Understanding spine terminology may feel overwhelming when you are living with chronic back or neck pain. This glossary offers clear, patient-friendly definitions of key terms related to spine anatomy, common pain-generating conditions, and the minimally invasive, non-surgical treatments our clinical team provides — so you can approach your care with greater confidence.

Spine Anatomy Terms

Intervertebral Disc

The intervertebral disc is a cushion-like structure positioned between each vertebra, functioning as the spine’s natural shock absorber while enabling movement and flexibility. Each disc consists of two main components: a tough, fibrous outer ring called the annulus fibrosus and a soft, gel-like center known as the nucleus pulposus. Disc health is central to many spine conditions because these structures are prone to degeneration and injury over time, which may lead to pain and reduced mobility.

Annulus Fibrosus

The annulus fibrosus is the strong, multi-layered outer ring of an intervertebral disc. Composed of roughly 17 concentric layers of collagen fibers, it encases and contains the nucleus pulposus. This robust structure provides tensile strength and resistance to pressure, contributing to spinal stability and flexibility. Tears or fissures in the annulus fibrosus are a recognized source of chronic back pain, as they may allow inflammatory chemicals from the disc’s interior to irritate nearby nerve tissue. Biologic disc repair treatments specifically target these painful annular tears.

Nucleus Pulposus

The nucleus pulposus is the soft, gel-like core at the center of each intervertebral disc. Rich in water, this resilient material distributes pressure across the vertebrae during movement and weight-bearing activities. When the annulus fibrosus develops a tear, the nucleus pulposus may leak or bulge outward, potentially compressing surrounding nerves and triggering inflammation. Maintaining the integrity of the annulus helps keep the nucleus pulposus contained and functional.

Common Spine Conditions

Annular Tear

An annular tear is a rip or fissure in the annulus fibrosus — the tough, fibrous outer ring of an intervertebral disc. These tears may result from injury, repetitive stress, or age-related degeneration. While some tears are asymptomatic, many are a significant source of chronic back pain because they allow inflammatory chemicals from the disc’s nucleus pulposus to leak and irritate spinal nerves. Because the disc has a limited blood supply, annular tears often struggle to heal without targeted intervention. Our clinical team specializes in biologic treatments designed to support the repair of these tears and promote disc healing.

Degenerative Disc Disease (DDD)

Despite its name, degenerative disc disease (DDD) is a condition — not a disease — describing the natural wear and tear that occurs in spinal discs over time. As discs age, they may lose hydration, become thinner, and develop tears, reducing their ability to absorb shock and maintain flexibility. This degeneration may contribute to chronic pain, stiffness, and related issues such as herniated discs or spinal stenosis. Regenerative approaches aim to address underlying disc degeneration rather than simply managing symptoms, though candidacy is evaluated individually.

Herniated Disc

A herniated disc occurs when the nucleus pulposus — the soft, gel-like center of a spinal disc — pushes through a tear in the annulus fibrosus. This displaced disc material may press on nearby spinal nerves, potentially causing pain, numbness, tingling, or weakness in the back, arms, or legs depending on where the herniation occurs. Often called a “ruptured disc” or “slipped disc,” a herniation may produce more pronounced symptoms than a bulging disc because of direct nerve compression and chemical irritation. For a closer comparison of these two conditions, see our overview of bulging disc vs. herniated disc.

Bulging Disc

A bulging disc is a condition in which an intervertebral disc extends beyond its normal perimeter, but the nucleus pulposus remains contained within the annulus fibrosus. Unlike a herniated disc — where the nucleus has broken through the outer layer — a bulging disc is analogous to a tire that is flattening and expanding outward. Although generally considered less severe than a herniation, a bulging disc may still cause pain, numbness, or weakness by placing pressure on nearby nerves or spinal structures.

Sciatica

Sciatica describes pain that radiates along the sciatic nerve’s pathway — from the lower back through the hips and buttocks and down one or both legs. It most commonly occurs when a herniated disc, bone spur, or spinal narrowing compresses part of the nerve, potentially triggering inflammation, pain, numbness, and tingling. Our clinical team focuses on identifying and addressing the underlying disc issues that may contribute to sciatic symptoms. For a detailed look at treatment options, visit our resource on myths about sciatica and non-surgical relief.

Radiculopathy

Radiculopathy describes a set of symptoms caused by compression or irritation of a nerve root as it exits the spinal column. Depending on the affected spinal region, symptoms may include pain, numbness, tingling, or weakness radiating along the nerve’s pathway. Cervical radiculopathy affects the neck and arms; lumbar radiculopathy impacts the lower back and legs and is often referred to as sciatica. Common underlying causes include herniated discs, bone spurs, and spinal stenosis.

Discogenic Pain

Discogenic pain refers to pain originating directly from a damaged or degenerated intervertebral disc rather than from nerve compression alone. This type of pain is typically centered in the back itself, though it may radiate to the buttocks or thighs. Patients often describe it as a deep, aching discomfort that worsens with activities such as sitting, bending, lifting, or prolonged standing — activities that increase disc pressure. Accurately identifying discogenic pain is an important step in evaluating whether biologic disc repair may be appropriate for a given patient.

Spinal Stenosis

Spinal stenosis is the narrowing of the spinal canal — the space housing the spinal cord and nerve roots — or of the openings (foramina) through which nerves exit. This narrowing typically develops through age-related changes such as bulging discs, thickened ligaments, or bone spurs. As these spaces diminish, the spinal cord and nerves may become compressed, potentially causing pain, numbness, tingling, or weakness. Symptoms often worsen with standing or walking and may improve with sitting or leaning forward. Learn more about the common symptoms of spinal stenosis.

Treatment and Procedure Terms

Fibrin

Fibrin is a natural protein present in blood that plays a central role in wound healing and tissue repair. When injury occurs, fibrin molecules polymerize into a mesh-like structure that helps stop bleeding and creates a scaffold for new tissue growth. In regenerative spine care, fibrin’s adhesive properties and its capacity to support cellular regeneration make it a useful material for sealing annular tears and potentially promoting the natural healing of damaged intervertebral discs.

Intra-Annular Fibrin Injection

An intra-annular fibrin injection is a minimally invasive procedure designed for the biologic repair of painful annular tears within spinal discs. During the treatment, a fibrin sealant derived from natural blood proteins is precisely injected into the torn annulus fibrosus under fluoroscopic (live X-ray) guidance. The fibrin acts as a biologic seal for the tear, potentially preventing further leakage of inflammatory chemicals from the disc’s core and providing a scaffold that may encourage the body’s natural healing processes. Candidacy is determined through a comprehensive evaluation; outcomes vary by individual. Explore more about annular tear repair as a non-surgical path.

Regenerative Medicine

Regenerative medicine is a clinical field focused on treatments that stimulate the body’s natural healing mechanisms to repair or regenerate damaged tissues. In spine care, regenerative approaches aim to address root causes of pain — such as disc degeneration and annular tears — by supporting cellular repair and restoring tissue function, rather than relying solely on symptom management or invasive surgery. Our clinical team applies regenerative therapies, including intra-annular fibrin injection, to provide non-surgical options for patients whose candidacy is confirmed through detailed evaluation.

Annulargram (Discogram)

An annulargram, also called a discogram, is a specialized diagnostic procedure used to identify annular tears and determine whether a specific disc is the source of a patient’s back pain. During the procedure, a small amount of contrast dye is injected directly into the intervertebral disc under fluoroscopic guidance. If a tear is present, the dye will leak out, making the tear visible. Crucially, if the injection reproduces the patient’s familiar pain pattern, it helps confirm that disc as the pain generator. This information is central to determining candidacy for targeted biologic disc repair treatments such as intra-annular fibrin injection. For more on the diagnostic process, see our guide to key diagnostic and procedural terms for spine treatment.

Expert Take

In our clinical team’s experience, patients who arrive with a clear understanding of their diagnosis — and of the terminology their providers use — tend to engage more effectively in shared decision-making. Knowing the difference between discogenic pain and radiculopathy, or between a bulging disc and a herniated disc, can meaningfully shape the evaluation process and the questions you bring to your consultation. Candidacy for any procedure, including intra-annular fibrin injection, is always assessed individually based on imaging, symptom history, and diagnostic findings.

For further reading, we recommend our related resource: Annular Tears: Causes, Symptoms, and Regenerative Repair Options.

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Disclaimer: This content is provided for general informational and educational purposes only and does not constitute medical advice; it is not intended to diagnose, treat, cure, or prevent any condition and should not be used as a substitute for professional medical evaluation, diagnosis, or treatment, and you should always consult a qualified healthcare provider regarding any questions about your health or a medical condition, as reading this content does not create a doctor-patient relationship. Some articles on this site may have been created with the use of generative AI tools and include hypothetical patient stories, examples, and scenarios created to illustrate conditions, treatment approaches, and the kinds of situations Valor Spine works with, and may contain errors or omissions; these scenarios are composite or fictionalized and do not depict any actual patient, and any names, ages, occupations, locations, and circumstances are illustrative only, with any resemblance to a real individual being coincidental, and no protected patient health information is used in these examples. Individual conditions and results vary, no specific outcome is guaranteed, and a clinical evaluation is the only way to determine whether a particular treatment is appropriate for you.