Joint Categories

Overview of Joints

Joints can be categorized based on the range of motion they permit and the type of material that connects the bones. There is always something in between two bones in a healthy joint, preventing direct contact. Ligaments, made of dense regular connective tissue, stabilize joints and resist tensile forces.

Types of Joints by Movement

Joints may be classified into three categories based on their range of movement:

1. Synarthrosis: These joints allow no movement between bones and are commonly found in the skull, such as sutures.

2. Amphiarthrosis: These joints permit limited movement, exemplified by the pubic symphysis and intervertebral discs.

3. Diarthrosis: These joints allow a larger range of movement and include most synovial joints.

Types of Joints by Material

Joints are also categorized based on their construction:

• Fibrous Joints: These joints rely on fibrous connective tissue as the primary connection between bones. For instance, sutures in the skull are synarthrosis and allow no movement. Another fibrous joint is the Gomphosis, where a tooth connects to its alveolar socket via the periodontal ligament, permitting no movement.

• Cartilaginous Joints: These utilize cartilage for connection.

  • Symphysis: Featuring fibrocartilage, these joints resist compression and allow slight movement, as seen between the pubic bones and vertebrae.

  • Synchondrosis: These involve hyaline cartilage and allow essentially no movement. Examples include the joint between the first pair of ribs and the sternum and the epiphyseal plate in developing bones.

Synovial Joints

The most common type of joint discussed in this context is the synovial joint, which allows a significant range of motion, categorizing it as a diarthrosis. These joints feature complex structures that facilitate movement and will be explored in greater detail in subsequent lectures.