Glossary of Bone Terminology

Bone Feature Terminology

Every feature name on a bone follows a pattern. Learn the pattern and you can read a bone you have never seen before. These definitions come from the Bone Feature Terminology Guide.

Bone feature terminology

• Condyle – A rounded, smooth, knuckle-like projection on a bone that forms part of a joint. Its smooth surface allows one bone to articulate (move) against another. Memory tip: Condyle = knuckle = joint surface. If you see “condyle,” the bone is making contact with another bone right there. It’s always smooth and rounded, never sharp.
• Crest & Line (Linea) – A crest is a prominent, ridge-like projection running along a bone’s surface — like the crest of a wave. A line (or linea ) is a lower, narrower version of the same thing. Both are elongated ridges rather than a single point or bump. Memory tip: Crest/Line = ridge = muscle attaches along a strip. Crests are palpable landmarks — you can feel the iliac crestSuperior ridge of the ilium; easily felt along the waistline. by placing your hands on your hips. It’s the top rim of the pelvis.
• Epicondyle – A projection located just above (epi-) a condyle. Epicondyles are not joint surfaces themselves — unlike condyles, they are not covered in cartilageA flexible connective tissue found in joints, the ear, nose, and rib cage. Cartilage can be of three. Instead, they are rough muscle attachment points located near a joint. Memory tip: Epi = above → epicondyle = bump above the condyle. It’s NOT a joint surface. The condyle articulates; the epicondyle is where muscles attach just above the joint.
• Foramen (plural: Foramina) – A hole or passageway through a bone. Foramina (the plural) serve as tunnels allowing nerves, blood vessels, or the spinal cordThe central nervous system structure that relays signals between the brain and body. to pass through bone. Memory tip: Foramen = hole = something passes through. Ask: what passes through this hole? The name often tells you — “supraorbital” = above the orbit, supplying the forehead.
• Fossa – A shallow pit, depression, or concave hollow on a bone surface. A fossa can cradle another structure, house a muscle attachment, or simply mark where soft tissue sat. Memory tip: Fossa = hollow = something fits in here or attaches here. When you see fossa, trace what fills it: Is it another bone? A muscle? A nerve?
• Malleolus (plural: Malleoli) – A rounded bony projection specifically found at the ankle, forming the medialToward the midline of the body and lateralAway from the midline of the body. “bumps” of the ankle joint. The malleoli act like brackets on either side of the talusAnkle bone that articulates with tibia and fibula; sits atop calcaneus. bone, forming the mortise of the ankle joint. Memory tip: Malleolus = the ankle bump. There are only two in the body. Medial = inner bump (tibiaShinbone; large, weight-bearing medial bone of the lower leg.). Lateral = outer bump (fibulaSlender lateral leg bone; stabilizes ankle but bears little weight.). The medial malleolusLarge inner ankle bump at distal tibia. is higher and rounder; the lateral malleolusLarge outer ankle bump at distal fibula. sits lower and more pointed.
• Meatus – A canal, tube, or passageway through or within bone. Unlike a foramen (a simple hole), a meatus is an elongated tunnel — it has some depth or length to it, like a corridor rather than a doorway. Memory tip: Meatus = a tunnel (not just a hole). Foramen = a doorway; meatus = a corridor. External auditory meatus = the ear canal bored into bone. “External” = facing outward.
• Notch – A curved indentation or cut-in on the edge or surface of a bone. Unlike a fossa (which is a depression on a flat surface), a notch is found at the border or edge of a bone — as if a piece has been scooped out. Memory tip: Notch = a scoop taken out of the edge. A fossa is like a bowl pressed into the middle of a surface; a notch is like a bite taken out of the rim.
• Process – Any projection or outgrowth from a bone. “Process” is the broadest bone marking term — it simply means something that sticks out. Processes vary enormously in shape and size; a second name (zygomaticCheekbones; form lateral walls of orbits and connect to temporal bones via zygomatic process., styloid, etc.) tells you the specific shape or location. Memory tip: Process = projection = something sticks out here. The first word (zygomatic, styloid, etc.) is the key — it describes the shape, location, or what attaches there. Focus your memorization on the modifier, not the word “process” itself.
• Ramus (plural: Rami) – A branch or arm-like extension of a bone that extends away from the main body of the bone. A ramus is part of the same bone — it’s like a branch on a tree, not a separate bone. Memory tip: Ramus = branch = an arm of the bone extending away from the main body. Think of the jaw’s “L” shape: the horizontal part is the body; the vertical part is the ramus.
• Spine & Spinous Process – A sharp, slender, thorn-like projection. An anatomical spineProminent ridge on the posterior scapula dividing it into supraspinous and infraspinous fossae. is sharper and more pointed than a process or crest. On vertebrae, the spinous processPosterior projection from vertebral arch; palpable bumps down the back. is the projection you can feel running down the middle of your back. Memory tip: Spine = thorn = sharper and more pointed than a process. The ASIS (anterior superior iliac spineProminent front projection of the iliac crest; common landmark for muscle attachment.) is the bony point you feel at the front of your hip — it’s literally a thorn-shaped point on the iliac crest.
• Sulcus (plural: Sulci) – A groove or furrow running along a bone surface. A sulcus is elongated and narrow — like a channel or slot — compared to a fossa (which is wider and shallower). Sulci guide tendons, nerves, or blood vessels along a path on the bone surface. Memory tip: Sulcus = groove = a tendon or vessel runs along here. “Intertubercular” tells you exactly where: inter = between; tubercular = the tubercles. It’s the groove between the greater and lesser tubercles.
• Trochanter – A large, blunt projection found only on the femurThigh bone; longest and strongest bone in the body; has a large round head and prominent trochanters, serving as a major attachment point for powerful hip muscles. Trochanters are larger and blunter than tubercles and are unique to the femur — no other bone has a trochanter. Memory tip: Trochanter = femur only = big hip muscle attachment. The greater trochanterLarge lateral projection near the head; palpable on the side of the hip. is the lateral hip bump; the lesser is tucked posteromedially. Hip fractures in the elderly often involve the trochanters.
• Trochlea – A pulley-shaped structure — a smooth, grooved, spool-like surface on a bone that guides another bone’s movementA fundamental property of life involving motion of the body or its parts., like a wheel on a track. It ensures a bone moves in one clean plane. Memory tip: Trochlea = pulley = spool-shaped = elbow hinge. The medial part of the distal humerusLong bone of the upper arm; articulates with scapula at shoulder and radius/ulna at elbow.. It pairs with the trochlear notchDeep, U-shaped depression between coronoid and olecranon processes that grips the trochlea. of the ulnaMedial forearm bone (pinky side); forms the elbow hinge with humerus.. Think of the trochleaSpool-shaped medial condyle that articulates with ulna at the elbow. as the wheel; the trochlear notch as the track.
• Tubercle & Tuberosity – A raised, often rough bump or knob on a bone surface where a tendon or ligament attaches. Tubercle is the smaller version; tuberosity is a larger, rougher version of the same thing. Both serve the same purpose. Memory tip: Tubercle/Tuberosity = rough bump = tendon or ligament attaches here. If a bone marking has the word “greater” or “lesser,” it’s comparing two bumps on the same bone (humerus has both greater and lesser tubercles).

Specially named features

• Acetabulum – Latin acetabulumDeep, cup-like socket on lateral side where femur head articulates; shared by all three hip bone reg = “vinegar cup” — a small Roman cup used at the table for vinegar. The deepAway from the surface of the body. cup-shaped socket in the pelvis that receives the femoral headRounded proximal end that fits into the acetabulum of the hip bone.. Much deeper than the glenoid fossaShallow, socket-like depression that articulates with the head of the humerus., making the hip more stable but less mobile than the shoulder.
• Acromion – Greek akron = “tip” or “peak” + omos = “shoulder.” The “tip of the shoulder.” The flat, lateral projection of the scapular spine that overhangs the shoulder joint and meets the clavicleS-shaped collarbone; connects sternum to scapula; helps brace the shoulder. at the acromioclavicular (AC) joint.
• Capitulum – Latin capitulumRounded lateral condyle that articulates with head of radius. = “little head” (diminutive of caput = head). The small, rounded lateral projection of the distal humerus. Articulates with the head of the radiusLateral forearm bone (thumb side); rotates around ulna during pronation/supination., forming the lateral side of the elbow joint.
• Coracoid process – Greek korax = “crow” or “raven” (same root as corvid ). The coracoid processHook-like projection anterior to the acromion; attachment for muscles of the arm and chest. is shaped like a crow’s beak — a hooked projection pointing anteriorly. Biceps (short head) and pectoralis minorDepressor / Protractor Under pectoralis major; pulls shoulder blade forward and downward. attach here.
• Cribriform plate – From Latin cribrum = “sieve.” The plate is literally riddled with small foramina like a kitchen sieve. Olfactory nerve fibers (CN I) pass through these holes from the nasal cavityThe internal space behind the nose that filters, warms, and humidifies incoming air. to the olfactory bulbs.
• Crista galli – Latin for “cock’s comb” ( crista = crest, galli = of the rooster). The upward-pointing vertical ridge of the ethmoidLight, spongy bone between the eyes; forms nasal septum and medial orbit walls. bone resembles a rooster’s comb. The falx cerebriA fold of dura mater that separates the two cerebral hemispheres. (brain covering) attaches here.
• Linea aspera – Latin linea = “line” + aspera = “rough.” The “rough line.” A prominent, roughened vertical ridge on the posterior femur shaft. Multiple thigh muscles (adductors, biceps femorisExtensor / Flexor Runs from back of thigh to outside of knee; extends hip and bends knee., vastus lateralisExtensor Outer thigh muscle; extends knee and supports patella movement./medialis) attach along its entire length.
• Manubrium – Latin manubriumSuperior, triangular portion of the sternum; articulates with clavicles and first ribs. = “handle” (of a sword or tool). The broad, upper portion of the sternumFlat bone forming the center of the chest; anchor for ribs and clavicles. Appears as a vertical dagg is shaped like the handle of a sword — with the body of the sternum forming the blade. Clavicles and first ribsCurved bones forming the rib cage; articulate with thoracic vertebrae and most with the sternum. attach here.
• Mastoid process – Greek mastos = “breast” + -oid = “shaped like.” The rounded bump behind the ear was thought to resemble a breast shape. Contains mastoid air cellsThe basic structural and functional units of life. (connected to the middle ear — this is why ear infections can spread to cause mastoiditis).
• Nasal conchaeCurved bony structures in the nasal cavity that increase surface area and help warm, humidify, and f / Turbinates – Latin concha = “shell” (like a seashell). Also called turbinates, from Latin turbo = “spinning top” — because they create turbulent airflow. Scroll-shaped projections that warm, humidify, and filter air.
• Olecranon – Greek olene = “elbow” + kranon = “head.” Literally “head of the elbow.” The prominent posterior projection of the ulna that you feel as your elbow point. Fits into the olecranon fossaLarge posterior depression for olecranon process when elbow extends. of the humerus during extension.
• Sella turcica – Latin for “Turkish saddle” ( sella = saddle, turcica = Turkish). The depression in the sphenoidButterfly-shaped bone in the middle cranial floor; unites cranial and facial bones. that holds the pituitary glandEndocrine gland at the brain’s base controlling many hormones. is shaped exactly like a saddle. Clinically critical — pituitary tumors enlarge this space.
• Styloid process – Greek stylos = “pillar” or “column” (also the stylus writing tool). A slender, spike-like projection resembling a writing stylus or pillar. Appears on three different bones — temporal, radius, and ulna — all with the same slender, pointed shape.
• Xiphoid process – Greek xiphos = “sword” + -oid = “shaped like.” The xiphoid is sword-shaped — a small pointed tip at the inferiorBelow or toward the lower part of the body. sternum. CPR landmark: hands go just above the xiphoid to avoid breaking it and lacerating the liverA large organ that produces bile, detoxifies blood, and stores nutrients..