Lumbar Spine Biomechanics

Question 1

At what level does the spinal cord terminate into the cauda equina?

Answer 1

L1-2.

Question 2

What neuro symptoms would accompany damage to the cauda equina?

Answer 2

i) flaccid paralysis
ii) diminished reflexes
iii) altered sensation

Question 3

What are the 5 key characteristics of cauda equina syndrome?

Answer 3

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

Question 4

What are the joint components of a lumbar spine motion segment?

Answer 4

One intervertebral joint and two z-joints.

Question 5

What are the components of the anterior/central joint of a spinal segment?

Answer 5

Two vertebral bodies and a common disc.

Question 6

What type of joint is the anterior intervertebral joint?

Answer 6

i) synarthroses (cartilagenous)

ii) symphysis

Question 7

What is the function of z-joints?

Answer 7

i) Limit extension and rotation
ii) 16% weight bearing
iii) direct movement of the spine

Question 8

What joint type is a z-joint?

Answer 8

i) synovial (diarthroses)
ii) complex
iii) planar

Question 9

Describe the concavity and convexity of the z-joints.

Answer 9

i) Inferior facet of superior vertebrae (IFSV): convex

ii) superior facet of inferior vertebrae (SFIV): concave

Question 10

What direction do the superior and inferior facet face in the lumbar spine?

Answer 10

i) superior facet: laterally and anteriorly

ii) inferior facet: medially and posteriorly

Question 11

What is the resting position of the z-joints?

Answer 11

Midway flexion and extension.

Question 12

What is the close packed position of the z-joints?

Answer 12

Extension.

Question 13

What is the capsular pattern of the z-joints?

Answer 13

SF = rot’n > extension.

Question 14

Describe the osteokinematics of lumbar spine flexion at the z-joints.

Answer 14

i) anterior rotation (8’-13’)

ii) anterior translation (1-3mm)

Question 15

Describe the osteokinematics of lumbar extension at the z-joints.

Answer 15

i) posterior rotation (1’-5’)

ii) posterior translation (1mm)

Question 16

Describe the arthrokinematics of lumbar flexion at the z-joints.

Answer 16

IFSV anterior roll, IFSV anterior and superior glide.

Question 17

Describe the arthrokinematics of lumbar extension at te z-joints.

Answer 17

IFSV posterior roll, IFSV posterior and inferior glide.

Question 18

Decribe the osteokinematics of side flexion at the z-joints.

Answer 18

i) Rotates in transverse plane
ii) lateral translation of superior vertebrae
iii) superior vertebrae tilts (rotate in coronal plane)

Question 19

Describe the arthrokinematics of side flexion at the z-joints.

Answer 19

i) ipsilateral IFSV glides inferiorly and posteriorly

ii) contralateral IFSV glides anteriorly and superiorly

Question 20

Which structures are loaded with lumbar compression?

Answer 20

i) disc
ii) vertebral body
iii) vertebral end plate

Question 21

Which structures are loaded with lumbar shear?

Answer 21

i) annular fibres
ii) z-joints
iii) spinal ligaments

Question 22

What structures are loaded with lumbar rotation?

Answer 22

i) annular fibres
ii) contralateral impaction of z-joint
iii) ipsilateral distraction of z-joint

Question 23

What are three key points from intradiscal pressure studies of the lumbar spine?

Answer 23

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)

Question 24

Which muscles of the inner unit core are use anticipatory activation in response to limb movement?

Answer 24

i) mid & lower fibres of transversalis abdominis

ii) mid & lower fibres of internal oblique

Question 25

Which muscle is the primary lumbopelvic stabilizer?

Answer 25

Transversalis abdominis.

Question 26

How does inner unit core activation change following presence of LBP?

Answer 26

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)

Question 27

What is the most effective muscle activation pattern to increase intra-abdominal pressure and what is the effect?

Answer 27

Compress cranially and caudally - diaphragm lowers and pelvic floor raises.

i) extensor torque (mild)
ii) stabilization

Question 28

Describe the habitual movements of lumbar flexion from above.

Answer 28

i) femur - (posterior?)
ii) pelvis - APT
iii) thoracolumbar - flexes
iv) sacrum on pelvis - nutates
v) L5 on sacrum - flexes

Question 29

Describe the habitual movements of lumbar extension from above.

Answer 29

i) femur - anterior
ii) pelvis - PPT
iii) thoracolumbar - extends
iv) sacrum on pelvis - nutated
v) L5 on sacrum - extends

Question 30

Describe the habitual movements of left lumbar side flexion from above.

Answer 30

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

Question 31

Describe the habitual movements of left lumbar rotation from above.

Answer 31

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