Lumbar Flashcards
What are the three divisions of the lumbar vertebrae?
- Vertebral body
- Pedicles
- Posterior elements
Which division of the lumbar vertebrae are designed for weight bearing?
Vertebral body
What are the posterior elements of the lumbar vertebrae?
- Laminae
- Articular processes
- Spinous processes
- Transverse processes
What is the connection between body and posterior elements?
Pedicles
Where does the strength of the lumbar vertebral body come from?
Multidirectional pattern of trabeculae
Lumbar vertebral bodies are slightly deformable in response to…
loading (some shock absorption)
In the lumbar spine, pedicles are…
short and strong
The intervertebral foramen is formed between…
the pedicles
Superior and inferior facets on the articular processes form what joint?
Zygapophyseal joint
Orientation of articular facets in lumbar spine helps prevent…
excess translational and rotational movement
Where is pars interarticularis?
Runs obliquely from lateral border or vertically oriented lamina and connects to the horizontally oriented pedicle
Injury to pars can result in…
spondylolisthesis
Pars interarticularis injury is commonly found in…
adolescent athletes (ie. repeated extension)
What are the three joints of the articular triad?
- Two true diarthrodial synovial zygapophyseal joints
- One amphiarthrodial cartilaginous joint
The intervertebral disc includes what two parts?
- Nucleus pulposis
- Annulus fibrosis
What are the contents of the nucleus pulposus?
Semi-fluid mass with cartilage and collagen in ground substance
The nucleus pulposus is a remnant of…
notochord
What can cause deformation of nucleus pulposus? How is volume affected?
Derformable under pressure but volume is not compressed
What are the contents of annulus fibrosis?
Collagen fibers arranged concentrically with alternation orientation
What types of cartilage are found at the vertebral endplates?
Hyaline and fibrocartilage
The vertebral endplates are vulnerable with…
axial loading
What are the two main functions of the disc?
Weight bearing and movement
Weight bearing and shock absorption involve what components of the disc?
All components
Which component of the disc resists buckling?
Annulus fibrosis (relatively stiff)
What is the function of annulus fibrosis in movement?
Acts similarly to ligamentous structures to restrain and stabilize joint movement
All fibers will resist distraction by alternating orientation of the fibers
Both weight bearing and movement aspects of IVD function are ultimately designed to…
dissipate mechanical stress
Spinal compression is resulting from…
- Body weight
- Weight held by arms and hands
When standing upright, where is total body center of gravity?
Anterior to the spinal column
When standing upright, the spine is placed under constant… movement
forward bending movement
What is the function of the facets?
Primarily guidance of motion, not weight bearing
The facets limit ___ of the superior vertebra
anterior motion
When seated, nearly all weight is carried by…
discs and vertebral bodies
When standing, 20% of body weight is…
transferred to the facets
About 75% of trunk flexion/extension occurs in…
lumbar spine
Which vertebral level of the lumbar spine has the greatest combined flexion/extension?
L5-S1 (17 degrees)
Which vertebral level of the lumbar spine has the least combined flexion/extension?
L1-L2 (12 degrees)
Which vertebral level of the lumbar spine has the greatest unilateral lateral flexion?
L3-L4 (8 degrees)
Which vertebral level of the lumbar spine has the least unilateral lateral flexion?
L5-S1 (3 degrees)
Which vertebral level of the lumbar spine has the least unilateral axial rotation?
L5-S1 (1 degree)
L1-L5 vertebral levels all have ___ degrees of unilateral axial rotation
2
In cervical spine, rotation of the vertebra is ___ the side of lateral flexion
towards
In thoracic spine, rotation of the vertebra is ___ with lateral flexion
variable
T1-4 behave more like cervicals
In lumbar spine, bodies rotate ___ the side of lateral flexion
away from
Arthrokinematics refers to…
joint movement
Osteokinematics refers to…
bone movement
In flexion from an upright position, the stability of the spine is maintained mostly by…
the facets
Resistance to flexion is:
39% from ___
29% from ___
19% from ___
13% from ___
39% from facet joints and their capsules
29% from discs (annulus)
19% from supra and interspinous ligaments
13% from ligamentum flavum
Extension is limited mostly by…
bony impaction (not ligamentous and capsular tension)
Resistance to rotational torque comes mostly from…
posterior elements
Resistance to rotation torque is:
65% from ___
35% from ___
65% from facet capsules, facet impaction, and interspinous ligaments
35% from discs (annulus)
