Anatomy and Physiology: Sacroiliac Joint and Pelvic Ligaments

Introduction

• Lecture by Kevin Tokeoff from Catalyst University
• Focus on the sacroiliac (SI) joint and associated pelvic ligaments
• Future topics: iliofemoral (hip) joint and other pelvic joints

Sacroiliac Joint (SI Joint)

• Definition: Low mobility synovial joint between sacrum and ilium
• Characteristics:
  • Very stable, low mobility
  • Surface area is extremely small
  • Lined with different cartilages:
    • Sacral side: Hyaline cartilage
    • Iliac side: Fibrocartilage

Pelvic Structures

• Ilium, Ischium, and Pubis:
  • Obtained from pelvis structure
  • Obturator foramen lined with obturator membrane
  • Obturator canal allows passage of obturator nerve

Key Ligaments

• Iliolumbar Ligament:

  • Connects L5 vertebra transverse process to sacrum (S1)
  • Blends with anterior sacroiliac ligament

• Anterior Sacroiliac Ligament:

  • Transverse fibers supporting SI joint

• Sacrotuberous and Sacrospinous Ligaments:

  • Sacrospinous: Connects sacrum to ischial spine, prevents sacral nutation
  • Sacrotuberous: Connects sacrum to ischial tuberosity, also prevents nutation

Iliofemoral Joint Ligaments (Hip Joint)

• Iliofemoral (Y) Ligament:

  • Connects ilium to femur in a Y-shape

• Pubofemoral Ligament:

  • Connects pubis to femur

Posterior View of Pelvis

• Posterior Sacroiliac Ligaments (Dorsal):

  • Short and long fibers, stabilize posterior SI joint

• Interosseous Sacroiliac Ligaments:

  • Deep to posterior ligaments, connect sacrum and iliac tuberosities

Stability of the Sacrum

• Position and Stability:
  • Sits between ilia, supporting upper body weight
  • Stability factors beyond ligaments (to be covered in next video)

Conclusion

• Importance of understanding pelvic ligament structures and the dynamics of the SI joint
• Upcoming discussions on further stabilizing factors of the sacrum

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