Medical Term Glossary
Plain-language explanations of the medical terms that appear on CT, MRI and X-ray reports — what each one means, when it matters, and what to ask your doctor.
C
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Coccyx
The tailbone — the small, triangular tip at the very bottom of the spine, just below the sacrum. It is the leftover of what would be a tail, made of a few tiny fused bones. On a report it is usually just naming the lowest point of the spine. The word itself is plain anatomy.
Also: bottom of the spine, coccygeal bone, tail bone
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Compression fracture
A break in one of the spine's bones where the front of the bone has collapsed and lost height, while the back wall typically stays intact. Most happen in the mid or lower back, and many occur from a small load — like a cough or a minor stumble — in bone that has been weakened by osteoporosis.
Also: VCF, collapsed vertebra, crushed vertebra
D
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normal
Degenerative changes
A general term radiologists use for the everyday wear-and-tear that accumulates in the spine over a lifetime — slightly flattened cushions between vertebrae, small bony ridges along the edges, and a bit of joint thickening. Extremely common after the mid-30s and found in plenty of people who have no back pain at all.
Also: age-related changes, degeneration, degenerative disease
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Disc bulge
A gentle, broad outward swell of one of the soft cushions that sit between the bones of the spine. The cushion stays intact — nothing has torn or leaked — but its outer edge pushes a little past its usual footprint. Extremely common with age and often found in people who have no symptoms at all.
Also: annular bulge, broad-based bulge, bulging disc
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Disc herniation
A small tear in the outer wall of one of the spinal cushions has let some of the soft inner core push outward into a focused lump. Unlike a broad, even bulge, this is a localized pocket that can press on a nearby nerve and cause arm or leg pain, tingling, or weakness along the nerve's path.
Also: disc extrusion, disc protrusion, herniated disc
F
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Facet joint
One of the small paired joints at the back of each level of the spine that link one vertebra to the next. They guide and limit movement — bending, twisting, leaning back — and share load with the disc at the front. Like every joint in the body, they can show wear over time.
Also: apophyseal joint, facet, facet arthropathy
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Foraminal narrowing
A tightening of one of the small side-doors of the spine that each nerve uses to leave the spinal canal and travel out to the body. When the door is smaller than usual, the nerve passing through can be pinched, leading to pain, tingling, or weakness along that nerve's path — usually on one side.
Also: exit foramen narrowing, foraminal stenosis, narrowing of the nerve exit
L
O
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Odontoid process
A small, tooth-shaped peg of bone rising from the second neck vertebra. The vertebra above pivots around it, letting you turn your head side to side to say no. Reports often name it when checking the upper neck after injury or to confirm the bone and its alignment look normal.
Also: C2 peg, dens, dens of C2
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Osteophyte
A small extra ridge of bone that grows along the edge of a joint or vertebra as the body responds to years of wear and load. Very common after middle age, usually painless on its own, and most often a marker of ageing rather than a disease — though large ones can crowd nearby nerves.
Also: bone spur, bony outgrowth, bony ridge
P
S
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Sacrum
The base of the tailbone — the large, triangular bone at the bottom of the spine, wedged between the two hip bones. It is made of fused vertebrae and forms the back wall of the pelvis. On a report it is usually just naming where at the bottom of the spine or back of the pelvis a finding sits.
Also: base of the spine, lower spine bone, sacral bone
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Spinal canal stenosis
A narrowing of the bony tunnel that houses the spinal cord and nerve roots. The narrowing crowds the structures running through it, which can cause back pain, leg pain, numbness, or weakness depending on the level. Most cases develop slowly with age; the severity on imaging often correlates loosely with symptoms.
Also: central canal narrowing, central canal stenosis, cervical stenosis
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Spinal cord
The thick bundle of nerves that runs from the base of the brain down through the protective spine, carrying messages between the brain and the rest of the body. It controls movement and sensation in your limbs and trunk. Reports often name it to confirm it looks normal or to locate a finding nearby.
Also: cord, medulla spinalis, neural cord
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Spinous process
The bony bump that sticks out backward from each vertebra, forming the knobbly ridge you can feel down the middle of your back. Muscles and ligaments attach to it to support and move the spine. Reports often name it to locate a finding or to confirm the bone looks normal after a knock.
Also: back bump, bony spine of vertebra, spine bump
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Spondylolisthesis
One of the bones in the spine has shifted forward, backward, or sideways relative to the bone below it, so the stack no longer lines up perfectly. The slip is often small and stable, but a larger shift can narrow the spinal canal or pinch a nerve, causing back pain or symptoms down a leg.
Also: anterolisthesis, degenerative spondylolisthesis, isthmic spondylolisthesis
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Spondylosis
A general term for the slow, age-related wear of the spine — drying cushions, small bony spurs, and stiffer joints. It is the back's version of grey hair: nearly universal after middle age, often visible on scans of people who feel completely fine, and usually a description of normal ageing rather than a disease.
Also: arthritis of the spine, cervical spondylosis, degenerative disc disease
V
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Vertebra
A single backbone — one of the small, stacked bones that build the spine. You have around 33 of them running from the base of the skull to the tailbone. On a report it is simply naming a level of the spine, the way a street number names a spot along a road. The word itself is just anatomy.
Also: back bone, backbone bone, spinal bone
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Vertebral body
The solid, weight-bearing front block of each backbone. It is the chunky, cylinder-shaped part of a vertebra that stacks up to carry your body's load, with cushioning discs sitting between each one. On a report it is just naming which part of the spine bone a finding sits in. The term itself is plain anatomy.
Also: body of vertebra, front of the vertebra, spine bone block
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Vertebral endplate
The flat top and bottom surfaces of each spinal bone, where the bone meets the cushioning disc that sits between vertebrae. These thin caps of bone and cartilage anchor the disc in place and let nutrients pass into it. Reports often name them when describing wear, height, or changes next to a disc.
Also: bony endplate, disc endplate, endplates
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