Pelvic Girdle

Lecture 5

Pelvic girdle bones and structures

(1) Sacrum

(2) The two hip bones, comprising the ilium

(3) Ischium

(4) pubic bone

(5) Pubic symphsis

(6) Acetabulum

(7) Obturator foramen

(8) Coccyx

The joints in the pelvic girdle

- The right and left sacroiliac joints (posterolaterally)

- The symphysis pubis (anteriorly)

- The lumbosacral joint (superiorly).

Pelvis Functions - During walking, the pelvic girdle moves as a unit in

all three planes to allow for relatively smooth motion.

- It supports and protects the pelvic viscera, provides attachment for muscles, and makes up the bony portion of the birth canal in females.

Pelvis Functions

- It receives GRF foot transmits them upward toward the vertebral column.

- Supports the weight of the body through the vertebral column hip bones.

False and True Pelvis

False pelvis

Also called the greater or major pelvis.

It is the bony area between the iliac crests and superior to the pelvic inlet.

There are no pelvic organs within the false pelvis.

True pelvis

Also called the lesser or minor pelvis.

The true pelvis area makes up the pelvic cavity.

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

In females, it forms the birth canal.

It lies between the pelvic inlet and the pelvic outlet.

The greater pelvis (yellow) is larger and superior to the lesser pelvis (red) where the pelvic inlet is located.

Why it’s called True/ False Pelvis???

Some believe that the false pelvis is actually part of the abdominal cavity and therefore that the true pelvis is the only "true" portion of the pelvis!!!

The false pelvis supports the intestines and transmits part of their weight to the anterior wall of the abdomen.

1 Extra Mark !!!

Female vs. Male Pelvis!!!!

Several comparisons can be made between the male and female pelvis.

Female vs. Male Pelvis!!!!

* The superior opening into the pelvic cavity is more oval in females and more heart-shaped in males.

* The pelvic cavity is shorter and less funnel-shaped in females.

* The sacrum is shorter and less curved, the pelvis walls are not as vertical, the acetabula and ischial tuberosities are farther apart in females.

Female vs. Male Pelvis!!!! * It can also be noted that the pelvic arch is wider

and more rounded in females. These arches can be visually represented by the arch of the extended thumb and index finger in females, and the extended index and middle finger in males.

Sacroiliac Joint

* Articulations???!!

* Joint type???!!!

a synovial plane joint

* Axis of rotation???!!!

Nonaxial joint

The sacrum and the ilium, its articular surfaces are very irregular (helps to lock the two surfaces together.)

The function of the sacroiliac joint is to transmit weight from the upper body through the vertebral column to the hip bones.

Sacroiliac Joint

Sacroiliac Joint

It is designed for great stability and has very little mobility.

Synovial joints, its articular surface is lined with hyaline cartilage, Synovial membrane lines the nonarticular portions of the joint. It has a fibrous capsule reinforced by ligaments

SI Joint Motion

The actual type and amount of movement occurring at the SI joint is the subject of considerable controversy. However, it is generally accepted that the motions that do occur at the SI joint are nutation and counternutation.

Nutation

(Sacral flexion)

the base of the sacrum (on the superior end) moves anteriorly and inferiorly.

This causes the inferior portion of the sacrum and the coccyx to move posteriorly.

The pelvic outlet becomes larger.

Counternutation

Sacral extension

The base of the sacrum moves posteriorly and superiorly

causing the tip of the coccyx to move anteriorly.

The pelvic inlet becomes larger.

The amount of motion that occurs in nutation and counternutation is minimal, and can only occur in association with other joint motions.

Nutation occurs with trunk flexion or hip extension.

Counternutation occurs with trunk extension or hip flexion.

Nutation vs. Counternutation

SI joint motions & Childbirth

These motions are also important during childbirth!!!!

In the early stages, when the baby moves through the pelvic inlet, the anterior-posterior diameter here needs to be larger the SI joints are in counternutation.

In the latter stages, when the baby passes through the pelvic outlet, it is important that this A-P diameter has increased. Putting the SI joints in nutation increases the A-P diameter.

Bones and Landmarks of the SI joint

The sacrum and the superior portion of the hip bone, the ilium.

The Sacrum

wedge-shaped and consists of five fused sacral vertebrae. It is located between the two hip bones and makes up the posterior border of the pelvis bone.

Its anterior surface, often called the pelvic surface, is concave. Because it is tilted, the sacrum articulates with the fifth lumbar vertebra at an angle lumbosacral angle.

lumbosacral angle/ Sacral angle

The significant landmarks are as follows: Base: Superior surface of S1.

Promontory: Ridge projecting along the anterior edge of the body of S1.

Superior articular process: Located posteriorly on the base, it articulates with the inferior articular process of L5.

Ala: Lateral flared wings that are actually fused transverse processes.

Ligaments

Sacroiliac joint take a great deal of stress while providing great stability it is a joint heavily endowed with ligaments.

SI joint ligaments:

- Primary ligaments

- Secondary (accessory ) ligaments

Primary ligaments/ Anterior SI ligament

is a broad, flat ligament on the anterior (pelvic) surface connecting the ala and pelvic surface of the sacrum to the auricular surface of the ilium. It holds the anterior portion of the joint together.

Primary ligaments/ Interosseous SI ligament

The deepest, shortest, and strongest of the sacroiliac ligaments It fills the roughened area immediately above and behind the auricular surfaces and anterior sacroiliac ligament….. It connects the tuberosities of the ilium to the sacrum.

Primary ligaments/ Posterior SI ligament

The short posterior sacroiliac ligament runs more oblique between the ilium and the upper portion of the sacrum on the dorsal surface. It prevents forward movement of the sacrum.

The long posterior sacroiliac ligament runs more vertically between the posterior superior iliac spine and the lower portion of the sacrum. It prevents downward movement of the sacrum.

Accessory ligaments

Three accessory ligaments further reinforce the sacroiliac joint.

- Sacrotuberous ligament - Sacrospinous ligament - Iliolumbar ligament

sacrotuberous ligament

a very strong, triangular- shaped ligament running from between the PSIS and PIIS of the ilium, from the posterior and lateral side of the sacrum inferior to the auricular surface, and from the coccyx. These fibers come together to attach on the ischial tuberosity.

It serves as an attachment for the gluteus maximus, and prevents forward rotation of the sacrum

sacrospinous ligament

is also triangular- shaped and lies deep to the sacrotuberous ligament. It has a broad attachment from the lower lateral sacrum and coccyx on the posterior side. It then narrows to attach to the spine of the ischium.

SS & ST ligaments convert the greater sciatic notch into a foramen through which passes the sciatic nerve.

iliolumbar ligament

connects the transverse process of L5 with the ala of the sacrum.

Pubic Symphysis joint

The pubic symphysis joint is located in the midline of the body.

Articulations???!!

The right and left pubic bones are joined anteriorly forming the pubic symphysis.

A fibrocartilage disk lies between the two bones.

Pubic Symphysis joint

* Joint type???!!!

an amphiarthrodial joint cartilaginous joint

Stability??!! Movements??!!!

However, in women during childbirth, it becomes much more moveable!!!!.

The pubic symphysis is held together primarily by two ligaments:

The superior pubic ligament attaches to the pubic tubercles on each side of the body and strengthens the superior and anterior portions of the joint.

The inferior pubic ligament attaches between the two inferior pubic rami. It strengthens the inferior portion of the joint.

Landmarks of pubic symphysis

Body:

- Superior ramus

- Inferior ramus provides attachment for the inferior pubic ligament.

Tubercle: Projects anteriorly on the superior ramus near the midline and provides attachment for superior pubic ligament.

Lumbosacral Joint

it is made up of the fifth lumbar vertebra and the first sacral vertebra.

The articulation between these vertebrae is the same as that for all other vertebrae…

The bodies separated intervertebral disk…. held together at the bodies by the anterior and posterior longitudinal ligaments.

The vertebrae articulate at the articular processes (inferior articular process of L5 and superior articular process of S1).

The ligaments holding together this portion of the joint are the supraspinal, interspinal, and ligamentum flava.

ligamentum flava

Iliolumbar ligament

hold the lumbosacral joint together.

-It attaches on the transverse process of L5 and runs laterally to the inner lip of the posterior portion of the iliac crest.

This ligament limits the rotation of L5 on S1, and assists the articular processes in preventing L5 from moving anteriorly on S1.

lumbosacral ligament

The lumbosacral ligament attaches on the transverse process of L5 It runs inferiorly and laterally to attach on the ala of the sacrum….Here its fibers intermingle with the fibers of the anterior sacroiliac ligament.

Lumbosacral Angle

Lumbosacral angle is determined by drawing one line parallel to the ground and another line along the base of the sacrum.

Lumbosacral Angle

This angle will increase as the pelvis tilts anteriorly and decrease as the pelvis tilts posteriorly.

-The optimal lumbosacral angle is approximately 30 degrees.

Lumbosacral Angle As the lumbar lordosis increases the angle

increases.

This causes the shearing stresses of L5 on S1 to increase.

the lumbar lordosis decreases lumbosacral angle decreases.

Forward movement of L5 on S1 is prevented by ligamentous support, the shape and fit of the inferior articular process of L5 inside and behind the superior articular process of S1.

Lumbosacral Angle & lumbar Lordosis

Pelvic Girdle Motions - two hip joints and the lumbar joints, particularly the

lumbosacral articulation between L5 and S1.

The pelvic motions occur in all three planes.

When standing in the upright position, the pelvis should be level; in the sagittal plane ASIS and pubic symphysis should be in the same vertical plane.

Anterior tilt

Anterior tilt occurs when the pelvis tilts forward

moving the ASIS anterior to the pubic symphysis.

Posterior tilt

Posterior tilt occurs when the pelvis tilts backward, moving the ASIS posterior to the pubic symphysis.

For the body to remain upright when the pelvis tilts forward, movement in the opposite direction must occur in the joints above and below the pelvis.

When the pelvis tilts anteriorly the lumbar portion of the vertebral column goes into hyperextension while the hip joints flex.

Anterior & posterior tilt

Thus, when a person with a hip flexion contracture stands in the upright position, the pelvis will tilt anteriorly while the lumbar region becomes hyperextended.

Conversely, a person with tight hamstrings may stand with the pelvis tilted posteriorly and lumbar curve flattened.

Pelvic girdle motion

In the frontal plane, the iliac crests should be level.

Placing your thumbs on the ASISs and determining if your thumbs are at the same level…

Lateral tilt

Lateral tilt occurs when the two iliac crests are not level.

Because the pelvis moves as a unit, one side moves up as the other side moves down.

Lateral tilt

Right/ Left Lateral tilt??!!!

a point of reference must be used!!!

-The side that is unsupported

- The side of the pelvis farthest from the joint

Left pelvic tilt  is when the right side of the pelvis is elevated higher than the left side (left side is dropped)

Right pelvic tilt  is when the left side of the pelvis is elevated higher than the right side (Right side is dropped)

During walking, the pelvis is level when both legs are in contact with the ground (double stance). However, when one leg leaves the ground (swing phase), while the another leg in contact with ground (single stance/ unilateral stance), it becomes unsupported and the pelvis on that side drops slightly.

In right unilateral stance;

Joint axis Right hip

The side of the pelvis farthest away Left side.

For example…..

Lateral tilt

Lateral tilt……

It is impossible to drop the pelvis on the weight-bearing side.

the point of reference for lateral tilt will be the unsupported, or less supported, side, or the side farthest from the weight-bearing joint axis. The person bears weight on the right leg while lifting the left leg from the ground The left side of the pelvis becomes unsupported and drops, or laterally tilts to the left.

To keep the body balanced, joints directly above and below will shift in the opposite direction.

As the pelvis tilts (drops) to the right the vertebral column laterally bends to the left.

While the weight-bearing hip joint (left) adducts, the unsupported hip (right) becomes more abducted.

Lateral tilt………

Lateral tilt…………..

For example…..

Left lateral pelvis tilt…….- Pelvis drops ????? - weight bearing side ????- Non weight bearing side ????- Vertebral column ????- Right hip ???? - Left hip ????

Lateral tilt……

Scoliosis LLD

( Leg Length Discrepancy)

A hemihyperplasia patient demonstrating lateral pelvic tilt.

Hip Hiking

It is possible to raise the pelvis on the unsupported side “hip hiking.”

Quadratus lumborum muscle Reversal of muscle action ???!!!

When walking with a long leg cast or brace, this motion assists the foot in clearing the floor during the swing phase.

Shifting from one ischial tuberosity to the other also involves raising the pelvis on one side. This is useful in allowing some pressure relief during sitting.

Hip Hiking………..

Pelvic girdle motion

In the Transverse plane around a vertical axis when one side of the pelvis moves forward or backward in relation to the other side Pelvic rotation ….. the significant landmarks again are the ASISs.

Pelvic Rotation

In the anatomical (neutral) position, both ASISs should be in the same plane

Forward / Backward Rotation??!!!!!

Forward rotation of the pelvis the non-weight bearing side is swinging forward moving the ASIS of the non-weight bearing side forward the ASIS of the weight bearing side.

Backward rotation of the pelvis the non-weight bearing side is swinging backward moving the ASIS of the non-weight bearing side backward the ASIS of the weight bearing side.

Example……

the left leg is weight bearing and the right leg is swinging forward.

This causes the right side of the pelvis to rotate forward moving the right ASIS forward of the left ASIS.

This pelvic rotation is occurring because the pelvis is moving on the weight-bearing hip joint.

Right / Left Rotation??!!!!!

The unsupported side is the point of reference!!!

Right Forward rotation of the pelvis the left leg is weight bearing and the right leg is swinging forward. This causes the right side of the pelvis to rotate forward moving the right ASIS forward of the left ASIS.

Example…….

Right Backward rotation of the pelvis The left leg weight bearing The right leg is swinging backward. The right side of the pelvis to rotate backward

moving the right ASIS backward of the left ASIS.

Example…….

Left Backward rotation of the pelvis The right leg weight bearing The left leg is swinging backward. The left side of the pelvis to rotate backward

moving the left ASIS backward of the right ASIS.

If there is right forward rotation of the pelvis, there is left hip medial rotation.

With right backward rotation of the pelvis, there is left hip lateral rotation.

Muscle Control

The pelvis is moved and controlled by groups of muscles acting as force couples. As the pelvis tilts in the anterior/posterior direction, it is the opposing muscle groups that provide the movement and control.

Anterior & Posterior tilt

To tilt the pelvis anteriorly, the lumbar trunk extensors, primarily the erector spinae, pull up posteriorly while the hip flexors pull down anteriorly.

Conversely, to tilt the pelvis posteriorly, the abdominals pull up anteriorly while the gluteus maximus and hamstrings pull down posteriorly.

In both cases, the opposite muscle groups are acting as a force couple, causing the pelvis to tilt

Lateral tilt

The force of gravity, without any muscle action, can tilt the pelvis laterally when that leg becomes unsupported. However, to control or limit the amount of lateral tilting, opposite muscle groups work as a force couple as well.

Example…..

in a reversal of muscle function action, the left trunk lateral benders, primarily the erector spinae and quadrates lumborum, pull up on the left side of the pelvis, while the right hip abductors (gluteus medius and minimus) pull down on the right side to keep the pelvis fairly level.

All of these same muscle groups can work together to provide stability by preventing the pelvis from moving.

Pelvic and trunk control are necessary to provide the stable foundation upon which the head and extremities can move.

Thank you