Anulus fibrosus disci intervertebralis

Anulus fibrosus disci intervertebralis (or simply anulus fibrosus) is a crucial component of the intervertebral disc, which is a fibrocartilaginous joint that connects the vertebrae in the spine. The anulus fibrosus encircles and protects the nucleus pulposus, the gel-like center of the intervertebral disc.

Structure

The anulus fibrosus is composed of several layers, or lamellae, of fibrocartilage. These layers are made up of water, collagen, and proteoglycans. The collagen provides strength and flexibility, while the proteoglycans help to maintain water content.

The anulus fibrosus is thicker at the front (anterior) and sides (lateral) of the disc, and thinner at the back (posterior). This variation in thickness helps to accommodate the different loads and movements experienced by the spine.

Function

The primary function of the anulus fibrosus is to contain the nucleus pulposus and distribute pressure evenly across the disc. By doing so, it helps to prevent damage to the vertebrae and other spinal structures.

In addition, the anulus fibrosus contributes to the spine's flexibility and range of motion. It allows the vertebrae to move in various directions, including bending forward and backward, twisting, and side bending.

Clinical significance

Damage to the anulus fibrosus can lead to a number of spinal conditions. For example, a tear in the anulus fibrosus can cause the nucleus pulposus to leak out, a condition known as a disc herniation. This can put pressure on the spinal nerves, leading to pain, numbness, or weakness in the limbs.

Furthermore, degeneration of the anulus fibrosus is a common cause of back pain. As the anulus fibrosus ages, it can become less flexible and more prone to tears and injury.

See also

• Intervertebral disc
• Nucleus pulposus
• Spine
• Vertebrae
• Disc herniation
• Back pain