chapter 9

Joint (Articulation)

Any point where two bones meet; allows movement and provides stability

Arthrology

Study of joint structure, function, and dysfunction

Kinesiology

Study of musculoskeletal movement

Synostosis (Bony Joint)

Immovable joint formed when two bones fuse together

Fibrous Joint (Synarthrosis)

Collagen fibers connect bones; little or no movement

Cartilaginous Joint (Amphiarthrosis)

Bones joined by cartilage; slight movement

Synovial Joint (Diarthrosis)

Freely movable joint with fluid-filled cavity

Articular Cartilage

Smooth hyaline cartilage that covers bone ends to reduce friction

Joint Capsule

Encloses and seals synovial joint cavity

Synovial Fluid

Lubricates, nourishes, and cushions joint surfaces

Ligament

Connects bone to bone for stability

Tendon

Connects muscle to bone for movement

Bursa

Fluid sac reducing friction between tendons or bones

Meniscus

Fibrocartilage pad that stabilizes and absorbs shock (knee)

Hinge Joint

Monoaxial joint allowing flexion and extension (elbow, knee)

Pivot Joint

Monoaxial rotation joint (atlas–axis)

Ball-and-Socket Joint

Multiaxial joint allowing all movement directions (shoulder, hip)

Condylar (Ellipsoid) Joint

Biaxial joint allowing flexion, extension, adduction, abduction (wrist)

Saddle Joint

Biaxial joint at thumb allowing rotation and grasping

Flexion

Decrease in angle between bones (bending)

Extension

Increase in angle between bones (straightening)

Abduction

Move limb away from midline

Adduction

Move limb toward midline

Rotation

Movement around an axis

Supination

Palm up position

Pronation

Palm down position

Elevation

Lifting body part upward

Depression

Lowering body part downward

Knee Joint (Tibiofemoral)

Largest hinge joint; includes patellar, ACL, PCL, and collateral ligaments

ACL (Anterior Cruciate Ligament)

Prevents tibia from sliding forward under femur

PCL (Posterior Cruciate Ligament)

Prevents tibia from sliding backward

Hip (Coxal) Joint

Ball and socket joint between femur and acetabulum; stable and multiaxial

Shoulder (Glenohumeral) Joint

Ball and socket joint; most freely movable, supported by rotator cuff

Elbow Joint

Hinge and pivot combination allowing flexion, extension, pronation, supination

Ankle (Talocrural) Joint

Hinge joint between tibia, fibula, and talus; dorsiflexion and plantar flexion

Rheumatism

General pain in joints, tendons, and ligaments

Arthritis

Inflammation of a joint

Osteoarthritis

“Wear-and-tear” arthritis with cartilage breakdown

Rheumatoid Arthritis

Autoimmune inflammation of synovial membrane causing fusion (ankylosis)

Arthroplasty

Surgical joint replacement