Biomechanics of Cervical Spine

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Questions and Answers

What is the percentage of water in the intervertebral disc?

50-60%

60-70%

90-95%

80-90% (correct)

What is the main function of the nucleus pulposus?

To facilitate spinal motion

To absorb shock and distribute pressure (correct)

To guide spinal growth and development

To provide mechanical support to the spine

What is the effect of compressive loading on the intervertebral disc?

It has no effect on the hydration of the disc

It increases the mechanical function of the disc

It increases the hydration of the disc

It decreases the hydration of the disc (correct)

What is the ratio between the vertebral body height and the disc height in the lumbar region?

Lowest ratio Signup and view all the answers

What is the main component of the proteoglycan molecule in the nucleus pulposus?

Chondrotin-4 sulfate Signup and view all the answers

What is the effect of aging on the hydration of the intervertebral disc?

It decreases the hydration of the disc Signup and view all the answers

What is the function of the annulus fibrosis in the intervertebral disc?

To translate compressive stresses into tensile stresses Signup and view all the answers

How many bones are in the vertebral column?

33 bones Signup and view all the answers

What is the primary function of the ligamentum nuchae?

To maintain the stability of the vertebral column Signup and view all the answers

What percentage of cervical rotation occurs at the atlanto-axial joint?

50% Signup and view all the answers

Which of the following ligaments is involved in the maintenance of head position during locomotion?

Ligamentum nuchae Signup and view all the answers

What is the total range of flexion-extension at the atlanto-occipital joint?

20 degrees Signup and view all the answers

What is the origin of the vertebral artery?

Subclavian artery Signup and view all the answers

Which of the following joints is responsible for flexion and extension?

Atlanto-occipital joint Signup and view all the answers

What is the function of the interspinous and intertransversarius ligaments?

To maintain the stability of the vertebral column Signup and view all the answers

What is the primary function of the lig. flavum?

To secure the interlaminar space Signup and view all the answers

What is the primary mechanism of nutrition for the avascular disc?

Diffusion through the end-plate Signup and view all the answers

What is the arrangement of collagen lamellae in the annulus fibrosis?

Concentric rings with alternating orientation at an angle of 120 degrees Signup and view all the answers

What is the function of the annulus fibrosis in terms of disc forces?

To control tensile loading from shear and accessory motions Signup and view all the answers

What is the most common location for disc herniation?

C5-6, C6-7, L4-5, and L5-S1 Signup and view all the answers

What is the term for a disc protrusion where the annulus is intact?

Protrusion Signup and view all the answers

What is the effect of tilting the flexion axis 30° away from pure flexion on the nucleus?

It causes the nucleus to track in a direction away from the axis Signup and view all the answers

What is the function of the posterior longitudinal ligament in relation to disc herniation?

It directs herniation posteriolaterally Signup and view all the answers

What is the structure that forms the neural arch?

Pedicles and lamina Signup and view all the answers

What is the primary function of the facet joint?

To guide intervertebral motion through their orientation in the transverse and frontal planes Signup and view all the answers

What is the strongest region of the facet joint capsule?

Thoracolumbar and cervicothoracic regions Signup and view all the answers

What is the result of osteophytic formation, hypertrophy of ligaments, and loss of disc height with aging on the intervertebral foramina?

Loss of space Signup and view all the answers

What is the result of extension on the intervertebral foramina?

Decrease in space by 20% Signup and view all the answers

What is the definition of spinal stability?

The ability of the spine to react to multiple forces placed on it Signup and view all the answers

What type of loading is characterized by a force that causes the vertebrae to rotate?

Torsion Signup and view all the answers

What is the characteristic of the C1 vertebra?

It has no body, disk, and spinous process, allowing for free space and a large neutral zone Signup and view all the answers

What is the characteristic of the C0-1 joint?

It is a concave-convex joint Signup and view all the answers

What is the course of the vertebral artery?

It ascends via the transverse foramina of C1 - C6 Signup and view all the answers

Which muscle is responsible for cervical stabilization?

Longus Colli and Longus Capitis Signup and view all the answers

What can be referred to the tip of the acromion or scapular region via the cutaneous branches of the upper thoracic posterior (dorsal) rami?

Pain from the cervical spine Signup and view all the answers

What is the likely cause of contralateral suboccipital muscle spasms and subsequent headaches?

A shorter levator scapulae on one side Signup and view all the answers

What can produce local pain, or refer pain to the suprascapular fossa or shoulder?

Rib articulations of the cervicothoracic region Signup and view all the answers

What is the likely indication of an insidious onset of symptoms?

A serious pathology such as a tumor Signup and view all the answers

What is the likely indication of symptoms that respond to mechanical stimuli in a predictable manner?

A mechanical source of pain Signup and view all the answers

What is the term for the muscles of the anterior cervical spine?

Deep cervical muscles Signup and view all the answers

Study Notes

Regions of the Vertebral Column

The vertebral column consists of 33 bones and 23 disks, divided into 5 regions: Cervical, Thoracic, Lumbar, Sacral, and Cocygeal.

Boney Anatomy of the Spine

The spine has 4 distinct curves in an adult, which were "C-shaped" prior to birth.
Spinal movement is a combination of intervertebral joints and facet joints.

Intervertebral Disc

Intervertebral disks make up 20-30% of the height of the vertebral column, with varying thickness in different regions.
The ratio between the vertebral body height and disk height dictates mobility, with the highest ratio in the cervical region allowing for the most motion.

Disc Structure

The nucleus pulposus (NP) is located in the center, except in the lumbar region where it lies slightly posterior.
The NP is a gelatinous mass rich in water-binding proteoglycan, which gives the disk its fluid-maintaining capacity.
The hydration of the disk decreases with age and compressive loading, leading to a loss of mechanical function.

Disc Function

The disk acts as a hydrostatic unit, allowing for uniform distribution of pressure throughout the disk.
Compressive stresses on the disk translate into tensile stresses in the annulus fibrosis, making the disk stiffer and adding stability to the spine.
The disk bears weight and guides motion, and is avascular, with nutrition diffusion through the end-plate.

Annulus Fibrosis

The annulus fibrosis is composed of collagen arranged in sheets called lamellae, with the outer layers being avascular and lacking innervation.
The annulus fibrosis controls tensile loading from shear and accessory motions in the anterior compartment and disk forces.

Disc Pathology - Herniation

Disc herniation occurs when the annulus fibrosis is disrupted, leading to bulging or prolapse of the nucleus pulposus.
Highest incidence of herniation occurs at C5-6, C6-7, L4-5, and L5-S1.

Posterior Structures (Elements) of Motion Segment

The posterior structures include pedicles and lamina forming the neural arch, facet joints between the superior and inferior articulating surfaces, transverse and spinous processes, and interspinous and supraspinous ligaments.
The facet joint guides intervertebral motion through its orientation in the transverse and frontal planes.

Ligaments

The ligaments include the anterior longitudinal ligament, posterior longitudinal ligament, ligamentum flavum, and interspinous and supraspinous ligaments.

Spinal Stability

The spinal column's ability to react to multiple forces, including axial compression, bending, torsion, and shear, is critical for stability.
Degeneration increases instability, which the body reacts to through fibrous and osteophytic changes.

Cervical Spine Anatomy

The cervical spine consists of 7 vertebrae (C1-C7), with C1 and C2 being atypical and C7 being transitional.
The intervertebral disk, articulations, ligaments, and neurologic structures are important components of the cervical spine.

Atlanto-Occipital Joint

The atlanto-occipital joint has a total range of flexion-extension of 20 degrees.

Atlanto-Axial Joint

The atlanto-axial joint has a range of rotation of 50% of cervical rotation, with a loose fibrous capsule enclosing the joints at articular margins.

Muscles of the Cervical Spine

The muscles of the lateral and posterior cervical spine include the upper trapezius, scalenes, splenius capitis, and erector spinae.

Blood Supply

The vertebral artery arises from the subclavian artery and ascends via transverse foramina of C6-C1, supplying the ipsilateral upper cervical spinal cord.

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Description

A review of the biomechanics of the cervical spine, covering the 5 regions of the vertebral column, boney anatomy, curvatures, and spinal motion.