Vertebral Column Movements, Joints, and Ligaments

Zygapophysial Joint

-synovial plane joint between the superior and inferior articular processes of the vertebra

• also called facet joints

• plane joint = the surfaces of the joint are flat and “glide” over each other

-surrounded by a joint capsule due to it being a synovial joint

-cervical articular facets are oriented relatively horizontally and less tightly interlocked than other regions, making them more mobile and subject to dislocation

• superior articular facet faces posteriorly and the inferior faces anteriorly

-specific angle and direction of the facets vary regionally and influence the motion available

-can be visualized on radiograph imaging

Intervertebral Disc

-symphysis joint sitting between adjacent vertebral bodies

-permits movement and absorbs shock

Intervertebral Disc Symphysis

-symphysis between adjacent vertebral bodies is formed by a layer of hyaline cartilage AND an intervertebral disc lying between those cartilage layers

-intervertebral disc is made up of: an outer anulus fibrosus and an inner nucleus pulposus

• nucleus pulposus is gelatinous early in life, then becomes harder with age

Which type of imaging best shows details of the intervertebral discs?

-MRI

Anterior and Posterior Longitudinal Ligaments

-anterior longitudinal ligament is attached anteriorly to the vertebral bodies and the intervertebral discs

-posterior longitudinal ligament is attached posteriorly to the vertebral bodies; narrower than the interior

-both anterior and posterior longitudinal ligaments run the entire length of the vertebral column

Whiplash and the Anterior Longitudinal Ligaments

-whiplash causes traumatic hyperextension of the neck and may cause strain/tears to the anterior longitudinal ligament

Disc Herniation and the Posterior Longitudinal Ligament

-the PLL is located within the vertebral canal, posterior to the vertebral bodies

-its structure being narrower than the ALL causes it to provide less support to the intervertebral discs → WEAKNESS

• this weakness makes causes the risk of intervertebral disc herniation with posterolateral movement in the areas lacking PLL support

Ligamenta Flava

-yellow ligament

-connect adjacent laminae of the vertebral column

-made of many short ligamentous sections

-predominantly elastic tissue

Interspinous Ligaments

-connect spinous processes of adjacent vertebra

Supraspinous Ligament

-connects tips of spinous processes

-runs most of the length of the vertebral column

Nuchal Ligament

-also called ligamentum nuchae

• “nuchal” = neck

-special ligament in the cervical spine that attaches from the external occipital protuberance over all 7 cervical spinous processes

-contains fibroelastic tissue

-resists flexion, aids returning head to anatomical position from flexion

-provides attachments for muscles on its lateral surface

Which ligaments become taught and limit the vertebral column in vertebral flexion?

-PLL

-Ligamentum flavum

-Interspinous ligaments

-Supraspinous ligaments

Which ligaments become taught and limit the vertebral column in vertebral extension?

-ALL

-anterior body musculature also limits extension under normal circumstances and is a source of pain during whiplash injury

Regional Variation in Spinal Motion

*the shape and thickness of intervertebral discs in the cervical and lumbar region also contribute to the curvatures found in this region

Atlantooccipital Joint (OA)

-occipital condyles of the skull articulate with the superior articular facets of “The Atlas” (C1)

-nodding the head (flexion and extension movement) and lateral flexion occur at this joint

Atlantoaxial Joint (AA)

-joint between “The Atlas” and “The Axis” (C1 and C2) vertebra

-rotation is the only motion available in this joint

-rotation is limited by the alar ligaments

-about half of all rotation in the cervical region occurs at the AA joint, while the rest occurs occurs as a composite motion between C2-C7

Transverse Ligament of “The Atlas”

-keeps the dens of the C2 vertebra from moving posterior and impinging upon the spinal cord