Detailed Notes on the Pelvis

Introduction to the Pelvis
  • Functions of the Pelvis:
    • Supports weight bearing and locomotion (movement).
    • Protects organs:
    • Reproductive organs
    • Digestive organs (bowel)
    • Urinary organs
    • Connects trunk to lower limbs.
  • Shape and Structure:
    • Built for strength and stability rather than mobility.
    • Joints move very little (sacroiliac joint and pubic symphysis).
Bony Structure of the Pelvis
  • Main Bones:
    • Ilium: The superior bone, identified by the iliac crest.
    • Sacrum: Located between the two ilia, formed from five fused vertebrae.
    • Pubis: The more anterior bone.
    • Ischium: The bone that appears posteriorly and inferiorly.
  • Fusion of Bones:
    • By puberty, ilium, pubis, and ischium are fused, meaning little growth occurs in relation to each other.
Anatomical Features of the Ilium
  • Iliac Crest: The prominent upper edge of the ilium.
  • Iliac Fossa: A depression for muscle attachment (label: F O S S A).
  • Anterior Superior Iliac Spine (ASIS): The prominent forward jut of the ilium.
  • Anterior Inferior Iliac Spine (AIIS): A similar structure located just below the ASIS.
  • Acetabulum:
    • The hip joint socket, shaped like a cup (latin: little vinegar cup).
    • Formed by contributions from ilium, pubis, and ischium.
  • Obturator Foramen:
    • A large opening between the pubis and ischium.
Joints of the Pelvis
  • Sacroiliac Joints:
    • Connects sacrum and ilium; very strong and stable with thick ligaments.
  • Pubic Symphysis Joint:
    • Located anteriorly, between the two pubic bones; has limited movement.
    • Stabilized by superior and inferior pubic ligaments and a fibrocartilaginous disc.
Differences Between Male and Female Pelvis
  • Shape Variations:
    • Male pelvis: Taller and narrower ilium.
    • Female pelvis: Broader and wider, facilitating childbirth.
  • Subpubic Angle:
    • Male: Smaller angle
    • Female: Greater angle, accompanying wider ischial tuberosities for childbirth.
Summary of Anatomical Terms
  • Common terms to label:
    • Sacroiliac Joints: Connect sacrum and ilium.
    • Sacrum: Triangular bone between the iliac bones.
    • Iliac Fossa: Depression area on the ilium.
    • Coccyx: Tailbone below the sacrum.
    • Acetabulum: Hip joint socket.
    • Pubic Symphysis: Joint between the pubic bones.
    • Ischium: Bone forming part of the pelvis.
    • Ischial Tuberosities: Thickened areas on posterior pelvis, serve as weight-bearing surfaces.
Conclusion
  • Reflect on the anatomical features and consider gender differences in pelvis shape to gain a deeper understanding of the pelvis's structure and function.