Pelvic Stability and Vertebral Column

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Questions and Answers

What forms a co-ordinated articular system with two joints?

The sacrum, the iliac bone and the lower limbs

The vertebral column and the sacrum

The vertebral column, the sacrum, the iliac bone and the lower limbs (correct)

The vertebral column and the lower limbs

What tends to lower the promontory?

The reaction of the ground

The weight of the trunk (correct)

The movement of nutation

The weight of the lower limbs

What movement occurs at the sacrum due to the weight of the trunk?

Movement of nutation (correct)

Anterior tilt of the pelvis

Movement of counternutation

Posterior tilt of the pelvis

What stops the tip of the sacrum moving away from the ischial tuberosity?

The sacrospinous and sacrotuberous ligaments Signup and view all the answers

What forms a rotatory couple with the body weight?

The reaction of the ground Signup and view all the answers

What is the result of the rotatory couple acting at the sacrum?

The iliac bone tilts posteriorly Signup and view all the answers

Which joints have no muscles that control their movements directly?

The sacroiliac joints and symphysis pubis Signup and view all the answers

What can be divided into groups to support the pelvic girdle as well as the lumbar spine and hips?

The muscles that support the pelvic girdle Signup and view all the answers

What is the primary function of the outer group of muscles in relation to the pelvis?

To stabilize the pelvis Signup and view all the answers

Which muscle is part of the deep longitudinal system?

Biceps femoris Signup and view all the answers

What is the primary function of the inner group of muscles?

To actively stabilize the pelvic joints Signup and view all the answers

Which muscle is part of the anterior oblique system?

Internal obliques Signup and view all the answers

What is the function of the multifidus muscle?

To stabilize the pelvic joints Signup and view all the answers

Which muscle system helps to stabilize the pelvic joints during gait and pelvic rotational activities?

Inner group of muscles Signup and view all the answers

What is the function of the gluteus medius muscle?

To stabilize the pelvis Signup and view all the answers

Which muscle system includes the latissimus dorsi and gluteus maximus?

Superficial posterior oblique system Signup and view all the answers

Study Notes

Pelvic Stability by Forces

The vertebral column, sacrum, iliac bones, and lower limbs create a coordinated system centered on the hip and sacro-iliac joints.
Weight from the trunk acting on S1 tends to lower the sacral promontory, inducing nutation (N2) of the sacrum.
Nutation movement is restricted by anterior sacro-iliac ligaments, along with sacrospinous and sacrotuberous ligaments preventing excessive movement.
Ground reaction forces (R), transmitted through the femur to the hip, create a rotary couple at the sacrum, triggering posterior tilting of the iliac bones (N1).
This pelvic backward tilt enhances nutation at the sacroiliac joints.

Pelvic Stability by Muscles

No muscles directly control the sacroiliac joints or symphysis pubis, but muscle actions provide necessary stability.
Muscle movements of the lumbar spine and hip influence pelvic stability due to their attachments to the sacrum and pelvis.
Muscles that support pelvic stability are categorized into outer and inner groups:
- Outer Group: Consists of four groupings that work in crossing or oblique force patterns to stabilize the pelvis.
- Inner Group: Contains deep muscles such as the transverse abdominis, diaphragm, multifidus, and pelvic floor muscles, crucial for actively stabilizing pelvic joints.

Key Muscle Systems for Stability

Deep Longitudinal System: Includes erector spinae, deep lamina of the thoracolumbar fascia, biceps femoris (hamstrings), and sacrotuberous ligament.
Superficial Posterior Oblique System: Comprised of latissimus dorsi, gluteus maximus, and thoracolumbar fascia.
Anterior Oblique System: Contains internal and external obliques, contralateral thigh adductors, and anterior abdominal fascia.
Lateral System: Made up of gluteus medius and minimus, along with contralateral thigh adductors.
Innermost Muscles: Feature multifidus, transversus abdominis, diaphragm, and pelvic floor muscles.

Functional Significance

These muscle systems play a vital role in stabilizing pelvic joints and facilitate effective load transfer during dynamic activities like walking and rotational movements.

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Description

Understand the coordinated articular system of the vertebral column, sacrum, iliac bone, and lower limbs, including the hip joint and sacro-iliac joint. Learn how the weight of the trunk affects the sacrum and how ligaments limit its movement. Test your knowledge of pelvic stability and anatomy.