Spinal Articulations Quiz

Interbody Joints

• Capable of translations and tilts in all directions

Zygapophyseal Articulation

• True synovial joints
• Fibroadipose meniscoid structures present
• Facet joint capsule restrains axial rotation
• Resistance to anterior shear

Lumbosacral Articulation

• Located between 5th lumbar vertebra and 1st sacral segment
• 1st sacral segment is inclined slightly anteriorly and inferiorly, forming an angle with the horizontal (lumbosacral angle)
• Increase in lumbosacral angle increases lumbar lordosis and shearing stress at the lumbosacral joint

Ligaments

• Supraspinous ligament: well developed only in the upper lumbar region, terminates at L4 or L3
• Intertransverse ligaments: not true ligaments in the lumbar area, replaced by the iliolumbar ligament at L4
• Interspinous ligament: has the least overall stiffness
• Anterior longitudinal ligament: strong and well developed in this region
• Posterior longitudinal ligament: thin ribbon in the lumbar region
• Ligamentum flavum: thickened in the lumbar region
• Iliolumbar ligaments: series of bands extending from the transverse processes of L4 and L5 to the iliac crests of the pelvis, with three bands (ventral, dorsal, and sacral)

Ligament Function

• Anterior longitudinal ligament: limits extension
• Posterior longitudinal ligament: limits forward flexion
• Ligamentum flavum: limits forward flexion
• Supraspinous ligament: limits forward flexion
• Interspinous ligaments: limit forward flexion
• Intertransverse ligaments: limit contralateral lateral flexion
• Iliolumbar ligament: resists anterior sliding of L5 and S1

Muscles of Lower Spine Region

• Serve roles of producing and controlling movement of the trunk
• Stabilizing the trunk for motion of the lower extremities
• Assist in attenuating extensive forces that affect this area

Posterior Muscles

• 3 layers: superficial, intermediate, and deep

Spinal Coupling

• Kinematic phenomenon in which movement of the spine in one plane is associated with an automatic movement in another plane
• Most consistent pattern involves an association between axial rotation and lateral flexion

Lumbo-Pelvic Rhythm

• Kinematic relationship between the lumbar spine and hip joints during sagittal plane movements
• Bending forward: lumbar flexion (40°) followed by anterior tilting of the pelvis at the hip joint (70°)
• Return to erect: posterior tilting at the pelvis at the hips followed by extension of the lumbar spine

Kinetics

• Forces that cause, arrest, or modify motion in a system: gravity, muscles, friction, and external resistance

Compression

• Lumbar region provides support for the weight of the upper part of the body in static and dynamic situations
• Lumbar region must withstand tremendous compressive loads produced by muscle contraction
• Lumbosacral loads in erect standing posture: 0.82 to 1.18 times body weight
• Lumbosacral loads during level walking: 1.41 to 2.07 times body weight

Interbody Joint Motion

• Lumbar extension: increases lumbar lordosis, posterior tilting, and gliding of superior vertebra
• Lumbar extension reduces the diameter of intervertebral foramina
• Fewer ligaments checks extension
• Nucleus pulposus displaces anteriorly

Lateral Flexion

• Superior vertebra laterally tilts, rotates, and translates over the vertebra below
• Annulus fibrosus is compressed on the concavity of the curve and stretched on the convex side
• Nucleus pulposus migrates slightly towards the convex side of the bend

Spinal Rotation

• Rotation causes movement of the vertebral arch in the opposite direction
• Ipsilateral facet joints go for gapping and contralateral facet joints for impaction
• Axial rotation is limited due to the shape of the zygapophyseal joints and restricted by tension created in the stretched capsule of the apophyseal joints and stretched fibers within the annulus fibrosus