Lecture Notes: The Pelvis in the Kinetic Chain

Introduction

• The pelvis is a crucial link in the kinetic chain, functioning as the fulcrum connecting the lower and upper extremities.
• Fulcrum Definition: A center point on which levers rest or are supported.
  • Pelvis as the center point for upper and lower body forces.
  • Ground Reaction Forces and Top-Down Forces converge at the pelvis.

Sacroiliac (SI) Joint

• Convergence point of forces at the pelvis.
• Location: Where the iliac bones meet the spine at the sacrum.
• Common site of pain due to force mismanagement in the kinetic chain.
• Pelvis as a relay station for force transmission.

Pelvis and Lumbar Spine

• Focus on movement interventions.

Gait and Muscle Function

• 29 Muscles attach to the pelvis; these include core and leg muscles.
• Teaching approach: move from sagittal to frontal to transverse planes.

Sagittal Plane Dynamics

• Anterior Side:
  • Hip Flexors: Active during swing phase of gait, responsible for hip flexion and knee extension.
  • Eccentric contraction during mid-stance to slow hip extension.
• Posterior Side:
  • Glute Max, Medius, Hamstrings:
    • Decelerate hip flexion and knee extension during swing phase.
    • Drive hip extension and knee flexion during mid-stance.

Frontal Plane Dynamics

• Adductors:
  • Act as struts providing stability, much like cross braces on table legs.
  • Contract to adduct the femur, preventing lateral shifts.
• Abductors (Glute Medius, Tensor Fasciae Latae):
  • Contract to stabilize pelvis, preventing lateral shifts.
  • Form a lateral subsystem with glute medius for upright function.

Transverse Plane Dynamics

• Not covered in detail in this lecture; discussed in slides.
• Important for comprehensive understanding of pelvic stability.

Conclusion

• The pelvis functions as a link and force transmitter in the body.
• Acts as a fulcrum for levers, essential for stability and movement.
• Critical role in the lumbo-pelvic hip complex as the core of the kinetic chain.