The Pelvic Girdle

What 4 bones does the pelvis contain?

• Sacrum

• Coccyx

• Two hip bones (ilium + ischium + pubis_

What 6 joints are in the pelvic girdle?

• 3 joints within the pelvis: pubic symphysis, and 2 sacroiliac joints

• 3 joints of the pelvis that articulate with other body regions: lumbosacral joint, and 2 hips joints

What are the function of the pelvis?

• Supports weight of the body

• Receives ground forces

• Supports and protects the pelvic viscera

• Provides attachment for muscles

• Makes up the bony portion of the birth canal

What are 5 the movements that occur at the pelvis?

• Anterior and posterior pelvic tilt (sagittal plane, frontal axis)

• Right and left lateral tilt (frontal plane, sagittal axis)

• Right and left pelvic elevation (frontal plane, sagittal axis)

• Right and left pelvic rotation (horizontal plane, vertical axis)

• Right and left pelvic shift (frontal plane, no axis, it’s a linear movement)

What is the false pelvis?

• Greater or major pelvis

• Bony area between the iliac crests

• Superior to the pelvic inlet

• No plevic organ

What is the true pelvis?

• Lesser or minor pelvis

• Lies between the pelvic inlet and outlet

• Makes up the pelvic cavity

• It contains portions of the GI tract, urinary tract, and some reproductive organs

• Forms the birth canal in females

What is the shape of the female pelvis?

Oval-shaped

What is the shape of the male pelvis?

Heart-shaped

What is the difference between the female and male pelvic cavity?

Female pelvis is shorter and less funnel-shaped

What is the difference between the female and male sacrum?

Female is shorter and less curved

What are differences in the male and female ischial tuberosities?

The female acetabula and ischial tuberosities are farther apart

What are the sacroiliac joints?

• 2 joints between the sacrum and the ilium on either side

• Synovial, nonaxial joint

• Plane joints with irregular articular surfaces

• Functions to transmit weight from the upper body through the vertebral column to the hip bones

What kind of motion occurs at the SI joint?

Minimal motion

What is the pubic symphysis?

• A cartilaginous joint formed by the anterior portion of the right and left pubic bones

• Has a fibrocartilaginous disk between the two bones

What is nutation (sacral flexion)?

• Occurs when the superior portion of the sacrum moves anteriorly and inferiorly and the inferior portion of the sacrum moves posteriorly

• Occurs with trunk flexion or hip extension

• Pelvic outlet becomes larger

What is counternutation (sacral extension)?

• The superior portion of the sacrum moves posteriorly and superiorly and the inferior portion moves anteriorly

• Occurs during trunk extension or hip flexion

• The pelvic inlet becomes larger

Where does the rectus femoris attach?

The AIIS

What is the anterior sacroiliac ligament?

Holds the anterior portion of the SI joint together

What is the sacrospinous ligament?

A triangular ligament that goes from the posterior side of the lateral sacrum and coccyx to the spine of the ischium

What is the sacrotuberous ligament?

• A triangular ligament that goes from the PSIS and PIIS of the ilium, sacrum, and coccyx to the ischial tuberosity

• Prevents forward rotation of the sacrum

What is the interosseous sacroiliac ligament?

• Fills the roughened area immediately above and behind the auricular surfaces and the anterior sacroiliac ligament

• Connects the tuberosities of the ilium and sacrum

What is the posterior sacroiliac ligament?

• Short posterior sacroiliac ligament + long posterior sacroiliac ligament

• Prevents forward and downward movement of the sacrum

What is the lumbosacral joint?

• Between L5 and S1

• Cartilaginous joint (with a fibrocartilaginous disk)

What is the lumbosacral angle?

• The angle between the superior surface of the sacrum and a horizontal line

• PPT says 30 dgs is best, book says 40 dgs

• An significant increase causes shear stress at L5 and S1

• Increases during anterior pelvic tilt and decreases during posterior pelvic tilt

What movements occur at the lumbosacral joint?

• Mainly flexion and extension (sagittal plane, frontal axis)

• Little rotation (transverse plane, vertical axis)

• Lateral flexion (frontal plane, sagittal axis)

What is anterior pelvic tilt?

The superior aspect of the pelvis tilts forward and moves the ASIS anterior to the pubic symphysis

What happens to the lumbar spine during anterior pelvic tilt?

• Causes lumbar lordosis (hyperextension of lumbar spine) and hip flexion - looks like sticking your butt out while pulling your head back

What increases anterior pelvic tilt and lumbar lordosis?

Shortened hip flexors (hip flexor contracture)

What is posterior pelvic tilt?

The superior aspect of the pelvis tilts backward and moves the ASIS posterior to the pubic symphysis

What happens to the lumbar spine during posterior pelvic tilt?

Flattens the lumbar curve (makes a flat back)

What plane does anterior and posterior tilt happen in? What axis?

The sagittal plane and frontal axis

What increases posterior pelvic tilt and decreases lumbar lordosis?

Shortened hamstrings (hamstring contracture)

What is swayback (of the pelvis and spine)?

When the pelvis is pushed forward and the trunk leans back

What is lateral tilt?

• Occurs when the two iliac crests are not level (horizontally)

• Occurs in the frontal plane and sagittal axis

• Happens during ambulation as the pelvis dips side to side

What side is the lateral tilt named for?

The side of the unsupported leg; the non-weight bearing, lower side (if you are leaning your weight on your right leg, it is left lateral tilt)

What is pelvic elevation (AKA hip hiking)?

• When the pelvis rises on the unsupported side due to a concentric contraction

• Named for the higher side; ex. left pelvic elevation is when the left side is high and the weight is on the right leg

When standing on the RLE so that the LLE raises, what side of pelvic elevation is it? What muscles are causing this elevation?

Left hip elevation, right hip abductors, left quadratus lumborum

What is Trendelenburg gait pattern?

When one side of the pelvis drops during the the swing phase of walking due to weakness of the opposite side gluteus medius

What is pelvic rotation?

• Occurs in transverse plane

• The pelvis moves forward and backward in relation to the other side

• In neutral, both the ASISs are in the same plane

• During anterior rotation of the right pelvis the left plevis rotoates around the femoral head (medial rotation)

How is pelvic rotation named?

The side of the pelvis that is more anterior (or more forward, like during a step)

What are the mechanics of the pelvic rotation?

• The front leg laterally rotates

• The back leg medially rotates

What happens to the right pelvis during anterior rotation (stepping forward)? What hapens to the left pelvis during this same motion?

• The right side (front leg) laterally rotates

• The left side (back leg) medially rotates

What happens to the right pelvis during posterior rotation (stepping backward)? What happens to the left pelvis during the same motion?

• The right pelvis (back leg) medially rotates

• The left pelvis (front leg) laterally rotates

What force couple occurs during anterior pelvic tilt?

• The lumbar trunk extensors pull superiorly on the posterior side

• Simultaneously, the hip flexors pull inferiorly on the anterior side

What force couple occurs during posterior pelvic tilt?

• The abdominals pull superiorly on the anterior side

• The hamstrings pull inferiorly on the posterior side

What force couple occurs during lateral tilt?

When standing on the right LE:

• The left trunk lateral benders pull up on the left hip (quadratus lumborum)

• The right hip abductors pull inferiorly on the right hip (abductors and gluteus medius)