Intro to Joints Flashcards
Joints
aka articulations
2 fxns: support and movement
Bones articulate at joints
Skeletal muscles CROSS over joints in order to achieve movement
More mobile=less stable
Can be classified by fxn or structure
Functional Classification
Relate to the amount of movement allowed at the joint.
Synarthrosis, Amphiarthrosis, Diarthrosis
Synarthrosis
immovable
ex: skull sutures, epiphyseal plates
Amphiarthrosis
slightly movable
ex: pubic symphysis
Diarthrosis
freely movable
ex: joints in limbs
Structural Classification
Based on CT that binds the bones together (fibers, cartilages) and presence/absence of a joint cavity
Fibrous: connected by fibrous (CT) tissue
–ex: skull and sutures
Cartilaginous: connected by cartilage tissue
–ex: pubic symphysis
Synovial: connected at a joint cavity w/ in a capsule
–ex: elbow, knee, shoulder… (most joints)
Cartilaginous Joints
Synchondroses: bones joined by hyaline cartilage
–ex: costochondral joints, epiphyseal plates
Symphyses: fibrocartilage between articulating joints
–ex: intervertebral joints, pubic symphysis
Synovial Joints
Most joints are synovial joints
Synovial joints are the most movable joint type
All synovial joints are diarthroses
All synovial joints contain a fluid-filled joint cavity
Typical synovial joint
Articular (fibrous) capsule: 2 parts: outer fibrous layer continuous w/ periosteum, inner synovial membrane that secretes synovial fluid
Joint (articular) cavity: space filled w/ synovial fluid
Synovial fluid: liquid in cavity and cartilages. Provides lubrication
Articular (hyaline) cartilage: absorbs forces on the joint, protects bone
Ligaments: connect bone to bone, strengthen joint. Can be internal or external to articular capsule
Joints do have a blood supply and they’re innervated too!
Additional Features
Bursae
–saclike structure w/ synovial fluid
Tendon Sheaths
–wraps around tendons
Both reduce friction where bones, ligaments, and tendons may rub together
