Pelvic Girdle and Hip Bone Structure

Pelvic Girdle Structure

• The pelvic girdle is formed by two coxal (hip) bones and the sacrum.
• The terms "pelvic girdle" and "pelvis" have slightly different meanings
• Pelvic girdle bones (coxal bones and sacrum) are large and heavy.
• They are securely attached to the axial skeleton.
• The pelvic girdle is crucial for weight-bearing.
• It supports the reproductive organs, urinary bladder, and parts of the large intestine.

Hip Bone Composition

• Each hip bone is a fusion of three bones: ilium, ischium, and pubis.

• The ilium is a large, flaring bone, forming most of the hip bone.

• The ilium's wing-like portions are called alae.

• The iliac crest, the upper edge of an ala, is a key anatomical landmark.

• The ischium is the lower part of the hip bone.

• The ischial tuberosity is a rough area that bears weight during sitting.

• The ischial spine is crucial for pelvic outlet width, particularly in pregnancy.

• The pubis is the most anterior part of the hip bone.

• The pubic bones form a cartilaginous joint called the pubic symphysis.

• The ilium, ischium, and pubis fuse at the acetabulum, a deep socket receiving the thigh bone head.

Pelvic Cavity and Dimensions

• The pelvis is partitioned into false and true pelvis regions.
• The false pelvis is above the flared ilia.
• The true pelvis lies below this area, surrounding the pelvic brim (Figure 5.24c).
• The size and shape of the true pelvis are critical for childbirth.
• The inlet and outlet are key dimensions measured carefully by obstetricians.

Sex-Specific Pelvis Variations

• The female pelvis usually differs from the male pelvis in several aspects:
  • The female inlet is larger and more circular.
  • The female pelvis is generally shallower, with lighter and thinner bones.
  • The female ilia flare more laterally creating a wider hip.
  • The female sacrum is shorter and less curved.
  • The female ischial spines are shorter and separated more, enlarging the outlet.
  • The female pubic arch is more rounded, with a greater angle.

Test your understanding of the pelvic girdle and hip bone composition with this detailed quiz. Explore the anatomy, function, and importance of the coxal bones, sacrum, and their roles in supporting various body systems. Perfect for anatomy students!