Pelvic Girdle Function and Structure

Pelvic Girdle Function

• Primary functions:
  • Bears weight of the upper body during sitting and standing
  • Transfers weight from axial to lower appendicular skeleton for standing and walking
  • Provides attachment for locomotion/posture muscles and abdominal wall muscles, withstanding generated forces.

Pelvic Girdle Bones

• Composed of:
  • Right and left hip bones (coxal/pelvic bones)
    • Each forms from the fusion of three bones: ilium, ischium, pubis
  • Sacrum: formed by fusion of five originally separate sacral vertebrae

Differences Between Male and Female Pelvis

• General Structure

  • Male: Thick and heavy, deep
  • Female: Thin and light, shallow

• Pelvic Inlet/Aperture:

  • Male: Narrow and deep, tapering
  • Female: Wide and shallow, cylindrical

• Pelvic Outlet/Aperture:

  • Male: Comparatively small, heart-shaped and narrow
  • Female: Comparatively large, oval and rounded

• Pubic Arch/Subpubic Angle:

  • Male: Narrow (<70°), inverted V shape
  • Female: Wide (>80°), nearly 90°

• Obturator Foramen:

  • Male: Round
  • Female: Oval

• Acetabulum:

  • Male: Small
  • Female: Large

• Greater Sciatic Notch:

  • Male: Narrow
  • Female: Wide

Pelvic Cavity Contents

• Terminal parts of ureters
• Urinary bladder
• Rectum
• Pelvic genital organs
• Blood vessels, lymphatics, and nerves

Pelvic Diaphragm Muscles

• Coccygeus
• Levator Ani
• Pelvic fascia (connective tissue space between peritoneum and pelvic walls)

Pelvic Artery/Anastomosis

• Gonadal (testicular in male, ovarian in female)
• Superior rectal
• Median sacral
• Internal iliac

Pelvic Kinematics (Nutation/Counternutation)

• Nutation: Sacral base tips forward and downward relative to the ilium
• Counternutation: Sacral base tips backward and upward. The reverse of nutation.

Lumbo-Pelvic Rhythm

• Forward bending: Pelvis tilts anteriorly, lumbar spine flexes to maintain balance and greater range of motion
• Returning to upright position: Lumbar spine extends as pelvis tilts posteriorly.