Thoracolumbar Flashcards
How are the zygapophyseal joints in the thoracic region aligned?
Coronal Orientation
‘Tall’ superior articular process
60-80 degrees to transverse plane (more vertical than cervical)
What movements do the z-joints in the thoracic region allow?
Axial rotation and lateral flexion
How are z-joints in the lumbar region aligned?
90 degrees to transverse with a sagittal plane orientation
What movements do the z-joints in the lumbar region allow?
Flexion-Extension
Not so much axial rotation as the more vertical z joints ‘block’ the rotation
Explain the mechanism causing a pars interarticularis defect
Defect in between articulating Z joints – lamina of vertebrae (collar of scotty dog)
Caused by repetitive hyperextension and axial loading = too much force going through pars interarticularis (inferior facet is ramming into superior facet)
Defect = fracture/weakening of bone tissue (spondylolysis)
What is spondylolysis
breakdown of bone tissue at pars interarticularis
What is spondylolisthesis
forward translation of superior vertebrae relative to the inferior vertebrae
isthmic spondylolisthesis occurs as a result of a pars interarticularis defect
What ligaments provide stability to the Lumbosacral junction?
iliolumbar and lumbosacral ligament
What is the function of the iliolumbar ligament?
Primary restraint of L5 moving on S1
What is the function of the lumbosacral ligament?
Resist lumbosacral extension and Contralateral flexion
What structure is superficial to lumbar multifidus?
Erector Spinae aponeurosis
What structure innervates lumbar multifidus?
Medial branch of lumbar dorsal rami
Explain the lumbar lordosis
Anterior tilt of sacrum
L5/S1 inervertebral disc and L5 vertebra are wedged shape and taller anteriorly
L1-L4 posterior tilt
What is FLEXION in the lumbar region limited by?
impact anterior part of articular processes
tension in: Zygapophysial joint capsules Supraspinous ligament Interspinous ligament Ligamentum flavum Posterior annulus fibrosus
compression of: Anterior annulus fibrosus
What is EXTENSION in the Lumbar region limited by?
compression of interspinous ligament
impaction of spinous processes or inferior articular process with lamina below*
Tension in anterior Annulus Fibrosus
What is AXIAL ROTATION in the Lumbar region limited by?
Impact on z joints
Tension in posterior ligaments
Tension in annulus fibrosus
What is LATERAL FLEXION in the Lumbar region limited by?
Ligamentum Flavum
Explain the Anterior and Posterior shear forces on the lumbar spine
When lumbar spine flexes, the superior body weight exerts compressive and anterior shear force on the intervertebral joints.
What are the PRIME EXTENSORS of the trunk?
Longissimus thoracis pars thoracis
iliocostalis lumborum pars thoracis
Why are the Longissimus thoracis pars thoracis and
Iliocostalis lumborum pars thoracis PRIME EXTENSORS?
Vertical line of action
Large PCSA
Large posterior moment arm
How is the external flexion moment, generated by gravity acting on the mass of the trunk, resisted during trunk flexion from anatomical position?
Trunk supported by erector spinae, posterior intervertebral disc, interspinous and supraspinous ligaments, fascia
Initial active tension in the erector spinae relaxes at 75%-85% of trunk flexion as the connective tissue components of the muscle and posterior intervertebral discs and ligaments are tensed
Sacral nutation limited by: sacrospinous, sacrotuberous,
sacroiliac ligaments
Hip F limited by tension in: hamstrings - biceps femoris,
semimembranosus, semitendinosus
What are some characteristics of the Lumbar intervertebral disc?
More proportion of Nucleus Pulposus
Wedged
Taller anteriorly
