Lumbar spine 2020.pptx

biomechanics of lumber spine

1. BIOMECHANICS OF LUMBAR SPINE

2. Topics to be discussed; Structure of lumbar spine Lumbar articulations Ligaments & Fascia Lumbopelvic rhythm Kinematics of lumbar spine Kinetics of lumbar spine

3. Structure of Lumbar spine The first four lumbar L1-L4 vertebrae are similar in structure . The fifth lumbar L5 vertebra has structural adaptations for articulation with the sacrum.

4. 5 TH LUMBAR VERTEBRA It is a transitional vertebra: involving , providing, or consisting of a passage, movement, or change from one state, condition, subject, place, etc., to another L5 has a wedge-shaped body The L5/S1 disk also is wedge shaped. The superior discal surface area of L5 is about 5% greater than the areas of discs at L3 and L4. The inferior discal surface area of L5 is smaller than the discal surface area at other lumbar levels. The spinous process of L5 is smaller than other lumbar spinous processes The transverse processes of L5 are large and directed superiorly and posteriorly

5. Lumbosacral articulation It is formed by the L5 and S1. The 1 sacral segment, which is inclined slightly anteriorly and inferiorly, forms an angle with the horizontal called the Lumbosacral Angle. An increase in this angle will result in an increase in lordosis of the lumbar curve. Increase the amount of shearing stress at the lumbosacral joint

6. ARTICULATION Interbody joints The interbody joints of the lumbar region are capable of translations and tilts in all directions. Zygapophyseal joints Allows flexion , extension , rotation and lateral bending

7. Intertransverse Ligament Supraspinous Ligament Content Here Content Here Ligaments of the Lumbar Spine Supraspinous ligament is well developed in upper lumbar region and may terminate at L3 and L4. The ligament is almost always absent at L5/S1 Intertransverse ligaments are not true ligaments in the lumbar area and are replaced by the iliolumbar ligament at L4. Iliolumbar Ligament There are three primary bands: Ventral (or anterior) band Dorsal (or posterior) band Sacral band (lumbosacral ligament) The illiolumber ligaments is very strong and stabilizing the 5 lumbar vertebra (preventing the vertebra from anterior displacement) resisting flexion, extension, axial rotation, and lateral bending of L5 on S1

8. Lumbar Pelvis Rhythm It is a specific instance of coordinated, simultaneous activity of lumbar flexion and anterior tilting of the pelvis in the sagittal plane during trunk flexion and extension. This combined lumbar and pelvic motion is lumbar-pelvic rhythm

9. Lumbar Pelvis Rhythm Bending over to touch one’s toes with knees straight Lumbar flexion followed by anterior tilting of the pelvis at the hip joints Return to the erect posture Lumber extension Initiated by posterior tilting of the pelvis at the hips

10. Kinematics of Lumbar Movements Flexion Extension Lateral flexion Rotation (limited by zygapophyseal joints)

11. Kinetics Compression: The increase size of the lumbar vertebral bodies and discs in comparison with their counterparts in the other regions help the lumbar structures support the additional weight.

12. Shear: In the upright standing position, the lumbar segments are subjected to anterior shear forces cause by the lordotic position, the body weight, and ground reaction forces. This anterior shear or translation of the vertebra is resisted by direct impaction of the inferior zygapophyseal facets of the superior vertebra against the superior zygapophyseal facets of the adjacent vertebra below.

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