Discs

Spinal discs are composed of a nucleus pulposis the inner, central soft part of the intervertebral disk, and the outer part the annulus fibrosus.

Nucleus pulposus consists of proteoglycan and hyalouronic long chains.

Hyalouronic chains in the nucleus pulposus have avidity for water and hydrate the center of the disc.

The annulus fibrosus surrounds the nucleus pulposus and attaches to the vertebral bodies above and below.

If the nucleus pulposus loses turgor and elasticity the disk bulges outwears beyond the margins of the body of the vertebra.

A longitudinal ligament attaches to the vertebral bodies and to the discs anteriorly and posterior.

The cartilaginous endplate of each disc is attached to the bony endplate of the vertebral body.

The anterior longitudinal ligament resists forces to extension, and is stronger than the posterior longitudinal ligament.

The posterior longitudinal ligament rests forces of flexion.

The posterior ligament attaches strongly to the annulus fibrosus.

Tears to the posterior longitudinal ligament occur commonly when there is free fragment disc herniation.

The height of the disc maintains the separation distance between the adjacent vertebral bodies.

Discs allow motion to occur, with the cumulative effect of each spinal segment yielding the total range of motion of the spine in any of several directions.

Discs allow for proper spacing that permits the intervertebral foramen to maintain its height, and allows the segmental nerve roots room to exit each spinal level without compression.

The disc allows for shock absorption of the spine and permits it to compress and rebound when the spine is axially loaded during such activities as jumping and running.

The intervertebral disc resists the downward pull of gravity on the head and trunk during prolonged sitting and standing.

The disc’s elasticity allows motion coupling, so that the spine may flex, rotate, and bend.

Leave a Reply

Your email address will not be published. Required fields are marked *