Detailed lecture on the functions of the spine or the motions of spine. The functions of spine involves the following predominant motions flexion, extension, lateral flexion and rotation. The movements of spine also occur as coupled motions where coupled motions are motions around one axis consistently associated with motions in another axis. The degree of coupled motions of spine are determined by a lot factors such as regional variations of spine,between individuals, depends on extensibility of muscles and ligaments as well as fluidity and elasticity of the intervertebral disc too.
The flexion and extension or any motion of spine is determined by the disc between spine as well as orientation of zygoapophyseal joints or facet joints. The intervertebral disc determines the tilting motions of spine whereas the orientation of zygoapophyseal joint determine the direction of motion. When zygaapophyseal joints are in frontal plane as in thoracic vertebra then the motion of lateral flexion predominates than the motion of flexion which is more in lumbar region due to the orientation of facet joints in the sagittal plane.
During motion of flexion of spine there is anterior tilt and upward slide and in extension there is posterior tilt and downward slide. When it comes to lateral flexion there is lateral tilt and lateral or side ways translation of spine.
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