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Joint Types

Notes

Joint Types

Sections


Functional and Structural Classification systems

Functional classification

Determined by the degree of movement permitted by the joint. An inverse relationship exists between joint mobility and stability.

  • Synarthrosis joints, which are immovable and stable.
  • Amphiarthrosis joints, which are slightly moveable and slightly stable.
  • Diarthrosis, which are freely moveable and very unstable.

Structural classification

Determined by the joint's connective tissue type and whether there is a cavity within the joint.

  • Fibrous joints are connected by fibrous connective tissue.

Three subtypes of fibrous joints:
Syndemosis (as between the bones of the forearm)
Suture (as between the bones of the skull)
Gomphosis (as between the teeth and the bones of the jaws)

  • Cartilaginous joints are connected via cartilage.

Two subtypes of cartilaginous joints:
Symphysis joints (joined via a fibrocartilage pad, as the two pubic bones)
Synchondrosis joints (joined by hyaline cartilage, as between the ribs and the sternum)

  • Synovial joints comprise an articular cavity enclosed in a deep synovial membrane and a superficial fibrous membrane. The synovial and fibrous membranes comprise the articular capsule.

There are several subtypes of synovial joints:

  • Gliding joints occur where flat surfaces meet to allow sliding and twisting. The wrist bones, or carpals, are joined by gliding joints.
  • Pivot joints form where a round projection fits inside a ring to allow rotation. The first and second cervical vertebrae articulate via a pivot joint.
  • Condylar joints occur where one bone fits into an oval-shaped depression in another bone, such as where the radius cradles the carpals.
  • Saddle joints occur when the saddle-shaped region of one bone articulates with a depression on another bone, such as where the carpal and first metacarpal (the thumb) meet.
  • Ball-and-socket joints form where a ball-like process fits inside a cup-like depression, which allows maximum freedom of motion, such as between the head of the humerus and the glenoid cavity of the scapula.

Clinical Correlation:

  • Synovitis is a painful inflammatory condition of the synovial membrane that commonly occurs in rheumatologic conditions such as rheumatoid arthritis, lupus, gout, or simply by overuse injury.