Individual joints are typically named by combining the names of the two bones that meet at that joint. The shoulder joint, for example, is formally called the glenohumeral joint because it connects the glenoid cavity of the scapula to the humerus. This bone-combination rule is the default naming convention across anatomy, though a handful of familiar joints like the elbow, hip, and knee break the pattern and go by common names instead.
Beyond this primary rule, joints also pick up names from their structure, their movement type, and sometimes from the historical figures who first described them. Understanding these overlapping systems makes it much easier to decode unfamiliar joint names when you encounter them.
Naming Joints After Their Bones
The most straightforward system takes parts of each bone’s name and fuses them together. The ankle, for instance, is formally the talocrural joint because it connects the talus bone in the foot to the distal ends of the tibia and fibula in the leg (“crural” means “leg”). The proximal radioulnar joint sits where the radius and ulna meet near the elbow. The femoropatellar joint is where the patella (kneecap) meets the distal femur.
This pattern works the same way in the skull. Each cranial suture, a type of fibrous joint, is named after the bones it connects. The coronal suture joins the frontal and parietal bones. The squamous suture connects the temporal and parietal bones above the ears. Smaller sutures follow the same logic: the frontolacrimal suture, for example, simply connects the frontal bone to the lacrimal bone.
In the spine, joints between vertebrae are named by their spinal level. The disc between the fourth and fifth lumbar vertebrae is called the L4-L5 disc, and the small facet joints (also called zygapophysial joints) at the same level are referred to as the L4-L5 facet joints. The same numbering system applies in the cervical and thoracic spine.
Why Some Joints Have Common Names
The elbow, hip, and knee are notable exceptions to the bone-combination rule. These joints are so functionally important and so commonly referenced that their everyday names stuck. But each of these “simple” names actually covers multiple articulations. The knee, for instance, consists of three separate joints: the femoropatellar joint (between the kneecap and thighbone), the medial tibiofemoral joint, and the lateral tibiofemoral joint. The elbow similarly includes the humeroulnar joint, the humeroradial joint, and the proximal radioulnar joint, all bundled under one common name.
You’ll also hear informal names like “knuckle” for the metacarpophalangeal joints in your hand, or “big toe joint” for the first metatarsophalangeal joint. In clinical settings, the formal bone-derived name is preferred because it pinpoints exactly which structures are involved.
Naming by Structure
Joints are also categorized and named by what physically holds them together. There are three structural categories, and each contains subtypes with their own names:
- Fibrous joints are connected by dense connective tissue. Subtypes include sutures (the joints between skull plates), syndesmoses (like the joint binding the tibia to the fibula in your lower leg), and gomphoses (the joints anchoring your teeth into the jawbone).
- Cartilaginous joints are connected by cartilage. Synchondroses use a firm, glassy type of cartilage, while symphyses (like the pubic symphysis connecting the left and right pelvic bones) use a tougher, more flexible type.
- Synovial joints have a fluid-filled capsule and allow the most movement. These are the joints most people think of: shoulders, knees, fingers, hips.
Naming by Movement Type
A parallel system classifies joints by how much they can move, which gives them a functional name on top of their structural one:
- Synarthrosis: immovable or nearly immovable. Skull sutures and tooth sockets fall here.
- Amphiarthrosis: slightly movable. The joints between vertebrae and the pubic symphysis are examples.
- Diarthrosis: freely movable. All synovial joints belong to this group.
Freely movable joints get further classified by the shape of their surfaces and the type of motion they allow. A hinge joint (like the elbow) opens and closes in one direction. A ball-and-socket joint (like the shoulder or hip) rotates in multiple planes. A pivot joint in the neck lets you turn your head side to side. A saddle joint at the base of the thumb lets it oppose your fingers. Condyloid joints at the wrist allow movement in two planes, and planar joints between the small carpal bones of the wrist allow gliding.
Joints can also be described by the number of axes they move along. A uniaxial joint like the elbow moves in one plane. A biaxial joint like the wrist moves in two. A multiaxial joint like the hip moves in three.
Eponyms: Joints Named After People
Some joints carry the name of the physician or anatomist who first described them. The Lisfranc joint (the junction between the midfoot and forefoot) and the Chopart joint (the midtarsal joint in the foot) are classic examples. These eponymous names are still widely used in clinical practice, even though the trend in anatomy has been toward descriptive terms.
A National Institutes of Health statement on medical eponyms recommended keeping existing names unless there’s a compelling reason for change, and many eponyms remain firmly embedded in everyday medical language. In practice, you’ll often see both names used interchangeably, with the descriptive term appearing in textbooks and the eponym showing up in conversation between clinicians.
Greek and Latin Roots in Joint Names
Many joint-related terms are built from a small set of Greek and Latin word parts. The prefix “arthro-” means joint, which is why joint inflammation is called arthritis (arthro- plus -itis, the suffix for inflammation). The prefix “syn-” means together, appearing in terms like synarthrosis (joined together with no movement), synchondrosis (joined by cartilage), and symphysis (grown together).
Once you recognize a few of these building blocks, unfamiliar terms become much easier to parse. “Tibiofemoral” is just tibia plus femur. “Humeroulnar” is humerus plus ulna. “Talocrural” is talus plus crus (leg). The naming system is repetitive by design, so learning the pattern lets you decode most joint names without memorizing each one individually.