Lumbar Spine Flashcards
Lumbar Spine
Lordotic curve
L1-L5 vertebrae
Intervertebral discs
Larger vertebral bodies compared to CS and TS
Articulates with sacrum
Function of the LS
primary goals of the lumbar region are to augment mobility at the hip joints to increase total mobility of the trunk and to effectively absorb and adjust body weight forces from head, arms, and trunk above and ground reaction forces below in weightbearing
LS Vertebral Body
Massive
Transverse diameter > A-P diameter and > height of the body
Support great compressive loads by body weight, ground reaction forces and muscle contraction
LS Pedicles
Short and thick
Face posterolaterally
LS Laminae
Short and broad
LS facets
Inferior facets of the SUPERIOR vertebrae:
inferior, anterior, lateral
Superior facets of the INFERIOR vertebrae:
superior, posterior, medial
L1-4 Facet Orientation
Biconcave, predominantly favors sagittal plane
L5-S1 Facet Orientation
Shifts towards frontal plane more
Superior facets - Mammillary processes
Small bumps posterior to edges of superior facets
Serve as attachment sites for the multifidus and medial intertransverse muscles
Inferior facets
Vertical and convex
Face slightly anteriorly and laterally
LS Transverse processes
Long and slender and extends horizontally
LS Spinous processes
Broad, thick, rectangular shaped, extends horizontally
LS vertebral foramen
Triangular and >TS, but <CS
Atypical LS vertebra
L5is a transitional vertebra
Body is more wedge shaped
SP is shorter
Inferior facets oriented more anteriorly to articulate with posteriorly-facing sacral facets
Lumbosacral articulation
L5 and S1; forms and angle with the horizontal plane
“lumbosacral angle”
Intervertebral discs
Collagen fibers of the annulus fibrosus are arranged in sheets -lamellae
Able to resist tensile forces in all directions
Largest
Concave posteriorly
Interbody Joints
capable of translations and tilts in all directions
Zygapophyseal Joints
Synovial joints
Fibroadipose meniscoid structures
Joint capsule lax>TS; taut>CS
Posterior capsule subject to compressive and tensile forces
Supraspinous ligament
More developed in the upper lumbar
Ligamentum flavum
Thickens in the lumbar region
What replaces the intertransverse ligaments?
iliolumbar ligament
Supraspinous ligament
Blends with the thoracolumbar fascia
Posterior long. ligament
thin ribbon
Anterior long. ligament
strong and well developed
Iliolumbar ligament
Consists of 2 bands running from L5 TP to the iliac tuberosity
Strong
Stabilize L5 vertebra
Prevent ant. displacement
Resist flexion, extension, axial rotation, and lateral bending of L5 on S1
Thoracolumbar fascia
3 layers:
Posterior: large, thick, and fibrous
Middle: Posterior becomes the middle layer as it travels medially along the anterior surface of the erector spinae and attaches back to the transverse processes and intertransverse ligaments of the lumbar spine
Anterior: derived from the fascia of the quadratus lumborum muscle, where it joins the middle layer, inserts into the transverse processes of the lumbar spine, and blends with the intertransverse ligaments
Osteokinematics
Flexion/Extension
Lateral flexion
Rotation
Which motion is favored by the lumbar zygapophyseal facets?
flexion and extension because of the predominant sagittal plane orientation
greatest amount takes place in the lumbosacral joint (L5-S1)
Lateral flexion
Most free in the upper lumbar region and is less in the lower region
Flexion Arthrokinematics
The vertebral body tilts and slides anteriorly while the inferior facets slide upwardly on the facets below
Both facets - up and forward (upslide)
Extension Arthrokinematics
the vertebral body tilts and slides posteriorly while the inferior facets slide downwardly on the facets below
Both facets - down and back (downslide)
Lateral flexion Arthrokinematics
The vertebral body tilts and slides to the ipsilateral side while the contralateral inferior facet slides upward and the ipsilateral inferior facet slides downward on the facets below
Ipsilateral: down and back
Contralateral: up and forward
Rotation Arthrokinematics
the vertebral body tilts and slides ipsilateral while the ipsilateral inferior facet joint distracts (opens) and the contralateral inferior facet joint compresses
Ipsilateral: down and back
Contralateral: up and forward
