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Joints of the Vertebral Column
Anatomy 1
• Vertebrae from C2 to S1
– 3 Joints
• Anterior joint
• 2 posterior joints
• Craniovertebral joints
– Atlanto-occipital joint
– Atlanto-axial joint
Intervertebral disc
• Anterior intervertebral joint
• Classification
– Symphysis
–
– Material that connects the bones:
•
Overall structure of intervertebral
disc
• Hyaline cartilage on surface of bodies
• Disc – made of fibrocartilage
– Anulus fibrosis
– Nucleus pulposus
Anulus fibrosus
• Fibrous rim of disc
• Concentric lamellae of fibrocartilage
– Fibers run at an angle
– Fibers in one lamellae are perpendicular to
fibers in the next lamellae
– Lamellae are thinner and less numerous
posteriorly than anteriorly or laterally
Nucleus pulposus
• Central core of disc
• Located more
posteriorly than
central
• More cartilaginous
than fibrous
Blood supply to nucleus pulposus
• Nucleus is avascular
• Diffusion from blood vessels in the
periphery of the anulus fibrosus
• Nucleus pulposus water content
– High water content
– Desiccation starts around age 30
Function of nucleus pulposus
• Shock absorber
for axial forces
• Acts like semiliquid ball bearing
• Becomes broader
when
compressed
Disc Injury
• If anulus fibrosis is weakened, the nucleus
pulposus may rupture and protrude
– AF strength?
– Ligamentous suppport?
• May press on:
– Spinal cord
– Nerve roots
– Cauda equina
Joints of the vertebral arch
• Zygapophyseal joints
– Synovial joint
– Classification
• Inferior vertebrae – superior articular facet
• Superior vertebrae – inferior articular facet
Structure of Zygapophyseal Joints
• Cartilage on facets: (type)
• Joint capsule
– Attached to margins of processes
– Longer and looser in the:
Function of zygapophyseal joints
• Allow gliding movement
• Control flexion, extension and rotation in
the cervical and lumbar regions
• Share weight-bearing with intervertebral
discs
Innervation of zygapophyseal
joints
• Nerves from medial branches of the
posterior primary rami
• Figure (page 506)
Craniovertebral joints
• Atlanto-occipital joint
• Atlanto-axial joint
Structures
• Atlas
– Anterior and posterior arches
– Lateral mass
– Posterior tubercle
– No spinous process
– Transverse process
• Transverse foramen
– Vertebral foramen
– Joints
• Superior articular facet
• Joint with dens and transverse ligament
• Axis
– Body
– Bifid spinous process
– Dens (facet for atlas)
• Occipital bone
– Foramen magnum
– Occipital condyles
• Anterolateral to foramen magnum
Atlanto-occipital joint
• Articulating bones
–
–
• Movements
– Primarily:
– Slight:
Atlanto-Occipital joint
• Classification of joint
• How many degrees of movement?
• Loose articular capsule with synovial
membrane
Atlanto-occipital membranes
• Connect C1 and skull
• Anterior and posterior atlanto-occipital
membranes
• Extend from anterior and posterior arches
of atlas to the anterior and posterior
margins of the foramen magnum
Cruciate ligament
• Transverse
ligament of
the atlas
• Superior and
inferior
longitudinal
bands
Transverse Ligament of the Atlas
• Strong band
• Between tubercles on
medial sides of the
lateral masses of the
atlas
• Holds dens in place
against anterior arch
of atlas
• Forms synovial joint
between bones
Superior and inferior longitudinal
bands of the cruciate ligament
• Attach to the occipital bone superiorly
and the body of axis inferiorly
Alar ligaments
• From dens to lateral margins of foramen
magnum
• Round cords and as thick as pencils
• Check lateral rotation and side-to-side
movements of the head
• Attach skull to axis
Tectorial membrane
• Superior continuation of posterior
longitudinal ligament
• Attaches to:
– Body of axis
– Internal surface of occipital bone
• Covers the alar and cruciate ligaments
Atlanto-axial joint
• Between C1 and C2
• 3 joints
– Medial joint
– 2 lateral joints
• Movement: the skull and C1 rotate as a
unit on C2
Apical ligament of the dens
• Tip of dens to internal surface of occipital
bone
General movements of the
vertebral column
• Limits of movement
– Intervertebral discs
– Resistance from muscles and ligaments in the
back
– Shape of the zygapophyseal joints and the
tension of their respective joint capsules
Physiological Curves of the Back
• Embryo
• Curves change during development
1º curvatures
• Develop during fetal period
• Concave anteriorly
• Which parts of the spine?
2º Curvatures
• Present at birth, but not well developed
• Concave posteriorly
• Regions of the spine
• Develop more after birth
Abnormal curves
• Lordosis
• Kyphosis
• Scoliosis