Lumbar Spine Biomechanics Flashcards
At what level does the spinal cord terminate into the cauda equina?
L1-2.
What neuro symptoms would accompany damage to the cauda equina?
i) flaccid paralysis
ii) diminished reflexes
iii) altered sensation
What are the 5 key characteristics of cauda equina syndrome?
i) Altered sensation: saddle parasthesia
ii) Altered bladder fuction: premonition, control
iii) Loss of sexual function
iv) Loss of anal tone: premonition, control
v) Bilateral neurogenic sciatica
What are the joint components of a lumbar spine motion segment?
One intervertebral joint and two z-joints.
What are the components of the anterior/central joint of a spinal segment?
Two vertebral bodies and a common disc.
What type of joint is the anterior intervertebral joint?
i) synarthroses (cartilagenous)
ii) symphysis
What is the function of z-joints?
i) Limit extension and rotation
ii) 16% weight bearing
iii) direct movement of the spine
What joint type is a z-joint?
i) synovial (diarthroses)
ii) complex
iii) planar
Describe the concavity and convexity of the z-joints.
i) Inferior facet of superior vertebrae (IFSV): convex
ii) superior facet of inferior vertebrae (SFIV): concave
What direction do the superior and inferior facet face in the lumbar spine?
i) superior facet: laterally and anteriorly
ii) inferior facet: medially and posteriorly
What is the resting position of the z-joints?
Midway flexion and extension.
What is the close packed position of the z-joints?
Extension.
What is the capsular pattern of the z-joints?
SF = rot’n > extension.
Describe the osteokinematics of lumbar spine flexion at the z-joints.
i) anterior rotation (8’-13’)
ii) anterior translation (1-3mm)
Describe the osteokinematics of lumbar extension at the z-joints.
i) posterior rotation (1’-5’)
ii) posterior translation (1mm)
Describe the arthrokinematics of lumbar flexion at the z-joints.
IFSV anterior roll, IFSV anterior and superior glide.
Describe the arthrokinematics of lumbar extension at te z-joints.
IFSV posterior roll, IFSV posterior and inferior glide.
Decribe the osteokinematics of side flexion at the z-joints.
i) Rotates in transverse plane
ii) lateral translation of superior vertebrae
iii) superior vertebrae tilts (rotate in coronal plane)
Describe the arthrokinematics of side flexion at the z-joints.
i) ipsilateral IFSV glides inferiorly and posteriorly
ii) contralateral IFSV glides anteriorly and superiorly
Which structures are loaded with lumbar compression?
i) disc
ii) vertebral body
iii) vertebral end plate
Which structures are loaded with lumbar shear?
i) annular fibres
ii) z-joints
iii) spinal ligaments
What structures are loaded with lumbar rotation?
i) annular fibres
ii) contralateral impaction of z-joint
iii) ipsilateral distraction of z-joint
What are three key points from intradiscal pressure studies of the lumbar spine?
i) Increased pressure in sitting vs standing erect
ii) Lifting with knees bent helps to decrease presure
iii) Load held in front of body increases pressure (esp. with forward bend)
Which muscles of the inner unit core are use anticipatory activation in response to limb movement?
i) mid & lower fibres of transversalis abdominis
ii) mid & lower fibres of internal oblique
Which muscle is the primary lumbopelvic stabilizer?
Transversalis abdominis.
How does inner unit core activation change following presence of LBP?
i) transversalis abdominis has reactive activation, not anticipatory, to limb movement.
ii) multifidus demonstrates preferential segmental atrophy (30% in days of onset, also with bedrest)
What is the most effective muscle activation pattern to increase intra-abdominal pressure and what is the effect?
Compress cranially and caudally - diaphragm lowers and pelvic floor raises.
i) extensor torque (mild)
ii) stabilization
Describe the habitual movements of lumbar flexion from above.
i) femur - (posterior?)
ii) pelvis - APT
iii) thoracolumbar - flexes
iv) sacrum on pelvis - nutates
v) L5 on sacrum - flexes
Describe the habitual movements of lumbar extension from above.
i) femur - anterior
ii) pelvis - PPT
iii) thoracolumbar - extends
iv) sacrum on pelvis - nutated
v) L5 on sacrum - extends
Describe the habitual movements of left lumbar side flexion from above.
i) femur - L ABD, R ADD
ii) pelvis - ipsilateral tilt coronal plane
iii) innominate - R posterior rotation, L anterior rotation
iv) thoracolumbar - side flexes
v) sacrum - R rotation
vi) L5 on sacrum - R rotation, R side flexion
Describe the habitual movements of left lumbar rotation from above.
i) femur - L flex/IR (postero-medial), R ext/ER (anteromedial)
ii) pelvis - L rotation, tranverse plane
iii) innominate - L posterior rotation, R anterior rotation
iv) thoracolumbar - rotates
v) sacrum - L rotation
vi) L5 on sacrum - L rotation
