Understanding the language used to describe chronic back and neck pain may help patients navigate their treatment journey more confidently. The terms below define common spine structures, conditions, and symptoms — equipping you to discuss your diagnosis and potential options more clearly with your healthcare provider. Individual presentations vary, and this glossary is intended for educational purposes only.

Spine Anatomy: Key Structures

Annulus Fibrosus

The annulus fibrosus is the tough, fibrous outer ring of an intervertebral disc, composed of multiple layers of collagen fibers. Its primary role is to contain the gel-like center of the disc (nucleus pulposus) and provide structural integrity and stability to the spine. When this structure develops tears or damage, it can become a significant source of chronic back pain. Inflammatory chemicals may leak through the tear, irritating nearby nerves, and the damage may eventually contribute to disc herniation if left unaddressed. For a deeper look at how annular tears drive chronic pain, see our article on annular tears as a root cause of back pain.

Nucleus Pulposus

The nucleus pulposus is the soft, gel-like core inside each intervertebral disc, encased by the annulus fibrosus. Its main function is to act as a shock absorber, distributing pressure evenly across the vertebrae during movement and weight-bearing activities. This highly hydrated material gives the spine its flexibility and cushioning. If the surrounding annulus fibrosus develops a tear, nucleus pulposus material may extrude and press on nearby spinal nerves, potentially causing pain, numbness, tingling, or weakness — symptoms commonly associated with a herniated disc.

Intervertebral Disc

The intervertebral disc is a cushion-like structure positioned between each vertebra of the spinal column, from the neck down to the lower back. These discs act as shock absorbers, protect the vertebrae during daily activities, and enable the spine’s flexibility and range of motion. Each disc comprises an outer annulus fibrosus and an inner nucleus pulposus. Over time, discs may degenerate or sustain damage such as tears or herniations, making them one of the most common anatomical sources of chronic back and neck pain. Learn more about common conditions in our overview of 10 common lumbar spine conditions.

Foramen

In the context of the spine, a foramen is an opening or passageway through which spinal nerves exit the spinal canal to branch out to various parts of the body. The intervertebral foramen is located between adjacent vertebrae where nerve roots exit. When conditions such as disc bulging, herniation, bone spurs, or thickened ligaments reduce the available space within these openings, the exiting spinal nerves may become compressed. This compression can result in radicular pain, numbness, or weakness that radiates into the arms or legs, depending on the affected spinal level.

Facet Joint

Facet joints are small, paired synovial joints located at the back of each vertebra, linking one vertebra to the next. They guide and limit spinal movement — allowing bending, twisting, and extending — while helping prevent excessive motion that could lead to injury. Like other joints in the body, facet joints may develop osteoarthritis over time, a condition often called facet joint syndrome. When inflamed or degenerated, these joints can become a distinct source of localized back or neck pain, separate from disc-related issues.

Vertebra

A vertebra is one of the 33 individual bones that form the vertebral column, commonly known as the spine. These bones are categorized into regions: cervical (neck, 7 vertebrae), thoracic (mid-back, 12 vertebrae), lumbar (lower back, 5 vertebrae), sacral (fused, 5 vertebrae), and coccygeal (tailbone, fused, 4 vertebrae). Each vertebra protects the spinal cord and nerves, supports the body’s weight, and provides attachment points for muscles. Damage to or misalignment of vertebrae may contribute to spinal instability, nerve compression, and chronic pain.

Common Disc Conditions

Annular Tear

An annular tear is a rupture or fissure in the annulus fibrosus — the tough outer ring of an intervertebral disc. These tears are a recognized cause of discogenic back pain because they may allow inflammatory chemicals from the nucleus pulposus to leak out and irritate nearby spinal nerves. Annular tears often contribute to persistent, chronic pain and can compromise the disc’s structural integrity, potentially leading to further degeneration over time. Due to the limited blood supply within the disc, these tears frequently struggle to heal on their own, and many patients are evaluated for targeted treatment. Our article on non-surgical annular tear repair explores available options in more detail.

Expert Take

Annular tears are among the most underdiagnosed sources of chronic discogenic pain. Standard MRI may not always visualize smaller fissures clearly, which is why a thorough clinical evaluation — sometimes including advanced diagnostic testing — is important before treatment decisions are made. Outcomes from targeted repair approaches vary by patient and by the extent of the tear.

Degenerative Disc Disease (DDD)

Degenerative Disc Disease (DDD) is a common condition characterized by the gradual breakdown of one or more intervertebral discs over time. Despite its name, DDD is a condition rather than a traditional disease, and disc degeneration is a natural part of aging for many individuals. It typically involves a loss of disc height, reduced hydration within the nucleus pulposus, and the development of annular tears. Not everyone with DDD experiences significant pain; for those who do, symptoms may include chronic back or neck pain that tends to worsen with sitting, bending, or lifting. Pain may arise from inflammation, nerve irritation, or disc instability. See our dedicated resource on degenerative disc disease and non-surgical options for more context.

Herniated Disc

A herniated disc occurs when the nucleus pulposus pushes through a tear in the annulus fibrosus and extends outside the normal disc space — sometimes called a “ruptured disc” or “slipped disc.” When disc material protrudes, it may directly compress or irritate nearby spinal nerves, potentially leading to symptoms such as sharp pain, numbness, tingling, or weakness that radiates into the arms (cervical herniation) or legs (lumbar herniation). The severity and character of symptoms vary by individual and by the degree of nerve involvement. For a comparison with bulging discs, visit our article on bulging disc vs. herniated disc.

Bulging Disc

A bulging disc describes a condition where the outer wall of the intervertebral disc — the annulus fibrosus — extends beyond its normal boundary, creating a generalized protrusion. Unlike a herniated disc, where the nucleus pulposus breaks through the outer ring, in a bulging disc the nucleus pulposus remains contained within the annulus. While it does not involve a full rupture, a bulging disc may still cause significant symptoms if the disc material presses on nearby spinal nerves or other structures within the spinal canal, resulting in localized back pain or radiating nerve symptoms.

Pain and Symptom Terms

Discogenic Pain

Discogenic pain refers specifically to pain that originates from a damaged intervertebral disc itself, rather than from nerve compression caused by the disc. This type of pain is typically centered in the back and is often described as a deep, aching sensation that may worsen with activities such as sitting, bending, lifting, or twisting. It results from inflammatory processes within the disc or from the irritation of nerve endings that penetrate the outer layers of a torn or degenerated annulus fibrosus. Diagnosing discogenic pain can be challenging and may require specific diagnostic tests — such as an annulogram — to confirm the disc as the primary pain source. Our glossary of diagnostic terms for disc conditions provides additional context.

Sciatica

Sciatica is a type of pain that radiates along the path of the sciatic nerve — the longest nerve in the human body. This nerve originates in the lower back, travels through the buttock, and extends down the back of the leg, often reaching the foot. Sciatica is not a diagnosis in itself but a symptom of an underlying condition, most commonly caused by compression or irritation of the nerve roots that form the sciatic nerve — often due to a herniated disc, spinal stenosis, or bone spurs. It is typically characterized by shooting pain, numbness, tingling, or weakness in the affected leg, though the character and severity of symptoms vary considerably among individuals. Our article on 10 myths about sciatica addresses common misconceptions.

Radiculopathy

Radiculopathy is a medical term for a condition in which a nerve root in the spine is compressed or irritated, producing symptoms that travel along the nerve’s pathway. These symptoms may include pain, numbness, tingling (often described as “pins and needles”), or muscle weakness. Depending on the affected nerve root’s location, radiculopathy is categorized as cervical (neck, causing symptoms in the arms and hands) or lumbar (lower back, causing symptoms in the legs and feet). Common causes include herniated discs, bone spurs, and spinal stenosis. Our cervical radiculopathy FAQ provides more detail on the cervical form.

Spinal Stenosis

Spinal stenosis is a condition characterized by the abnormal narrowing of the spinal canal or the smaller nerve passageways (foramina) within the spinal column. This narrowing may be caused by disc bulging, bone spurs (osteophytes), thickened ligaments, or arthritic changes in the facet joints. When the spinal canal narrows, the spinal cord or exiting nerves may become compressed, leading to symptoms that often include pain, numbness, tingling, or weakness — particularly in the legs — that may worsen with standing or walking and may improve with sitting or leaning forward. Symptoms and their severity vary by individual. See our resource on 10 common symptoms of spinal stenosis for more information.

Post-Surgical Conditions

Failed Back Surgery Syndrome (FBSS)

Failed Back Surgery Syndrome (FBSS) is a term used to describe the persistence or recurrence of chronic back or neck pain — and sometimes new symptoms — following one or more spinal surgeries. FBSS is not a specific diagnosis but rather a general descriptor for ongoing pain after spinal intervention. Potential contributing factors include scar tissue formation, inadequate nerve decompression, recurrent disc herniation, or adjacent segment changes. Many patients living with FBSS seek evaluation for non-surgical or regenerative alternatives to find meaningful relief. Recovery and outcomes vary by patient and by the underlying cause of persistent symptoms. Our article on avoiding failed back surgery with regenerative disc repair discusses what to consider before and after surgical intervention.

Expert Take

FBSS is a complex clinical challenge that is best approached through thorough re-evaluation rather than immediate repeat surgery. Identifying the precise source of ongoing pain — whether it is a residual annular tear, adjacent segment degeneration, or scar tissue — guides more targeted treatment planning. Non-surgical options may be appropriate for some patients; candidacy is evaluated individually.

Related Reading

For broader context on how these conditions are diagnosed and treated without surgery, we recommend exploring our companion glossaries: key terms in diagnosing disc conditions, key terms in non-surgical and minimally invasive spine procedures, and essential spine anatomy terms.