Pelvic Girdle

Pelvic structure-bones

Sacrum

Coccyx

2 hip bones (ilium + ischium + pubis)

Pelvic structure-joints

Sacroiliac (2)

Pubic symphysis

Lumbosacral

Function of the pelvis

Supports body weight

Receives ground forces

Supports/protects pelvic viscera (reproductive organs)

Muscle attachment

Bony portion of birth canal

False pelvis

Bony area between iliac crests

No pelvic organs

Greater/major pelvis

True pelvis

Makes up the pelvic cavity

Contains pelvic organs

Birth canal

Lesser/minor pelvis

Male pelvis

Superior opening is heart shaped

Female pelvis

Superior opening is oval shaped

Pelvic cavity is shorter, less funnel shaped

Sacrum is shorter and less curved

Acetabulum and isschial tuberosities are farther apart

Sacroiliac joint

Synovial, non-axial

Transmits weight from upper body through vertebral column to the hip bones

Nutation (sacral flexion)

Occurs with trunk flexion or hip extension

Counternutation (sacral extension)

Occurs with trunk extension and hip flexion

Anterior sacroiliac ligament

Holds anterior portion of SI joint together

Sacrospinous ligament

Triangular ligament

Sacrotuberous ligament

Prevents forward rotation of sacrum

Interosseous sacroiliac ligament

Connects the tuberosities of ilium and sacrum

Posterior sacroiliac ligament

Prevents forward and downward movement of sacrum

Lumbosacral joint

Between 5th lumbar vertebra and sacrum

Optimal angle is 30 dg

Lumbar lordosis

Increased lumbar lordosis leads to increased lumbosacral angle and leads to increased shear stress at L5-S1

Anterior pelvic tilt

Pelvis tilts forward

Posterior pelvic tilt

Pelvis tilts backwards

Lateral tilt

Occurs when iliac crests are not level

Pelvic rotation

Step forward with R leg → pelvis is internally rotated on L side, externally rotated on R side

Step forward with L leg → pelvis is internally rotated on R side, externally rotated on L side

Anterior pelvic tilt force couple

Lumbar extensors pull posterior pelvis UP, hip flexors pull anterior pelvis DOWN

Posterior pelvic tilt force couple

Abdominal muscles pull anterior pelvis UP, hamstrings pull posterior pelvic DOWN

Anterior pelvic tilt clinical application

Increased lumbar lordosis

Trunk extensors and hip flexors adaptively SHORTEN and trunk flexors and hip extensors adaptively LENGTHEN

Posterior pelvic tilt clinical application

Reduced lumbar lordosis

Trunk flexors and hip extensors adaptively SHORTEN and trunk extensors and hip flexors adaptively LENGTHEN