vertebral forward flexion
anterior tilting of vertebral body over nucleus
compression and bulging of anterior intervertebral disc
tension on posterior intervertebral disc
nucleus deforms posteriorly
vertebrae during forward flexion
intervertebral foramen increase in size
spinous processes separate
decreased compression on facet joints
ligaments during vertebral forward flexion
slack anterior longitudinal ligament
tension on:
supraspinous l.
interspinous l.
intertransverse l.
ligamentum flava
posterior longitudinal l.
vertebral backward extension
posterior tilting of vertebral body over nucleus
compression and bulging of posterior intervertebral disc
tension on anterior intervertebral disc
nucleus deforms anteriorly
vertebrae during backward extension
intervertebral foramen decrease in size
spinous processes converge
increased compression on facet joints
ligaments during vertebral backward extension
tension on anterior longitudinal ligament
slack:
supraspinous l.
interspinous l.
ligamentum flava
posterior longitudinal l.
vertebral side bending (lateral flexion)
lateral tilting of vertebral body over nucleus
on side toward movement
compression and bulging of intervertebral disc
on side toward movement
tension on intervertebral disc
on opposite side of movement
nucleus deforms toward opposite side of movement
vertebrae during side bending (lateral flexion)
intervertebral foramen decreases in size on side of movement
intervertebral foramen increases in size on side opposite movement
increased compression on facet joints on side of movement
decreased compression on facet joints on side opposite of movement
ligaments during vertebral side bending (lateral flexion)
tension on inter transverse ligament on side opposite moment
slack on inter transverse ligament on side of movement
vertebral rotation
increased compression of nucleus
shear stress on annulus fibrosis
increased compression on facet joint opposite of rotation
decreased compression on facet joint on side of rotation
tension on joint capsule on side of rotation
sacroiliac joint
limited movement
mainly in anterior posterior direction
rotation and translation occur
nutation
movement of the sacrum
related to ilium
i.e. forward bending; squatting
torsion
movement of ilium
relative to sacrum
ie. in supine, knee to chest
pelvic tilt
anterior pelvic tilt increases lumbar lordosis
posterior pelvic tilt decreases lumbar lordosis
atlanto-occipital joint loads
lowest in full extension
highest in full flexion
C7-T1 loads
least when head is facing directly forward and chin tucked in
greater when head is in correct posture
even greater when head is extended
greatest when head is fully flexed
lumbar spine loads
least when lying supine
low with relaxed standing
greater with supported sitting
greatest with unsupported sitting
compression loads are greatest during toe off
increase as velocity of walking increases
forward trunk flexion from standing
abdominals and iliopsoas move trunk forward
gravity pulls trunk downward
erector spine eccentrically control downward movement
pelvis rotates anteriorly at the hips after 60 degrees
gluteus maximus and hamstrings eccentrically control anterior pelvic rota
trunk extension from full flexion
erector spine very active in stabilizing spine
pelvis rotates posteriorly at hips during first 30 degrees
gluteus maximus and hamstrings concentrically produce this pelvic rotation
erector spinae concentrically produce extension during last 60 degrees
trunk side bending
quadratus lumborum, erector spinae, and abdominals on side of movement initiate trunk side bending
gravity pulls trunk further laterally
eccentrically controlled by opposite side
reverse to return to erect posture