Rehabilitation Sciences 3060A/B Lecture Notes - Lecture 4: Lumbar Vertebrae, Iliac Crest, Synovial Joint
5 Apr 2018
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Document Summary
It all depends on the orientation and the often leads to orientation one over the other. When the upper vertebrae rotates to the left, the right facet will compress while the left facet will distract; continued rotational force will cause lateral shearing of the disc. There is only 3 degrees of rotation at each disc, anything past those 3 degrees, it will create a lateral shear on the intervertebral disc. More of a coronal facet (top diagram) will allow for more rotation; hence less shearing compared to the sagittal facets. Rotation is resisted mostly by the posterior elements (65%) and then the i. v. discs (35%) Lumbar zygapophyseal joints: paired synovial joints guide rails for sagittal (flexion) & transverse plane (rotation) movement restrain axial rotation & excessive translation, protect disc from torsional & shearing strains. Local and global stabilizers combine to provide functional lumbar stabilization.
