Lecture 4: Vertebral Column 1 Flashcards
What are the curvatures of the vertebral column and what is their purpose?
1˚ curve: thoracic and sacral
2˚ curve: cervical and lumbar
increase shock absorbing resilience
What are some examples of abnormal curvatures of the vertebral column?
excessive thoracic kyphosis: exaggerated thoracic curvature
excessive lumbar lordosis: exaggeration of lumbar curve
scoliosis: abnormal lateral curvature with rotational deformity of vertebrae
What is a motion segment?
a functional unit of the vertebral column which comprises of two adjacent vertebrae and the associated soft tissues
What are the joints contained by each motion segment?
intervertebral disc (symphysis) between vertebral bodies right and left zygapophyseal joints (synovial plane multiaxial) between superior and inferior articular processes
How much ROM do motion segments provide?
permit small segmental ROM but large total ROM
- > flexion/extension
- > lateral flexion
- > rotation
What are the regional characteristics of vertebrae?
body shape and size, vertebral foramen shape and size, transverse process, spinous process, articular processes (zygapophyseal joints)
What is spondylolysis?
fracture of the pars interarticularis (region between superior and inferior articular facets)
weakest portion of neural/vertebral arch
congenital or mechanical
What is spondylolisthesis?
complete bilateral fracture of pars interarticularis = anterior slippage of vertebra with respect to vertebra below it (90% occur lumbosacral joint L5/S1)
What is the effect of aging of vertebrae?
bone density and strength decreases from the 4th decade (spondylosis)
osteophytes (bony spurs) can develop due to changes in bone shape with age due to altered mechanical stresses on joints
osteoporosis is not a normal part of aging
resistance exercise increases bone strength through mechanical loading
What is the hyaline cartilaginous end plate and what does it do?
transmits weight to adjacent vertebral body
confines nucleus pulposus and annulus fibrosus
helps provide nutrition to IV disc
What is the annulus fibrosus and what does it do?
thick, outer fibrocartilaginous alternating rings
holds the vertebral bodies together
What is the nucleus pulposus and what does it do?
central gelatinous substance with high fluid content
keep vertebral bodies apart, permitting them to roll over one another to allow frictionless movement
shock absorbing capabilities
What are features of the IV disc?
largely avascular -> discs rely on body movement to pump nutrients in and waste products out via diffusion
innervation -> outer 1/3 annulus fibrosus innervated in healthy, young people
account for 25-33% of vertebral column length
What does the annulus act as?
annulus acts as a coiled spring whose tension holds the vertebral bodies together against the resistance of the nucleus pulposus
What does the nucleus pulposus act as?
acts like a ball bearing composed on incompressible gel that the vertebrae roll over during flexion/extension/lateral bending and rotation while the facet joints guide these movements
Which types of stresses are IV discs exposed to?
compressive, tensile and shear stresses
What are terms used for disc pathologies?
- > bulge, herniation, desiccation
- > posterior or posterolateral aspect
- > lower cervical and lumbar regions most affected
What is the annulus fibrosus like in cervical IV discs?
anterior: distinct, strong, thick
posterior: thin vertically oriented fibres (NOT alternating layers)
lateral: absent (i.e. not a continuous ring)
What is the annulus fibrosus like in thoracic IV discs?
60% of disc volume
equal height anteriorly and posteriorly
height of IV disc relative to vertebral body is smaller compared to cervical and lumbar regions (esp. upper thoracic region)
What is the annulus fibrosus like in lumbar IV discs?
highest and widest discs
posterior concavity
posterior-lateral portion not as well reinforced
What is the nucleus pulposus like in cervical IV discs?
fibrocartilage core, with no gelatinous component uncovertebral clefts (horizontal fissures) penetrate the core in adolescence (increased movement)
What is the nucleus pulposus like in thoracic IV discs?
slightly posteriorly directed gelatinous nucleus
What is the nucleus pulposus like in lumbar IV discs?
slightly posteriorly directed gelatinous nucleus
What is the role of the anterior longitudinal ligament?
resists vertical separation of anterior vertebral bodies i.e. limits lumbar extension
What is the role of the posterior longitudinal ligament?
resists separation of posterior vertebral bodies i.e. limits lumbar flexion
What is the role of the ligamentum flavum?
resists separation of laminae (blends with anterior part of zygapophyseal joint capsule) i.e. limits flexion
What is the role of the interspinous ligament?
resists separation of posterior vertebral bodies i.e. oblique fibres control vertebral rotation throughout flexion
What is the role of the supraspinous ligament?
resists separation of spinous process (expands as ligamentum nuchae in cervical region) i.e. limits excessive forward flexion
What is the role of the intertransverse ligament?
resists separation of transverse processes i.e. limits lateral flexion
What is the role of the iliolumbar ligament?
resists flexion/extension, rotation, & lateral flexion
What is ankylosing spondylitis?
ossification of the annulus fibrosus that bridges adjoining vertebral bodies
ossification of supraspinous and interspinous ligament
What are joints unique to cervical vertebrae?
craniovertebral joints (atlanto-occipital joints and atlanto-axial joints) uncovertebral joints
What are ligaments unique to cervical vertebrae?
flexion limited by tectorial membrane, cruciform (transverse & longitudinal), alar & apical
cervical IV disc rings missing posteriorly, reinforced by posterior longitudinal ligament
What is the implication of the transverse ligament of atlas being stronger than dens (C2)?
increases occurrence of dens fractures, commonly at the base = avascular necrosis
What is whiplash and what can it lead to?
severe hyperextension of the neck during rear-end collisions
can lead to cervical spondylolysis, transverse, alar, anterior longitudinal ligament damage, C2/3 IV disc rupture, spinal cord damage
hyperflexion injury may also occur as the head ‘rebounds’ after hyperextension, dislocating zygapophyseal joints
