Pelvic brim

• Sacral promontory posteriorly.
  
• Top inner border of the body of the pubic bone.
  
• Top inner border of the symphysis pubis anteriorly.
  

Mid pelvis

• Ischial spine.
  

Outlet

• Ischial tuberosity laterally.
  
• Inferior border of symphysis pubis anteriorly.
  
• Tip of coccyx.