Understanding spinal anatomy and treatment options helps patients navigate care decisions more confidently. This glossary defines key terms across spinal anatomy, common disc conditions, surgical procedures, and non-surgical regenerative approaches — giving patients a foundation to discuss options with their clinical team and evaluate whether surgical or non-surgical paths may suit their individual case.

Vertebra

The human spine is composed of 33 individual bones called vertebrae, which stack on top of each other to form the spinal column. These bones protect the spinal cord, bear the body’s weight, and provide a framework for movement. Each region of the spine — cervical (neck), thoracic (mid-back), and lumbar (lower back) — has a specific number of vertebrae, and their health is central to overall spinal function. When vertebrae are healthy, they maintain proper alignment and facilitate smooth motion; however, issues such as fractures, misalignment, or degenerative changes may lead to pain and compromise spinal stability.

Intervertebral Disc

Between each vertebra, from the neck to the lower back, lies an intervertebral disc. These cushion-like structures act as natural shock absorbers for the spine, allowing for flexibility and protecting the vertebrae from impact during daily activities like walking, bending, and lifting. Each disc consists of a tough, fibrous outer ring (annulus fibrosus) and a soft, gel-like inner core (nucleus pulposus). Over time, or due to injury, these discs may degenerate, leading to pain and potentially requiring intervention if conservative treatments are ineffective.

Annulus Fibrosus

The annulus fibrosus is the multi-layered outer ring of an intervertebral disc. Composed of strong collagen fibers arranged in concentric circles, its role is to contain the nucleus pulposus — the disc’s inner gel — and withstand the pressures placed on the spine. It provides structural integrity and helps stabilize the vertebrae. Tears or cracks in the annulus fibrosus, often called annular tears, are a frequent source of chronic back pain, as they may allow inflammatory chemicals to leak out and irritate nearby nerves, prompting consideration of various treatment options.

Nucleus Pulposus

Nestled within the annulus fibrosus, the nucleus pulposus is the soft, gel-like inner core of an intervertebral disc. Rich in water, this central portion functions as a shock absorber, distributing pressure across the vertebrae during movement and weight-bearing. Its pliable nature allows the disc to adapt to various spinal positions. When the surrounding annulus fibrosus is compromised by a tear, the nucleus pulposus may extrude, leading to a herniated disc that can compress nearby nerves and cause radiating pain, numbness, or weakness.

Foramen

The term “foramen” refers to the small openings on either side of the spinal column through which spinal nerves exit to branch out to other parts of the body. These pathways allow nerve signals to travel between the brain and the rest of the body. When intervertebral discs bulge or herniate, or when bone spurs develop due to degeneration, these foramina may narrow — a condition known as foraminal stenosis. This narrowing may compress exiting nerves, leading to symptoms such as pain, numbness, tingling, or weakness in the arms or legs, often prompting investigation into surgical or non-surgical solutions.

Annular Tear

An annular tear is a rupture or fissure in the annulus fibrosus, the tough outer layer of a spinal disc. These tears may result from injury, repetitive stress, or age-related degeneration. They are a common cause of discogenic pain — where pain originates directly from the disc — as inflammatory chemicals may leak out and irritate nearby nerve roots. Unlike many tissues, annular tears often struggle to heal naturally due to the disc’s limited blood supply, making them a primary target for non-surgical annular tear repair in appropriate candidates.

Degenerative Disc Disease (DDD)

Degenerative Disc Disease (DDD) reflects the natural aging process of the spine, where intervertebral discs gradually lose hydration, height, and elasticity over time. Despite the name, it is considered a condition rather than a true disease, and not every person with DDD experiences pain. For many patients, however, it may lead to chronic back or neck pain, stiffness, and reduced mobility as the discs become less effective shock absorbers. DDD may also contribute to disc herniation or spinal stenosis, and patients with persistent symptoms often explore surgical or regenerative treatment options — with candidacy evaluated individually.

Herniated Disc

A herniated disc occurs when the soft nucleus pulposus pushes through a tear in the tough outer annulus fibrosus, extending beyond its normal boundary. This is a common cause of nerve compression, leading to symptoms such as sharp, radiating pain, numbness, tingling, or weakness in the arms or legs (radiculopathy). Often called a “slipped disc” or “ruptured disc,” herniation may result from injury, heavy lifting, or gradual wear and tear. While some herniations respond to conservative care, persistent symptoms may prompt evaluation for non-surgical or surgical options on a case-by-case basis.

Spinal Stenosis

Spinal stenosis is a narrowing of the spinal canal or nerve root passageways (foramina) within the spine, which may put pressure on the spinal cord or nerve roots. This narrowing is most commonly caused by age-related changes such as bulging discs, thickened ligaments, or bone spurs (osteophytes). Symptoms may include pain, numbness, tingling, or weakness in the legs or arms, often worsening with standing or walking and improving with sitting. Patients with significant symptoms often explore options ranging from physical therapy to non-surgical decompression approaches or surgery, depending on individual severity.

Failed Back Surgery Syndrome (FBSS)

Failed Back Surgery Syndrome (FBSS) is a complex condition characterized by persistent or recurring back and/or leg pain following one or more spinal surgeries. Some patients continue to experience chronic pain despite a technically successful surgical intervention to address specific anatomical issues. Contributing factors may include scar tissue formation, residual nerve compression, or problems at adjacent spinal segments. FBSS underscores the value of careful patient selection for surgery and the importance of exploring non-surgical and regenerative treatment alternatives when initial surgeries do not deliver the expected outcome.

Discectomy

Discectomy is a surgical procedure performed to remove the portion of a herniated intervertebral disc that is compressing a spinal nerve or the spinal cord. This intervention aims to relieve nerve impingement and alleviate symptoms like radiating pain, numbness, or weakness in the arms or legs. Typically, only the offending fragment is removed, not the entire disc. While discectomy may reduce immediate nerve compression in appropriate candidates, it does not repair the underlying annular tear or address the disc’s degenerative state. Patients whose symptoms persist after discectomy may benefit from reviewing next-step options for lasting relief.

Spinal Fusion

Spinal fusion is a surgical procedure designed to permanently connect two or more vertebrae together, eliminating motion between those bones to stabilize the spine, correct deformity, or reduce pain caused by instability or severe degeneration. Bone graft material is typically used to encourage the vertebrae to grow together over time. Fusion may be appropriate for specific conditions, but it limits spinal flexibility and may increase stress on adjacent segments, sometimes leading to new problems over time. Patients considering fusion are encouraged to seek a second opinion and review whether non-surgical alternatives may be a fit for their case.

Laminectomy

A laminectomy involves removing part or all of the lamina — the back part of a vertebra that forms the roof of the spinal canal. The primary purpose is to create more space within the spinal canal and relieve pressure on the spinal cord or spinal nerves, particularly in cases of severe spinal stenosis. By decompressing these neural structures, a laminectomy aims to alleviate symptoms such as pain, numbness, tingling, and weakness. It does not directly address underlying disc damage, and candidates are evaluated individually to determine whether surgical or non-surgical decompression is the better fit for their situation.

Fibrin

Fibrin is a natural protein found in blood that plays a central role in clotting and wound healing. When tissue is injured, fibrin forms a mesh-like scaffold that helps stop bleeding and provides a framework for new cells to repair the damaged area. In the context of biologic disc repair and intra-annular fibrin injection, concentrated fibrin is introduced into damaged spinal discs to seal annular tears and provide a supportive matrix. This approach aims to contain the disc’s inner material, prevent further leakage, and support the body’s natural regenerative processes — offering a non-surgical pathway for managing chronic disc pain in carefully evaluated candidates.

Regenerative Medicine

Regenerative medicine is a field of healthcare focused on developing treatments that repair, replace, or regenerate damaged cells, tissues, and organs. Unlike traditional approaches that often manage symptoms or remove damaged tissue surgically, regenerative treatments aim to harness the body’s inherent healing capabilities. In spine care, this includes approaches such as biologic disc repair and fibrin disc treatment, which target the structural integrity of damaged spinal discs. For patients seeking alternatives to invasive surgery, regenerative medicine may offer a path toward long-term relief by supporting the body’s natural repair mechanisms — though outcomes vary by individual case and are never guaranteed.

Intradiscal Injection

An intradiscal injection is a procedure in which substances are delivered directly into the center of an intervertebral disc. Unlike epidural injections, which target the space around spinal nerves, intradiscal injections precisely target the damaged disc itself. This method is central to regenerative disc treatments such as intra-annular fibrin injection, where the goal is to introduce healing agents into annular tears or the nucleus pulposus to support repair. Administered under fluoroscopic (live X-ray) guidance for accuracy, intradiscal injections represent a targeted, minimally invasive approach to treating disc-related pain in carefully evaluated candidates — outcomes vary by individual case.

For more on how these conditions are evaluated and compared, see our overview of disc conditions and patient terminology.