Back pain terminology spans the anatomy, conditions, and treatments most patients encounter during diagnosis. Understanding these terms — from annulus fibrosus to radiculopathy — may help you evaluate your options more clearly. This glossary explains each concept in plain language; individual conditions vary, and your care plan should reflect your specific imaging and clinical picture.

Annulus Fibrosus

The annulus fibrosus is the tough, fibrous outer ring of each intervertebral disc. Composed of multiple layers of collagen fibers, it contains the gel-like nucleus pulposus and provides the structural integrity that allows the spine to bend and twist. When this outer layer develops tears or fissures, pain, progressive disc degeneration, and herniation of inner disc material may follow. Many chronic back pain conditions stem from damage to the annulus fibrosus — and targeted treatments such as intra-annular fibrin injection aim to address these tears directly.

Nucleus Pulposus

The nucleus pulposus is the soft, gel-like center of an intervertebral disc. Rich in water, it acts as the spine’s primary shock absorber, distributing pressure across the vertebrae during movement. When the surrounding annulus fibrosus is torn, the nucleus pulposus may push against the outer wall or leak through, producing disc bulge, herniation, nerve irritation, and significant pain. Maintaining the health of this inner core is central to long-term spinal function.

Intervertebral Disc

An intervertebral disc is a flexible, cushion-like structure situated between each vertebra in the spinal column. These discs absorb shock, protect the vertebrae from impact, and enable the spine’s range of motion. Each disc has two main components: the tough outer annulus fibrosus and the gel-like nucleus pulposus. Over time, or following injury, discs may degenerate, bulge, or herniate — becoming a common source of chronic back and neck pain. Our clinical approach focuses on repairing and supporting these structures rather than removing them when non-surgical options are appropriate.

Foramen

The foramen (plural: foramina) refers to the small, bony openings on each side of a vertebra through which spinal nerves exit the spinal canal to reach the arms, legs, and internal organs. When a disc bulges or herniates, or when bone spurs develop, these openings can narrow — a condition called foraminal stenosis. That narrowing may compress or irritate the exiting nerve, producing pain, numbness, tingling, or weakness in the areas the nerve serves. This is a frequent mechanism behind sciatica and radiculopathy.

Facet Joint

Facet joints are small, paired joints at the back of each vertebra that connect the vertebrae into the spinal column. Two facet joints link each vertebral pair, providing stability while permitting bending, twisting, and extension. Like other joints in the body, facet joints carry cartilage that can wear down over time, potentially leading to arthritis and inflammation. When these joints become irritated or damaged, they may be a significant source of localized back pain — one that can sometimes be distinguished from disc-related pain through careful clinical evaluation.

Vertebra

A vertebra is one of the 33 individual bones that form the human spinal column. Stacked one upon another and separated by intervertebral discs, they create a protective channel for the spinal cord. Vertebrae are grouped by region: cervical (neck), thoracic (mid-back), lumbar (lower back), sacral (pelvis), and coccygeal (tailbone). Each vertebra includes a body, an arch, and bony processes that anchor muscles and ligaments. Damage or misalignment — often combined with disc deterioration — may contribute to chronic pain and spinal instability in some patients.

Annular Tear

An annular tear is a rip or fissure in the annulus fibrosus, the tough outer ring of an intervertebral disc. These tears develop through age-related degeneration, repetitive mechanical stress, or acute injury. Once present, inflammatory chemicals from the disc’s interior can escape through the tear and irritate nearby spinal nerves, producing pain. Because spinal discs have a limited blood supply, annular tears often struggle to heal on their own — leading to persistent symptoms and progressive disc degeneration. Biologic disc repair targets these tears directly, aiming to seal and support the healing environment.

Expert Take

Annular tears are frequently under-identified on standard MRI because imaging sensitivity for fissures varies. When discogenic pain is suspected, our clinical team evaluates the full picture — symptom pattern, imaging, and functional history — to determine whether a patient may be a candidate for fibrin-based annular repair. Outcomes vary by individual; not every tear responds the same way, and candidacy is assessed case by case.

Degenerative Disc Disease (DDD)

Degenerative Disc Disease (DDD) describes the progressive breakdown of one or more intervertebral discs. Despite the name, it reflects a natural aging process rather than a conventional disease — though injury and genetics may accelerate it. DDD involves loss of disc height, reduced hydration in the nucleus pulposus, and the development of annular tears. These changes may lead to chronic back pain, stiffness, instability, and related conditions such as herniated discs or spinal stenosis. Some patients with DDD may benefit from regenerative disc treatment options; candidacy is evaluated individually based on imaging and clinical criteria.

Herniated Disc

A herniated disc occurs when the nucleus pulposus pushes through a tear in the annulus fibrosus and extends beyond the disc’s normal boundary — also called a ruptured disc or slipped disc. When disc material protrudes, it may compress or irritate nearby spinal nerves, causing sharp pain, numbness, tingling, or weakness that radiates into the arms or legs (radiculopathy or sciatica). Many herniated discs respond to non-surgical treatments, including regenerative options that focus on repairing the underlying annular tear rather than removing disc tissue.

Sciatica

Sciatica describes pain that travels along the path of the sciatic nerve — the longest nerve in the body — typically originating in the lower back, passing through the buttock, and extending down the back of one leg. It is a symptom rather than a standalone condition, signaling compression or irritation of the lumbar nerve roots from causes such as a herniated disc, spinal stenosis, or bone spurs. Pain intensity varies widely among patients and may be accompanied by numbness, tingling, or muscle weakness in the affected leg. Recovery trajectories differ significantly between individuals.

Radiculopathy

Radiculopathy is characterized by pain, numbness, tingling, or weakness that radiates along the path of a compressed or irritated spinal nerve root as it exits the spinal canal. Location determines which body region is affected: cervical radiculopathy produces symptoms in the neck, shoulders, arms, and hands, while lumbar radiculopathy — including sciatica — affects the lower back, buttocks, and legs. Common causes include herniated discs, bone spurs, degenerative disc disease, and spinal stenosis. Identifying the specific nerve root involved is a key step toward developing an appropriate treatment plan.

Discogenic Pain

Discogenic pain originates directly from a damaged intervertebral disc rather than from nerve compression. It is typically localized to the back itself and often intensifies with activities that load the disc — sitting, bending, lifting, or coughing. The mechanism involves tears in the annulus fibrosus that expose internal nerve endings to inflammatory disc chemicals. Diagnosing discogenic pain requires careful evaluation, as standard imaging may not fully capture the extent of annular damage. It is a primary target for biologic disc repair in patients who meet candidacy criteria.

Fibrin

Fibrin is a natural, insoluble protein central to the body’s healing processes, particularly blood clotting and tissue repair. Following an injury, fibrin molecules link together to form a mesh-like scaffold that stops bleeding and provides a framework for new tissue growth. In regenerative spine care, fibrin is applied for its adhesive and structural properties. Our clinical team uses fibrin in intra-annular fibrin injections to seal annular tears and create a biologic scaffold intended to support the body’s natural repair mechanisms — with outcomes that vary by patient and disc condition.

Intra-annular Fibrin Injection

An intra-annular fibrin injection is a minimally invasive procedure designed to repair tears in the annulus fibrosus. It involves injecting a specialized fibrin sealant directly into the damaged disc under imaging guidance. The fibrin acts as a biologic scaffold, sealing the tear and creating an environment that may support the body’s natural healing response. The goal is to address the structural source of discogenic pain and work toward restoring disc integrity. This fibrin disc treatment is offered as a non-surgical option for patients who meet candidacy criteria; individual response varies and is not guaranteed.

Regenerative Medicine

Regenerative medicine is a field focused on treatments that stimulate the body’s natural healing processes to repair or restore damaged cells, tissues, or organs. In spine care, regenerative approaches aim to address root causes of conditions such as degenerative disc disease and annular tears — not simply mask symptoms. Treatments like intra-annular fibrin injection work to support the body’s own repair capacity and may help restore disc function in selected candidates. Our clinical team evaluates each patient individually to determine whether regenerative options align with their specific diagnosis and goals.

For a deeper look at the structural terms behind these conditions, see our related resource: A Glossary of Key Terms in Spine Anatomy and Disc Conditions.