Overview
This lecture covers the classification of joints (articulations) in the human skeleton, focusing on their functional and structural types, with examples.
Joint Basics
- An articulation (joint) is where two or more bones meet.
- Joints can be classified by function (amount of movement), structure (material holding bones together), and specific type.
Functional Types of Joints
- Synarthrosis: Joints with no movement (e.g., skull sutures).
- Amphiarthrosis: Joints with slight movement (e.g., pubic symphysis).
- Diarthrosis: Freely movable joints (e.g., shoulder, elbow).
Structural Types of Joints
- Fibrous joints: Bones held together by fibers; typically immovable (e.g., sutures in the skull).
- Cartilaginous joints: Bones connected by cartilage; may allow slight movement (e.g., cartilage between ribs and sternum).
- Bony fusion: Bones fused with no visible line; completely immovable (e.g., frontal bone).
Examples of Joint Types
- Suture: Fibrous joint between skull bones (parietal bones).
- Gomphosis: Fibrous joint holding teeth in sockets, stabilized by the periodontal ligament.
- Synchondrosis: Cartilaginous bridge between bones; immovable (e.g., first rib and sternum).
- Synostosis: Bony fusion, as in fused frontal bones or pelvis.
- Syndesmosis: Slightly movable fibrous joint (e.g., ligament between tibia and fibula).
- Symphysis: Slightly movable cartilaginous joint with a pad of cartilage (e.g., pubic symphysis, intervertebral discs).
- Synovial joint: Freely movable joint with synovial fluid (e.g., shoulder, wrist).
Synovial Joints
- All diarthroses are structurally synovial and contain synovial fluid for lubrication and shock absorption.
- Synovial joints can be monoaxial (one plane, e.g., elbow), biaxial, or triaxial.
Key Terms & Definitions
- Articulation (joint) â Point where two or more bones meet.
- Synarthrosis â Immovable joint.
- Amphiarthrosis â Slightly movable joint.
- Diarthrosis â Freely movable joint.
- Fibrous joint â Joint connected by fibrous tissue.
- Cartilaginous joint â Joint connected by cartilage.
- Bony fusion (synostosis) â Fused bones with no movement.
- Suture â Fibrous joint in skull.
- Gomphosis â Fibrous tooth-to-socket joint.
- Synchondrosis â Immovable cartilaginous joint.
- Syndesmosis â Slightly movable fibrous joint by ligament.
- Symphysis â Slightly movable joint with cartilage pad.
- Synovial joint â Freely movable joint with fluid-filled cavity.
Action Items / Next Steps
- Review structure and function of synovial joints in detail.
- Learn axes of movement (monoaxial, biaxial, triaxial) for synovial joints.