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.
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Achilles tendinopathy
Gradual wear, thickening, or degeneration of the thick tendon cord at the back of the ankle, most often caused by repeated strain rather than a single injury. It is one of the most common overuse conditions seen in runners and active people of any age.
Also: Achilles overuse injury, Achilles tendinitis, Achilles tendinosis
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Achilles tendon
The thick, strong cord at the back of the ankle that joins the calf muscles to the heel bone. It lets you push off, rise on your toes, and absorb force when walking or running. Reports mention it when describing thickening, inflammation, or a tear, best seen on MRI or ultrasound.
Also: Achilles, calcaneal tendon, heel cord
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ACL reconstruction
Surgery that replaces a torn anterior cruciate ligament with a new graft, most often taken from the patient's own hamstring, patellar, or quadriceps tendon. When this term appears on a knee MRI report, it usually describes the expected post-surgical appearance of a graft rather than a new problem.
Also: ACL graft, ACL repair, ACL replacement surgery
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ACL tear
Damage to the anterior cruciate ligament, a key band of tissue deep inside the knee that keeps the shinbone from sliding forward under the thighbone. It can be a partial stretch or a complete rupture, and it's one of the most common serious sports-related knee injuries.
Also: ACL injury, ACL rupture, ACL tear knee
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Acromioclavicular (AC) joint
The small joint where the collarbone meets the tip of the shoulder blade, felt as a bony bump on top of the shoulder. It's a common site for arthritis, small bone spurs, and separation injuries from falls or sports, and reports often note its condition as a routine part of shoulder imaging.
Also: AC joint, AC-joint, acromio-clavicular joint
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Acromion
This is the bony tip at the very top of your shoulder, the firm bump you can feel where the shoulder blade reaches over toward the collarbone. It forms a small roof above the shoulder joint. Reports name it to point to that top-of-shoulder spot when describing a finding.
Also: acromial process, acromial tip, shoulder blade tip
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Adhesive capsulitis (frozen shoulder)
A gradual tightening and thickening of the capsule surrounding the shoulder joint, which slowly restricts movement and causes deep, aching pain. It typically develops over months without a clear injury and is often described by the informal name most people search for: frozen shoulder.
Also: capsular fibrosis of the shoulder, frozen shoulder, frozen shoulder syndrome
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Ankle syndesmosis
The set of strong ligaments that bind the two lower leg bones together just above the ankle joint, keeping them tightly locked as a stable frame. It is checked closely after a forceful twisting injury, often called a high ankle sprain.
Also: ankle syndesmosis complex, distal tibiofibular joint, high ankle ligament
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Anterior talofibular ligament (ATFL)
A short, strong band of tissue on the outer side of the ankle that connects the shin bone's outer bump to the ankle bone, helping keep the joint stable. It is the ligament most often stretched or torn in a classic ankle sprain from rolling the foot inward.
Also: ATFL, ATFL sprain, ankle inversion ligament
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Avascular necrosis (osteonecrosis)
Death of bone tissue caused by a loss of its blood supply, most often affecting the hip. Without blood flow, the bone weakens and can eventually collapse if untreated. Catching it early, before collapse, gives the most treatment options and the best chance of preserving the joint.
Also: AVN, aseptic necrosis, avascular necrosis of the femoral head
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Avulsion fracture
A small piece of bone pulled away from the main bone by the sudden, forceful tug of an attached tendon or ligament, usually during a sports injury or hard fall. Despite the word 'fracture,' it's really a tendon or ligament injury with a bone fragment attached, and many heal well without surgery.
Also: avulsion injury, bone chip fracture, bony avulsion
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Baker's cyst
A fluid-filled swelling behind the knee, formed when the joint makes extra lubricating fluid that bulges into a pouch at the back. It is usually a sign of something irritating the knee — like arthritis or a cartilage tear — rather than a problem in its own right. Many cause no symptoms at all.
Also: baker cyst, bakers cyst, cyst behind the knee
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Bone bruise (contusion)
Microscopic bleeding and swelling inside the bone marrow after an impact, without an actual crack or break in the bone. It is a softer injury than a fracture and generally heals on its own within several weeks to a few months.
Also: bone contusion, bone marrow edema, bruised bone
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Bone island (enostosis)
A small, dense spot of extra-compact bone found inside an otherwise normal bone, usually spotted by chance on a scan done for another reason. It is a harmless variation in how bone is built, not a tumour, and needs no treatment.
Also: benign bone island, bone islet, compact bone island
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Bone marrow edema
An area inside a bone where extra fluid has built up among the soft tissue that fills its core. It usually signals that the bone is reacting to something — a recent injury, repeated stress, inflammation, or a nearby joint problem — and shows up as a bright patch on MRI sequences sensitive to water.
Also: bone bruise, bone marrow edema syndrome, bone marrow lesion
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Bursa
A small, flat fluid-filled sac that sits between tissues such as tendon and bone, acting as a cushion so they glide without rubbing. Bursae are found around the shoulder, hip, knee, and elbow. Reports mention them when describing fluid or inflammation, called bursitis, best seen on MRI or ultrasound.
Also: bursae, bursal sac, fluid cushion
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Bursitis
Inflammation of a bursa — one of the small fluid-filled cushions that sit between bone and the soft tissues around joints. When a bursa becomes irritated, it fills with extra fluid and shows up on imaging as a fluid pocket. Most cases settle with rest and time; a smaller number are infected and need treatment.
Also: bursa inflammation, bursal distension, bursal inflammation
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Calcaneus
The heel bone — the large, sturdy bone at the back of your foot that you stand and land on. It forms the heel and anchors the Achilles tendon from your calf. On a report it is usually just naming the back of the foot. The word itself is plain anatomy.
Also: calcanei, heel, heel bone
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Calcific tendinopathy
A buildup of calcium deposits within a tendon, most often in the rotator cuff of the shoulder, which can range from a silent incidental finding to a source of sharp, sudden pain. It results from a natural cycle of calcium formation and reabsorption within the tendon tissue.
Also: calcific tendinitis, calcific tendinosis, calcifying tendinopathy
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Carpal bones
These are the eight small bones of your wrist, packed in two rows between the forearm and the hand. They let your wrist bend, tilt, and rotate smoothly. Reports name them to point to the wrist region, or to a specific little wrist bone, when describing a finding.
Also: carpals, carpus bones, small wrist bones
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Carpal tunnel syndrome
A pinched nerve at the wrist that causes numbness, tingling, and weakness in the thumb and first three fingers. It happens when the median nerve is squeezed as it passes through a narrow tunnel of bone and ligament, and it is one of the most common nerve problems in the hand.
Also: CTS, carpal tunnel compression neuropathy, median nerve compression
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Cartilage
The smooth, slippery tissue that caps the ends of bones inside a joint and cushions them so they glide without grinding. It also forms structures like the meniscus, ear, and windpipe rings. Reports mention it when describing thinning, wear, or damage, best seen on MRI.
Also: articular cartilage, chondral surface, gristle
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Chondromalacia
Softening, thinning, or fraying of the smooth cartilage that caps the ends of bones in a joint, most often under the kneecap. It is a very common cause of front-of-knee pain, ranges from mild to advanced, and usually improves with strengthening and activity changes rather than surgery.
Also: cartilage softening, chondromalacia patella, chondromalacia patellae
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Clavicle
The collarbone — the slim, slightly S-shaped bone you can feel running across the top of your chest from the breastbone to the shoulder. It props the shoulder out to the side and links the arm to the body. On a report it is usually just naming where near the shoulder or upper chest a finding sits.
Also: clavicles, collar bone, collarbone
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Collateral ligament
A strong band along the side of a joint that stops it bending sideways. In the knee, the MCL runs on the inner side and the LCL on the outer side. Similar ligaments brace the elbow and ankle. Reports mention them when describing a sprain or tear, best seen on MRI.
Also: LCL, MCL, collateral ligaments
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Condyle
This is the smooth, rounded knob at the end of a bone where it meets another bone to form a joint. You have them at the knee, elbow, jaw, and more. Reports use the word to point to that bulging, rounded end of a particular bone when describing a finding.
Also: bone knob, condyles, knuckle of bone
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Cortical bone
The hard, dense outer layer of bone — the part you would feel if you tapped a bone with your knuckle. It surrounds and protects the softer, spongy inner bone (called trabecular or medullary bone). Most of the strength of a bone comes from this outer shell, and radiologists pay close attention to it for fractures.
Also: bone cortex, compact bone, cortex
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Cruciate ligament
One of two strong bands deep inside the knee that cross each other like an X and stop the shin bone sliding too far forward or back on the thigh bone. The front one is the ACL, the back one the PCL. Reports mention them when describing a sprain or tear, best seen on MRI.
Also: ACL, PCL, anterior cruciate ligament
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Cubital tunnel syndrome (ulnar neuritis)
Irritation or compression of the ulnar nerve as it passes through a narrow tunnel on the inner side of the elbow, the same nerve responsible for the "funny bone" sensation. It's a common cause of tingling, numbness, or weakness in the ring and little fingers.
Also: cubital tunnel neuropathy, funny bone nerve syndrome, ulnar nerve compression
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Deltoid
The large triangular muscle that caps the outer shoulder and gives it its rounded shape. It is the main muscle that lifts the arm out, forward, and back. Reports mention it when describing the muscle bulk, a strain, or, less commonly, a tear, usually best seen on MRI.
Also: deltoid muscle, deltoids, outer shoulder muscle
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Deltoid ligament (ankle)
A strong, fan-shaped band of tissue on the inner side of the ankle that connects the shinbone to the foot bones below. It is the main stabilizer against the ankle rolling inward and is checked whenever a sprain involves the inside of the ankle.
Also: deltoid ligament ankle, deltoid ligament complex, inner ankle ligament
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DEXA bone density scan
A low-radiation X-ray test that measures how dense and strong your bones are, most often at the hip and spine, to screen for osteoporosis or track bone health over time. Results are reported as T-scores and Z-scores that compare your bone density to reference populations.
Also: DXA scan, T-score bone scan, bone densitometry
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Dislocation
A joint where the bones are no longer lined up the way they should be. In the full form the bone surfaces have lost contact completely; in a partial form (subluxation) they are misaligned but still touch. Most need to be put back into place promptly, although the urgency varies by joint and whether nearby structures are injured.
Also: dislocated joint, displaced joint, joint displacement
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Enchondroma
A benign growth of cartilage that forms inside a bone, most often in the small bones of the hand or in the long bones of the arms and legs. It grows slowly, rarely causes symptoms, and is usually discovered by chance on an X-ray or scan done for an unrelated reason.
Also: benign cartilage lesion, bone cartilage growth, cartilage tumor of bone
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Enthesophyte
A small, bony spur that forms where a tendon or ligament attaches to bone, such as at the back of the heel where the Achilles tendon inserts. It is a common sign of wear and tear at that attachment point and is usually not a cause for concern on its own.
Also: bone spur, calcaneal spur, entheseal osteophyte
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Femoroacetabular impingement (FAI)
A mismatch in the shape of the hip ball and socket that causes the two to bump or pinch during certain movements, such as deep squatting or twisting. Common in younger, physically active adults and a frequent cause of groin or hip pain, though many people have the shape without ever noticing it.
Also: FAI, cam impingement, cam-pincer impingement
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Femur
The thigh bone — the long, strong bone running from your hip down to your knee. It is the largest and strongest bone in the body, carrying your full weight with every step. On a report it is usually just naming where in the thigh or hip a finding sits. The word itself is plain anatomy.
Also: femora, thigh bone, thighbone
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Fibula
The calf bone — the thin, long bone running down the outer side of your lower leg, alongside the thicker shinbone. It carries little body weight but steadies the leg and forms the bony bump on the outer ankle. On a report it is usually just naming where in the lower leg a finding sits.
Also: calf bone, lower leg bone, outer leg bone
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Flatfoot (pes planus)
A reduced or absent arch along the inner side of the foot, so more or all of the sole makes contact with the ground while standing. It can be a lifelong, flexible trait that never causes problems, or it can develop later in life and contribute to pain from uneven weight distribution across the foot and ankle.
Also: acquired flatfoot deformity, collapsed arch, fallen arches
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Ganglion cyst
A small, fluid-filled sac that forms near a joint or tendon, most often at the wrist or knee. It's one of the most common soft-tissue lumps in the body, almost always harmless, and frequently found without causing any symptoms at all.
Also: Bible cyst, ganglion, ganglionic cyst
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Glenoid
This is the shallow socket of your shoulder, the cup on the shoulder blade that the round top of the arm bone sits in. It is the dish side of the shoulder's ball-and-socket joint. Reports name it to point to the socket part of the shoulder when describing a finding.
Also: glenoid cavity, glenoid fossa, shoulder cup
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Haglund deformity
An extra bony prominence on the back-upper part of the heel bone, where the Achilles tendon attaches. It can rub against the back of shoes and irritate the nearby tendon and soft tissue, sometimes leading to pain and swelling, but the bump itself is a normal variation in bone shape rather than a disease.
Also: Haglund syndrome, Haglund's deformity, heel bump
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Hamstring strain
A stretch or partial tear in one of the three muscles that run down the back of the thigh, often from sprinting, kicking, or sudden acceleration. Most are mild to moderate injuries to the muscle fibres or surrounding connective tissue rather than a complete rupture, and the large majority heal well with rest and gradual rehabilitation.
Also: hamstring injury, hamstring muscle strain, hamstring pull
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Hill-Sachs lesion
A small dent or compression fracture on the back of the round part of the upper arm bone, created when it forcefully struck the shoulder socket's rim during a dislocation. It's a common companion finding to shoulder instability and helps explain why a shoulder may keep slipping out of place.
Also: Hill-Sachs defect, Hill-Sachs deformity, Hill-Sachs fracture
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Hoffa's fat pad
A cushion of fatty tissue that sits behind and below the kneecap, filling the space in front of the knee joint. It absorbs shock during movement and is mentioned in almost every knee MRI report, whether or not anything is wrong with it.
Also: Hoffa fat pad, Hoffa's disease, Hoffa's syndrome
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Humerus
The upper arm bone — the long bone running from your shoulder down to your elbow. Its rounded top forms the ball of the shoulder joint, and its lower end helps build the elbow. On a report it is usually just naming where in the upper arm a finding sits. The word itself is plain anatomy.
Also: arm bone, humeri, upper arm
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Iliotibial band syndrome
Irritation and inflammation where a long, tough band of tissue running down the outer thigh rubs repeatedly over the outer edge of the knee. It's one of the most common causes of outer-knee pain in runners and cyclists, usually settling well with rest, stretching, and activity changes.
Also: IT band friction syndrome, IT band syndrome, ITBS
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Impingement
A radiology word for pinching — when two structures inside a joint rub or compress each other during normal movement instead of gliding cleanly past each other. Most often described in the shoulder (between the bones at the top) and the hip (between the ball and the rim of the socket), and not always painful.
Also: FAI, femoroacetabular impingement, hip impingement
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Infraspinatus
One of the four rotator cuff muscles, sitting across the back of the shoulder blade. It turns the arm outward and helps hold the ball of the arm bone in its socket. Reports mention it when describing wear, inflammation, or a tear in its tendon, usually best seen on MRI.
Also: infraspinatus muscle, infraspinatus tendon, rotator cuff muscle
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Joint effusion
Extra fluid inside the capsule that wraps around a joint. A small amount of fluid is normal and keeps the joint lubricated; a larger amount usually signals that something has stirred up the lining — an injury, arthritis, infection, gout, or inflammation — and is making more fluid than the joint can absorb.
Also: fluid in the joint, fluid on the knee, intra-articular effusion
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Joint loose body
A small fragment of bone, cartilage, or both that has broken free and floats within a joint, most often the knee, elbow, ankle, or shoulder. It can drift around harmlessly or occasionally lodge between joint surfaces, causing catching, locking, or pain.
Also: cartilage loose body, free floating joint fragment, intra-articular loose body
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Joint space narrowing
A reduced gap between the two bones of a joint on x-ray, which usually means the cushioning cartilage between them has thinned. It is one of the most common signs of ordinary joint wear and ageing, and is very often mild, gradual, and manageable rather than alarming.
Also: cartilage thinning, joint space loss, loss of joint space
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Labral tear
A break in the labrum, the ring of soft fibrous cartilage that deepens the socket of the shoulder or hip and helps hold the ball of the joint in place. Tears can come from a sudden injury, from repeated load over years, or simply from the shape of the joint itself. Common, and often found on scans of pain-free adults.
Also: SLAP tear, hip labral tear, labrum tear
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Labrum
A rim of firm cartilage that deepens the shallow sockets of the shoulder and hip, helping to grip the ball of the joint and keep it stable. Reports mention it when describing a fray, a tear, or age-related wear of this rim, which is best seen on MRI.
Also: cartilage rim, glenoid labrum, hip labrum
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Lateral epicondylitis (tennis elbow)
Wear and micro-tearing of the tendons that attach the forearm's wrist-extending muscles to the bony bump on the outer elbow. Despite the name, it is usually caused by repetitive gripping and wrist motion at work or home rather than by playing tennis.
Also: common extensor tendinopathy, extensor tendinosis of the elbow, lateral elbow tendinopathy
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Ligament tear
A break in one of the tough fibrous bands that hold two bones together at a joint. Tears range from a few stretched fibres (a sprain) to a complete rupture across the whole band. Most happen during a sudden twist, pivot, or impact, and the joint involved shapes how serious it is.
Also: ACL tear, MCL tear, ligament rupture
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Lipoma
A soft, benign growth made of ordinary fat cells, usually sitting just under the skin or between muscle layers. It is one of the most common soft tissue lumps in adults, grows slowly if at all, and almost never turns into cancer.
Also: adipose tumor, benign fat mass, fat tumor
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Malalignment
Bones or joints that do not line up in their normal position or angle on a scan. It is a broad descriptive term covering anything from minor age-related shifts and old healed injuries to fresh injuries needing attention, so its importance depends on the cause and site.
Also: abnormal alignment, alignment abnormality, bones out of alignment
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Malleolus
These are the two bony bumps on the sides of your ankle, the knobs you can feel and see on the inner and outer ankle. They are the lower tips of the shin bones that cradle the ankle joint. Reports name them to point to one of those ankle bumps when describing a finding.
Also: ankle bone, ankle bone bump, ankle bump
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Medial patellofemoral ligament (MPFL) tear
A stretch or tear of the short ligament running along the inner side of the knee that normally holds the kneecap in its groove. It's the ligament most often injured when the kneecap slips or pops out sideways, and its condition helps guide whether the knee needs bracing, rehab, or repair.
Also: MPFL rupture, MPFL sprain, MPFL tear
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Meniscal tear
A split in one of the two C-shaped pads of cartilage that sit between the thigh bone and the shin bone inside the knee. These pads cushion and stabilise the joint. Tears can follow a sudden twist or develop gradually with age, and not every tear seen on a scan causes pain.
Also: bucket-handle tear, lateral meniscus tear, medial meniscus tear
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Meniscectomy
Surgery to trim away or remove damaged meniscus cartilage from the knee, usually performed through small arthroscopic incisions after a tear that won't heal on its own. On a follow-up scan, this term explains why part of the cushioning cartilage looks smaller or missing rather than signaling a new injury.
Also: arthroscopic meniscectomy, knee cartilage removal surgery, meniscal resection
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Meniscus
One of two C-shaped pads of cartilage inside the knee that sit between the thigh bone and the shin bone. They cushion the joint, spread load, and add stability. Reports mention them when describing wear, a tear, or age-related thinning, all best seen on MRI.
Also: knee cartilage, knee meniscus, lateral meniscus
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Meralgia paresthetica
A nerve irritation causing numbness, tingling, or burning across the outer thigh, caused by pressure on the lateral femoral cutaneous nerve as it passes near the front of the hip. Tight clothing, extra abdominal weight, pregnancy, and prolonged standing or sitting are the usual triggers.
Also: Bernhardt-Roth syndrome, lateral femoral cutaneous nerve entrapment, meralgia paraesthetica
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Metacarpal
These are the long bones inside the palm of your hand, the ones whose knuckles you see when you make a fist. There are five, one running from the wrist to the base of each finger. Reports name them simply to mark where in the hand a finding sits.
Also: hand bones, knuckle bones, metacarpal bones
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Metatarsal
These are the long bones in the middle of your foot, the ones you can feel under the top of the foot running from the arch toward the toes. There are five of them, one leading to each toe. Reports name them simply to point to where a finding sits in the foot.
Also: foot bones, long foot bones, metatarsal bones
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Morton's neuroma
A benign thickening of the tissue around a nerve running between two toe bones in the ball of the foot, usually the third and fourth. Repeated compression — often from tight or narrow shoes — irritates the nerve until it swells. It causes burning pain, tingling, or a sense of a pebble underfoot, and it is not a tumor.
Also: Morton neuroma, Morton's toe neuroma, interdigital neuroma
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Muscle atrophy
Shrinkage and weakening of a muscle that has lost its normal nerve signal, blood supply, or regular use over time. It often develops after a chronic tendon tear, a pinched or injured nerve, or prolonged immobilisation, building gradually rather than appearing overnight, and can hint at how long a problem has existed.
Also: denervation atrophy, disuse atrophy, fatty muscle atrophy
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Olecranon
This is the bony point of your elbow, the firm tip you lean on when you rest your elbow on a table. It is the upper end of the larger forearm bone, hooking around the back of the elbow joint. Reports name it to point to the elbow tip when describing a finding.
Also: elbow bone, elbow point, elbow tip
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Osgood-Schlatter disease
A common, usually self-limiting irritation where the patellar tendon attaches to the top of the shinbone, seen in growing children and teens during growth spurts and sports. It causes a tender, sometimes bony-feeling bump just below the kneecap and typically settles once growth is complete.
Also: Osgood Schlatters, Osgood-Schlatter syndrome, growing knee bump
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Osteoarthritis
The most common form of joint wear. The smooth cartilage that lines the ends of the bones inside a joint gradually thins, the joint space narrows, and small bony ridges form along the edges. Extremely common with age — most adults over 60 show some of it on imaging, and many feel nothing from it.
Also: DJD, OA, degenerative arthritis
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Osteochondral lesion
Damage to both the smooth cartilage covering a joint surface and the layer of bone directly underneath it. It's a common finding in the ankle and knee after a twisting injury, ranging from a small area of bruising to a loose fragment of bone and cartilage.
Also: OCD lesion, cartilage-bone injury, chondral and subchondral injury
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Osteoporosis
A gradual thinning and weakening of bone that makes it more porous and easier to fracture. It develops silently over years with no pain of its own, and imaging often picks it up as an incidental observation on a spine or hip CT done for another reason.
Also: bone thinning, brittle bone disease, decreased bone mineral density
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Paralabral cyst
A fluid-filled sac that forms next to a tear in the labrum, the ring of cartilage rimming the hip or shoulder socket, when joint fluid leaks out through the tear and collects nearby. It's usually a marker of an underlying labral tear rather than a problem needing treatment on its own.
Also: hip paralabral cyst, labral cyst, labrocele
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Patella
The kneecap — the small, flat, roughly triangular bone that sits at the front of your knee. You can feel it move when you straighten your leg. It protects the knee joint and gives the big thigh muscle leverage to extend the leg. On a report it is usually just naming the front of the knee.
Also: knee bone, knee cap, kneecap
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Patellar subluxation/dislocation
The kneecap slipping partly or fully out of the shallow groove at the end of the thigh bone where it's meant to glide. A partial slip is a subluxation; a complete slip is a dislocation, usually from a twist, pivot, or direct blow, ranging from a brief wobble to a visibly displaced kneecap.
Also: dislocated kneecap, kneecap dislocation, kneecap popped out of place
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Patellar tendinopathy (jumper's knee)
Overuse-related thickening and mild internal damage in the tendon connecting the kneecap to the shin bone, most often at the lower pole of the kneecap. Common in athletes who jump, sprint, or squat repeatedly, and in anyone who has ramped up knee-loading activity quickly.
Also: PT tendinopathy, jumper's knee, jumpers knee
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Patellofemoral pain syndrome
Ongoing pain at the front of the knee, around or behind the kneecap, that's related to how the kneecap tracks and loads against the thigh bone rather than to a specific tear or fracture. It's one of the most common causes of knee pain, especially in young, active people, and usually improves with targeted exercise.
Also: PFPS, anterior knee pain, kneecap pain syndrome
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Periosteal reaction
New bone laid down by the thin outer wrapping of a bone when that bone is irritated by injury, infection, or another process. It shows up as a fine line or layer along the bone surface on x-ray, and its pattern helps the radiologist judge how concerning it is.
Also: bone surface reaction, periosteal bone reaction, periosteal change
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Peroneal tendons
Two tendons that run behind the outer ankle bone and attach to the foot, helping turn the foot outward and support the outer arch. They are a frequent source of lateral ankle pain and are commonly injured, inflamed, or found to be unstable after a sprain.
Also: fibular tendons, fibularis tendons, lateral ankle tendons
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Phalanx
This is simply the medical word for a finger or toe bone. Each finger has three of these small bones and the thumb and big toe have two, stacked end to end. Reports use the term to point precisely to which finger or toe segment a finding sits in.
Also: digit bone, finger bone, finger bones
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Piriformis syndrome
A pattern of buttock and leg pain caused when the piriformis, a small muscle deep in the hip, presses on or irritates the sciatic nerve running beneath or through it. It can feel a lot like sciatica from a herniated disc, but the pinch happens in the hip rather than the spine.
Also: buttock sciatica, deep gluteal syndrome, hip pocket sciatica
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Plantar fascia
A thick band of fibrous tissue along the sole of the foot, running from the heel to the base of the toes. It supports the arch and acts like a spring while you walk. Reports mention it when describing thickening or inflammation, often called plantar fasciitis, best seen on MRI or ultrasound.
Also: arch tendon, foot arch band, plantar aponeurosis
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Plantar fasciitis
Irritation and micro-tearing of the thick band of tissue that runs along the bottom of the foot from the heel to the toes, most often felt as stabbing heel pain with the first steps in the morning. It is one of the most common causes of heel pain and usually improves with simple, non-surgical care.
Also: fasciitis of the foot, heel pain syndrome, heel spur syndrome
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Radius (forearm bone)
This is one of the two bones in your forearm, the one on the thumb side that runs from the elbow to the wrist. It does most of the work at the wrist and rotates your hand palm-up and palm-down. Reports name it to point to that forearm bone when describing a finding.
Also: forearm bone, radial bone, radius
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Rotator cuff
A group of four small muscles and their tendons that wrap over the top of the shoulder and keep the upper arm bone seated in its shallow socket. Together they let you lift, turn, and steady the arm. Reports mention it when describing wear, inflammation, or tears in one of its tendons.
Also: cuff muscles, cuff tendons, rotator cuff tendons
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Rotator cuff tear
Damage to one of the four small muscle-tendons that wrap around the top of the shoulder and keep the arm bone seated in its socket. The tear can be a thin partial fray on the surface or a full break through the tendon. Many are gradual age-related wear; others follow a sudden injury.
Also: cuff tear, partial-thickness cuff tear, rotator cuff injury
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Scapula
The shoulder blade — the flat, triangular bone on each side of your upper back. It connects the arm to the collarbone and forms the socket of the shoulder joint. Many muscles attach to it, letting your shoulder move freely. On a report it is usually just naming where in the upper back or shoulder a finding sits.
Also: scapulae, shoulder blade, shoulderblade
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Sinus tarsi
A small, cone-shaped canal on the outer side of the foot, between the ankle bone and the heel bone, filled with ligaments, fat, and nerve endings that help sense joint position. Pain centered here, called sinus tarsi syndrome, is a distinct diagnosis often following an ankle sprain.
Also: sinus tarsi canal, sinus tarsi space, sinus tarsi syndrome
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SLAP tear
A tear along the top of the shoulder's labrum, the ring of cartilage that deepens the shoulder socket, specifically where the biceps tendon anchors to it. It's common in athletes who throw or lift overhead, and while it can cause catching or deep shoulder pain, many SLAP tears are found on scans of shoulders with no symptoms at all.
Also: SLAP injury, SLAP labral tear, SLAP lesion
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urgent
Soft tissue sarcoma
A rare cancer that grows in muscle, fat, nerves, blood vessels, or other connective tissue rather than bone or organs. It is one of the differentials radiologists consider for a soft-tissue mass on MRI, and while most soft-tissue lumps turn out to be benign, this possibility is why further testing is often recommended.
Also: STS, connective tissue cancer, malignant soft tissue tumor
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Stress fracture
A small crack or area of bone weakening caused by repeated, low-level stress rather than a single hard impact, common in runners and athletes who ramp up training quickly. It develops gradually from overuse and, caught early, usually heals well with rest, unlike a sudden traumatic break.
Also: bone stress injury, fatigue fracture, hairline fracture
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Subchondral cyst
A small, fluid- or gel-filled pocket that forms in the bone just beneath the cartilage lining a joint. It's one of the earliest changes radiologists look for when assessing wear-and-tear joint disease, and on its own it rarely causes symptoms or needs treatment.
Also: bone cyst, degenerative cyst, geode
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Subluxation
A partial slipping of a joint, where the two bones have lost some of their normal alignment but are still partly in contact. It sits between a normal joint and a full dislocation, and depending on the joint and cause it can range from minor to something needing prompt care.
Also: joint malalignment, joint slipping, partial dislocation
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Subscapularis
The largest rotator cuff muscle, sitting on the front of the shoulder blade between it and the rib cage. It turns the arm inward and helps hold the ball of the arm bone in its socket. Reports mention it when describing wear, inflammation, or a tear in its tendon.
Also: rotator cuff muscle, shoulder muscle, subscapularis muscle
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Supraspinatus
The top muscle of the rotator cuff, running across the top of the shoulder blade and over the ball of the arm bone. It starts the movement of lifting the arm out to the side. Reports mention it often because its tendon is the most common spot for shoulder wear and tears.
Also: rotator cuff muscle, shoulder muscle, supraspinatus muscle
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Synovitis
Swelling and irritation of the thin lining that coats the inside of a joint, often causing pain, warmth, and stiffness. It is a common finding on MRI and can point to arthritis, an old injury, or general overuse rather than a single disease on its own.
Also: inflamed synovium, joint lining inflammation, reactive synovitis
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Talus
The bone that sits at the top of the foot, wedged between the shinbone and the heel bone, forming the core of the ankle joint. It is often named as the site of a fracture, cartilage damage, or reduced blood flow after injury.
Also: ankle bone, astragalus, talar bone
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Tarsal bones
These are the seven bones at the back and middle of your foot, between the ankle and the long foot bones. They include the heel bone and the bones that form the arch. Reports name them to point to the ankle and midfoot region, or to one specific bone, when describing a finding.
Also: ankle bones, hindfoot bones, midfoot bones
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Tarsal tunnel
A narrow passageway on the inner side of the ankle, formed by bone and a band of fibrous tissue, through which the posterior tibial nerve and several tendons pass on their way into the foot. Reports mention it when describing this nerve or the tissues around it.
Also: ankle nerve tunnel, flexor retinaculum tunnel, medial ankle tunnel
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Tendinopathy
A catch-all term for a tendon that's been irritated, overloaded, or worn down over time. The tissue thickens, loses some of its tidy fibre pattern, and may show small areas of damage inside it. Common in shoulders, elbows, knees, and ankles, and often linked to repeated load rather than a single injury.
Also: tendinitis, tendinosis, tendon degeneration
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Tendon
A tough, rope-like band of tissue that connects a muscle to a bone, transmitting the muscle's pull so the joint can move. Tendons are found throughout the body. Reports mention them when describing wear, inflammation, or a tear, all of which are best seen on MRI.
Also: fibrous cord, muscle tendon, sinew
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Tenosynovitis
Inflammation of the thin lubricating sheath that wraps around a tendon, causing pain, swelling, and sometimes difficulty moving the affected area. It commonly follows overuse, injury, or infection and typically responds well to rest, anti-inflammatory treatment, or addressing the underlying cause.
Also: flexor tenosynovitis, peroneal tenosynovitis, stenosing tenosynovitis
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TFCC tear
A tear of the triangular fibrocartilage complex, a small cushion of cartilage and ligaments on the pinky-finger side of the wrist that supports the joint and cushions load between the forearm bones. It commonly causes pain when twisting or gripping, and can come from a sudden fall or from years of repetitive strain.
Also: TFC tear, TFCC injury, TFCC lesion
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Tibia
The shinbone — the large, strong bone at the front of your lower leg, the one you feel just under the skin along your shin. It carries most of your body weight between the knee and the ankle. On a report it is usually just naming where in the lower leg a finding sits. The word itself is plain anatomy.
Also: lower leg bone, shin, shin bone
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Trigger finger
A condition where a finger or thumb tendon has trouble sliding smoothly through its surrounding tunnel, causing the digit to catch, click, or lock as it bends and straightens. It stems from swelling or thickening of the tendon or its pulley, is common and treatable, and doesn't usually reflect anything more serious.
Also: catching finger, digital flexor tenosynovitis, locked finger
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Trochanteric bursitis
Irritation of a small fluid-filled cushion on the outer point of the hip bone, a frequent cause of pain on the side of the hip. It is usually related to overuse, tight surrounding muscles, or friction rather than a serious underlying disease, and it typically responds well to conservative treatment.
Also: greater trochanteric bursitis, greater trochanteric pain syndrome, hip bursitis
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Trochlear dysplasia
An abnormally shallow or flattened groove at the end of the thigh bone, where the kneecap is meant to glide. Without a deep enough groove to guide it, the kneecap can ride off-center or dislocate more easily. It's often found while investigating recurrent kneecap instability rather than by itself.
Also: dysplastic femoral groove, flattened trochlea, patellofemoral dysplasia
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