Spinal Biomechanics Focused

Question 1

Define the 80-20 rule.

Answer 1

The posterior column does not really work as a load bearing column. They work as an articulated chain. The posterior structure is primarily loaded by tensile forces which are counteracted by the architecture and function of joints, ligaments and muscles. They transmit 20% of the load as a sagittally directed shear force. This is where the 80-20 rule is derived.

Question 2

What are the 3 functions of the disc?

Answer 2

To act as a shock absorber
To facilitate movement of the spinal column
To maintain vertebral spacing

Question 3

What anatomical components comprise the posterior column?

Answer 3

The pedicles, articular processes and laminae bones.

Question 4

Give an example of a first order level in the spine.

Answer 4

The facet joints of the spine.

Question 5

What types of motion is a vertebral motion segment capable of?

Answer 5

Axial rotation
Lateral bending
Lateral movement