Vertebral Column Anatomy

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Questions and Answers

What is the function of the other trabecular systems in the body?

To resist shearing forces

Where is the area of weakness in the body?

In the anterior portion of the body

What is the structure that is made up of three columns?

The entire spine

What is the formula to quantify the resistance of a curved column?

R is directly proportional to the number N of curvatures + 1 Signup and view all the answers

What is the index that quantifies the resistance of the spinal column?

Delmas index Signup and view all the answers

What is the typical Delmas index for a spinal column with normal curvatures?

95% Signup and view all the answers

What is the central portion of the intervertebral disk called?

Nucleus pulposus Signup and view all the answers

What type of collagen is concentrated in the annulus fibrosus?

Both type I and II Signup and view all the answers

What happens to the inferior articular processes of the upper vertebra during flexion?

They glide upwards Signup and view all the answers

What is the effect of flexion on the intervertebral foramina?

It increases their size Signup and view all the answers

What happens to the load during flexion?

It is transferred from the apophyseal joints to the intervertebral discs Signup and view all the answers

What is the primary factor responsible for the movements of the vertebral spine?

The mobility of the mobile segment Signup and view all the answers

What happens to the ligaments of the facet joint during flexion?

They are stretched Signup and view all the answers

What is the function of the posterior arch in the vertebral functional components?

Dynamic role Signup and view all the answers

What happens to the upper vertebra during extension?

It tilts and moves posteriorly Signup and view all the answers

What is the relationship between lateral flexion and ipsilateral axial rotation in the middle and lower cervical spine?

They are always ipsilateral Signup and view all the answers

During primary lateral bending, what is the tendency of the thoracic spine and the lumbar spine?

The thoracic spine extends and the lumbar spine flexes Signup and view all the answers

What happens to the intervertebral discs during extension?

They become flatter posteriorly and thicker anteriorly Signup and view all the answers

What happens to the nucleus during extension?

It is pushed anteriorly, away from the neural tissue Signup and view all the answers

What is the smallest functional unit in the spine?

Two adjacent vertebrae and the intervening intervertebral disk Signup and view all the answers

What happens to the spinous processes during extension?

They touch each other Signup and view all the answers

What is the function of the vertebral body in the vertebral functional components?

Supporting structure Signup and view all the answers

What is the composition of the mobile segment in the vertebral spine?

The intervertebral disk, the intervertebral foramen, the facet joints, and the ligamentum flavum Signup and view all the answers

During primary axial rotation, what is the direction of the coupled lateral bending in the thoracic spine and the lumbar spine?

Ipsilateral in the thoracic spine and contralateral in the lumbar spine Signup and view all the answers

What is the function of the intervertebral disc in the vertebral column?

To cushion the axial compression forces acting on the column Signup and view all the answers

What type of movement is allowed at the interbody joints?

Translation and rotation Signup and view all the answers

What is the result of creep on the supporting structures of the spine?

Elongation and lack of stability Signup and view all the answers

What determines the ability of the vertebral column to resist an applied load?

The type, duration, and rate of loading, the person's age and posture, and the condition and properties of the various structural elements Signup and view all the answers

What is the result of sustained compressive loading on the vertebral column?

Fluid is expressed from the nucleus pulposus and the annulus fibrosus Signup and view all the answers

Where is the highest torsional stiffness found in the spine?

Thoracolumbar junction Signup and view all the answers

What is the role of the paravertebral muscles in the vertebral column?

To provide active cushioning Signup and view all the answers

What is the effect of torsion on the annulus fibrosus fibers?

Half of the fibers resist clockwise, and the other half resist counterclockwise rotations Signup and view all the answers

What is the term for the number of independent movements allowed at a joint?

Degrees of freedom Signup and view all the answers

What is the effect of shear on the vertebrae?

It causes each vertebra to move anteriorly, posteriorly, or from side to side Signup and view all the answers

What is the function of the articular process in the vertebral column?

To act as a fulcrum Signup and view all the answers

What is the role of the apophyseal joints in the lumbar spine?

They resist some of the shear force Signup and view all the answers

What type of stress is exerted on the vertebral column?

Axial compression, tension, bending, torsion, and shear Signup and view all the answers

What is the effect of flexion on the intervertebral disc?

It reduces the thickness of the disc anteriorly and increases it posteriorly Signup and view all the answers

What happens to the nucleus pulposus during flexion?

It moves posteriorly, toward neural tissue Signup and view all the answers

What is the effect of flexion on the annulus fibrosus?

It compresses and bulges the anterior side of the annulus fibrosus Signup and view all the answers

Study Notes

Stability and Mobility of the Spine

The entire spine is made up of three columns: one major column (A) anteriorly located and made up of stacked vertebral bodies, and two minor columns (B and C) posterior to the body and made up of stacked articular processes.
The spinal curvatures increase resistance to axial compression forces, with a resistance (R) directly proportional to the number of curvatures (N) + 1.
The Delmas index, expressed as H/L x 100, measures the ratio of the height of the spinal column to its fully extended length, with a normal index of 95% ± 1%.

Intervertebral Disk

The disk is composed of two parts: the nucleus pulposus and the annulus fibrosus.
Water and proteoglycans concentrations are highest in the gelatinous nucleus, while collagen concentrations are highest in the annulus.
The collagen fibers of the annulus are arranged in sheets called lamellae.

Coupling Movements

The most consistent pattern involves an association between lateral flexion and ipsilateral axial rotation in the middle and lower cervical spine.
During primary lateral bending, there is significant ipsilateral axial rotation in the thoracic spine and a contralateral coupled axial rotation in the thoracolumbar joint and lumbar spine.

Motion/Mobile Segment

The smallest functional unit in the spine consists of any two adjacent vertebrae, the intervening intervertebral disk, and all the soft tissues that secure them together.
The functional components of the vertebral include the vertebral body as the anterior pillar, the posterior arch supporting the articular processes, and the intervertebral disk and ligaments.
The mobility of the active (mobile) segment is responsible for the movements of the vertebral spine.

Types of Movement

Available movements at the interbody joints include gliding, distraction, compression, and rotation.
There are 6 degrees of freedom (DoF) allowed at a joint, including 3 translational and 3 angular movements.

Stability

The stiffness of the vertebral column is its ability to resist an applied load, varying among spinal regions and dependent on factors such as age, posture, and condition of structural elements.
Axial compression occurs due to gravity, ground reaction forces, and ligaments and muscular contractions.
Torsional forces are created during axial rotation, with the highest torsional stiffness found at the thoracolumbar junction.
Shear forces act on the midplane of the disk, tending to cause each vertebra to move anteriorly, posteriorly, or from side to side in relation to the inferior vertebra.

Movements of the Spine

Flexion: the upper vertebra tilts and glides forward, reducing the thickness of the intervertebral disc anteriorly and increasing it posteriorly.
Extension: the upper vertebra tilts and moves posteriorly, decreasing the size of the opening of the intervertebral foramina.
Lateral flexion: the upper vertebra tilts on the side of flexion, with the disc becoming wedge-shaped and thicker on the other side.

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