Learning Outcomes: Students will be able to:
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The pelvic girdle is located between the trunk (lumbar area) and the thighs (femurs). The pelvic girdle functions primarily to provide stability and support for the upper body and transmits upper body weight to the lower limbs when standing (or to the ischial tuberosity when sitting). It also contributes to walking by providing a sturdy base for trunk and lower extremity muscles to move the more distal segments (distal mobility and proximal stability).
Figure 1 | The bones of the pelvic girdle consist of two os coxae, or innominates, formed by the embryonic fusion of the ilium, ischium, and pubis. The os coxae (innominates) are joined to the sacrum posteriorly at the sacroiliac joints, and to one another anteriorly at the pubic symphysis.. The pelvic girdle articulates with the fifth lumbar vertebra superiorly at the lumbosacral joint and inferiorly to the two femurs at the acetabulofemoral (hip) joints. |
Pubis Symphysis (amphiarthrodial) – the junction between the two pubic bones.
two pubic bones and during childbirth becomes softer allowing more movement at the joint.
on each side, strengthening the superior and anterior portions of the joint.
Attaches to the two inferior pubic rami, strengthening the inferior portion of the joint.
also help strengthen and stabilize this joint. |
Figure 2 |
Sacroiliac (SI) Joints (arthrodial) – the junction between the “auricular” surfaces of the sacrum and the “auricular” surfaces of the ilium. The function of the sacroiliac joint is to transmit weight from the upper body through the vertebral column to the hips and femurs. The sacroiliac ligaments support the SI joint on the anterior and posterior surfaces of the joint.
posterior surface of the upper sacrum to the posterior surface of the ilium.
from the posterior superior iliac spine to the lower sacrum.
surface of the sacrum and ala to the auricular surface of ilium, stabilizing the anterior surface of the joint.
attaches from the sacrum to the ischial tuberosity.
attaches from the sacrum to the ischial spine. |
Figure 3 |
Sacroiliac Joint Motion |
The actual type and amount of movement occurring at the SI joint is controversial. However, it is generally accepted that only a very small amount of movement (1-3 mm) occurs, it must be in conjunction with other motions, and is described as nutation or counternutation. | |
Note: In the initial moments of these movements the sacrum actually moves opposite of what is stated, but as soon as the joint ligaments become taut the sacrum follows the pelvis and spine. |
Lumbosacral Joint | |
The lumbosacral joint is the articulation between the sacrum and L5 vertebra (L5-S1 spinal segment). Movement of the pelvis at the lumbosacral joint is limited. When the pelvis moves at the lumbosacral joint, the rest of the spine will begin to move once the motion at the lumbosacral joint has reached its limit. In addition to the spinal ligaments, this joint is also supported by:
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Figure 5 |
Pelvic Girdle Movements |
The joints directly involved in pelvic girdle movement include the two hip joints and the lumbosacral joint. Because the axial skeleton attaches to the pelvis through the sacroiliac joint, movement of the pelvis in relationship to the hip also influences spinal movements. |
In good posture the anterior superior iliac spine (ASIS) and the pubic symphysis are in the same vertical plane, known as spine neutral or neutral spine. | Figure 6 |
Sagittal Plane Movement | ||
Anterior Pelvic Rotation: occurs when the pelvis rotates forward, moving the ASIS anterior to the pubic synthesis, decreasing the angle between the pelvis and the femoral shafts, resulting in closed chain hip flexion. A force couple is creating by the simultaneous contraction of the hip flexors and trunk extensors.
Figure 7 Anterior Pelvic Tilt: Tilt reflects a postural fault due to muscular imbalance: tight hip flexors and low back extensors, weak trunk flexors and hip extensors. | Posterior Pelvic Rotation: occurs when the pelvis rotates backward, moving the ASIS posterior to the pubic synthesis, increasing the angle between the pelvis and the femoral shafts, resulting in closed chain hip extension. A force couple is created by the simultaneous contraction of the hip extensors and trunk flexors.
Figure 8 Posterior Pelvic Tilt: Tilt reflects a postural fault due to muscular imbalance: tight hip extensors and trunk flexors, weak hip flexors and low back extensors. | |
Frontal Plane Movement | ||
Left Lateral Pelvic Rotation: the right pelvis is elevated while the left moves inferiorly, resulting in left hip abduction and right hip adduction.
Figure 9 Front View | Right Lateral Pelvic Rotation: the left pelvis is elevated/hiked rotating the pelvis toward the right as it moves inferiorly, resulting in right hip abduction and left hip adduction.
Figure 10 Front View |
Transverse Plane Movement | ||
Left Transverse Pelvic Rotation: With rotation of the pelvis to the body’s left, the right iliac crest moves anteriorly in relation to the left iliac crest, which moves posteriorly. Closed chain right hip external rotation and left hip internal rotation occur during left transverse pelvic rotation.
Figure 11 | Right Transverse Pelvic Rotation: With rotation of the pelvis to the body’s right, the left iliac crest moves anteriorly in relation to the right iliac crest, which moves posteriorly. Closed chain right hip external rotation and left hip internal rotation occur during left transverse pelvic rotation.
Figure 12 |
Open Chain Pelvofemoral Motions
Hip Flexion: will be accompanied by ipsilateral posterior pelvic rotation to allow further hip flexion ROM, and contralateral anterior pelvic rotation.
Hip Extension: will be accompanied by ipsilateral anterior pelvic rotation to allow further hip extension ROM, and contralateral posterior pelvic rotation.
Acetabulofemoral (enarthrodial- triaxial) Closed Pack Position: Fully extended, internally rotated, and abducted Open Pack Position: Flexed 30º and abducted 30º |
The acetabulofemoral joint is the articulation between the acetabulum of the os coxa/innominate and the head of the femur. Being an enarthrodial joint, it is surrounded by a fibrous joint capsule that provides significant stability for the joint. To help further strengthen this joint the capsule contains strong circular deep fibers called the zona orbicularis that surround the neck of the femur. In addition, three strong capsular ligaments reinforce the hip joint anteriorly.
Hip Joint Movements | |
Hip Flexion: Anterior movement of the femur in the sagittal plane | Hip Extension: movement of the femur straight posteriorly from any point in the sagittal plane away from the pelvis |
Hip Abduction: Lateral movement of the femur in the frontal plane away from the body midline | Hip Adduction: Medial movement of the femur in the frontal plane toward the body midline |
Hip External Rotation: Lateral rotary movement of the femur in the transverse plane around its longitudinal axis away from the body midline | Hip Internal Rotation: Medial rotary movement of the femur in the transverse plane around its longitudinal axis toward the body midline |
Hip Joint Range of Motion | |
Flexion: 120° (knee flexed) 90° (knee extended) Extension: 30° Abduction: 45° Adduction: 30° | Internal Rotation: 45° External Rotation: 45° |
Femoral Angle of Inclination |
The angle between the femoral neck and femoral shaft. In infants this angle may be around 160º, but by adulthood normally averages 125º.
Figure 16
These changes alter the alignment of a muscle’s line of pull and can lead to decreased muscle strength due to changes in the length of the muscular force arm. This malalignment can also increase joint stress and lead to joint dysfunction. Specifically:
Femoral Angle of Torsion | |||
The angle between the shaft of the femur and the neck of the femur in the transverse plane. Normally the head is rotated anteriorly (anteverted) from the shaft approximately 15º.
Figure 17 |
Muscle Innervation & Cutaneous Distribution | |
Figures 18, 19, 20, 21
Muscles of the Hip Joint | |
Anterior – primarily hip flexion
| Posterior – primarily hip extension
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Lateral – primarily hip abduction
| Medial – primarily hip adduction
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Muscles of the Anterior Hip | ||||||
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Figure 22
Figure 23
Figure 24 |
Muscles of the Lateral Hip | ||||
| Figure 26 |
Deep 6 External Rotators | |
Origin: Anterior sacrum, posterior portions of the ischium and obturator foreman Insertion: Superior and posterior aspect of the greater trochanter of the femur Action: Hip external rotation Nerve: Branches of the sacral plexus and the obturator nerve | Figure 27 |
Piriformis Syndrome | |
Description: Compression of the sciatic nerve (L4-S2) as it passes under (or through) the Piriformis causing pain to radiate into the buttock and distally along the course of the sciatic nerve. How to locate Piriformis: ½ distance between PSIS & sacral apex. Drop off edge of sacrum → lies between edge and greater trochanter. | Figure 28 |
Muscles of the Posterior Hip | |||||
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Figure 29
Figure 30 |
Muscles of the Medial Hip | |||||
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Figure 31
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Hip Flexion & IT Band Tightness Tests |
Figure 33
Tight Hamstrings |
Pelvis and Hip Joint Review Questions |
Step. You then hike or elevate your hip on the side hanging off the side of the step. When doing this movement,
what hip movement is being performed on the side that is hanging off and what hip movement is being performed on
the opposite side?
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