Anatomy and Physiology / Unit 4: The Skeletal System
4.6 Joints
Notes
A joint (articulation) is where two bones meet. Classification by function: synarthrosis (immovable), amphiarthrosis (slightly movable), diarthrosis (freely movable). By structure: fibrous, cartilaginous, synovial.
- Fibrous: bones joined by dense connective tissue (skull sutures).
- Cartilaginous: bones joined by cartilage (pubic symphysis, intervertebral discs).
- Synovial joints have a joint cavity, articular cartilage, a joint capsule, synovial fluid and ligaments. Types: ball-and-socket (shoulder, hip; widest motion), hinge (elbow, knee; one plane), pivot (atlas-axis), gliding (between carpals), saddle (thumb), condyloid (wrist).
- Ligaments connect bone to bone. Tendons connect muscle to bone.
- Arthritis: joint inflammation. Osteoarthritis is wear-and-tear of cartilage; rheumatoid arthritis is autoimmune.
Practice
Which joint type allows movement in only one plane, like a door?
Hinge joints (elbow, knee) bend and straighten.
The sutures of the adult skull are an example of a:
Skull sutures are fibrous synarthroses.
A runner has damaged the articular cartilage in the knee through years of wear. This condition is most likely:
Gradual wear-and-tear of cartilage is osteoarthritis. Rheumatoid arthritis is autoimmune.
Ready for more? Take the Unit 4 test.