Pelvis Bone Anatomy and Function

Structure and Composition

• The pelvis bone is a basin-shaped structure composed of four bones: two innominate bones, the sacrum, and the coccyx.
• The innominate bones are formed by the fusion of three bones: ilium, ischium, and pubis.
• The pelvis bone is made up of compact and cancellous bone tissue.

Functions

• The pelvis bone provides a base of support for the spine and upper body.
• It acts as a point of attachment for muscles, ligaments, and tendons.
• The pelvis bone protects the reproductive organs, bladder, and rectum.
• It plays a crucial role in childbirth, as it expands to allow the baby to pass through.

Features and Landmarks

• The pelvis bone has several key features, including:
  • Iliac crest: the curved ridge at the top of the ilium bone.
  • Acetabulum: the socket in the pelvis bone that forms the hip joint.
  • Ischial tuberosity: the bony prominence on the bottom of the pelvis bone.
  • Pubic symphysis: the cartilaginous joint that connects the two pubic bones.
  • Sacroiliac joint: the joint that connects the sacrum and ilium bones.

Types of Pelvis

• There are four main types of pelvis bones, classified based on their shape and size:
  • Gynaecoid pelvis: the typical female pelvis, characterized by a wide, rounded inlet.
  • Android pelvis: the typical male pelvis, characterized by a narrow, triangular inlet.
  • Anthropoid pelvis: a rare type of pelvis, characterized by a narrow, oval inlet.
  • Platypelloid pelvis: a rare type of pelvis, characterized by a flat, oval inlet.