguous vertebrae
-superficial layer composed of long fibers which span many vertebrae
poster longitudinal spinal ligament
runs within the vertebral canal along the posterior aspect of the vertebral bodies
extends from the occipital bone to the sacrum
prevents excessive flexion
directs/prevents intervertebral disk herniation posterolaterally thereby affecting spinal nerves
zygopophyseal joints in the cervical region and the movement they allow
oblique in coronal plane
allow for flexion, extension, rotation and lateral flexion
zygopophyseal joints in the thoracic region and the movement they allow
sit vertically in the coronal plane
MOSTLY FOR ROTATION and LATERAL FLEXION
thoracic region needs to be stable and ribs need to move in the thoracic region
can flex fairly well, but LIMIT EXTENSION
limit anterior and posterior translation
zygophoyseal joints in the lumbar region and the movement they allow
vertically in the sagittal plane
NO ROTATION
YES FOR FLEXION AND EXTENSION
SIDE BENDING
ligamentum flavum general info
yellow- due to high percentage of elastic fibers
unites internal surface of adjacent laminae from CV2 downward
covering the zygopophyseal joint
function of the ligamentum flavum
maintains upright posture by limiting FLEXION of the vertebral column
ALSO returns vertebral column to its normal posture by aligning facet joints (recoil memory)
STRONGEST of the 4 ligaments located posteriorly to the vertebral bodies
interspinal ligament
unites adjacent spinous processes from tip to laminae
most robust in lumbar region
insignificant in cervical and thoracic areas due to the respective distance b/w contiguous spinous processes
5 ligaments to consider in spinal column
anterior and posterior longitudinal spinal ligament
ligamentum flavum
interspinal ligament
supraspinal ligament
nuchal ligament
supraspinal ligament
connects tips of spinous processes from CV7 to sacrum
composed of TWO laminae
deep-span adjacent spinous proces.
superficial- spans several vertebrae
what is the supraspinal ligament continuous with at the deep surface
and above CV7
on deep surface continuous with interspinous ligament
above CV7 continuous with nuchal ligament
when you go into flexion what happens to the zygopophyseal joints>
they separate and spread out a bit so ligamentum flavum prevents this
nuchal ligament
median sheet like upward extension of the supraspinal ligament
extends from CV7 spinous process to external occipital protuberance
intermuscular septum for posterior deep muscles of the neck
site of MUSCULAR ATTACHMENT without limiting extension of the cervical column
superior and inferior border of the intervertebral foramina
superior –> inferior vertebral notch of vertebra above
inferior–> superior vertebral notch of vertebra below
anterior and posterior borders of the intervertebral foramina
anterior–> posterior part of vert. above and intervertebral disk
posterior–> facet joint b/w 2 opposing vertebrae
osteoarthritis
can cause inflammation and bulging into the spinal nerve area…. OUCHY
this is relevant to the discussion on the intervertebral foramen and why you don’t want to impinge upon it
Contents of the intervertebral foramina (4)
dorsal and ventral roots
dorsal root ganglion
spinal nerve
spinal artery and intervertebral vein
the intervertebral foramina has depth ….
the width of the pedicle
atlantooccipital joint
plane synovial joint b/w occipital condyles of skull and superior articulating facets of CV1 atlas
loose joint promotes between skull and atlas in “YES” range==> flexion and extension
accessory ligaments of the atlantooccipital joint
Anterior atlanto-occipital membrane
-b/w anterior arch of the atlas and anterior margin pf foramen magnum
Posterior atlanto-occipital membrane
-posterior margin of both atlas and foramen magnum
what does the posterior atlantooccipital membrane have an opening for?
vertebral artery and suboccipital nerve (dorsal ramus of spinal nerve C1)
atlantoaxial joint (2 different types of articulations)
lateral articulations–> gliding type synovial joint b/w CV1 and CV2 articular processes
median articulations–> pivot type joint b/w dens of the axis and the anterior arch of the atlas
where is the location of the dens/atlas articulation
anterior arch of atlas
what type of movement does the medial atlantoaxial articulation provide
“NO” action (rotation)
accessory ligaments of the atlantoaxial joint
transverse ligament of the atlas*** most important
superior crus
inferior crus
these form the CRUCIFORM LIGAMENT of the atlas
transverse ligament of the atlas
attaches to the internal surfaces of the anterior arch of the atlas forming a socket b/w itself and the anterior arch
superior crus and inferior crus
superior–> pass from transverse ligament superiorly to attach to the anterior edge of foramen magnum
inferior–> passes from the transverse ligament inferiorly to attach to the posterior surface of the body of the axis
apical dental ligament
weak ligament which passes from the apex of the dens to the anterior edge of foramen magnum deep to the superior crus
alar ligaments
bilateral ligament
arise from dens and attach to the occipital condyles
what happens if you tear the alar ligament
increase rotation of the skull by approximately 30 degrees
example–> owl has very lax alar ligament
tectorial membrane
covers the dens and associated ligaments
extends from the anterior edge of foramen magnum to the body of CV2 where it fuses with the posterior longitudinal spinal ligament
anterior antantoaxial membrane
anterior–> from the anterior arch of the atlas to the anterior body of the axis
is overlain by the superior most extension of the anterior longitudinal ligament
posterior atlantoaxial membranes
from the posterior arch of the atlas to the lamina of the axis
continuous with the ligamentum flavum
spondyloysis
elongated pars interarticularis
UNILATERAL
usually from development BUT can be trauma induced (fracture–> heal—> elongate)
spondylolisthesis
BILATERAL fracture or problem of the pars interarticularis
the affected vertebra, as well as the entire spinal column above slips foward on the vertebrae below
MOST COMMON AT LV5 and SV1 b/c of weight bearing area
this causes stretching to nerve roots
important note*** on vasculature…
All spinal nerve roots have what?
associated radicular or segmental medullary arteries
most roots have radicular arteries
both types of arteries run along the roots
radicular arteries
end before reaching anterior or posterior spinal arteries
segmental medullary arteries
continue on from roots to supply a segment of the anterior or posterior spinal arteries
spinal arteries arise from what?
arise from vessels which parallel the vertebral column
ie: verterbral artery ascending cervical artery posterior intercostal artery lumbar artery lateral sacra artery
spinal arteries?
anterior spinal artery
paired posterior spinal artery
connected to segmental medullary arteries but NOT radicular arteries
4 things i need to know about veins
Four venous plexuses drain the vertebral column
all four run the entire length
all four freely intercommunicate
they do NOT posses valves
Plexuses
Anterior and posterior external venous plexuses
-either on vertebral body or external surfaces of the transverse, spinous or articular processes
Anterior and posterior internal venous plexuses
-in epidural space
venous flow (2 types)
Basivertebral
Intervertebral
Basivertebral venous flow
drain the bodies of the vertebrae to the anterior internal plexus
intervertebral veins
receive drainage from ALL 4 venous plexuses
drain to
- vertebral
- posterior intercostal
- lumbar
- lateral sacral veins
Batson’s plexus
NO VALVES
so….. receives blood from abdominal, pelvic, thoracic, and cranial cavities
so changes in intra-abdominal pressures are accompanied by changes of flow within these plexuses
RESPONSIBLE FOR METASTATIC SPREAD OF CANCER (prostate and breast)