Download Pelvic Girdle

Pelvic Girdle
Four bones: sacrum, coccyx and two hip bones (ilium, sichium and pubis)
Joints:
R and L sacroiliac posterolaterally
Symphysis pubis anteriorly
Lumbosacral superiorly
Functions:
Supports body weight
Transmits ground forces upward toward vertebral column
During ambulation provides movement on three planes
Supports viscera
Provides attachment for muscles
Formation of the bony portion of the birth canal
SI joint
Synovial, nonaxial between sacrum and ilium
A plane joint that locks firmly through rough surfaces
Function to transmit weight from upper body through column to hip bones
Designed for stability
Has no voluntary motion
Ligaments
Anterior sacroiliac is broad and flat on the anterior surface to connect the sacrum to the
ilium
Interosseous sacroiliac is the deepest, shortest and strongest
Short posterior sacroiliac runs more oblique between ilium and sacrum on dorsal surface
Long posterior sacroiliac more vertical between SIS and sacrum to prevent downward
movement of sacrum
Pubic Symphysis
Anterior connection of pelvis with fibrocartilage disk and little movement
Superior pubic ligament strengthens the superior and anterior portions
Inferior pubic ligament between the two inferior pubic rami to strengthen inferior portion
LS Joint
Has two additional ligaments: iliolumbar on the transverse process of L5 laterally to inner
lip of posterior crest to limit rotation and lumbosacral along transverse processes L5 to
sacrum
Pelvic Movements
With pelvic movement, three areas need be considered:
• The LS spine
• The SI joint
• The hip joints
A/P Tilt
During Anterior tilt the iliac crests and the ASIS move in an anterior direction. This
results in lumbar spine extension (and increase in lordosis) and hip flexion.
Muscles involved:
hip flexors (iliopsoas) and erector spinae
During Posterior tilt (aka therapeutic tilt) the iliac crest and the ASIS move in a posterior
direction. This results in lumbar spine flexion (a decrease in lordosis) and hip extension.
Muscles involved: gluteus maximus; hamstrings; abdominals
Lateral Tilts
The iliac crest drops toward that side; e.g. lateral tilt to the right means the right side is
lower, the left hip is hiked. With lateral pelvic tilt to the right you also get:
Trunk lateral flexion, but in the opposite direction
Hip abduction on the right
Hip adduction on the left
Muscles involved: (with lateral tilt to right)
Contralateral abdominals, erector spinae, quadratus lumborum and hip adductors
Ipsilateral hip abductors
Rotation
With rotation to the left the right side of the pelvis moves forward and vice versa.
With pelvic rotation to the left you also get:
Trunk rotation to the opposite side
Left hip IR
Right hip ER
Muscles involved:
Ipsilateral external oblique and contralateral internal oblique
Ipsilateral hip internal rotators; contralateral external rotators
Example: pelvic rotation to the left will be from a concentric contraction of the left
external oblique and the right internal oblique. If they did not contract, the trunk would
move with the pelvis in rotation